[FELIX-6041] scr gogo commands require gogo runtime to be present when scr resolves

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: scr-2.1.14
• Fix Version/s: scr-2.1.16
• Component/s: Declarative Services (SCR)
• Assignee: Tom Watson
• Reporter: Tom Watson
• Created: 29/Jan/19 15:01
• Updated: 02/Apr/19 15:03
• Resolved: 29/Jan/19 19:30

Description

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.

1. 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.
2. 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.

Issue Links

• relates to: KARAF-6208 Fix scr:* commands
• links to: GitHub Pull Request #174