Hello,
From previous emails on this list, I take it that this list is the
best place to post questions from newbies (developers making use of
existing OSGi implementations).
Having looked around for information on when to uses the "uses"
directive for the last 3 days I am now at a loss and decided to post a
question to this mailing list instead
Short summary of what I understand (having read a number of blog
entries and even attempting to read chapter 3 in the specification)
the uses directive continues to be a mystery.
In the interest of explaining my question, I have stolen the example
below from
http://felix.apache.org/site/presentations.data/osgi-berlin-20070321.pdf
specifically slides 30-37.
Initial state of OSGi container
A: Export-Package : foo
D: Export-Package : foo
Assuming the state of these bundles in now 'active'
New bundle added to the container
C : Import-Package: foo, bar
Package bar is not available, hence this bundle stays in state
'installed' i.e. is not resolved at this time
B: Import-Package: foo
Export-Package: bar; uses:="foo"
Bundle is resolved by selecting bundle A as the provider for the package foo
Bundle C can now be resolved by selecting bundle B as the provider
for package bar, resolution on package foo (this is where the slides
indicate the application of uses directive) is done by selecting
bundle A as the provider for foo.
Question : I do not understand the need for the "uses" directive
here, tho there are potentially 2 providers for the interface 'foo'
the requirement of class space consistency is easily achieved by
existing class space affinity, i.e. why would the container not
attempt to resolve package 'foo' using the previously determined class
space without the need of the "uses" directive.
It would also be great if someone could point me to an example that
I could deploy in an OSGi container which actually results in a
failure, I tried this more than a few times but just could not get a
Class*Exception.
Thanks
Bhaskar
_______________________________________________
OSGi Developer Mail List
osgi-dev@mail.osgi.org
https://mail.osgi.org/mailman/listinfo/osgi-dev
