The CSCW group at the German National Research Centre for Computer Science (GMD FIT.CSCW) has been developing collaborative systems for over 10 years. Since October 1994, the Basic Support for Cooperative Work project (BSCW) has been investigating the suitability of the World-Wide Web (W3) as an enabling technology, which can be extended with flexible and lightweight mechanisms to support cooperative work. Our efforts to date have yielded the BSCW Shared Workspace system - an extended W3 server which provides basic facilities for collaborative information sharing, activity awareness, and external application integration across Macintosh, PC and Sun platforms .
The BSCW Shared Workspace system was conceived as an alternative to tools which currently support collaborative working between widely-dispersed participants, such as electronic mail and ftp. Such systems are effective in supporting the exchange of information, but provide little help for true information sharing, where the context in which information is provided and modified is supported and presented by the system to cooperating users. As such, the BSCW shared workspace integrates the simple facilities found in ftp - namely the storage and retrieval of documents - with more sophisticated features such as member administration, a check-in/out facility, access to meta-information about documents and members, and a simple event service with which users are kept informed, at-a-glance, of changes in the status of information in the workspace. These facilities are provided by an extended HTTP server , integrated with a simple object database, and can be accessed using any standard W3 client on a number of different platforms. Where additional client-side functionality is required, (as is the case for example with local file browsers for adding documents to a workspace), this has been realised as client-specific 'helper applications'.
In the proposed presentation, we will describe and demonstrate the design and implementation of the BSCW Shared Workspace system. For the most part, this has involved extension of the NCSA HTTP daemon through the standard CGI interface, but has also required some modification of the server itself. We will describe these modifications, such as the implementation of the PUT protocol to support document transmission to a W3 server, and the extension of the logging facilities most servers provide, and explain the need for such basic modifications when considering the implementation of systems to support collaborative work. Based on our experiences gained over the last year of working with W3, we will also discuss the suitability of the stateless HTTP protocol, the HTML mark-up language, and the general central-server W3 architectural model for realising collaborative applications. Finally we will highlight some current trends in W3 development which potentially address some of the current problems with W3 as a basis for development of more powerful CSCW systems - most notably the potential for client side execution and inter client communication offered by the Java interpreter, already supported in Sun's HotJava client and soon to be integrated with the Netscape navigator.
 The current version of the BSCW Shared Workspace system is an extension of the NCSA HTTP 1.4.2 daemon