User-Centered Social Software – Beyond Closed Community Platforms Vanda Lehel, Florian Matthes, Sheng Wei Technical Report Technische Universität München Lehrstuhl Software Engineering betrieblicher Informationssysteme Boltzmannstrasse 3 85748 Garching bei München {lehel, matthes, weis}@in.tum.de Abstract: This paper gives a structural overview of social software and its use for content aggregation and publication. We then extend this view to a user-centered perspective. We propose a lightweight XML-based content syndication architecture. It supports bidirectional information flow, as a proper extension and unification mechanism to facilitate the usage of several social software systems at once. Finally, we explain technical requirements based on usage scenarios and discuss benefits and limitations of this architecture. 1. Introduction and Motivation The newly emerging class of social software facilitates interaction and collaboration among individuals. It allows individuals to form different communities to connect or to collaborate with each other based on their social context. Different types of systems and services like instant messaging, internet relay chat, forums, wikis, weblogs, social networking services, and object-centered social software are examples of this category of software [Burg05]. In the aforementioned cases, XML networking plays an essential role in two ways: XML is the payload and XML is part of the protocol [MD04]. XML is widely used in social software since it is self-describing and also due to its strengths concerning interoperability, reuse, flexibility, and extensibility. The join between the ubiquitous HTTP protocol and XML gives rise to several new kinds of network protocols and architectures in the area of social software. The usage of XML-technologies by social software will be explained in detail in chapter 2. In recent years, centralized software systems like information portals have long been in use for communication, collaboration and knowledge management purposes throughout enterprises and institutions. In this centralized architecture all information is managed at a single location and can be accessed by users role-based and device-independently. In contrast, the use of social software implies the membership of a user on different community platforms in several social contexts. This results in a distributed architecture of all personally published and available information. For accessing this information, already many XML-based protocols and proprietary formats for content syndication and information exchange exist, but there is a lack of a unified mechanism to interoperate with different systems. Thus, it is difficult to achieve a user-centered integrated view on all available information. We address this problem by proposing in this paper an emerging form of information collecting, sharing and publishing also referred to as a user-centered social software system with an appropriate content syndication architecture. In chapter 2, we present the fundamental concepts of the relevant kinds of social software systems and the XML-technologies they use. We then introduce the idea of user-centered social software in chapter 3. Chapter 4 explains our approach for an XML- based lightweight content syndication architecture and discusses it by means of current popular social software-related technologies. The paper concludes with a discussion of the benefits and limitations and an outlook on future research work. 2. Fundamental Concepts and XML-Technologies of Social Software The use of XML-technologies has been established for several purposes in representing and exchanging resources managed by social software. In the succeeding sections, relevant concepts and functions of weblogs, social networking services, and object- centered social software are explained along with their related XML-technologies. 2.1 Weblogs “Weblogging” is a common practice in social software to easily publish personal knowledge and information on the Web displayed in reverse chronological order as postings. The latter can be commented on by other internet users. The popularity of weblogs results from the quality content that is found in them in spite of the absence of centralized control [Paqu03] and from the immediate reflection of ownership. Besides that, weblog-related technologies foster selective syndication of published content and social networking among people. In fact, users intend to share more personal information if they can have similar control over their published content like if they managed it on their personal devices [LMS03]. Collections of postings and comments of a weblog can be made available as items of RSS feeds. Originally, RSS is an XML-based news syndication format (see [RSS05]) that can also be used for the exchange of other content types, like postings in this case. With RSS Enclosure, multimedia content can be embedded in the items as well. Then, other users can subscribe to the RSS feeds of their favorite weblogs (e.g. using special client tools, like feed readers) and remain up-to-date about the latest content by notification mechanisms. Another popular content syndication format for weblogs is Atom, see [Atom05] for details. For the exchange of hierarchically structured resources also XML-based formats like OPML [OPML05] exist. Pingbacks [Ping05] provide a mechanism for the owner of a weblog to be notified about comments to his weblog in external systems (remote commenting) using an XML-based representation format. Trackbacks address the same issue based on the concept of pingbacks and extending it by details about the remote comment and an URI of the referenced posting. Therefore, these mechanisms deal with linking together related content from different systems by using XML-technologies. Moreover, weblog community systems usually offer Weblog APIs to allow users posting to their weblogs using client tools instead of creating each posting manually by visiting the weblog. Popular examples include the Blogger API [Blog05] and the Atom API [Atom05]. 2.2 Social Networking Services Social networking services provide the opportunity to explicitly build up and manage contact relationships between individuals on a community platform. Well-established examples of social networking services are Linkedln [Link05] in the USA and OpenBC [Open05] in Europe, both widely used for managing business contacts. The main value for their members lies in viewing the path of indirect contacts leading to any other community member. Research based on social networks, i.e. social network analysis, focuses on mapping and measuring relationships and information flows between community members and other information/knowledge processing entities [WF94]. The limitation of social networking services as contact management tools becomes apparent if individuals are considered as members of different communities. Information exchanging and collaborating between different networks are difficult to achieve. An approach to address this problem is the XML-based FOAF [FOAF05] format to represent relationships between contacts and thereby describe the structure of the social network of an individual. 2.3 Object-Centered Social Software Object-centered social software is another class of online community platforms that focuses on allowing users to store, categorize and share a personal collection of objects. The term “objects” can be interpreted as different types of content like bookmarks of web pages, bibliographic references, multimedia files etc. Unlike traditional formal methods of taxonomic classification, freely chosen keywords by different users are used for collaborative categorization. This practice is called “Folksonomy” or “tagging”. The keywords (tags) chosen by a member represent shared metadata and context information about this user in the community. Widely adopted communities are Del.icio.us [Deli05] for bookmark sharing, CiteULike [Cite05] for bibliographic reference sharing and 43things [Fort05] for task sharing. In contrast to social networking services, object-centered social software tries to group people around shared objects, such as photos in Flickr [Flic05]. In [HHLS05] an overview is given about the motivations for tagging: it is essential to consider who is the tag creator and who is the tag user. For example, Flickr users normally manage their collection of photos for private use, while members of community systems like Del.icio.us tend to use collections of references from other users. From these usage patterns of shared context in a community different kinds of social networks are built implicitly around shared objects. For administrative purposes, these systems also offer proprietary APIs similar to the Weblog APIs (section 2.1) like the Flickr API [Flickr05a]. 3 User-Centered Social Software Based on social software we propose an extension of personal information management (PIM) with an emphasis on social community platforms. Therefore, we define the new class of user-centered social software as a client software for organizing information in a social way, that is in the social context of a user. We call this kind of client software a social organizer. 3.1 User-Centered Social Software as an Extension of Personal Information Management In figure 1, a view on user-centered social software as an extension of PIM is shown. There, we depict a three-faceted view of content, context and contact that are managed using individual desktop tools, like text editing and image editing tools, feed reader or