The adaptor and stream concepts

The concepts of adaptor and stream are introduced to allow plug and play distributed processing environments (DPEs) extended for multimedia applications.

Adaptors allow:

• distributed system suppliers to produce plug and play DPEs
• system integrators to configure DPEs to application type
• application programmers to choose and configure DPE functions (software and hardware) which are appropriate for their application.

Streams allow:

• service providers to specify interfaces to isochronous multimedia data flows
• system integrators to supply multimedia service components
• application programmers control over the stream through standard operational interfaces
• end users a way to specify what quality of service they are willing to pay for

An adaptor encapsulates a specific protocol. It is resourced explicitly to deliver predictable behaviour. It is resourced statically by a DPE supplier or system integrator or dynamically by the application programmer perhaps as late as the binding stage. It also provides the application programmer with that part of the API which is specific for their application.

Adaptors for streams offer stream interfaces. Typing these interfaces allows type safety as well as an opportunity to specify stream componentware for multimedia applications.

The adaptor approach thus leads to extremely modular distributed processing infrastructures, with built in extensiblity, whilst allowing conformance to standards such as OMGs CORBA.

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