The DIME project is a subproject of the strategic university programme Distributed and Parallel Systems (DOPS). DOPS receives funding from the Norwegian Science Council (NFR). The duration of the funding from NFR is Jan 1996 - Dec 1998. DIME focuses on the development of abstractions and architecture services of distributed object management systems supporting distributed multimedia applications in heterogeneous environments.
A common requirement of multimedia applications is the need to communicate multimedia streams of various kind between source and presentation devices. In general, this basic requirement can present a multimedia system designer with a difficult problem, largely stemming from the degree of heterogeneity currently found across hardware devices, audio/video formats, and compressions schemes. The introduction of a network exacerbates the problem through the introduction of futher sources of heterogeneity such as those found across different network protocols. In short, flexible support for transmission of multimedia streams between source and presentation devices will be an important interoperability requirement of next generation computing environments.
The approach of the project is to develop object management facilities of distributed object management systems capable of interconnecting endpoints exhibiting various forms of heterogeneity with respect to media stream quality and structure. An important foundation on which to build this kind of support is a proper type model for continuous media flows - a model allowing stream endpoint conformance and compatibility to be checked and resolved.
The type model will form the basis for the definition of an Interface Definition Language (IDL) extension that allows the definition of multimedia stream interfaces. Furhermore, we envisage that from IDL specifications of application stream interfaces, can be (automatically) derived application level QoS requirements that again will form the basis of application and system level QoS negotiations.
The results produced so far in the project, include the development of a type model for continuous media flows. This work has mainly been done in cooperation with researchers at GTE Laboratories, Waltham, Mass., USA. A salient feature of the type model is to interpret a type specification as a set of potetial flow qualities and flow structures. This supports the definition of a variety of flow type relationships based on set theory. In particular we define subtyping rules supporting the definition of conformance of stream interfaces, and a weaker compatibility relationship that can be used as a basis for run-time flow quality and flow structure (QoS) negotiations during binding of stream interfaces.
Eliassen, F., A Conformance Relationship for Stream Interfaces, in proceedings of 2nd Int'l Conference on Formal Methods in Open Object-based Distributed Systems, Canterbury 21-23 July 1997, Chapman & Hall 1997 (to appear)
Eliassen, F,. Nicol J.R., Supporting Interoperation of Continuous Media Objects, Theory and Practice of Object Systems: Special Issue on Distributed Object Management Systems (ed. Gail Mitchell), Vol.2, No.2, Wiley 1996 pp. 95-117.
Eliassen, F,. Nicol J.R., Interoperability of Multimedia Information Systems, in proceedings of 8th ERCIM DBRG workshop on Distributed Information Systems, Trondheim, 23-25 Aug., 1995, pp. 167-180.
Eliassen, F,. Nicol J.R., Supporting Openness in Distributed Multimedia Systems, in proceedings of Norwegian Informatics Conference (NIK'95), TAPIR, 1995, pp 113-122.
Eliassen, F,. Nicol J.R., A Flexible Type Checking Model for Stream Interface Binding, in proceedings of Int'l Workshop on Multimedia Software Development, Berlin March 25-26, 1996, IEEE CS Press, 1996, pp. 52-60.
Eliassen, F., A Continuous Media Flow Type Model for Distributed Object-based Systems Architectures, in proceedings of 9th ERCIM DBRG workshop on Multimedia Database Management Systems, Darmstadt, 18-19 March, 1996, pp. 59-70 (invited talk).
Eliassen, F,. Nicol J.R., Polymorphic Typing for Continuous Media Flows and its Application to QoS Brokerage, GTE Laboratories Technical Report TR-0303-07-95-380, July 1995.
Yu, W., Modeling Transactions for Distributed Multimedia Databases, in Proceedings of 7th International Hong Kong Computer Society Database Wokshop on Multimedia, Knowledge-based and Object-Oriented Databases, Hong Kong, May 24-25, 1996.