AFNOR comments on DIS 10746-3 - Annex
From the lively debate which took place between the various national bodies about bindings, the following conflicting questions appeared:
1- Do we need a binding object?
In case we do, do we need to make it visible in the computational viewpoint?
2- Do we need to allow binding objects to have interfaces?
Does that create a non-terminating recursion problem?
3- How can we distinguish bound versus unbound interfaces?
4- Do we want to include in the computational viewpoint some semantical way to support end-toend QoS constraints?
In case we do, how signals and binding object notions are affected?
We first introduce and explain the AFNOR proposal which is the most complete. Then we summarize each of the alternatives and contrast it with this solution, trying to weigh the advantages and the drawbacks. Paragraph 2 alternative is called A1 whereas paragraph 3 thesis is called A2. Every solution is analysed according to its answer to the previous "conflicting" questions.
1 A generic binding process creating a binding object.(AFNOR)
1.1 Main characteristics
This solution is mainly based on the notions of binding objects and signals as they are introduced in
the present DIS document. This would only require in the present document to add an explanation
of a generic binding process that would fit in the "Binding rules" paragraph. In this solution, an
explicit binding is materialized in the computational model by a visible binding object which nature
is not different from that of a computational object except that it supports binding interfaces which
are essentially signal interface and have a synchronous communication semantics. The generic
explicit binding process below explains in computational terms the instantiation mechanism of an
explicit binding. It must be understood as an example of such a binding process, of how it could be
built and not at all as a standard proposal.
In this proposal we do consider that interactions between a basic computational object and a binding object are composed of atomic actions called signals which are semantically synchronous (i.e.: instantaneous) instead of being asynchronous like operations.
1.2 An example binding process
The generic explicit binding process could have the following sketch:
(a) locate a binding object factory of the appropriate type;
(b) request the creation of a new binding object (possibly by passing identifiers of interfaces to be bound);
(c) obtain in return binding interface identifiers and control interface identifiers; (d) locate "link" interfaces corresponding to the interfaces to be bound;
(e) pass binding interface identifiers to the relevant "link" interfaces thus completing their binding.