We have a lot of default implementations for the system services (for
example, all the model factories, processors and system utilities) and the
declarations of such services are not in a separate module which can be
removed.
Thanks,
Raymond
--------------------------------------------------
From: "ant elder" <[email protected]>
Sent: Tuesday, May 19, 2009 10:26 AM
To: <[email protected]>
Subject: Re: Supporting an optional ranking attribute for system services
I still think we need to understand a more complete picture.
If its just to enable using different ContributionClassLoaderProvider
impls then maybe ContributionClassLoaderProvider should just be in a
separate module so it can be removed if someone wants to use their
own. Would that solve this particular problem without needing the
complications of a new ranking system?
...ant
On Tue, May 19, 2009 at 5:58 PM, Raymond Feng <[email protected]> wrote:
Hi,
My original proposal is not only just for pluggable extensions which can
be
easily removed. The primary use case is for vendors to embed Tuscany and
replace some of the system functions. For example, we have the
ContributionClassLoaderProvider and Tuscany provides a default
implementation. If the vendor decides to override that, a new module will
be
added but the default one from Tuscany is still there. Now the one from
the
vendor has higher ranking and it will be the effective one.
We can potentially leverage the idea to control the ordering of the
module
activators and other extensions for a given extension point.
The selection of a set of modules to form a Tuscany runtime is a
different
topic. We now have the feature/profile idea to group them.
Thanks,
Raymond
--------------------------------------------------
From: "ant elder" <[email protected]>
Sent: Tuesday, May 19, 2009 9:13 AM
To: <[email protected]>
Subject: Re: Supporting an optional ranking attribute for system services
On Tue, May 19, 2009 at 4:54 PM, Raymond Feng <[email protected]>
wrote:
It's easy. The user can just add a "fragment" module that only contains
the
META-INF/services declarations. For example, if the default ranking for
Jetty is 1 and Tomcat is 2 and the user wants to use Jetty instead of
Tomcat, he/she can just add a new declaration for Jetty using ranking
3.
Thanks,
Raymond
Wouldn't it be (a lot) easier for the user to just remove the tomcat
module?
I think we need to step back a bit and all understand the use cases.
We've currently got tuscany as lots of little modules so you can
configure a system by choosing the modules you want to include, and
working that way i'm not sure i see why we need a ranking mechanism.
If we want to just include all the tuscany modules and then configure
a runtime then explicitly configuring which modules to activate and
the order they start may be easier and more flexible than a ranking
system. And an explicit config file would also do what you need in the
use case you're describing wouldn't it?
...ant
