Tripcom - Triple Space Communication. This is the official website of the Specific target research project tripcom. tripcom is to be funded by the european commission under the 6th framework programme, priority 2 information society technologies (IST) under the project number IST-4-027324-STP
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Description of Work

The visionary approach of Triple Space Communication is based on the insight that Web Services do not follow the Web paradigm of 'persistently publish and read'. This approach is clear when Web pages are analyzed. Anybody can define a Web page persistently and publish it at an Internet service provider or at a server at home or at work (this is usually done with help of Web servers). Publication means that the Web page is made accessible by anybody who knows the URI of that Web page and has a Web browser to display it. Persistent publication means that the Web page does not get lost in case of power or network failures. Once the power is back on or the network link is re-established, the Web page is available again and unmodified compared to its content before the failure. Reading a Web page means to retrieve the Web page from the Web server by typing in the URI into a browser bar and requesting the display of it. Both, the publication and the reading can be done independently of each other, i.e., asynchronously. [Fensel, 2004] proposes to follow exactly this paradigm for the communication of data between software systems across the Internet: publish the data persistently and make it available for reading it. The location for storing and accessing data is called triple space, and, as it will be later introduced, it is a virtual storage location.

Instead of following the 'persistently publish and read' paradigm, many Web Services based on the Web Service Definition Language (WSDL) and the SOAP require a synchronous Hypertext Transfer Protocol (HTTP) connection to transmit data transparently bypassing the power of the Web paradigm. This means that many Web Services require the sender and receiver of data to have a tight same-time synchronous connection, to agree on the data format, to know each other and share a common representation. However, there are several attempts to provide asynchronous communication to Web Services like substituting HTTP by Simple Mail Transfer Protocol (SMTP),WS-Addressing, WS-Notification and WS-Eventing. In this document, we will introduce Triple Space computing as a new alternative to achieve persistent asynchronous communication for Web Services.

Triple Space computing establishes the mechanism to publish communication data according to the Web paradigm of 'persistently publish and read' and in this way TripCom brings machine-to-machine Web Service communication to the Web in its real sense: 'Web' Services. Moreover, Triple Space computing follows the same goals for the Semantic Web services as the Web for humans: re-define and expand current communication paradigm (cf. Fig. 1). Triple Space is the necessary communication infrastructure where Semantic Web and Semantic Web services will become true. As was pointed out: "Triple Space may become the web for machines as the web based on HTML became the Web for humans".

Triple Space is based on the evolution and integration of several well-known technologies such as Tuple Space Computing, Shared Object Space, Persistent Message-based Architecture , and RDF.

This has several benefits. The provider of data can publish it at any point in time (time autonomy), independent of it internal storage (location autonomy), independent of the knowledge about potential readers (reference autonomy):

  • Processes communicating with each other do not need to know explicitly of each other. They exchange information by writing and reading tuples from the tuples pace; they do not need to set up an explicit connection, i.e., reference-wise the processes are completely de-coupled.
  • Processes that interact through Triple Space do not need to be up at the same time, i.e. time-wise the processes are partially de-coupled.
  • Processes can run in completely different computational environments as long as both can make access to the same Tuple Space, i.e., space-wise the processes are completely de-coupled.

This decoupling has obvious design advantages for defining reusable, distributed, heterogeneous, and quickly changing applications as promised by Web services technology. Also, complex interaction patterns of current Web services technology will boil down to a read and write operation in a ace. It is worth to note that a service paradigm based on the Tuple Space paradigm also revisits the web paradigm; information is persistently written on a global place where other processes can smoothly access it without starting a cascade of message exchanges.

One of the important goals is to bring Triple Spaces to an Internet-scale level. This means that any number of data providers and readers can write and read communication data across the whole Internet. Like in the case of Web pages, there should be no limitation in principle: the architecture is independent of system properties like response-time and throughput. The limitations that exist come only through the technology used. In order to become Internet-scalable, TripCom is based on proven technology and their combination. We will study the applicability of HTTP protocol and the Resource Description Framework (RDF) technology and commercially available storage components like databases or file systems. In that regard, exactly the same technology is used as in case of (Semantic) Web pages.

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EC 6th Framework Programme, Information Society Technologies (IST)
project number: IST-4-027324-STP