Thomas Watson created FELIX-6041:
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Summary: scr gogo commands require gogo runtime to be present when
scr resolves
Key: FELIX-6041
URL: https://issues.apache.org/jira/browse/FELIX-6041
Project: Felix
Issue Type: Bug
Components: Declarative Services (SCR)
Affects Versions: scr-2.1.14
Reporter: Thomas Watson
I cannot seem to find the actual jira issue this was worked under. At some
point in the 2.1 version of SCR the scr gogo commands were significantly
reworked with the following commit:
https://github.com/apache/felix/commit/d6232f91ffb386835d3ae22dd2f003c854310ef5
This put a hard dependency on the gogo package
{{org.apache.felix.service.command}} package. The dependency was declared as
optional, but this means that if the gogo.runtime bundle is installed/resolved
after the scr bundle then the scr bundle will never wire to the package for the
Converter service. SCR then proceeds to register a Converter service using a
ServiceFactory, but this service cannot be used for two reasons.
# For the gogo.runtime to see the service the scr bundle must be wired to the
service package otherwise the framework will not give the service to the
gogo.runtime.
# Even if the gogo.runtime could see the service the ServiceFactory would
ultimately fail to create the Converter service object with some class loading
error.
This ultimately leaves the scr commands that require DTO conversion/formating
by the gogo.runtime to fall back to using toString which prints out confusing
(for the user) json like output.
Perhaps some use of late binding dynamic import could be used, but that would
require some kind of trigger to SCR to load the class from the package to force
the dynamic wire and then registration of the Converter service. Even then it
would cause a re-resolve of the SCR bundle if the gogo bundles are then
uninstalled which I would like to avoid.
One possible solution is to track the CommandProcessor service and when it is
available then register a Proxy Converter service with the BundleContext of the
bundle that registers the CommandProcessor. This way we do not need a hard
requirement on the {{org.apache.felix.service.command}} in order to get good
output from the scr gogo commands.
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