BitTorrent (abbreviated to BT) is a communication protocol for peer-to-peer file sharing (P2P) which is used to distribute data and electronic files over the Internet.

BitTorrent is one of the most common protocols for transferring large files, such as digital video files containing TV shows or video clips or digital audio files containing songs. Peer-to-peer networks have been estimated to collectively account for approximately 43% to 70% of all Internet traffic (depending on location) as of February 2009.^[1] In February 2013, BitTorrent was responsible for 3.35% of all worldwide bandwidth, more than half of the 6% of total bandwidth dedicated to file sharing.^[2]

To send or receive files, a person uses a BitTorrent client on their Internet-connected computer. A BitTorrent client is a computer program that implements the BitTorrent protocol. Popular clients include μTorrent, Xunlei,^[3]Transmission, qBittorrent, Vuze, Deluge, BitComet and Tixati. BitTorrent trackers provide a list of files available for transfer, and allow the client to find peer users known as seeds who may transfer the files.

Programmer Bram Cohen, a former University at Buffalo student,^[4] designed the protocol in April 2001 and released the first available version on 2 July 2001,^[5] and the most recent version in 2013.^[6]BitTorrent clients are available for a variety of computing platforms and operating systems including an official client released by BitTorrent, Inc.

As of 2013, BitTorrent has 15–27 million concurrent users at any time.^[7]As of January 2012, BitTorrent is utilized by 150 million active users. Based on this figure, the total number of monthly BitTorrent users may be estimated to more than a quarter of a billion.^[8]

• 2Operation
• 3Adoption
• 5Technologies built on BitTorrent
  • 5.2Web seeding
• 11Malware
  • 11.1BitErrant attack

Description[edit]

The BitTorrent protocol can be used to reduce the server and network impact of distributing large files. Rather than downloading a file from a single source server, the BitTorrent protocol allows users to join a 'swarm' of hosts to upload to/download from each other simultaneously. The protocol is an alternative to the older single source, multiple mirror sources technique for distributing data, and can work effectively over networks with lower bandwidth. Using the BitTorrent protocol, several basic computers, such as home computers, can replace large servers while efficiently distributing files to many recipients. This lower bandwidth usage also helps prevent large spikes in internet traffic in a given area, keeping internet speeds higher for all users in general, regardless of whether or not they use the BitTorrent protocol. A user who wants to upload a file first creates a small torrent descriptor file that they distribute by conventional means (web, email, etc.). They then make the file itself available through a BitTorrent node acting as a seed. Those with the torrent descriptor file can give it to their own BitTorrent nodes, which—acting as peers or leechers—download it by connecting to the seed and/or other peers (see diagram on the right).

The file being distributed is divided into segments called pieces. As each peer receives a new piece of the file, it becomes a source (of that piece) for other peers, relieving the original seed from having to send that piece to every computer or user wishing a copy. With BitTorrent, the task of distributing the file is shared by those who want it; it is entirely possible for the seed to send only a single copy of the file itself and eventually distribute to an unlimited number of peers. Each piece is protected by a cryptographic hash contained in the torrent descriptor.^[6] This ensures that any modification of the piece can be reliably detected, and thus prevents both accidental and malicious modifications of any of the pieces received at other nodes. If a node starts with an authentic copy of the torrent descriptor, it can verify the authenticity of the entire file it receives.

Pieces are typically downloaded non-sequentially and are rearranged into the correct order by the BitTorrent client, which monitors which pieces it needs, and which pieces it has and can upload to other peers. Pieces are of the same size throughout a single download (for example a 10 MB file may be transmitted as ten 1 MB pieces or as forty 256 KB pieces).Due to the nature of this approach, the download of any file can be halted at any time and be resumed at a later date, without the loss of previously downloaded information, which in turn makes BitTorrent particularly useful in the transfer of larger files. This also enables the client to seek out readily available pieces and download them immediately, rather than halting the download and waiting for the next (and possibly unavailable) piece in line, which typically reduces the overall time of the download. Once a peer has downloaded a file completely, it becomes an additional seed. This eventual transition from peers to seeders determines the overall 'health' of the file (as determined by the number of times a file is available in its complete form).

The distributed nature of BitTorrent can lead to a flood-like spreading of a file throughout many peer computer nodes. As more peers join the swarm, the likelihood of a completely successful download by any particular node increases. Relative to traditional Internet distribution schemes, this permits a significant reduction in the original distributor's hardware and bandwidth resource costs. Distributed downloading protocols in general provide redundancy against system problems, reduce dependence on the original distributor^[9] and provide sources for the file which are generally transient and therefore harder to trace by those who would block distribution compared to the situation provided by limiting availability of the file to a fixed host machine (or even several).

One such example of BitTorrent being used to reduce the distribution cost of file transmission is in the BOINC client-server system. If a BOINC distributed computing application needs to be updated (or merely sent to a user), it can do so with little impact on the BOINC server.^[10]

Operation[edit]

A BitTorrent client is any program that implements the BitTorrent protocol. Each client is capable of preparing, requesting, and transmitting any type of computer file over a network, using the protocol. A peer is any computer running an instance of a client. To share a file or group of files, a peer first creates a small file called a 'torrent' (e.g. MyFile.torrent). This file contains metadata about the files to be shared and about the tracker, the computer that coordinates the file distribution. Peers that want to download the file must first obtain a torrent file for it and connect to the specified tracker, which tells them from which other peers to download the pieces of the file.

Though both ultimately transfer files over a network, a BitTorrent download differs from a classic download (as is typical with an HTTP or FTP request, for example) in several fundamental ways:

• BitTorrent makes many small data requests over different IP connections to different machines, while classic downloading is typically made via a single TCP connection to a single machine.
• BitTorrent downloads in a random or in a 'rarest-first'^[11] approach that ensures high availability, while classic downloads are sequential.

Taken together, these differences allow BitTorrent to achieve much lower cost to the content provider, much higher redundancy, and much greater resistance to abuse or to 'flash crowds' than regular server software. However, this protection, theoretically, comes at a cost: downloads can take time to rise to full speed because it may take time for enough peer connections to be established, and it may take time for a node to receive sufficient data to become an effective uploader. This contrasts with regular downloads (such as from an HTTP server, for example) that, while more vulnerable to overload and abuse, rise to full speed very quickly and maintain this speed throughout. In general, BitTorrent's non-contiguous download methods have prevented it from supporting progressive download or 'streaming playback'. However, comments made by Bram Cohen in January 2007^[12] suggest that streaming torrent downloads will soon be commonplace and ad supported streaming^[13] appears to be the result of those comments. In January 2011 Cohen demonstrated an early version of BitTorrent streaming, saying the feature was projected to be available by summer 2011.^[14]As of 2013, this new BitTorrent streaming protocol is available for beta testing.^[15]

Creating and publishing torrents[edit]

The peer distributing a data file treats the file as a number of identically sized pieces, usually with byte sizes of a power of 2, and typically between 32 kB and 16 MB each. The peer creates a hash for each piece, using the SHA-1 hash function, and records it in the torrent file. Pieces with sizes greater than 512 kB will reduce the size of a torrent file for a very large payload, but is claimed to reduce the efficiency of the protocol.^[16] When another peer later receives a particular piece, the hash of the piece is compared to the recorded hash to test that the piece is error-free.^[6] Peers that provide a complete file are called seeders, and the peer providing the initial copy is called the initial seeder. The exact information contained in the torrent file depends on the version of the BitTorrent protocol. By convention, the name of a torrent file has the suffix .torrent. Torrent files have an 'announce' section, which specifies the URL of the tracker, and an 'info' section, containing (suggested) names for the files, their lengths, the piece length used, and a SHA-1hash code for each piece, all of which are used by clients to verify the integrity of the data they receive. Though SHA-1 has shown signs of cryptographic weakness, Bram Cohen did not initially consider the risk big enough for a backward incompatible change to, for example, SHA-3. BitTorrent is now preparing to move to SHA-256.

Torrent files are typically published on websites or elsewhere, and registered with at least one tracker. The tracker maintains lists of the clients currently participating in the torrent.^[6] Alternatively, in a trackerless system (decentralized tracking) every peer acts as a tracker. Azureus was the first^[17] BitTorrent client to implement such a system through the distributed hash table (DHT) method. An alternative and incompatible DHT system, known as Mainline DHT, was released in the Mainline BitTorrent client three weeks later (though it had been in development since 2002)^[17] and subsequently adopted by the µTorrent, Transmission, rTorrent, KTorrent, BitComet, and Deluge clients.

After the DHT was adopted, a 'private' flag – analogous to the broadcast flag – was unofficially introduced, telling clients to restrict the use of decentralized tracking regardless of the user's desires.^[18] The flag is intentionally placed in the info section of the torrent so that it cannot be disabled or removed without changing the identity of the torrent. The purpose of the flag is to prevent torrents from being shared with clients that do not have access to the tracker. The flag was requested for inclusion in the official specification in August 2008, but has not been accepted yet.^[19] Clients that have ignored the private flag were banned by many trackers, discouraging the practice.^[20]

Downloading torrents and sharing files[edit]

Users find a torrent of interest, by browsing the web or by other means, download it, and open it with a BitTorrent client. The client connects to the tracker(s) specified in the torrent file, from which it receives a list of peers currently transferring pieces of the file(s) specified in the torrent. The client connects to those peers to obtain the various pieces. If the swarm contains only the initial seeder, the client connects directly to it and begins to request pieces. Clients incorporate mechanisms to optimize their download and upload rates; for example they download pieces in a random order to increase the opportunity to exchange data, which is only possible if two peers have different pieces of the file.

The effectiveness of this data exchange depends largely on the policies that clients use to determine to whom to send data. Clients may prefer to send data to peers that send data back to them (a 'tit for tat' exchange scheme), which encourages fair trading. But strict policies often result in suboptimal situations, such as when newly joined peers are unable to receive any data because they don't have any pieces yet to trade themselves or when two peers with a good connection between them do not exchange data simply because neither of them takes the initiative. To counter these effects, the official BitTorrent client program uses a mechanism called 'optimistic unchoking', whereby the client reserves a portion of its available bandwidth for sending pieces to random peers (not necessarily known good partners, so called preferred peers) in hopes of discovering even better partners and to ensure that newcomers get a chance to join the swarm.^[21]

Although 'swarming' scales well to tolerate 'flash crowds' for popular content, it is less useful for unpopular or niche market content. Peers arriving after the initial rush might find the content unavailable and need to wait for the arrival of a 'seed' in order to complete their downloads. The seed arrival, in turn, may take long to happen (this is termed the 'seeder promotion problem'). Since maintaining seeds for unpopular content entails high bandwidth and administrative costs, this runs counter to the goals of publishers that value BitTorrent as a cheap alternative to a client-server approach. This occurs on a huge scale; measurements have shown that 38% of all new torrents become unavailable within the first month.^[22] A strategy adopted by many publishers which significantly increases availability of unpopular content consists of bundling multiple files in a single swarm.^[23] More sophisticated solutions have also been proposed; generally, these use cross-torrent mechanisms through which multiple torrents can cooperate to better share content.^[24]

Concerns[edit]

BitTorrent does not, on its own, offer its users anonymity nor security. It is possible to obtain the IP addresses of all current and possibly previous participants in a swarm from the tracker. This may expose users with insecure systems to attacks.^[21] It may also, in rare cases, expose users to the risk of being sued, if they are distributing files without permission from the copyright holder(s). However, there are ways to promote anonymity; for example, the OneSwarm project layers privacy-preserving sharing mechanisms on top of the original BitTorrent protocol. A moderate degree of anonymity, enough to keep ISPs from giving the user trouble at least, can be achieved with seedboxes which download the torrent files first to the companies' servers, followed by a direct download to the user.^[25][26] Torrents can be downloaded with a high degree of anonymity by using services such as i2p. Tor does not provide anonymity on BitTorrent,^[27] and its use is also discouraged (by blocking this type of connections) for performance reasons.^[28] Unlike Tor, i2p is designed to work with BitTorrent^[29] However, with i2p, torrents can only be downloaded from within the i2p network. This can be useful for users trying to avoid copyright complaints from their ISPs, maintaining privacy, or avoiding censorship.

Private trackers offer users a greater degree of privacy, compared to public trackers, but have the downside of a single centralized point of failure.

Bridging between i2p and the clearnet[edit]

Vuze is the only client that makes clearnet torrents available on i2p and vice versa. It has a plugin that connects to the i2p network. If the user adds a torrent from i2p or clearnet, it will be seeded on both i2p and the clearnet. For this reason, torrents previously published only on i2p are made available to the entire Internet, and users of i2p can download any torrent on the Internet while maintaining the anonymity of i2p.^[30][31]

Adoption[edit]

A growing number of individuals and organizations are using BitTorrent to distribute their own or licensed works (e.g. indie bands distributing digital files of their new songs). Independent adopters report that without using BitTorrent technology, and its dramatically reduced demands on their private networking hardware and bandwidth, they could not afford to distribute their files.^[32]

Some uses of BitTorrent for file sharing may violate laws in some jurisdictions (see legal issues section).

Film, video, and music[edit]

• BitTorrent Inc. has obtained a number of licenses from Hollywood studios for distributing popular content from their websites.
• Sub Pop Records releases tracks and videos via BitTorrent Inc.^[33] to distribute its 1000+ albums. Babyshambles and The Libertines (both bands associated with Pete Doherty) have extensively used torrents to distribute hundreds of demos and live videos. US industrial rock band Nine Inch Nails frequently distributes albums via BitTorrent.
• Podcasting software is starting to integrate BitTorrent to help podcasters deal with the download demands of their MP3 'radio' programs. Specifically, Juice and Miro (formerly known as Democracy Player) support automatic processing of .torrent files from RSS feeds. Similarly, some BitTorrent clients, such as µTorrent, are able to process web feeds and automatically download content found within them.
• DGM Live purchases are provided via BitTorrent.^[34]
• VODO, a service which distributes 'free-to-share' movies and TV shows via BitTorrent.^[35][36][37]

Broadcasters[edit]

• In 2008, the CBC became the first public broadcaster in North America to make a full show (Canada's Next Great Prime Minister) available for download using BitTorrent.^[38]
• The Norwegian Broadcasting Corporation (NRK) has since March 2008 experimented with bittorrent distribution, available online.^[39] Only selected works in which NRK owns all royalties are published. Responses have been very positive, and NRK is planning to offer more content.
• The Dutch VPRO broadcasting organization released four documentaries in 2009 and 2010 under a Creative Commons license using the content distribution feature of the Mininova tracker.^[40][41][42]

Personal works[edit]

• The Amazon S3 'Simple Storage Service' is a scalable Internet-based storage service with a simple web service interface, equipped with built-in BitTorrent support.^[43]
• Blog Torrent offers a simplified BitTorrent tracker to enable bloggers and non-technical users to host a tracker on their site. Blog Torrent also allows visitors to download a 'stub' loader, which acts as a BitTorrent client to download the desired file, allowing users without BitTorrent software to use the protocol.^[44] This is similar to the concept of a self-extracting archive.

Software[edit]

• Blizzard Entertainment uses BitTorrent (via a proprietary client called the 'Blizzard Downloader', associated with the Blizzard 'BattleNet' network) to distribute content and patches for Diablo III, StarCraft II and World of Warcraft, including the games themselves.^[45]
• Wargaming uses BitTorrent in their popular titles World of Tanks, World of Warships and World of Warplanes to distribute game updates.^[46]
• CCP Games, maker of the space Simulation MMORPG Eve Online, has announced that a new launcher will be released that is based on BitTorrent.^[47][48]
• Many software games, especially those whose large size makes them difficult to host due to bandwidth limits, extremely frequent downloads, and unpredictable changes in network traffic, will distribute instead a specialized, stripped down bittorrent client with enough functionality to download the game from the other running clients and the primary server (which is maintained in case not enough peers are available).
• Many major open source and free software projects encourage BitTorrent as well as conventional downloads of their products (via HTTP, FTP etc.) to increase availability and to reduce load on their own servers, especially when dealing with larger files.^[49]

Government[edit]

• The UK government used BitTorrent to distribute details about how the tax money of UK citizens was spent.^[50][51]

Education[edit]

• Florida State University uses BitTorrent to distribute large scientific data sets to its researchers.^[52]
• Many universities that have BOINC distributed computing projects have used the BitTorrent functionality of the client-server system to reduce the bandwidth costs of distributing the client-side applications used to process the scientific data.
• The developing Human Connectome Project uses BitTorrent to share their open dataset.^[53]

Others[edit]

• Facebook uses BitTorrent to distribute updates to Facebook servers.^[54]
• Twitter uses BitTorrent to distribute updates to Twitter servers.^[55][56]
• The Internet Archive added BitTorrent to its file download options for over 1.3 million existing files, and all newly uploaded files, in August 2012.^[57][58] This method is the fastest means of downloading media from the Archive.^[57][59]

As of 2011, BitTorrent had 100 million users and a greater share of network bandwidth than Netflix and Hulu combined.^[60][61] In early 2015, AT&T estimates that BitTorrent represents 20% of all broadband traffic.^[62]

Routers that use network address translation (NAT) must maintain tables of source and destination IP addresses and ports. Typical home routers are limited to about 2000 table entries^{[citation needed]} while some more expensive routers have larger table capacities. BitTorrent frequently contacts 20–30 servers per second, rapidly filling the NAT tables. This is a known cause of some home routers ceasing to work correctly.^[63][64]

Indexing[edit]

The BitTorrent protocol provides no way to index torrent files. As a result, a comparatively small number of websites have hosted a large majority of torrents, many linking to copyrighted works without the authorization of copyright holders, rendering those sites especially vulnerable to lawsuits.^[65] A BitTorrent index is a 'list of .torrent files, which typically includes descriptions' and information about the torrent's content.^[66] Several types of websites support the discovery and distribution of data on the BitTorrent network. Public torrent-hosting sites such as The Pirate Bay allow users to search and download from their collection of torrent files. Users can typically also upload torrent files for content they wish to distribute. Often, these sites also run BitTorrent trackers for their hosted torrent files, but these two functions are not mutually dependent: a torrent file could be hosted on one site and tracked by another unrelated site. Private host/tracker sites operate like public ones except that they may restrict access to registered users and may also keep track of the amount of data each user uploads and downloads, in an attempt to reduce 'leeching'.

Web search engines allow the discovery of torrent files that are hosted and tracked on other sites; examples include Mininova, BTDigg, BTJunkie, Torrentz, Torrentus, The Pirate Bay and isoHunt. These sites allow the user to ask for content meeting specific criteria (such as containing a given word or phrase) and retrieve a list of links to torrent files matching those criteria. This list can often be sorted with respect to several criteria, relevance (seeders-leechers ratio) being one of the most popular and useful (due to the way the protocol behaves, the download bandwidth achievable is very sensitive to this value). Bram Cohen launched a BitTorrent search engine on www.bittorrent.com/search that co-mingles licensed content with search results.^[67]Metasearch engines allow one to search several BitTorrent indices and search engines at once. DHT search engines monitors the DHT network and indexes torrents via metadata exchange from peers. In the 2010s, some P2P, decentralized alternatives to Torrent search engines have emerged, see decentralized keyword search below.

Technologies built on BitTorrent[edit]

The BitTorrent protocol is still under development and may therefore still acquire new features and other enhancements such as improved efficiency.

Distributed trackers[edit]

On 2 May 2005, Azureus 2.3.0.0 (now known as Vuze) was released,^[68] introducing support for 'trackerless' torrents through a system called the 'distributed database.' This system is a Distributed hash table implementation which allows the client to use torrents that do not have a working BitTorrent tracker. The following month, BitTorrent, Inc. released version 4.2.0 of the Mainline BitTorrent client, which supported an alternative DHT implementation (popularly known as 'Mainline DHT', outlined in a draft on their website) that is incompatible with that of Azureus. Recent measurement shows users of Mainline DHT is from 10 million to 25 million, with a daily churn of at least 10 million.^[69] Mainline DHT is arguably the largest realistic DHT in the world.

Current versions of the official BitTorrent client, µTorrent, BitComet, Transmission and BitSpirit all share compatibility with Mainline DHT. Both DHT implementations are based on Kademlia.^[70] As of version 3.0.5.0, Azureus also supports Mainline DHT in addition to its own distributed database through use of an optional application plugin.^[71] This potentially allows the Azureus/Vuze client to reach a bigger swarm.

Another idea that has surfaced in Vuze is that of virtual torrents. This idea is based on the distributed tracker approach and is used to describe some web resource. Currently, it is used for instant messaging. It is implemented using a special messaging protocol and requires an appropriate plugin. Anatomic P2P is another approach, which uses a decentralized network of nodes that route traffic to dynamic trackers. Most BitTorrent clients also use Peer exchange (PEX) to gather peers in addition to trackers and DHT. Peer exchange checks with known peers to see if they know of any other peers. With the 3.0.5.0 release of Vuze, all major BitTorrent clients now have compatible peer exchange.

Web seeding[edit]

Web 'seeding' was implemented in 2006 as the ability of BitTorrent clients to download torrent pieces from an HTTP source in addition to the 'swarm'. The advantage of this feature is that a website may distribute a torrent for a particular file or batch of files and make those files available for download from that same web server; this can simplify long-term seeding and load balancing through the use of existing, cheap, web hosting setups. In theory, this would make using BitTorrent almost as easy for a web publisher as creating a direct HTTP download. In addition, it would allow the 'web seed' to be disabled if the swarm becomes too popular while still allowing the file to be readily available. This feature has two distinct specifications, both of which are supported by Libtorrent and the 26+ clients that use it.

Hash web seeding[edit]

The first was created by John 'TheSHAD0W' Hoffman, who created BitTornado.^[72][73] This first specification requires running a web service that serves content by info-hash and piece number, rather than filename.

HTTP web seeding[edit]

The other specification is created by GetRight authors and can rely on a basic HTTP download space (using byte serving).^[74][75]

Other[edit]

In September 2010, a new service named Burnbit was launched which generates a torrent from any URL using webseeding.^[76] There are server-side solutions that provide initial seeding of the file from the webserver via standard BitTorrent protocol and when the number of external seeders reach a limit, they stop serving the file from the original source.^[77]

RSS feeds[edit]

A technique called broadcatching combines RSS feeds with the BitTorrent protocol to create a content delivery system, further simplifying and automating content distribution. Steve Gillmor explained the concept in a column for Ziff-Davis in December 2003.^[78] The discussion spread quickly among bloggers (Ernest Miller,^[79]Chris Pirillo, etc.). In an article entitled Broadcatching with BitTorrent, Scott Raymond explained:

I want RSS feeds of BitTorrent files. A script would periodically check the feed for new items, and use them to start the download. Then, I could find a trusted publisher of an Alias RSS feed, and 'subscribe' to all new episodes of the show, which would then start downloading automatically – like the 'season pass' feature of the TiVo.

The RSS feed will track the content, while BitTorrent ensures content integrity with cryptographichashing of all data, so feed subscribers will receive uncorrupted content. One of the first and popular software clients (free and open source) for broadcatching is Miro. Other free software clients such as PenguinTV and KatchTV are also now supporting broadcatching. The BitTorrent web-service MoveDigital added the ability to make torrents available to any web application capable of parsing XML through its standard REST-based interface in 2006,^[81] though this has since been discontinued. Additionally, Torrenthut is developing a similar torrent API that will provide the same features, and help bring the torrent community to Web 2.0 standards. Alongside this release is a first PHP application built using the API called PEP, which will parse any Really Simple Syndication (RSS 2.0) feed and automatically create and seed a torrent for each enclosure found in that feed.^[82]

Throttling and encryption[edit]

Since BitTorrent makes up a large proportion of total traffic, some ISPs have chosen to 'throttle' (slow down) BitTorrent transfers. For this reason, methods have been developed to disguise BitTorrent traffic in an attempt to thwart these efforts.^[83] Protocol header encrypt (PHE) and Message stream encryption/Protocol encryption (MSE/PE) are features of some BitTorrent clients that attempt to make BitTorrent hard to detect and throttle. As of November 2015, Vuze, Bitcomet, KTorrent, Transmission, Deluge, µTorrent, MooPolice, Halite, qBittorrent, rTorrent, and the latest official BitTorrent client (v6) support MSE/PE encryption. In September 2006 it was reported that some software could detect and throttle BitTorrent traffic masquerading as HTTP traffic.^[84]

Reports in August 2007 indicated that Comcast was preventing BitTorrent seeding by monitoring and interfering with the communication between peers. Protection against these efforts is provided by proxying the client-tracker traffic via an encrypted tunnel to a point outside of the Comcast network.^[85] Comcast has more recently called a 'truce' with BitTorrent, Inc. with the intention of shaping traffic in a protocol-agnostic manner.^[86] Questions about the ethics and legality of Comcast's behavior have led to renewed debate about net neutrality in the United States.^[87] In general, although encryption can make it difficult to determine what is being shared, BitTorrent is vulnerable to traffic analysis. Thus, even with MSE/PE, it may be possible for an ISP to recognize BitTorrent and also to determine that a system is no longer downloading but only uploading data, and terminate its connection by injecting TCP RST (reset flag) packets.

Multitracker[edit]

Another unofficial feature is an extension to the BitTorrent metadata format proposed by John Hoffman^[88] and implemented by several indexing websites. It allows the use of multiple trackers per file, so if one tracker fails, others can continue to support file transfer. It is implemented in several clients, such as BitComet, BitTornado, BitTorrent, KTorrent, Transmission, Deluge, µTorrent, rtorrent, Vuze, and Frostwire. Trackers are placed in groups, or tiers, with a tracker randomly chosen from the top tier and tried, moving to the next tier if all the trackers in the top tier fail.

Torrents with multiple trackers can decrease the time it takes to download a file, but also have a few consequences:

• Poorly implemented^[89] clients may contact multiple trackers, leading to more overhead-traffic.
• Torrents from closed trackers suddenly become downloadable by non-members, as they can connect to a seed via an open tracker.

Decentralized keyword search[edit]

Even with distributed trackers, a third party is still required to find a specific torrent. This is usually done in the form of a hyperlink from the website of the content owner or through indexing websites like isoHunt, Torrentz, BTDigg, Torrentus or The Pirate Bay. The Tribler BitTorrent client is the first to incorporate decentralized search capabilities.

With Tribler, users can find .torrent files that are hosted among other peers, instead of on a centralized index sites. It adds such an ability to the BitTorrent protocol using a gossip protocol, somewhat similar to the eXeem network which was shut down in 2005. The software includes the ability to recommend content as well. After a dozen downloads the Tribler software can roughly estimate the download taste of the user and recommend additional content.^[90]

In May 2007, researches at Cornell University published a paper proposing a new approach to searching a peer-to-peer network for inexact strings,^[91] which could replace the functionality of a central indexing site. A year later, the same team implemented the system as a plugin for Vuze called Cubit^[92] and published a follow-up paper reporting its success.^[93]

A somewhat similar facility but with a slightly different approach is provided by the BitComet client through its 'Torrent Exchange'^[94] feature. Whenever two peers using BitComet (with Torrent Exchange enabled) connect to each other they exchange lists of all the torrents (name and info-hash) they have in the Torrent Share storage (torrent files which were previously downloaded and for which the user chose to enable sharing by Torrent Exchange). Thus each client builds up a list of all the torrents shared by the peers it connected to in the current session (or it can even maintain the list between sessions if instructed). At any time the user can search into that Torrent Collection list for a certain torrent and sort the list by categories. When the user chooses to download a torrent from that list, the .torrent file is automatically searched for (by info-hash value) in the DHT Network and when found it is downloaded by the querying client which can after that create and initiate a downloading task.

Implementations[edit]

The BitTorrent specification is free to use and many clients are open source, so BitTorrent clients have been created for all common operating systems using a variety of programming languages. The official BitTorrent client, µTorrent, qBittorrent, Transmission, Vuze, and BitComet are some of the most popular clients.^{[95][96][97][98]}

Some BitTorrent implementations such as MLDonkey and Torrentflux are designed to run as servers. For example, this can be used to centralize file sharing on a single dedicated server which users share access to on the network.^[99] Server-oriented BitTorrent implementations can also be hosted by hosting providers at co-located facilities with high bandwidth Internet connectivity (e.g., a datacenter) which can provide dramatic speed benefits over using BitTorrent from a regular home broadband connection. Services such as ImageShack can download files on BitTorrent for the user, allowing them to download the entire file by HTTP once it is finished. The Operaweb browser supports BitTorrent,^[100] as does Wyzo. BitLet allows users to download Torrents directly from their browser using a Java applet. An increasing number of hardware devices are being made to support BitTorrent. These include routers and NAS devices containing BitTorrent-capable firmware like OpenWrt. Proprietary versions of the protocol which implement DRM, encryption, and authentication are found within managed clients such as Pando.

Development[edit]

An unimplemented (as of February 2008) unofficial feature is Similarity Enhanced Transfer (SET), a technique for improving the speed at which peer-to-peer file sharing and content distribution systems can share data. SET, proposed by researchers Pucha, Andersen, and Kaminsky, works by spotting chunks of identical data in files that are an exact or near match to the one needed and transferring these data to the client if the 'exact' data are not present. Their experiments suggested that SET will help greatly with less popular files, but not as much for popular data, where many peers are already downloading it.^[101] Andersen believes that this technique could be immediately used by developers with the BitTorrent file sharing system.^[102]

As of December 2008, BitTorrent, Inc. is working with Oversi on new Policy Discover Protocols that query the ISP for capabilities and network architecture information. Oversi's ISP hosted NetEnhancer box is designed to 'improve peer selection' by helping peers find local nodes, improving download speeds while reducing the loads into and out of the ISP's network.^[103]

Legal issues[edit]

Although the protocol itself is legal,^[104] problems stem from using the protocol to traffic copyright infringing works. There has been much controversy over the use of BitTorrent trackers. BitTorrent metafiles themselves do not store file contents. Whether the publishers of BitTorrent metafiles violate copyrights by linking to copyrighted works without the authorization of copyright holders is controversial. Various jurisdictions have pursued legal action against websites that host BitTorrent trackers. High-profile examples include the closing of Suprnova.org, TorrentSpy, LokiTorrent, BTJunkie, Mininova, Demonoid and Oink's Pink Palace. The Pirate Bay torrent website, formed by a Swedish group, is noted for the 'legal' section of its website in which letters and replies on the subject of alleged copyright infringements are publicly displayed. On 31 May 2006, The Pirate Bay's servers in Sweden were raided by Swedish police on allegations by the MPAA of copyright infringement;^[105] however, the tracker was up and running again three days later. In the study used to value NBC Universal in its merger with Comcast, Envisional examined the 10,000 torrent swarms managed by PublicBT which had the most active downloaders. After excluding pornographic and unidentifiable content, it was found that only one swarm offered legitimate content.^[106]

In the United States, more than 200,000 people have been sued for filesharing on BitTorrent since 2010.^[107] On 30 April 2012, the UK High Court ordered five ISPs to block BitTorrent search engine The Pirate Bay.^[108]

Security problems[edit]

One concern is the UDP flood attack. BitTorrent implementations often use µTP for their communication. To achieve high bandwidths, the underlying protocol used is UDP, which allows spoofing of source addresses of internet traffic. It has been possible to carry out Denial-of-service attacks in a P2P lab environment, where users running BitTorrent clients act as amplifiers for an attack at another service.^[109] However this is not always a effective attack because ISPs can check if the source adress is correct.

Challenges[edit]

'Leeches', are those users who download more than they share. As BitTorrent is a collaborative distributed platform, there is a section of the community that wants solutions to punish and discourage such behaviour.^[110]

Malware[edit]

Several studies on BitTorrent have indicated that there exist files, containing malware, available for download via BitTorrent. In particular, one small sample^[111] indicated that 18% of all executable programs available for download contained malware. Another study^[112] claims that as much as 14.5% of BitTorrent downloads contain zero-day malware, and that BitTorrent was used as the distribution mechanism for 47% of all zero-day malware they have found.

BitErrant attack[edit]

Due to SHA1 collisions, an attacker can alter the execution path of the executable by serving altered chunks when the victim is downloading the executable using the BitTorrent protocol.^[113]

Criticism of BitErrant attack[edit]

Despite the fact that a proof of concept exists, the attack may succeed in very limited cases: such as small chunk size (32kB). By selecting larger chunks (i.e. >256kB) the amount of resources required to find SHA1 collision is tremendous, which makes the attack virtually impossible.

See also[edit]

References[edit]

1. ^Schulze, Hendrik; Klaus Mochalski (2009). 'Internet Study 2008/2009'(PDF). Leipzig, Germany: ipoque. Archived from the original(PDF) on 1 April 2014. Retrieved 3 October 2011. Peer-to-peer file sharing (P2P) still generates by far the most traffic in all monitored regions – ranging from 43% in Northern Africa to 70% Eastern Europe.
2. ^'Application Usage & Threat Report'. Palo Alto Networks. 2013. Archived from the original on 31 October 2013. Retrieved 7 April 2013.
3. ^Van der Sar, Ernesto (4 December 2009). 'Thunder Blasts uTorrent's Market Share Away - TorrentFreak'. TorrentFreak. Archived from the original on 20 February 2016. Retrieved 18 June 2018.
4. ^'UB Engineering Tweeter'. University at Buffalo's School of Engineering and Applied Sciences. Archived from the original on 11 November 2013.
5. ^Cohen, Bram (2 July 2001). 'BitTorrent – a new P2P app'. Yahoo eGroups. Archived from the original on 2 July 2011. Retrieved 15 April 2007.
6. ^ ^abcdCohen, Bram (October 2002). 'BitTorrent Protocol 1.0'. BitTorrent.org. Archived from the original on 8 February 2014. Retrieved 19 April 2013.
7. ^Wang, Liang; Kangasharju, J. (1 September 2013). 'Measuring large-scale distributed systems: Case of Bit Torrent Mainline DHT'. IEEE P2P 2013 Proceedings. pp. 1–10. doi:10.1109/P2P.2013.6688697. ISBN978-1-4799-0515-7. Archived from the original on 18 November 2015. Retrieved 7 January 2016.
8. ^'BitTorrent and µTorrent Software Surpass 150 Million User Milestone'. Bittorrent.com. 9 January 2012. Archived from the original on 26 March 2014. Retrieved 9 July 2012.
9. ^Menasche, Daniel S.; Rocha, Antonio A. A.; de Souza e Silva, Edmundo A.; Leao, Rosa M.; Towsley, Don; Venkataramani, Arun (2010). 'Estimating Self-Sustainability in Peer-to-Peer Swarming Systems'. arXiv:1004.0395 [cs.NI]. by D. Menasche, A. Rocha, E. de Souza e Silva, R. M. Leao, D. Towsley, A. Venkataramani.
10. ^Costa, Fernando; Silva, Luis; Fedak, Gilles; Kelley, Ian (2008). 'Optimizing the data distribution layer of BOINC with Bit Torrent'. 2008 IEEE International Symposium on Parallel and Distributed Processing. IEEE International Symposium on Parallel and Distributed Processing, 2008. IPDPS 2008.(PDF) format= requires url= (help). IEEE. p. 1. doi:10.1109/IPDPS.2008.4536446. ISBN978-1-4244-1693-6.(registration required)
11. ^Urvoy-Keller (December 2006). 'Rarest First and Choke Algorithms Are Enough'(PDF). SIGCOMM. Archived(PDF) from the original on 23 May 2012. Retrieved 9 March 2012.
12. ^Ernesto (17 January 2007). 'Interview with Bram Cohen, the inventor of BitTorrent'. TorrentFreak. Archived from the original on 15 July 2013. Retrieved 7 April 2013.
13. ^Ernesto (18 December 2007). 'BitTorrent Launches Ad Supported Streaming'. TorrentFreak. Archived from the original on 19 June 2013. Retrieved 7 April 2013.
14. ^Cohen, Bram (January 2011). 'BitTorrent Inventor Demos New P2P Live Streaming Protocol'. torrentfreak.com. Archived from the original on 27 October 2013. Retrieved 19 January 2011.
15. ^'BitTorrent Live'. Bittorrent.com. Archived from the original on 25 October 2013. Retrieved 4 March 2013.
16. ^'BitTorrent Specification'. Wiki.theory.org. Archived from the original on 26 June 2013. Retrieved 9 July 2012.^[dubious]
17. ^ ^abJones, Ben (7 June 2015). 'BitTorrent's DHT Turns 10 Years Old'. TorrentFreak. Archived from the original on 11 June 2015. Retrieved 5 July 2015.
18. ^'Unofficial BitTorrent Protocol Specification v1.0'. Archived from the original on 14 December 2006. Retrieved 4 October 2009.^[dubious]
19. ^Harrison, David (3 August 2008). 'Private Torrents'. Bittorrent.org. Archived from the original on 24 March 2013. Retrieved 4 October 2009.
20. ^'BitComet Banned From Growing Number of Private Trackers'. Archived from the original on 26 March 2014. Retrieved 4 October 2009.
21. ^ ^abTamilmani, Karthik (25 October 2003). 'Studying and enhancing the BitTorrent protocol'. Stony Brook University. Archived from the original(DOC) on 19 November 2004. Retrieved 6 May 2006.
22. ^Kaune, Sebastian; et al. (2009). 'Unraveling BitTorrent's File Unavailability: Measurements and Analysis'. arXiv:0912.0625 [cs.NI].
23. ^D. Menasche; et al. (1–4 December 2009). Content Availability and Bundling in Swarming Systems(PDF). CoNEXT'09. Rome, Italy: ACM via sigcomm.org. ISBN978-1-60558-636-6. Archived(PDF) from the original on 1 May 2011. Retrieved 18 December 2009.
24. ^Kaune, Sebastian; et al. 'The Seeder Promotion Problem: Measurements, Analysis and Solution Space'(PDF). Queen Mary's University London. Archived(PDF) from the original on 9 August 2014. Retrieved 20 July 2017.
25. ^'This Website Could Be The Ultimate All-In-One Torrent Machine'. 8 April 2016. Archived from the original on 8 April 2016.
26. ^'Torrent From the Cloud With Seedr - TorrentFreak'. 17 January 2016. Archived from the original on 19 April 2016. Retrieved 8 April 2016.
27. ^'Bittorrent over Tor isn't a good idea - The Tor Blog'. Archived from the original on 13 October 2016. Retrieved 2 October 2016.
28. ^Inc., The Tor Project,. 'Tor Project: FAQ'. Archived from the original on 22 October 2016. Retrieved 2 October 2016.
29. ^'I2P Compared to Tor - I2P'. Archived from the original on 22 December 2015. Retrieved 16 December 2015.
30. ^'Vuze Speeds Up Torrent Downloads Through 'Swarm Merging' - TorrentFreak'. 20 March 2015. Archived from the original on 17 October 2017. Retrieved 16 December 2015.
31. ^'I2PHelper HowTo - VuzeWiki'. Archived from the original on 20 October 2017. Retrieved 16 December 2015.
32. ^See, for example, 'Why Bit Torrent'. Archived from the original on 28 January 2013.. tasvideos.org.
33. ^'Sub Pop page on BitTorrent.com'. Archived from the original on 14 January 2007. Retrieved 13 December 2006.
34. ^'DGMlive.com'. DGMlive.com. Archived from the original on 11 November 2013. Retrieved 9 July 2012.
35. ^'VODO – About..'. Retrieved 15 April 2012. (WebCite).
36. ^Cory Doctorow (15 October 2009). 'Vodo: a filesharing service for film-makers'. Boing Boing. Happy Mutants LLC. Retrieved 15 April 2012. (WebCite)
37. ^Ernesto. 'Pioneer One, The BitTorrent Exclusive TV-Series Continues'. TorrentFreak. Retrieved 15 April 2012. (WebCite)
38. ^'CBC to BitTorrent Canada's Next Great Prime Minister:'. CBC News. 19 March 2008. Archived from the original on 14 June 2010. Retrieved 19 March 2008.
39. ^'Bittorrent' (in Norwegian). Nrkbeta.no. 2008. Archived from the original on 24 October 2013. Retrieved 7 April 2013.
40. ^'Torrents uploaded by EeuwvandeStad'. MiniNova. 2009. Archived from the original on 4 November 2013. Retrieved 7 April 2013.
41. ^Denters, M. (11 August 2010). 'Tegenlicht – Download California Dreaming'. VPRO.nl. Archived from the original on 26 March 2014. Retrieved 7 April 2013.
42. ^Bol, M. (1 October 2009). 'Tegenlicht – VPRO gemeengoed' (in Dutch). VPRO.nl. Archived from the original on 26 March 2014. Retrieved 7 April 2013.
43. ^'Using BitTorrent with Amazon S3'. Archived from the original on 26 March 2014.
44. ^Rustad, Roger E. (26 August 2004). 'Blog Torrent and Participatory Culture'. Grep Law. Archived from the original on 12 June 2006. Retrieved 9 May 2006.
45. ^'Blizzard Downloader'. Curse Inc. 4 November 2010. Archived from the original on 26 March 2014. Retrieved 4 November 2010.
46. ^'World of Tanks FAQ'. Wargaming. 15 December 2014. Archived from the original on 18 December 2014. Retrieved 15 December 2014.
47. ^MJ Guthrie (11 March 2013). 'EVE Online reconfiguring launcher to use BitTorrent'. Massively.joystiq.com. Archived from the original on 13 February 2014. Retrieved 7 April 2013.
48. ^CCP Games (20 July 2010). 'All quiet on the EVE Launcher front? – EVE Community'. Community.eveonline.com. Archived from the original on 13 March 2013. Retrieved 7 April 2013.
49. ^'Complete Download Options List – BitTorrent'. Ubuntu.com. Archived from the original on 24 April 2010. Retrieved 7 May 2009.
50. ^HM Government (4 September 2012). 'Combined Online Information System'. Data.Gov.Uk Beta. Controller of Her Majesty's Stationery Office. Archived from the original on 26 March 2014. Retrieved 7 September 2012.
51. ^Ernesto (4 June 2010). 'UK Government Uses BitTorrent to Share Public Spending Data'. TorrentFreak. Archived from the original on 27 October 2013. Retrieved 7 September 2012.
52. ^'HPC Data Repository'. Florida State University. Archived from the original on 2 April 2013. Retrieved 7 April 2013.
53. ^'Torrents Help Researchers Worldwide to Study Babies' Brains'. Torrent Freak. 3 June 2017. Archived from the original on 5 January 2018. Retrieved 4 January 2018.
54. ^Ernesto (25 June 2010). 'Facebook Uses BitTorrent, and They Love It'. Torrent Freak. Torrent Freak. Archived from the original on 19 April 2014. Retrieved 7 September 2012.
55. ^Ernesto (10 February 2010). 'Twitter Uses BitTorrent For Server Deployment'. Torrent Freak. Torrent Freak. Archived from the original on 26 March 2014. Retrieved 7 September 2012.
56. ^Ernesto (16 July 2010). 'BitTorrent Makes Twitter's Server Deployment 75x Faster'. Torrent Freak. Torrent Freak. Archived from the original on 26 March 2014. Retrieved 7 September 2012.
57. ^ ^abErnesto (7 August 2012). 'Internet Archive Starts Seeding 1,398,875 Torrents'. TorrentFreak. Archived from the original on 8 August 2012. Retrieved 7 August 2012.
58. ^'Hot List for bt1.us.archive.org (Updated August 7, 2012, 7:31 pm PDT)'. Archived from the original on 3 August 2012. Retrieved 8 August 2012.. Archive.org.
59. ^'Welcome to Archive torrents'. Archived from the original on 19 January 2016. Retrieved 22 December 2015.. Archive.org. 2012.
60. ^Carr, Austin (4 January 2011). 'BitTorrent Has More Users Than Netflix and Hulu Combined—and Doubled'. fastcompany.com. Archived from the original on 10 January 2011. Retrieved 9 July 2012.
61. ^Hartley, Matt (1 July 2011). 'BitTorrent turns ten'. Financialpost.com. Archived from the original on 4 November 2013. Retrieved 9 July 2012.
62. ^'AT&T patents system to 'fast-lane' BitTorrent traffic'. Thestack.com. 8 May 2006. Archived from the original on 23 February 2015. Retrieved 5 March 2015.
63. ^'FAQ:Modems/routers that are known to have problems with P2P apps'. uTorrent.com. Archived from the original on 13 September 2008. Retrieved 7 April 2013.
64. ^Halkes, Gertjan; Pouwelse, Johan (2011). Jordi Domingo-Pascual; et al. (eds.). UDP NAT and Firewall Puncturing in the Wild. NETWORKING 2011:10th International IFIP TC 6 Networking Conference, Valencia, Spain, May 9–13, 2011, Proceedings. Springer. p. 7. ISBN9783642207976. Archived from the original on 9 May 2013. Retrieved 7 April 2013.
65. ^Ernesto (12 July 2009). 'PublicBT Tracker Set To Patch BitTorrent' Achilles' Heel'. Torrentfreak. Archived from the original on 26 March 2014. Retrieved 14 July 2009.
66. ^Chwan-Hwa (John) Wu, J. David Irwin. Introduction to Computer Networks and Cybersecurity. Chapter 5.4.: Partially Centralized Architectures. CRC Press. February 4, 2013. ISBN9781466572133
67. ^Worthington, David; Nate Mook (25 May 2005). 'BitTorrent Creator Opens Online Search'. BetaNews. Archived from the original on 24 February 2009. Retrieved 9 May 2006.
68. ^'Vuze Changelog'. Azureus.sourceforge.net. Archived from the original on 1 December 2006.
69. ^Wang, Liang; Kangasharju, Jussi. (2013). 'Measuring Large-Scale Distributed Systems: Case of BitTorrent Mainline DHT'(PDF). IEEE Peer-to-Peer. Archived(PDF) from the original on 12 May 2014. Retrieved 15 May 2014.
70. ^'Khashmir.Sourceforge.net'. Khashmir.Sourceforge.net. Archived from the original on 2 July 2012. Retrieved 9 July 2012.
71. ^'Azureus.sourceforge.net'. Azureus.sourceforge.net. Archived from the original on 1 August 2012. Retrieved 9 July 2012.
72. ^'HTTP-Based Seeding Specification'. BitTornado.com. Archived from the original(TXT) on 22 August 2011. Retrieved 9 May 2006.
73. ^John Hoffman, DeHackEd (25 February 2008). 'HTTP Seeding – BitTorrent Enhancement Proposal № 17'. Archived from the original on 13 December 2013. Retrieved 17 February 2012.
74. ^'HTTP/FTP Seeding for BitTorrent'. GetRight.com. Archived from the original on 28 December 2009. Retrieved 18 March 2010.
75. ^Michael Burford (25 February 2008). 'WebSeed – HTTP/FTP Seeding (GetRight style) – BitTorrent Enhancement Proposal № 19'. Bittorrent.org. Archived from the original on 13 December 2013. Retrieved 17 February 2012.
76. ^'Burn Any Web-Hosted File into a Torrent With Burnbit'. TorrentFreak. 13 September 2010. Archived from the original on 9 August 2011. Retrieved 9 July 2012.
77. ^'PHP based torrent file creator, tracker and seed server'. PHPTracker. Archived from the original on 19 December 2013. Retrieved 9 July 2012.
78. ^Gillmor, Steve (13 December 2003). 'BitTorrent and RSS Create Disruptive Revolution'. EWeek.com. Retrieved 22 April 2007.
79. ^Miller, Ernest (2 March 2004). 'BitTorrent + RSS = The New Broadcast'. Archived from the original on 23 October 2013.. The Importance of.. Corante.com.
80. ^Raymond, Scott (16 December 2003). 'Broadcatching with BitTorrent'. scottraymond.net. Archived from the original on 13 February 2004.
81. ^'MoveDigital API REST functions'. Move Digital. 2006. Archived from the original on 11 August 2006. Retrieved 9 May 2006. Documentation.
82. ^'Prodigem Enclosure Puller(pep.txt)'. Prodigem.com. Archived from the original(TXT) on 26 May 2006. Retrieved 9 May 2006. via Internet Wayback Machine.
83. ^'Encrypting Bittorrent to take out traffic shapers'. Torrentfreak.com. 5 February 2006. Archived from the original on 26 March 2014. Retrieved 9 May 2006.
84. ^Sales, Ben (27 September 2006). 'ResTech solves network issues'. studlife.com. Archived from the original on 26 March 2014.
85. ^'Comcast Throttles BitTorrent Traffic, Seeding Impossible'. Archived from the original on 11 October 2013., TorrentFreak, 17 August 2007.
86. ^Broache, Anne (27 March 2008). 'Comcast and BitTorrent Agree to Collaborate'. News.com. Archived from the original on 9 May 2008. Retrieved 9 July 2012.
87. ^Soghoian, Chris (4 September 2007). 'Is Comcast's BitTorrent filtering violating the law?'. Cnet.com. Archived from the original on 15 July 2010. Retrieved 9 July 2012.
88. ^'BEP12: Multitracker Metadata Extension'. BitTorrent Inc. Archived from the original on 27 December 2012. Retrieved 28 March 2013.
89. ^'P2P:Protocol:Specifications:Multitracker'. wiki.depthstrike.com. Archived from the original on 26 March 2014. Retrieved 13 November 2009.^[dubious]
90. ^'DecentralizedRecommendation –'. Tribler.org. Archived from the original on 2 December 2008. Retrieved 9 July 2012.
91. ^Wong, Bernard; Vigfusson, Ymir; Gun Sirer, Emin (2 May 2007). 'Hyperspaces for Object Clustering and Approximate Matching in Peer-to-Peer Overlays'(PDF). Cornell University. Archived(PDF) from the original on 17 June 2012. Retrieved 7 April 2013.
92. ^Wong, Bernard (2008). 'Cubit: Approximate Matching for Peer-to-Peer Overlays'. Cornell University. Archived from the original on 31 December 2012. Retrieved 26 May 2008.
93. ^Wong, Bernard. 'Approximate Matching for Peer-to-Peer Overlays with Cubit'(PDF). Cornell University. Archived(PDF) from the original on 29 October 2008. Retrieved 26 May 2008.
94. ^'Torrent Exchange'. Archived from the original on 5 October 2013. Retrieved 31 January 2010. The torrent sharing feature of BitComet. Bitcomet.com.
95. ^Van Der Sar, Ernesto (4 December 2009). 'Thunder Blasts uTorrent's Market Share Away'. TorrentFreak. Archived from the original on 15 September 2011. Retrieved 15 September 2011.
96. ^'uTorrent Dominates BitTorrent Client Market Share'. TorrentFreak. 24 June 2009. Archived from the original on 3 April 2014. Retrieved 25 June 2013.
97. ^'Windows Public File Sharing Market Share 2015'. opswat. Archived from the original on 14 April 2016. Retrieved 1 April 2016.
98. ^Henry, Alan. 'Most Popular BitTorrent Client 2015'. lifehacker. Archived from the original on 9 April 2016. Retrieved 1 April 2016.
99. ^'Torrent Server combines a file server with P2P file sharing'. Turnkeylinux.org. Archived from the original on 7 July 2012. Retrieved 9 July 2012.
100. ^Anderson, Nate (1 February 2007). 'Does network neutrality mean an end to BitTorrent throttling?'. Ars Technica, LLC. Archived from the original on 16 December 2008. Retrieved 9 February 2007.
101. ^Himabindu Pucha; David G. Andersen; Michael Kaminsky (April 2007). 'Exploiting Similarity for Multi-Source Downloads Using File Handprints'. Purdue University, Carnegie Mellon University, Intel Research Pittsburgh. Archived from the original on 18 June 2013. Retrieved 15 April 2007.
102. ^'Speed boost plan for file-sharing'. BBC News. 12 April 2007. Archived from the original on 7 December 2008. Retrieved 21 April 2007.
103. ^Johnston, Casey (9 December 2008). 'Arstechnica.com'. Arstechnica.com. Archived from the original on 12 December 2008. Retrieved 9 July 2012.
104. ^'Is torrenting safe? Is it illegal? Are you likely to be caught?'. 29 November 2018. Archived from the original on 6 October 2018. Retrieved 5 October 2018.
105. ^'The Piratebay is Down: Raided by the Swedish Police'. TorrentFreak. 31 May 2006. Archived from the original on 16 April 2014. Retrieved 20 May 2007.
106. ^'Technical report: An Estimate of Infringing Use of the Internet'(PDF). Envisional. 1 January 2011. Archived(PDF) from the original on 25 April 2012. Retrieved 6 May 2012.
107. ^'BitTorrent: Copyright lawyers' favourite target reaches 200,000 lawsuits'. The Guardian. 9 August 2011. Archived from the original on 4 December 2013. Retrieved 10 January 2014.
108. ^Albanesius, Chloe (30 April 2012). 'U.K. High Court Orders ISPs to Block The Pirate Bay'. PC Magazine. Archived from the original on 25 May 2013. Retrieved 6 May 2012.
109. ^Adamsky, Florian (2015). 'P2P File-Sharing in Hell: Exploiting BitTorrent Vulnerabilities to Launch Distributed Reflective DoS Attacks'. Archived from the original on 1 October 2015. Retrieved 21 August 2015.
110. ^Bhakuni, A; Sharma, P; Kaushal, R (2014). 'Free-rider detection and punishment in Bit Torrent based P2P networks'. 2014 IEEE International Advance Computing Conference (IACC). International Advanced Computing Conference. p. 155. doi:10.1109/IAdCC.2014.6779311. ISBN978-1-4799-2572-8.
111. ^Berns, Andrew D.; Jung, Eunjin (EJ) (24 April 2008). 'Searching for Malware in Bit Torrent'. University of Iowa, via TechRepublic. Archived from the original on 1 May 2013. Retrieved 7 April 2013.(registration required)
112. ^Vegge, Håvard; Halvorsen, Finn Michael; Nergård, Rune Walsø (2009), 'Where Only Fools Dare to Tread: An Empirical Study on the Prevalence of Zero-Day Malware', 2009 Fourth International Conference on Internet Monitoring and Protection(PDF), IEEE Computer Society, p. 66, doi:10.1109/ICIMP.2009.19, ISBN978-1-4244-3839-6, archived from the original(PDF (orig. work + pub. paper)) on 17 June 2013
113. ^'BitErrant'. biterrant.io. Archived from the original on 19 March 2017. Retrieved 23 April 2017.

Further reading[edit]

• Pouwelse, Johan; et al. (2005). 'The Bittorrent P2P File-Sharing System: Measurements and Analysis'. Peer-to-Peer Systems IV. Berlin: Springer. pp. 205–216. doi:10.1007/11558989_19. ISBN978-3-540-29068-1. Retrieved 4 September 2011.

External links[edit]

• BitTorrent at Curlie
• Unofficial BitTorrent Protocol Specification v1.0 at wiki.theory.org
• Unofficial BitTorrent Location-aware Protocol 1.0 Specification at wiki.theory.org
• Czerniawski, Michal (20 December 2009). 'Responsibility of Bittorrent Search Engines for Copyright Infringements'. SSRN. doi:10.2139/ssrn.1540913. SSRN1540913.Missing or empty url= (help)
• Cohen, Bram (16 February 2005). 'Under the hood of BitTorrent'. Computer Systems Colloquium (EE380). Stanford University.

Servicios Personalizados

• Como citar este artículo

• Citado por SciELO

• Citado por Google
• Similares en SciELO
• Similares en Google

versión On-line ISSN 0718-2724

http://dx.doi.org/10.4067/S0718-27242016000300005

Associations for Disruptiveness - The Pirate Bay vs. Spotify

Bjorn Remneland Wikhamn ¹*, David Knights²

¹ Department of Business Administration, School of Business, Economics and Law, University of Gothenburg, Sweden

² Department of Organization, Work and Technology, Lancaster University Management School, UK
*Corresponding author: bjom.remneland@handels.gu.se

Abstract: Most studies on disruptive innovations adopt technology-centric assumptions when explaining how industries are affected by a technology's creative destruction. This paper argues that the power of a technology lies in how it performatively associates with the cultural and social norms of the wider society. Hence, a technology is not disruptive or sustaining in itself but is potentially a productive outcome of network linkages with other social and material elements. To illustrate this claim, two digital music services will be analyzed, respectively a misfit and a maverick both challenging mainstream providers of music - The Pirate Bay and Spotify - in relation to each other and how they are positioned toward the transformation of the music industry as a whole.

Keywords: Innovation; disruptive technologies; discontinuous innovation; radical innovation; digitalization; translation; Actor Network Theory; music industry; Spotify; The Pirate Bay

Introduction

The idea of disruptive technologies (Christensen, 1997) has been often highlighted in the management and innovation literature in recent years. Much of this theorizing focuses on the 'incumbents' curse' (Chandy & Tellis, 2000; Foster, 1986) and the difficulties for established firms to align to new technological paradigms (Dosi, 1982). Some have directed attention to how firms can manage radical, discontinuous and disruptive innovations in relation to existing internal knowledge structures and processes (Dewar & Dutton, 1986; Ettlie, Bridges, & O'keefe, 1984; McDermott & O'Connor, 2002). Others (e.g. Rogers, 1962; Utterback, 1994) have looked at how novel innovations form distinct diffusion patterns, where critical masses over time have the ability to weed out old regimes through positive feedback loops. Both these directions take the quasi-deterministic stance where the technology is seen to have an innate capacity to transform society and the focus of these authors is simply to record the processes. From this viewpoint, disruptive power is exerted through the technology's inertial force and the medium's way of transmitting its execution in an effective manner.

This article will highlight an alternative framework to explain disruptive outcomes, arguing in line with actor network theory (Callon, 1986, 2007; Callon & Latour, 1981; Latour, 1986) that the disruptive power of a technology is not found merely in its inner core, but rather in how it performatively associates with the cultural and social norms of the wider society. In this sense we need to focus on the numerous and complex ways that certain notions of technology 'are (or fail to be) articulated and mobilized in diverse - academic, consumer, media as well as practitioner - discourses' (Knights, Noble, Vurdubakis, & Willmott, 2002, p. 113). A technology is not in this framework disruptive or sustaining in itself but just often labelled so (Knights & Vurdubakis, 2005) whereas it is more often a productive outcome of a network of enrolled linkages with other social and material elements (Callon, 2007). This actor network theory (ANT) approach is still comparatively rare in the theoretical analyses of disruptive innovation since generally precedence is given either to the material aspects (i.e. technology) or to the social aspects to explain disruptive outcomes (Orlikowski, 2007). Put differently, the most common approaches to innovation take either a technological determinist view where new technologies are seen to disrupt organizational and social routines or a social shaping approach in which it is the cultural and social interpretations of a technology that are seen as instrumental in creating change (MacKenzie & Wajcman, 1999). ANT breaks down this technical - cultural binary to facilitate a socio-material understanding of the enrolment of material artefacts and actors in the mobilisation of alliances that stimulate and sustain change and innovation.

To illustrate the socio-material link in disruptive innovations, two digital music services will be analyzed - The Pirate Bay and Spotify - in relation to each other and also in how they are positioned toward the transformation of the music industry as a whole. Both ventures could be seen as successfully implemented innovations, with the same Swedish geographical roots and performing similar tasks of distributing music to end-users through the application of new digital technology. But as they have gained acceptance among music consumers, the two initiatives have had a very different reception in relation to the dominant incumbents of the music industry. This facilitates a comparative analysis and a nuanced theoretical reflection on the performance of digital technologies in the music industry, and how 'disruptive' innovations rely on elements beyond their technological core (Knights and Vurdubakis, 2005). Indeed, the way digital media is designed but also organized and associated with various other elements poses radically different challenges and implications for the protection and creative development of the music industry.

According to the International Federation of the Phonographic Industry (IFPI), global recorded music revenues fell from US$ 25.1 billion in 2002 to US$ 15.0 billion in 2013 (IFPI, 2014). The industry is often portrayed to be in crisis and the main evil is piracy, facilitated through the 'digital revolution' of peer-to-peer file sharing. Digitalization is repeatedly said to strike hard on creative industries, such as music, film, books, and games, as the non-rivalry of digital goods are able to travel without necessarily taking copyright issues into consideration (Benkler, 2006; Lessig, 2004). 'Digitalization' is thus frequently equated with 'radical' and 'disruptive' movements on the market (Bower & Christensen, 1995). Interestingly, though, despite the decline in overall music revenues, sales through digital services have increased to a US$5.9 billion business in 2013, making up for more than a quarter of the recording companies' current revenues (IFPI, 2014). Far too often, digital media is talked about in overly simplistic terms and lumped together as one technology with generalizable consequences, despite the obvious differences among the plenitude of digital media services emerging (Baym, 2010). Most of them can be seen as new and creative, but are they also inevitably disruptive to the incumbents' market positions in the sense that they challenge the oligopolistic corporate structure of the music industry? We seek to contribute to the debate by providing one possible answer to this question.

Method

The article is mainly conceptual, drawing on actor network theory as a lens through which to examine the organization and disorganization of radical innovation (e.g. digital technologies and peer-2-peer) in the music industry. A comparative case study is utilized to illustrate similarities and differences between radical innovations and their association and/or dissociation with industry incumbents and end-users. Case study research is a well-established method to generate new and empirically valid insights (Abbott, 1992; Eisenhardt, 1989; Eisenhardt & Graebner, 2007; Flyvbjerg, 2006; Stake, 2000). Keeping in mind that case studies do not allow for statistical generalisation, they can still provide analytical generalisation in the transformation of empirical data to theory, rather than to a population (Yin, 1994). Cases can provide good illustrations of dynamic processes played out over time (Siggelkow, 2007) and can generate insights about a particular issue or topic (Stake, 2000), such as the disruptive elements of music innovators.

The two cases in this article - Spotify and The Pirate Bay - as well as the industry as a whole, are all appropriate for the purpose of analysing radical and disruptive innovation. This is due to current transformations that are partly driven by technological advancements but also because of the rather intense rhetorical 'war' between the media corporations and the 'pirates'. The Spotify case represents the 'legal' actor, and the Pirate Bay case represents the 'illegal' actor. Over the years, both services have gained strong positions on the global music market and have taken active roles in transforming music consumption at large. The information about the two cases is based on official documentation in books, blogs, news articles, TV interviews, their websites, court material and through other similar references.

The article is structured as follows; in the first section we examine the literature on radical and disruptive technologies where the predominant model is that of diffusion, which we challenge. The second section explores a theoretical framework that focuses on the sociology of translation as developed by actor network theory. We then turn to our comparative analysis of the two innovations in the use of digital technology in the music industry - the Pirate Bay and Spotify.

Discontinuous, radical and disruptive technologies

Technology is often argued to act as a central force in shaping conditions for organizations and societies (e.g. Dosi, 1982; Solow, 1957; Teece, 1986; Tushman & Anderson, 1986). Much in line with Kuhn's (1965) theories of science, Dosi (1982) introduced the ideas of technology paradigms and technology trajectories to explain continuous and discontinuous change. He suggests that technology evolves through certain trajectories based on taken-for-granted paradigmatic assumptions on possibilities and limitations, which occasionally are being disrupted to form new trajectories (ibid.). Of course, technologies such as the instant communications provided by mobile phones can be simultaneously positive in facilitating innovations in production while disrupting its uninterrupted continuity (Rennecker & Godwin, 2005). As technology advancement is path dependent (Coombs & Hull, 1998), firms develop installed bases (Farrell & Saloner, 1985) and dominant designs (Anderson & Tushman, 1990) with high switching costs in both core capabilities and materialized structures. Schumpeter's (1934) notion of creative destruction points to the proposition that the obsolete must be torn down in order for something new to emerge. Technological innovations, thus, always have a relation to the past if only to be a contrast with that which they supersede.

The type, level and effect of a technology's creative destruction have been portrayed in various ways. Tushman and Anderson (1986) suggest that technology change happens through a cumulative, incremental process until it is punctuated by a major advance, what they call a discontinuous innovation. Such major breakthroughs strongly improve the performance or price level in relation to existing technologies and their advancements are so significant that older technologies cannot compete through greater efficiency, design or economies of scale. Another, highly interrelated, way of distinguishing the degree of innovativeness in relation to incremental change is through so called radical innovation. Ettlie, et al. (1984) argue that innovations are radical when they are new to the firm and to the industry, and/or require substantial and costly changes in the firms processes as well as output. Radical innovations have also been coined as breakthrough inventions (Ahuja & Lampert, 2001) or pioneering innovations (Ali, 1994) or highly innovative products (Kleinschmidt & Cooper, 1991) which are all based on substantial technolgoical advances that offer new technological trajectories and paradigms (Dosi, 1982). Chandy and Tellis (1998) classify innovations along two dimensions; newness of technology and degree of customer need fulfilment per dollar, arguing that incremental innovations are low on both dimensions, while radical innovations are high on both. All these ways of defining the extent to which innovations are radical relate to how they divert from established knowledge and practices.

Abernathy and Clark (1985) argue that major technological shifts can have both creative and destructive effects on the existing industry. Innovations can disrupt the market by introducing new knowledge competences and/or relationships but they can also consolidate existing knowledge competences, linkages and market positions. This view is also repeated by Tushman and Anderson (1986) who characterize technological discontinuities as competence-enhancing or competence-destroying, suggesting that the former builds on embodied know-how in the replaced technology while the latter render the knowledge in existing technologies obsolete. Christensen (1997, p. xv) popularized the term disruptive technologies, arguing that they 'bring to a market a very different value proposition than had been available previously'. Disruptive technologies are often characterized as initially underperforming dominant alternatives in the markets along the dimensions that the mainstream customers currently value. However, over time they will displace the dominant technologies because they offer alternative other features, which customers earlier did not want or were unaware of, but eventually will learn to appreciate. Disruptive technologies are also associated with the displacement of market power, where new entrants tend to weed out previously successful incumbents (Chandy & Tellis, 2000). This could be seen as a specific type of technological change, operating through specific mechanisms and having particular consequences (Danneels, 2004). Disruptive technologies can therefore be understood as acting on different dimensions than radical innovations such that, for instance, 'the radicalness is a technology-based dimension of innovations, and the disruptiveness is a market-based dimension' (Govindarajan & Kopalle, 2006, p. 14). In a sense, this moves the continuum further over so that the opposite of disruptive innovation becomes not incremental but sustaining innovation. As Sandstrõm (2011) has shown, these displacements can take place in both low-end and high-end segments.

Danneels (2004) has raised some further critiques of the notion of disruptive technologies. One such is the problem of defining what a disruptive technology really is (e.g. What are the essential characteristics of a disruptive technology?). For instance, Christensen's early work (Christensen, 1997) focuses on the technology aspect of innovation, while his later work (Christensen & Raynor, 2003) brings in a larger variety of innovation types as potentially disruptive for the incumbent firms. Markides (2006) argues for the importance of separate disruptive business model innovations as opposed to technological innovations since they 'pose radically different challenges for established firms and have radically different implications for managers' Markides (2006, p. 19). Danneels (2004) also points to the challenge of knowing at what exact time a technology becomes disruptive, and for the possibility of applying the theory to ex ante predictions. He urges further research to develop analytical tools for identifying (potentially) disruptive technologies - a call which has been accepted by, for instance, Govindarajan and Kopalle (2006).

Actor Network Theory as a framework to analyse disruption

In challenging the mainstream assumptions about disruptive techno-logies, this article raises questions whether it is possible to find the power of disruptiveness in the technology or the innovation itself. As Latour (Latour, 1986, p. 264) argues, 'power is not something one can possess - indeed it must be treated as a consequence rather than as a cause of action'. By this he separates out power in potentia, that is, something you perceive to 'have', and power in actu, i.e. actual power to enforce. The latter is always dependent on the actions of others rather than some intrinsic characteristics of the sender. Latour's argument is a continuation of Foucault's (1980, 1982) ideas that power is not possessed, but exercised, and that action is always action on the actions of others. Translating this discussion to the field of innovation, technologies can only be considered as disruptive if the surrounding elements act accordingly. True, to a large extent innovators try to inscribe the behaviours of the users (Akrich, 1992), but the intended scripts do often meet with anti-programs and descriptions that are unintended (Latour, 1987).

Callon (1991, 1992) explains the link between the 'social', 'technical' and 'economic' by introducing the concept of techno-economic network as 'a coordinated set of heterogeneous actors which interact more or less successfully to develop, produce, distribute and diffuse methods for generating goods and services' (Callon, 1991, p. 133). For him, the dynamic relationships amongst these actors are being held together through the circulation of intermediaries such as money, artefacts, texts and human beings, and the durability and robustness of these associations determine the success or failure of the innovation. Latour (1986) argues in similar ways, that the power of a token (e.g. an innovation) lies in its ability to hold together associations with other material and non-material elements in durable forms. 'It's not technology that is 'socially shaped', but rather techniques that grant extension and durability to social ties' (Latour, 2005, p. 238). Depending on which elements it succeeds in attracting and stabilizing, the innovation transforms activities and relations in different ways (Callon, 1986). In other words, an actor is a network of relations and it is from these relations that the innovation is perceived. In the making of such process, it is therefore not known whether the outcome will be sustaining or disruptive, and which actors or actants it will transform (Latour, 1996). For ANT, then knowledge and innovation is best understood as a hybrid of objects, social artefacts and discourses that are organized through material and non-material agents mobilised for purposes of securing the actor network, despite continual disruptions and processes of reassembly (Latour, 2005). Callon (1986) introduced four moments of translation; 1) problematization in which the actor is defining the nature and problems of stakeholder groups and making itself an 'obligatory passage point' for providing a good solution; 2) interessement, where the network locks the others into different proposed roles by building physical and mental infrastructures which tie the stakeholder groups to the network; 3) enrolment refers to the negotiations, seductions, argumentations and sometimes force to coordinate the emerging network; and 4) mobilization describes relations that have been strengthened in so far as the allies are (at least temporarily) obedient and opponents silenced, providing the initial actor with power in actu.

To illustrate this alternative framework inspired by the sociology of translation and actor network theory, a comparative case study of two digital music services will now be introduced and analysed in relation to the copyright owners and the music consumers. It demonstrates how the often labelled 'disruptive', radical and discontinuous digital technologies related to music production and distribution have had a creative impact on the music industry and its various stakeholders over the years.

Case comparison

Many new digital services have emerged in the last ten years to take advantage of the 'radical' information technologies in the music industry. MP3.com, Napster, KaZaa, Limewire, BearShare, iTunes, Amazon MP3, Myspace, YouTube, Zune, the PirateBay, LastFM, Spotify, MOG, WiMP, Beats Music, Vevo, Pandora, Deezer and Google Play are only a few of the many actors which have gained much public recognition through information-pull rather than information-push technologies (Duchêne & Waelbroeck, 2006). Some of these ventures act in a grey zone of intellectual property rights (or even clearly overriding them), which have made them official enemies of the big recording companies. The user-friendly, cheap and not easily controlled distribution process brings a perceived threat to actors traditionally earning their profits from exploiting copyright material, in the fear that pirate copies will substitute the purchase of the original and thus reduce company profit. But, as (Baym, 2010, p. 17) argues, 'even as we are concerned with their impact, we must avoid the temptation to look at new media only as a whole. Each of these media, as well as the mobile phone, offers unique affordances, or packages ofpotentials and constraints, for communication'. Pirate Bay and Spotify are two different kinds of these digital music services that illustrate similarities but also differences in how digital music services develop their strategic attempts to make a mark in the industry.

The case ofthe Pirate Bay

The Pirate Bay (TPB) has been known as an open website for indexing so called torrents, i.e. small protocols including metadata for directing the file sharers to digital content. As such it has functioned as a virtual meeting place for exchange of, among others, music files (MP3 and music videos), and has gained much attention among file-sharers as well as in the news media. TPB has over the years often been argued to be the biggest search tool for torrents, with tens of millions of active users and access to more than four billion torrent files.

The site was first launched in 2003 on a server in Mexico, where the Swedish hacker and one of the alleged founders, Gottfrid Svartholm Warg, was then working. The venture had emerged from loose conversations on an IRC channel between him and Fredrik Neij, with the initial idea to build a tracker for local, Swedish material. As the usage expanded also internationally, more hosting capacity was needed and TPB was moved to bigger servers in Sweden in 2004. Peter Sunde, a friend of Neij, also become involved early on in the project. As the most politically active of the three, he became a public spokesperson for the platform (a post he formally left in August 2009). The people behind TPB have from the start been actively involved in the public debate on file-sharing, arguing for the users' right to copy and spread digitalized culture. The logotype of TPB is a pirate ship with set sails. It carries a modification of the Jolly Roger flag, in which the skull is replaced by a cassette band, as an ironic critique to an anti-copyright infringement campaign from the 80s, 'Home Taping Is Killing Music'. On the website, TPB openly published letters from various actors threatening to take legal action against them. They also publish their own replies, which are written with a mixture of scorn, mockery and humour.

TPB was designed to provide a searchable index of torrents. It was built on a software called open tracker, which is one of several free trackers on the market and they are all designed to be fast and to use minimal system resources. A torrent is a small data file with an address to a specific content and a link to all the other users of the same torrent. These torrents can be downloaded from search engines such as TPB, but to activate the link in order to start the actual uploading and downloading, the user needs to have a certain client software (there are many free so called BitTorrent clients on the market). Through this program, the torrent locates other active torrents, to start the file-sharing. A group of users which have activated the same torrent is known as a 'swarm'. As one user begins to download the file, other active users in the swarm can start downloading the finished content from him or her. This makes it a fast and resilient process even for large data files, since it distributes the load to many users. In fact, contrary to when a file is accessible from only one location, this peer-to-peer technology makes the process faster the more users are taking part.

TPB was not designed to allow much social interaction between users, above the actual peer-to-peer sharing of digital content. Possibilities were created for the uploader of the torrent to add information about its content (type, number of files, size, tags, quality, name of songs, artists etc.) to other users, and for other users to give comments on the content and do ratings on its quality. However, very few social cues about the anonymous users were embedded in the system. Members could create individual profiles based on their user names, but this profile only discloses the level of activity in terms of the number of uploads. While limited in the variety of social cues, the profiles provide the opportunity for active users to build a reputation in relation to quantity, quality and newness of their uploaded material. The imputed tag information in the torrents together with the aggregated ratings and possible content comments, may also affect the propensity for new users to download a particular file.

In terms of storage, early on TPB decentralized the location of the actual digitalized content to the participating users' own hard drives. This gives at least three advantages; it reduces the risk of legal threats toward the service (although TPB did face a trial and prosecution in 2009), it makes the peer-to-peer technique more effective, and it provide users total offline access to the material. The fact that the content is downloaded as digital files of standardized formats, it spurs the mobility of the content. Users can easily replicate or convert the files and spread them further - to other users as well as to other types of devices. TPB has been positioned as 'the world's most resilient BitTorrent site' and as such it has a considerable reach, but it does not in any way prohibit or compete with other similar web services. Rather the opposite.

On 31 May 2006, the police made a big raid against TPB, confiscating all its servers. A preliminary investigation was conducted which on January 21 2008 led to Swedish prosecutors filing charges against Neij, Svartholm and Sunde together with the businessman Carl Lundstrõm who owned the company Rix Telecom where TPB servers were hosted in Sweden. All of them were charged with 'promoting other peoples infringements of copyright laws'. In April 2009, they were found guilty to accessory to crime against copyright law by the district court and sentenced to one year in jail each, as well as fines of approximately $3,5 million (30 million SEK) paid to a number of music-, movie- and game corporations. The lawyers of all four defendants appealed the verdict. On 26 November 2010, a Swedish appeals court returned the verdict, decreasing the original prison terms (Neij to 10 months, Sunde to 8 months and Lundstrõm to 4 months) but increasing the fine to 46 million SEK.

The legal process did, however, not totally shut down the website, despite the fact that those initially involved at least officially left the project. Several further setbacks have however occurred since. Following a complaint from the British Phonographic Industry (BPI), on 30^th of April 2012 the High Court in London issued a ruling that six major internet service providers in the UK should block their customers from using TPB site. Similar rulings have since then been taken in numerous other countries such as Belgium, Denmark, Finland, and Italy. Also web services such as Facebook and Microsoft Live Messenger have censored links to the Pirate Bay site. In August 2013, TPB announced the release of a free web browser which enables users to sidestep this type of 'censorship', and there are also numerous other simple ways to circumvent the block that are readily communicated through social networks. In December 2014, the Swedish police raided a web server location in Stockholm which made the TPB site go down. In a few days, several new alternative sites emerged, mirroring the old version of TPB. These forms of hostile actions from the legal system pose a great threat to websites such as TPB, and these actions mainly lead the 'pirates' to start looking for other, more effective alternatives. So despite a loss in the court leading to the closure of the TPB service, there have emerged new innovations and organizing mechanisms, or the enrolment of other actors that have developed less traceable interactions or other ways of commercializing the service. A few months later, the Pirate Bay opened again.

The case of Spotify

Spotify is a music streaming service founded in 2006 by the Swedish entrepreneurs' Daniel Ek and Martin Lorentzon. As summarized on Spotify's homepage in 2010;

Spotify is a new way to listen to music: Any track you like, any time you like. Just search for it in Spotify, then play it. Any artist, any album, any genre - all available instantly. With Spotify, there are no limits to the amount of music you can listen to. Just help yourself to whatever you want, whenever you want it. (2010-10-07)

The service was initially run as a beta version in a smaller invitation-based community until it was officially launched in October 2008. By signing licensing agreements with all the major record label companies, as well as a multitude of independent labels, Spotify positioned itself as a music provider, in contrast to 'piracy' alternatives. From the start the service was available in Sweden, Norway, Finland, Germany, Italy, France, the UK and Spain, but it rather quickly spread to other countries. Starting as a small venture, it has been established as a company with 200 employees and headquarters in the UK. In September 2010 Spotify had a big party in London, celebrating their outreach to10 million users across Europe. At that time, it offered access to a catalogue of more than 10 million tracks. In July 2011, Spotify launched its US service after years of negotiation with the major record companies. In December 2012 the service reached 20 million users with 5 million subscribers, and in January 2015 it had reached 60 million users with 15 million subscribers.

The service is based on a free but proprietary client program which the user needs to download and install, and is therefore not a pure web-based service. From the application, the user can search and play music and also put together own playlists for easy access. Spotify was initially built on a combination of server-based streaming and peer-to-peer technology where users transferred music in peer-to-peer fashion similar to the torrent technology. This technique allowed Spotify to reduce the huge costs for server resources as a startup, but as of the fall 2014, Spotify only stream from own servers. The fact that Spotify uses streaming technology where the music is not downloaded as a whole, makes it more complicated (although not impossible) to replicate and redistribute it to peers. Simultaneously, it gives a high flexibility and mobility for the user since the access to one's favourite playlists can be reached from multiple locations and hardware. For instance, the company launched applications for iPhone and Android mobile systems in 2009 and for Windows Mobile in late 2010, offering users access to their playlists through their mobile phones.

In 2010, Spotify opened up new social dimensions to their music service, as they introduced a function where users can create a profile and publish their playlists of artists and tracks for public view. The profiles in themselves are not including much information and functionality, but by linking them to social websites, such as Face-book, Twitter and Messenger, opened a possibility of sharing music tracks and playlists with peers. Initially, Spotify did not have features for users to communicate directly with each other via the client program, but in April 2013 they released such function. Still, however, Spotify does not allow its users to be directly involved in the development of functionality or content.

Unlike TPB, the users or artists themselves are not allowed to upload any content to the catalogues. This can only be done through the contracts signed with the record label companies or other established artist aggregators. Hence, Spotify retains a tight control over the music content, ensuring that property rights are not being violated. In that sense, Spotify has similarities to iTunes who use Digital Rights Management (DRM) to enforce users to respect copyright laws. But Spotify's streaming technology gives the user instant access to a large music content without needing to download and pay for each song. Spotify have a so called 'freemium' business model, where a base functionality is free for the user (although with advertisements interrupting between tracks), while premium functionality is offered to paid subscribers (approximately 10 euro per month) in terms of commercial-free, higher bit rate streams, access through mobile phone, and offline access to music. According to the license agreements, a proportion of the income streams are handed over to the copyright owners. The major record companies also received shares in Spotify when contracts were signed. The founders, Ek and Lorentzon, have been vocal in the debate about the digital revolution and its effect on the music industry, highlighting that Spotify is a legal alternative to the pirates. In several newspaper interviews, Ek has said that 'Our point of departure is to generate a legal service which can compete directly with the pirate services'. Indeed they seek to brand their offering precisely in opposition to illegal pirates in their internal promotions on the site, to the extent that on the free service, declarations of their being an alternative to pirate sites are as frequent as the commercial adverts. This approach probably helped Spotify to pronounce itself as a Technology Pioneer in the World Economic Forum 2010 and the entrepreneurs behind the web service have several times been collecting entrepreneurship prizes and awards. For instance, Daniel Ek was named by Wired Magazine as the greatest digital influence in Europe in 2014. As of 2012, the CEO and founder Daniel Ek was ranked 395^th on the British rich list with a calculated worth of £190 million.

However, voices have also been raised concerning the inadequacy of the licensing deals with the artists, arguing for a more transparent income process. For instance, in 2009, it was claimed that the superstar Lady Gaga received just $167 from Spotify for her hit 'Poker Face' during a five month period when the song was streamed over a million times. The company then insisted that the money would increase vastly as more subscribers enter and advertising revenues escalate. In 2014, the American country singer Taylor Swift also voiced her critique against Spotify and pulled out her whole catalogue of songs in protest of the size of royalties. Spotify answered in a blog post;

Quincy Jones posted on Facebook that 'Spotify is not the enemy; piracy is the enemy'. You know why? Two numbers: Zero and Two Billion. Piracy doesn't pay artists a penny - nothing, zilch, zero. Spotify has paid more than two billion dollars to labels, publishers and collecting societies for distribution to songwriters and recording artists. A billion dollars from the time we started Spotify in 2008 to last year and another billion dollars since then. (2014-11-11)

The 'disruptiveness' of TPB and Spotify and an actor network analysis

TPB and Spotify are to be considered as 'radical' music services in terms ofhow they have opened up new ways of providing music to the public, and in doing so have challenged the existing business structure in the industry. Both ventures have utilized new digital technologies as a vehicle for music distribution, but TPB and Spotify have different programs-of-actions inscribed in their 'radical' technologies, in line with the purpose of enrolling their different defined stakeholder groups. The technological designs are, thus, closely linked to how each initiative differentiates itself toward the incumbent firms, and how they are constructed to facilitate content and usage of content. This is what Callon (1986) calls interessement, i.e. the process of attracting selected parts of the environment to be mobilized into the venture.

For TPB, the end-users are considered the most relevant social group, and the interessement process is aimed at providing them a platform for sharing material in an easy, free, anonymous and effective way. For these users, the service provider has few restrictions as they do not censor any content or shut down any user accounts. TPB has instead chosen a highly distributed approach for uploading as well as downloading of content. The service is relying solely on user activities, and that is why it is important to involve the interest of the masses of active end-users. Due to its' nowadays millions of users' uploads, the website's search index includes a large variety of material - from the latest top hits to obscure bootlegs and private remixed versions. Of-ten, a huge number of tracks are zipped into one big file, e.g. a collection of albums from one specific artist, a music era or a genre, which escalates the downloading process further. The sound quality can of course also differ, the tag information can be diverted and files may be destroyed or, in a worst-case scenario, infected with a virus. However, since the users' ongoing file-sharing activities are disclosed together with members' comments, preferences and discriminations can guide the seeker to 'good' content in a self-organizing way.

Another potential stakeholder group for TPB is the intellectual property owners of content. In this case, TPB representatives did not put down effort to align the web service in accordance to this group's interests. The website has no compensation structures in place to pay artists, producers, distributers or any other copyright holders. The anti-programs from some of these actors have also been very outspoken as the dominant music industry actors both sue TPB in court and use public media to discredit the website as 'evil pirate'. From the rhetoric of the music industry and the media it is easy to get an impression that all of the material is illegal, but TPB hosts torrents directed toward both copyright- and non-copyright material and it can sometimes be difficult for the file-sharer to know which one is which. To answer the anti-programs of aggressive copyright owners, representatives of TPB earlier replied in a rather ironic and ridiculing language. This language war led to a positioning of the web service as an illegal copyright intruder, but also as a rebellious place for the young generation of music lovers. In fact, it could be argued that the design of the web service is enhancing resilience not only to an effective spread of digital content per se, but also to the shielding of file-sharers with illegal intentions; it is distributed to a large population which makes it difficult to trace and to sort out who is doing what, it is anonymous and accessible from any internet connection, and the interaction with the site is limited to the torrent downloading which is a very short time. The site's name and logo - indicating a calm bay for pirates - also supports this rather deliberate positioning in favour of piracy on almost ideological terms. Hence, the dissociation from the big record labels made them simultaneously one of the most important actants for mobilizing the website. The distributed users embraced to a large extent this 'pirate' position, and continued its 'mission' even after the initial founders were legally stopped by the court. Even for some property owners (predominantly smaller record labels and artists) TPB - with its radical image and effective distribution channels - was appreciated as a means to fight the dominant incumbents of the industry.

While sharing the same problematization of how to access music freely or at economic prices, Spotify differs from TPB both in the range of content it offers but also in the process of interessement through which it mobilizes parts of the environment. Rather than demonize the suppliers of its products, it has mobilized them, the law and advertisers as allies by which it can differentiate itself from those networks such as TPB that alienate suppliers by facilitating the breaching of copyright by users. Spotify has established a gatekeeping authority over the offered material, being an obligatory passage point (Callon, 1986) in deciding which tracks are allowed to be streamed by the users. This makes it possible to secure good sound quality and opens up possibilities to organize the content in a user-friendly way. Context information about the artist and the album can be imputed and changed whenever necessary and related music can be linked making it easy to find new favourites. In addition, because it is not illegal, Spotify is linked to other social media as means of enrolling and mobilizing additional users through its network of existing users. The established licensing agreements with record labels have formed a business model where copyright owners receive income from the activities on Spotify, and through the gatekeeping role it is possible to make sure that no illegal material is accessible. This also means that Spotify can remove access to a streamed track whenever they want, even if the users have bookmarked it in their playlists. The fact that Spotify has proprietary ownership of the technology allows them to support this strategy through Digital Rights Management (DRM) and to continuously upgrade and improve its functionality and copyright protection simultaneously.

Spotify has, hence, several parallel relevant social groups that they need continuously to enrol; (e.g. users, advertisers and content owners). Instead of opposing or ignoring intellectual property issues, the web service has rather utilized the copyright and DRM to accelerate their businesses although the business model operates on two distinct fronts - a free service with restrictions on users extending their network of use to non-internet connections or a subscription service that frees the user from these restrictions as well as from advertising interruptions. While funding the free service comes from advertising, this facilitates enrolment of users by giving them a basic service from which large numbers upgrade. The design of the music service facilitates, in terms of establishing control over content as well as technology, a positioning in direct opposition to the 'evil' pirates. By contrast, Spotify can claim to act as the noble knight who will rescue the confused music industry facing disruptive or destructive aspects of the digital revolution. While TPB can be seen as a service mainly delivering value to the file-sharers, Spotify is balancing the inclinations of various actors as well as mobilizing nonhuman actors in the network; copyright owners are protected from illegal file-sharing and receive new income streams, and users get a well-functioned, user friendly and accessible music service with a large up-to-date music catalogue within the confines of intellectual property.

The comparison between TPB and Spotify suggests that digital music services should not be lumped together into a homogeneous group since they differ on several key technological, organizational and intellectual property dimensions. These aspects are highly linked and congruent for TPB as well as for Spotify and their various combinations position them rather differently in relation to the industry incumbents and to the overall industry development as such. Put differently, their mobilized associations and dissociations to other social and technological elements make up the unique identity and direction of each venture.

From Christensen's (1997) argumentation on sustaining and disruptive innovations, TPB as a macro actor (Callon & Latour, 1981) shows many disruptive aspects. Due to its mobilization of millions of users and the hosting of about 5 million torrent files, TPB can speak with a disdainful or irreverent voice against the established power structures of the music industry. In this way it questions the view of consumers as passive content recipients and the business logic of paying for the carrier (e.g. cassette, LP, CD, DVD) of music. Continuing the journey that predecessors such as Napster and Kazaa started, TPB could be seen as having a transforming potential on the music industry and its enrolment process poses a threat to the big recording firms' oligopolistic structure in a vein not dissimilar to the independent labels' attempts in the 1950s. This is in line with the Schumpeterian (1934) view of entrepreneurship - as a function of creative destruction to the market, enforcing imbalances and opening up new opportunities. Actor network theory, however, provides a more detailed perception on how the creative destruction emerges in practice, as a translation and mobilization process of technical as well as social elements.

Spotify, on the other hand, has aimed to mobilize both the users and the intellectual property owners (including large incumbent music corporations) in parallel. This means a balancing of different proble-matization and interessement activities toward the two stakeholder groups. To users, the focus is put on quality, instant availability and user friendliness - above the fact that it is digital, free(mium) and legal. To content providers, the focus is put on being a new distribution channel to a large customer base through a service safe from illegal use and with a business model in place to protect the income streams of intellectual property owners. In this way, Spotify rather acts as a saviour to the music industry, supporting the big corporations in the war against pirates. And as legal music services such as Spotify are being incorporated into the income streams of large incumbent firms, peer-to-peer and streaming technologies are largely being transformed from a disruptive to a sustaining force.

Despite obvious differences in their associations with social and material elements, TPB and Spotify can be considered as having a symbiotic rather than conflicting relation. Although the Spotify founders speak loudly about pirates as a threat to the music industry, the existence of piracy is in fact one of the strongest door-openers for legal digital music services to be accepted by the dominant market actors. In effect, piracy provides Spotify with the conditions for generating their own legitimacy. Piracy is the unacceptable Other (Derrida, 1982) through which Spotify can secure its existence. In similar ways, TPB partly legitimizes itself as a revolt against the big corporations' power over the passive users. TPB and Spotify are in basic terms performing a similar service - i.e. providing music to a large population of music lovers utilizing 'radical' digital technology - but they have mobilized themselves differently in terms of rhetoric and associations to social and material elements. One of the actors is positioned as the biggest enemy of the established music industry and the other as the Entrepreneur of the year.

Streaming- and peer-to-peer technologies are arguably as radical to the music industry as the phonograph, the radio and the cassette tape recorder was earlier in history. But as the comparison between TPB and Spotify shows, it is not only the 'inner' features of the technologies that define their level of disruptiveness on the behaviours of users or the structure of the market. To an equal degree, it is the associations each venture has developed and maintained with respect to other elements, such as to the acceptance or rejection of the rights of dominant proprietary owners and to the discourses of piracy as good or evil, which energize its impact as a sustaining or disruptive inno-vation. The power of disruption is, hence, to be found in the music service's associations in actu, and will therefore always be up for grabs (Latour, 1986). Associations holding together a disruptive innovation could be strengthened or diminished, depending on how the various actors interact and intersect, but it is not only in the core technology that one will find the answer for what impact a certain initiative will have on the market, what direction it will move in, where it will be displaced. It is much more in the actor networks that are rendered more or less robust through complex relations within and between technological artefacts and socio-political associations.

Conclusion

Inspired by actor network theory, this article suggests an alternative framework for looking at disruptive innovations which challenge the mainstream approaches based on technology-centric and diffusion model-based assumptions. It agrees with previous critiques of the notion of disruption as non-precise and with limited predictive use (Dan & Chieh, 2010; Danneels, 2004; Markides, 2006; Tellis, 2006). What is or isn't a disruptive innovation has not been the main question for this article, but it is arguably important elsewhere to sort out the differences between disruption in terms of altered value proposi-tions, consumption patterns and/or market structures. Regardless of the definition and in contrast to the above critiques of ideas around disruption, however, we argue that the solution to the 'innovator's dilemma' (Christensen, 1997) is not to be found in a further examination of technological features and design, finer categories and classifications, and internal organizational structures and attitudes. Rather, one needs to thoroughly examine and describe the innovation in relation to its processes of establishing obligatory passage points around certain problematization and interests that enrol material and human actors around networks mobilized to a point where alternatives seem implausible or are denied. Hence, the disruptive power of innovation depends on how it succeeds in associating itself with certain cultural, political and social norms.

Determining the disruptive innovations through studying what is already-made rather than its development in the making (Latour, 1987) is rather unproblematic (although not necessarily useful), as all the associations then have been silenced and black-boxed (Callon & Latour, 1981). But we follow the proposition that innovations are travelling ideas (Czarniawska & Joerges, 1996) in continual processes of becoming constituted through associations that they themselves constitute. Here there is no presumption of stability since actor networks can implode as readily as reproduce themselves (Latour, 1986), but it forces analysts as well as network members to move away from a preoccupation with technology per se, and instead to examine more carefully the technology's linkages with social and organizational content in the contexts of innovation management.

For practitioners, to highlight not only the material but also the social, does perhaps not solve the 'incumbent's curse' (Chandy & Tellis, 2000), but it would potentially release the decision makers' energy toward actively enrolling and mobilizing new associations rather than solely protecting the already stabilized ones. Furthermore, the focus on social, economic and technical interactions rather than mainly on technological features illuminates the highly difficult managerial challenge of predictingfuture disruptive threats, as these forms of 'association battles in the making' often lead to unpredictable outcomes and unforeseen consequences (Callon & Law, 1982). It also facilitates the understanding that a technology's potential for disruption resides as much with followers as with inscribers (Latour, 1987) - including the industry actors (i.e. producers), but more so the users (including 'pirating' music lovers).

References

Abbott, A. (1992). What do cases do? Some notes on activity in sociological analysis. In C. C. Ragin & H. S. Becker (Eds.), What is a case? Exploring the foundations of social inquiry (pp. 53-82). Cambridge: Cambridge University Press. [ Links ]

Abernathy, W., & Clark, K. (1985). Innovation: Mapping the winds of creative destruction. Research Policy, 14(1), 3-22. [ Links ]

Ahuja, G., & Lampert, M. C. (2001). Entrepreneurship in the large corporation: A longitudinal study of how established firms create breakthrough inventions. Strategic Management Journal, 22(6-7), 521-543. [ Links ]

Akrich, M. (1992). The DeScription of Technical Objects. In W. E. Bijker & J. Law (Eds.), Shaping Technology/Building Society: Studies in Sociotechnical Change (pp. 205-224). Cambridge, Mass.: MIT Press. [ Links ]

Ali, A. (1994). Pioneering versus incremental innovation: review and research propositions. Journal of Product Innovation Management, 11(1), 46-61. [ Links ]

Anderson, P., & Tushman, M. (1990). Technological Discontinuities and Dominant Designs: A Cyclical Model of Technological Change. Administrative Science Quarterly, 35 (4), 604-633. [ Links ]

Baym, N. (2010). Personal Connections in the Digital Age. Cambridge; Malden, MA: Polity Press. [ Links ]

Benkler, Y. (2006). The Wealth of Networks: How Social Production Transforms Markets and Freedom. New Haven: Yale University Press. [ Links ]

Bower, J., & Christensen, C. (1995). Disruptive Technologies: Catching the Wave. Harvard Business Review, 73, 43-53. [ Links ]

Callon, M. (1986). Some Elements of a Sociology of Translation: Domestication of the Scallops and the Fishermen of St Brieuc Bay. In J. Law (Ed.), Power, Action and Belief (pp. 196-233). London, Boston and Henley: Routledge & Kegan Paul. [ Links ]

Callon, M. (1991). Techno-economic Networks and Irreversibility. In J. Law (Ed.), A Sociology of Monsters: Essays on Power, Technology and Domination (pp. 132-161). London: Routledge. [ Links ] Installer user interface mode not supported rtmt.

Callon, M. (1992). The Dynamics Of Techno-Economic Networks. In R. Coombs, P. Saviotti & V. Walsh (Eds.), Technological Change and Company Strategy (pp. 72-102). San Diego: Academic Press Inc. [ Links ]

Callon, M. (2007). What does it Mean to Say That Economics Is Performative? In D. A. MacKenzie, F. Muniesa & L. Siu (Eds.), Do Economists Make Markets? On the Performativity of Economics (pp. 311–357). Princeton: Princeton University Press. [ Links ]

Callon, M., & Latour, B. (1981). Unscrewing the Big Leviathan or How to do Actors Macrostructure Reality and How Sociologists Help Them Do So. In K. Knorr & A. Cicourel (Eds.), Advances in Social Theory and Methodology: Toward an Integration of Micro and Macro Sociologies (pp. 277-303). London: Routledge & Kegan Paul. [ Links ]

Callon, M., & Law, J. (1982). On Interest and Their Transformation: Enrolment and Counter-Enrolment. Social Studies of Science, 12(4), 615-625. [ Links ]

Chandy, R. K., & Tellis, G. J. (1998). Organizing for Radical Product Innovation: The Overlooked Role of Willingness to Canibalize. Journal of Marketing Research, 35(4), 474-487. [ Links ]

Chandy, R. K., & Tellis, G. J. (2000). The Incumbent's Curse? Incumbency, Size, and Radical Product Innovation. The Journal of Marketing, 64(3), 1-17. [ Links ]

Christensen, C. (1997). The Innovator's Dilemma: When New Technologies Cause Great Firms to Fail. Boston: Harvard Business School Press. [ Links ]

Christensen, C., & Raynor, M. (2003). The Innovator's Solution: Creating and Sustaining Successful Growth. Boston: Harvard Business School Press. [ Links ]

Coombs, R., & Hull, R. (1998). 'Knowledge management practices' and path-dependency in innovation. Research Policy, 27(3), 239-256. [ Links ]

Czarniawska, B., & Joerges, B. (1996). Travels of Ideas. In B. Czarniawska & G. Sevón (Eds.), Translating Organizational Change (pp. 13-48). Berlin: de Gruyter. [ Links ]

Dan, Y., & Chieh, H. (2010). A Reflective Review of Disruptive Innovation Theory. International Journal of Management Reviews, 12(4), 435-452. [ Links ]

Danneels, E. (2004). Disruptive technology reconsidered: A critique and research agenda. Journal of Product Innovation Management, 21(4), 246-258. [ Links ]

Derrida, J. (1982). Margins of Philosophy. Chicago: Universithy of Chicago Press. [ Links ]

Dewar, R., & Dutton, J. (1986). The adoption of radical and incremental innovations: an empirical analysis. Management Science, 32(11), 1422-1433. [ Links ]

Dosi, G. (1982). Technological paradigms and technological trajectories : A suggested interpretation of the determinants and directions of technical change. Research Policy, 11(3), 147-162. [ Links ]

Duchêne, A., & Waelbroeck, P. (2006). The Legal and Technological Battle in the Music Industry: Information-Push versus Information- Pull Technologies. International Review of Law and Economics, 26(4), 565-580. [ Links ]

Eisenhardt, K. (1989). Building Theory from Case Study Research. Academy of management Review, 14(4), 532-550. [ Links ]

Eisenhardt, K., & Graebner, M. (2007). Theory building from cases: Opportunities and challenges. Academy of Management Journal, 50(1), 25-32. [ Links ]

Ettlie, J. E., Bridges, W. P., & O'keefe, R. D. (1984). Organization strategy and structural differences for radical versus incremental innovation. Management Science, 30(6), 682-695. [ Links ]

Farrell, J., & Saloner, G. (1985). Standardization, Compatibility, and Innovation. Rand Journal of Economics, 16(1), 70-83. [ Links ]

Flyvbjerg, B. (2006). Five misunderstandings about case-study re search. Qualitative inquiry, 12(2), 219-245. [ Links ]

Foster, R. N. (1986). Innovation: The attacker's advantage. New York: McKinsey. [ Links ]

Foucault, M. (1980). Power/Knowledge: Selected Interviews and other Writings 1972-77. London: Tavistock. [ Links ]

Foucault, M. (1982). The Subject and Power. In H. L. Dreyfus & P. Rabinow (Eds.), Beyond Structuralism and Hermeneutics (pp. 208-226). Brighton, Sussex: Harvester Press. [ Links ]

Govindarajan, V., & Kopalle, P. (2006). The Usefulness of Measuring Disruptiveness of Innovations Ex Post in Making Ex Ante Predictions*. Journal of Product Innovation Management, 23(1), 12-18. [ Links ]

IFPI. (2014). Digital Music Report 2014. In. [ Links ]

Kleinschmidt, E. J., & Cooper, R. G. (1991). The impact of product innovativeness on performance. Journal of Product Innovation Mana gement, 8(4), 240-251. [ Links ]

Knights, D., Noble, F., Vurdubakis, T., & Willmott, H. (2002). Allegories of Creative Destruction: Technology and Organisation in Narratives of the e-Economy. In S. Woolgar (Ed.), Virtual Society? Technology, Cyberbole, Reality (pp. 99–114). Oxford: Oxford University Press. [ Links ]

Knights, D., & Vurdubakis, T. (2005). Editorial: Information technology as organization/disorganization. Information and Organization, 15(3), 181-184. [ Links ]

Kuhn, T. S. (1965). The Structure of Scientific Revolutions. Chicago: Phoenix books. [ Links ]

Latour, B. (1986). The Powers of Association. In J. Law (Ed.), Power, Action and Belief (pp. 264-280). London, Boston and Henley: Routledge & Kegan Paul. [ Links ]

Latour, B. (1987). Science in Action: How to Follow Scientists and Engineers through Society. Cambridge: Harvard Univ. Press. [ Links ]

Latour, B. (1996). Aramis or the Love of Technology. Cambridge; London: Harvard University Press. [ Links ]

Latour, B. (2005). Reassembling the Social: An Introduction To Actor- Network-Theory. Oxford; New York: Oxford University Press. [ Links ]

Lessig, L. (2004). Free Culture: How Big Media Uses Technology and the Law to Lock Down Culture and Control Creativity. New York: Penguin. [ Links ]

MacKenzie, D. A., & Wajcman, J. (1999). The Social Shaping of Technology. Buckingham and Philadelphia: Open University Press. [ Links ]

Markides, C. (2006). Disruptive Innovation: In Need of Better Theory*. Journal of Product Innovation Management, 23(1), 19-25. [ Links ]

McDermott, C., & O'Connor, G. (2002). Managing radical innovation: an overview of emergent strategy issues. Journal of Product Innovation Management, 19(6), 424-438. [ Links ]

Orlikowski, W. J. (2007). Sociomaterial Practices: Exploring Technology at Work. Organization Studies, 28(9), 1435-1448. [ Links ]

Rennecker, J., & Godwin, L. (2005). Delays and interruptions: A self- perpetuating paradox of communication technology use. Information and Organization, 15(3), 247-266. [ Links ]

Rogers, E. M. (1962). Diffusion of Innovations. New York: Free Press of Glencoe. [ Links ]

Sandström, C. (2011). High-end disruptive technologies with an inferior performance. International Journal of Technology Management, 56(2-4), 109-122. [ Links ]

Schumpeter, J. A. (1934). The Theory of Economic Development: An Inquiry Into Profits, Capital, Credit, Interest, and the Business Cycle. Cambridge: Harvard University Press. [ Links ]

Siggelkow, N. (2007). Persuasion with case studies. Academy of Management Journal, 50(1), 20-24. [ Links ]

Solow, R. M. (1957). Technical Change and the Aggregate Production Function. The Review of Economics and Statistics, 39(3), 312-320. [ Links ]

Stake, R. (2000). Case Studies. In N. Denzin & Y. Lincoln (Eds.), Handbook of Qualitative Research (Vol. 2, pp. 435-454). Thousand Oaks, CA: Sage. [ Links ]

Teece, D. J. (1986). Profiting from technological innovation: Implications for integration, collaboration, licensing and public policy. Research Policy, 15(6), 285-305. [ Links ]

Tellis, G. J. (2006). Disruptive Technology or Visionary Leadership? Journal of Product Innovation Management, 23(1), 34-38. [ Links ]

Tushman, M. L., & Anderson, P. (1986). Technological Discontinuities and Organizational Environments. Administrative Science Quarterly, 31(1), 439-465. [ Links ]

Utterback, J. M. (1994). Mastering the dynamics of innovation. Boston: Harvard Business School Press. [ Links ]

Yin, R. (1994). Case Study Research: Design and Methods (Vol. 5). Thousand Oaks, CA: Sage Publications. [ Links ]

Submitted: May 27th 2016 / Approved: September 11th 2016