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From "Wilfried Sibla (JIRA)" <>
Subject [jira] [Commented] (ACE-347) Redesign Management Agent
Date Fri, 17 May 2013 10:07:15 GMT


Wilfried Sibla commented on ACE-347:

I'm currently still evaluating ACE in total and especially the MA. Our environment is very
maven centric. Therefore it's not very easy to understand and handle the current project structure
and the built bundle artifacts and the run configurations.

Therefore I agree to your idea of redesigning the ACE MA very much. I would also prefer your
project structure instead of spreading the services over multiple projects and assembling
them again to a single jar.

I also found your launcher implementation very interesting and inspiriting.
What do you think about implementing nearly all stuff regarding the artifact management outside
of the OSGi container. I mean: within or as part of this launcher??
And providing a service as mentioned by you into the OSGi container?
This would have several benefits:
* separating artifact management (the artifact distribution part) from the deployment / installation
* allowing to even update the felix version etc.
* stopping and (re)starting the framework, even with different settings/properties (e.g. in
case of failures: restarting with deleted bundle cache)

I (we) have several conceptual ideas how such an interface could look like. How can I provide
my suggestions?

> Redesign Management Agent
> -------------------------
>                 Key: ACE-347
>                 URL:
>             Project: ACE
>          Issue Type: Improvement
>            Reporter: Bram de Kruijff
>            Assignee: Bram de Kruijff
> The Managent Agent was made "self-contained" in ACE-232 but there are still some concerns
with regard to complexity and functionality. This issue deals with restructuring the Managent
Agent code to make it easier to maintain, configure and extend. Also see ACE-324 / ACE-324.
> Management Agent code:   
> The MA implementation is setup very modular and it assembled mainly based on CM factories.
Maybe a little too much. The code is scattered over projects making it hard to maintain and
it is violating visibility rules to implementation classes which is nasty in bndtools.
> -> We should centralize the 'dedicated' MA code in the MA project allowing us to clean
up a lot of projects.
> Management Agent config:   
> The fact that we can theoretically reconfigure these services at runtime through CM does
not add much more then a runtime dependency on a CM impl. There is an obvisou catch-22 in
boostrapping and no mechanism to provision these configurations to a private CM and in fact
all configuration is done in code and it is very complex. 
> -> we should centralize configuration in a well documented format with a simple default
case and possible extension.
> Management Agent extension:   
> Bringing in extensions or customization on the bundle classpath is very hard on only
partially possible. There is a mechanism to disabled activators and one to add custom ones.
Theoretically one could also provide services from "user space", but there is no way do do
so in a simple way as there are no visible APIs and the CM catch-22.
> -> We should simplify extension on bundle classpath through a simple factory SPI.
Bringing these on the classpath can be done through wrapping (as launcher does) or maybe also
fragment bundles.
> -> User space extensions could have a real use case in management/monitoring. However,
this means we need to expose some API. Question is whether we want to expose prg.apache.ace.*
(or some subset) so that consumers can talk to for exmaple Log directly or that we should
facade this behind a single ManagementAgent API to keep it more contained.
> Multiple agents:   
> There is code to configure and handle multiple agents. Not sure if it really works as
it is a very exotic and possibly undesirable use-case. There are many conditionals for this
through the CM code.
> -> At least make it simpler and discuss wither we actually want/need this at all.
> Resource Processors:
> RPs need to resolve, typically requiring framework, deploymentadmin (spi) and eventadmin,
but maybe more. In the current situation the MA exports these package with an additional required
attribute (managementagent=true). As a result standard 3rd party RPs will not resolve. Therefore
the MA should be as self-contained as possible but still export these packages without the
attribute and (re)import them with the appropriate range.

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