The Social Semantic Web Bearbeitet von John Breslin, Alexandre Passant, Stefan Decker 1. Auflage 2009. Buch. IX, 300 S. Hardcover ISBN 978 3 642 01171 9 Format (B x L): 15,5 x 23,5 cm Gewicht: 1360 g Weitere Fachgebiete > EDV, Informatik > Informatik > Natürliche Sprachen & Maschinelle Übersetzung schnell und portofrei erhältlich bei Die Online-Fachbuchhandlung beck-shop.de ist spezialisiert auf Fachbücher, insbesondere Recht, Steuern und Wirtschaft. Im Sortiment finden Sie alle Medien (Bücher, Zeitschriften, CDs, eBooks, etc.) aller Verlage. Ergänzt wird das Programm durch Services wie Neuerscheinungsdienst oder Zusammenstellungen von Büchern zu Sonderpreisen. Der Shop führt mehr als 8 Millionen Produkte. 2 Motivation for applying Semantic Web technologies to the Social Web Many will have become familiar with popular Social Web applications such as blogging, social networks and wikis, and will be aware that we are heading towards an interconnected information space (through the blogosphere, in- ter-wiki links, mashups, etc.). At the same time, these applications are experi- encing boundaries in terms of information integration, dissemination, reuse, portability, searchability, automation and more demanding tasks like query- ing. The Semantic Web is increasingly aiming at these applications areas - quite a number of Semantic Web approaches have appeared in recent years to overcome the boundaries in these application areas, e.g. semantic wikis (Semantic MediaWiki), knowledge networking (Twine), embedded microcon- tent detection and reuse (Operator, Headup, Semantic Radar), social graph and data portability APIs (from Google and Facebook), etc. In an effort to consolidate and combine knowledge about existing efforts, we aim to educate readers about Social Web application areas and new avenues open to com- mercial exploitation in the Semantic Web. We shall give an overview of how the Social Web and Semantic Web can be meshed together. 2.1 Web 2.0 and the Social Web One of the most visible trends on the Web is the emergence of the Web 2.0 tech- nology platform. The term Web 2.0 refers to a perceived second-generation of Web-based communities and hosted services. Although the term suggests a new version of the Web, it does not refer to an update of the World Wide Web techni- cal specifications, but rather to new structures and abstractions that have emerged on top of the ordinary Web. While it is difficult to define the exact boundaries of what structures or abstractions belong to Web 2.0, there seems to be an agreement that services and technologies like blogs, wikis, folksonomies, podcasts, RSS feeds (and other forms of many-to-many publishing), social software and social networking sites, web APIs, web standards1 and online web services are part of Web 2.0. Web 2.0 has not only been a technological but also a business trend: ac- cording to Tim O’Reilly2: ‘Web 2.0 is the business revolution in the computer in- 1 http://www.webstandards.org/ (URL last accessed 2009-06-09) 2 http://radar.oreilly.com/archives/2006/12/web-20-compact.html (accessed 2009-06-09) J.G. Breslin et al., The Social Semantic Web, DOI 10.1007/978-3-642-01172-6_2, © Springer-Verlag Berlin Heidelberg 2009 12 The Social Semantic Web dustry caused by the move to the Internet as platform, and an attempt to under- stand the rules for success on that new platform’. Social networking sites such as Facebook (one of the world’s most popular SNSs), Friendster (an early SNS previously popular in the US, now widely used in Asia), orkut (Google’s SNS), LinkedIn (an SNS for professional relationships) and MySpace (a music and youth-oriented service) - where explicitly-stated networks of friendship form a core part of the website - have become part of the daily lives of millions of users, and have generated huge amounts of investment since they began to appear around 2002. Since then, the popularity of these sites has grown hugely and continues to do so. (Boyd and Ellison 2007) have described the history of social networking sites, and suggested that in the early days of SNSs, when only the SixDegrees service existed, there simply were not enough users: ‘While people were already flocking to the Internet, most did not have extended networks of friends who were online’. A graph from Internet World Stats3 shows the growth in the number of Internet users over time. Between 2000 (when SixDegrees shut down) and 2003 (when Friendster became the first successful SNS), the number of Internet users had doubled. Web 2.0 content-sharing sites with social networking functionality such as YouTube (a video-sharing site), Flickr (for sharing images) and Last.fm (a music community site) have enjoyed similar popularity. The basic features of a social networking site are profiles, friend listings and commenting, often along with other features such as private messaging, discussion forums, blogging, and media uploading and sharing. In addition to SNSs, other forms of social websites include wikis, forums and blogs. Some of these publish content in structured formats ena- bling them to be aggregated together. A common property of Web 2.0 technologies is that they facilitate collabora- tion and sharing between users with low technical barriers – although usually on single sites (e.g. Technorati) or with a limited range of information (e.g. RSS, which we will describe later). In this book we will refer to this collaborative and sharing aspect as the ‘Social Web’, a term that can be used to describe a subset of Web interactions that are highly social, conversational and participatory. The So- cial Web may also be used instead of Web 2.0 as it is clearer what feature of the Web is being referred to4. The Social Web has applications on intranets as well as on the Internet. On the Internet, the Social Web enables participation through the simplification of user contributions via blogs and tagging, and has unleashed the power of community- based knowledge acquisition with efforts like Wikipedia demonstrating the collec- tive ‘wisdom of the crowds’ in creating the largest encyclopaedia. One outcome of such websites, especially wikis, is that they can produce more valuable knowledge collectively rather than that created by separated individuals. In this sense, the So- cial Web can be seen as a way to create collective intelligence at a Web-scale 3 http://www.internetworldstats.com/emarketing.htm (URL last accessed 2009-06-09) 4 http://en.wikipedia.org/wiki/Social_web (URL last accessed 2009-06-09) 2 Motivation for applying Semantic Web technologies to the Social Web 13 level, following the ‘we are smarter than me’ principles5 (Libert and Spector 2008). Similar technologies are also being used in company intranets as effective knowledge management, collaboration and communication tools between employ- ees. Companies are also aiming to make social website users part of their IT ‘team’, e.g. by allowing users to have access to some of their data and by bringing the results into their business processes (Tapscott and Williams 2007). 2.2 Addressing limitations in the Social Web with semantics A limitation of current social websites is that they are isolated from one another like islands in the sea (Figure 2.1). For example, different online discussions may contain complementary knowledge and topics, segmented parts of an answer that a person may be looking for, but people participating in one discussion do not have ready access to information about related discussions elsewhere. As more and more social websites, communities and services come online, the lack of interop- erability between them becomes obvious. The Social Web creates a set of single data silos or ‘stovepipes’, i.e. there are many sites, communities and services that cannot interoperate with each other, where synergies are expensive to exploit, and where reuse and interlinking of data is difficult and cumbersome. The main reason for this lack of interoperation is that for most Social Web ap- plications, communities, and domains, there are still no common standards for knowledge and information exchange or interoperation available. RSS (Really Simple Syndication), a format for publishing recently-updated Web content such as blog entries, was the first step towards interoperability among social websites, but it has various limitations that make it difficult to be used efficiently in such an interoperability context, as we will see later. Another extension of the Web aims to provide the tools that are necessary to define extensible and flexible standards for information exchange and interopera- bility. The Scientific American article (Berners-Lee et al. 2001) from Berners-Lee, Hendler and Lassila defined the Semantic Web as ‘an extension of the current Web in which information is given well-defined meaning, better enabling com- puters and people to work in cooperation’. The last couple of years have seen large efforts going into the definition of the foundational standards supporting data interchange and interoperation, and currently a quite well-defined Semantic Web technology stack exists, enabling the creation of defining metadata and associated vocabularies. 5 http://www.wearesmarter.org/ (URL last accessed 2009-06-09) 14 The Social Semantic Web i ii iii iv Fig. 2.1. Creating bridges between isolated communities of users and their data6 A number of Semantic Web vocabularies have achieved wide deployment – successful examples include RSS 1.0 for the syndication of information, FOAF, for expressing personal profile and social networking information, and SIOC, for interlinking communities and distributed conversations. These vocabularies share a joint property: they are small, but at the same time vertical – i.e. they are a part of many different domains. Each horizontal domain (e.g. e-health) would typically reuse a number of these vertical vocabularies, and when deployed the vocabularies would be able to interact with each other.