Hi,

I have read David's blog post about the latest draft from the EEG (
http://osgithoughts.blogspot.de/2012/10/new-osgi-eeg-early-access-draft.html
). Thanks for the JavaEE Contracts proposal. This aims a good solution for 
that to solve the versioning problem.  But I think, contracts could be 
used in a wider scope.

1. The solution is for JavaEE, the problem may occur in SE environments 
too. Of course, the original cause was the Servlet API as discussed in 
https://bugs.eclipse.org/bugs/show_bug.cgi?id=360245, and, of course, 
positioning the solution within the Enterprise Specification leads to the 
fact the OSGi runtimes can optionally implement the feature, it's not 
mandatory. (Maybe this is not a good thing to say that OSGi Enterprise 
solutions are optional whereas OSGi Core solutions are mandatory - but 
this is another topic...)

2. Especially, in managed environments (as JEE containers are), there 
could be other contracts than a single API - e.g. a couple of APIs and 
some functionality that cannot get addressed on the package level. If you 
write a web service, you are not only dependent from the javax.ws package, 
and you are not dependent from the JAX-WS API, you are dependent from the 
JAX-WS runtime which would include that a HTTP port is available that 
allows to receive requests (in parallel) and to send responses. Maybe, the 
QoS could be expressed by a contract, e.g. if XML-Encryption should be a 
condition to run the web service.

3. Could the contract mechanism be used to cover the dependencies to Java 
Execution Environments? We have the fact the a dependency to JavaSE-1.5 
can be resolved within a JavaSE-1.7 environment. So this resolution, that 
OSGi runtimes already contain, might be a special use case for contracts, 
right?

Plz discuss!

Ralf Zahn

ARS Computer und Consulting GmbH, http://www.ars.de
Ridlerstrasse 55, 80339 Muenchen, Deutschland
Handelsregister Muenchen, HRB 101829, USt-ID: DE 155 068 909
Geschaeftsfuehrer:
Michael Arbesmeier, Kai-Uwe Rommel, Roland Schock, Joachim Gucker

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