[SUMMARY] Context

[Nicola Ken Barozzi]

I've been reading all your mails about the Context with great interest, and will try here to summarize the things that IMHO have emerged.

-oOo-

_Context_ and _Contextualizable_ are *the* way in which the Container can give the Component some *data*.

It's similar to a "ServiceManager", but it gives the Component some information, not services. Data objects are different from a service objects, because are not used to /act/, but to give simple pure data info.

The signature of the Context interface is very similar to the ServiceManager one, but the difference is that it gives data instead of services. This cannot be enforced as in Java Objects contain both informations, but it's a behavioural contract nevertheless.

As Services are cast to the correct service interface, each data item is cast to his correct interface.
As ServiceManagers are not cast to something else, Contexts should not be cast to anything else.

Services are declared beforehand to be served by the ServiceManager.
In the same fashion context data should be declared beforehand.

But since in the Context there are some values that are needed by most use-cases, it's sensible to define some standard keys beforehand, by using a URN, that all containers must honor.

This is to maximize portability of Components/Services between containers.

Non-standard keys are permitted, but limit the portability of the Components that rely on them. Becasue we want to make our components portable, all Components made here must ship without extra key dependencies. If it's not possible, we must come to a general definition of the required key/s and honor them for all containers.

--
Nicola Ken Barozzi [EMAIL PROTECTED]
- verba volant, scripta manent -
(discussions get forgotten, just code remains)
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