Berin Loritsch wrote:
Currently, we have the following jars:
meta-api -> The core API for interpreting meta info
meta-spi -> Interfaces for reading/writing meta info
meta-impl -> Different readers and writers for meta info, and a verifier
meta-tools -> ANT additions to generate meta-info, etc.
meta-plugin -> Maven plugin to directly work with meta-info
Overall I don't have a problem with this. However, I do have a few questions
as it is now defined:
1) What, precisely, is the difference between a Service and a Type?
- A Service defines contracts for client/component communication
- Programmatically what is the difference?
A Service is a meta-info object that describes a service.
A Type is a meta-info object that describes a component implementation.
The default notion of a service is a java interface class. The Service meta-info class provides support for the attribution of a version and supplimentary attributes to that defintion.
2) Why are the readers and serializers for types and services separate
and distinct?
- Aren't services a function of what is exported by a type?
Typically - yes. But this is not always the case. I have services that arte produced by non-components. I have components that produce services indirectly (ie. CORBA POA based servant activators). The seperation of Service and Type ensures that the meta-model does not make the assumption that services can only be produced by avalon component implementations.
- Are their information recorded separately, hense lending support to
the notion that an interface defines a service?
An interface does define a service. A Service suppliments that information.
3) Don't we want many readers, but only one official writer?
No. We want many readers are a snall number of endoreced writers.
- Do we want XML (safe between JRE changes)?
Yes.
- Do we want Serialization?
Yes.
- Do we want something else intirely (i.e. bytecode embedding)?
Maybe.
4) How about allowing for extensions to be incorporated into the reader/writers/
verifiers?
Lots of thinking and lots of work to be done before answering that. This is the sort of thing that should be experimented with (but not included in the core at this time) - but I'm about to dive and and take a look at what you have just added.
5) What do we have separate readers/writers for services and types? - I believe it would be cleaner to have one for each.
You want seperate writers because a custom service writer does not need to know about Type details. As far as readers are concerned, the Type and Service readers could be converged into a single interface.
Steve.
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Stephen J. McConnell mailto:[EMAIL PROTECTED] http://www.osm.net
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