Eclipse specific content has entered this thread so I will elaborate on what happens when p2 (or old eclipse update) manage an RCP application. In this case the management agent will call Bundle.start (START_ACTIVATION_POLICY) on the bundles that have lazy activation policies. So you should not have to worry about calling the start() method if you are using Eclipse RCP when your bundle has the lazy activation policy.
Tom
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|OSGi Developer Mail List <[email protected]>
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|04/30/2009 01:06 PM
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|Re: [osgi-dev] Certain service registration
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Note: This still requires that someone has called Bundle.start
(START_ACTIVATION_POLICY) on the bundle containing the DS components. This
only needs to be done once since the start state is persistently recorded.
DS will always ignore bundles in the RESOLVED state.
--
BJ Hargrave
Senior Technical Staff office: +1 386 848
Member, IBM 1781
OSGi Fellow and CTO of the mobile: +1 386 848
OSGi Alliance 3788
[email protected]
From: Thomas Watson/Austin/i...@ibmus
To: OSGi Developer Mail List <[email protected]>
Date: 2009/04/30 11:40
Subject: Re: [osgi-dev] Certain service registration
Sent by: [email protected]
Another option is to use Declarative Services and lazy activation. The DS
implementation in Equinox supports lazy activated bundles. A lazy activated
bundle can provide a service component while it is in the STARTING (waiting
for first class load) state. Once the service component is used the DS
runtime will load your service impl class and cause your bundle to move to
the ACTIVE state.
Tom
Inactive hide details for BJ Hargrave---04/30/2009 10:32:02 AM---I don't
know why you have 2 bundles: service and serviceimpl. BJ
Hargrave---04/30/2009 10:32:02 AM---I don't know why you have 2 bundles:
service and serviceimpl. Normally one does that to decouple the bundle
exporting the servi
From: BJ Hargrave/Austin/i...@ibmus
To: OSGi Developer Mail List <[email protected]>
Date: 04/30/2009 10:32 AM
Subject: Re: [osgi-dev] Certain service registration
I don't know why you have 2 bundles: service and serviceimpl. Normally one
does that to decouple the bundle exporting the service interfaces from the
bundle implementing the service. But you do that and then couple the
service bundle to the serviceimpl bundle by having the service bundle start
the serviceimpl bundle!
The simplest solution here seems to be: combine into one bundle and make
that bundle use lazy activation. Then the first time one of the service
interface classes is loaded, your activator will run and will register the
service.
--
BJ Hargrave
Senior Technical Staff Member, office: +1 386 848
IBM 1781
OSGi Fellow and CTO of the mobile: +1 386 848
OSGi Alliance 3788
[email protected]
From: Eugen Reiswich <[email protected]>
To: OSGi Developer Mail List <[email protected]>
Date: 2009/04/30 11:07
Subject: Re: [osgi-dev] Certain service registration
Sent by: [email protected]
Hi Neil,
you have exactly pointed out my problem with OSGi in RCP applications!
> I believe the solution is to use Declarative Services. In DS, services
> can be registered in the service registry before the actual
> implementation object for the service is instantiated -- in fact, this
> is the default behaviour. A bundle offering services via DS still need
> to be activated, but now the activation is "free" because a
> classloader does not need to be created for the bundle until the
> service is actually used.
Is DS really the only way? I have downloaded Eclipse M6 and tested the
DS-Editor. Well, how do I say it polite? If I have 2, 3 or even more
components in one bundle that require OSGi services I have to create
(if I got it right) 2, 3 or even more XML files with service-component-
descriptions. This sounds like XML-hell.
> To make this work in an Eclipse RCP environment, there are two
> possible approaches. First, explicitly name the bundles offering
> services in config.ini, and add the @start modifier. If you do not
> know in advance the names of the bundles then you could have an
> extender bundle which automatically starts any bundle with a
> Service-Component header.
I can't use the config.ini as I really don't know the names of the
bundles in advance. That's why we start each serviceimpl bundle in the
corresponding service bundle. But in case I do not want to use DS our
second solution was to start all bundles whose names end with
xxxx.serviceimpl in a dedicated startUp-bundle.
Kind regards,
Eugen
Am Apr 30, 2009 um 16:23 schrieb Neil Bartlett:
> While I agree with Peter and Hal, I think the heart of your problem is
> the mismatch between the preferred lifecycles of bundles in Eclipse
> environment vs the services-based approach.
>
> In Eclipse (both the SDK and RCP apps), activation of bundles is done
> as late as possible. Lazy activation helps to ensure that Eclipse
> starts quickly, and code implementing things like views and buttons is
> only loaded when the user actually shows an interest in those things,
> e.g. by clicking the button. The whole Eclipse extension registry is
> set up to enable this by examining bundles when they are in the
> RESOLVED state.
>
> Services traditionally have a different lifecycle: they are offered up
> by a bundle before it knows whether any other component (or the user)
> actually wants them! So the bundle needs to be "eagerly" activated...
> but Eclipse strongly discourages this practice because bundle
> activation has an up-front cost.
>
> I believe the solution is to use Declarative Services. In DS, services
> can be registered in the service registry before the actual
> implementation object for the service is instantiated -- in fact, this
> is the default behaviour. A bundle offering services via DS still need
> to be activated, but now the activation is "free" because a
> classloader does not need to be created for the bundle until the
> service is actually used.
>
> To make this work in an Eclipse RCP environment, there are two
> possible approaches. First, explicitly name the bundles offering
> services in config.ini, and add the @start modifier. If you do not
> know in advance the names of the bundles then you could have an
> extender bundle which automatically starts any bundle with a
> Service-Component header.
>
> Regards,
> Neil
>
>
>
> On Thu, Apr 30, 2009 at 8:46 AM, Eugen Reiswich
> <[email protected]> wrote:
>> Hi OSGi-devs,
>> I have the following problem with osgi services. We develop basically
>> applications where dynamic is not an issue. So what I would like to
>> make
>> sure in my application is that all services are registred properly
>> at start
>> up - if not, the application will be shut down. In addition to that
>> I want
>> to reuse my bundles in RCP applications so any concept must also be
>> applicable for RCP applications.
>> Say I have two bundles:
>> 1. org.mycompany.service (contains a service interface)
>> 2. org.mycompany.serviceimpl (contains the service implementation and
>> registers withing his activator an osgi-service)
>> What we do within the service bundle is this:
>> public void start(BundleContext context) throws Exception {
>> Bundle[] bundles = context.getBundles();
>> // find the implementation for the service bundle
>> for (Bundle bundle : bundles) {
>> if ("org.mycompany.serviceimpl".equals(bundle.getSymbolicName())) {
>> // service impl found
>> if (bundle.getState() != Bundle.ACTIVE) {
>> bundle.start();
>> }
>> }
>> }
>> // check if servicimpl has registred service properly
>> ServiceReference serviceReference = context
>> .getServiceReference(IMyService.class.getName());
>> if (serviceReference == null) {
>> // shut down application
>> }
>> ...
>>
>>
>> From my point of view this is pretty error prone and difficult to
>> maintain.
>> Is there a best practice approach how I can make sure that all
>> services are
>> registered properly at start up of my application? How can I start my
>> serviceimpl bundles in RCP application as no one depends on this
>> bundle
>> which is why the are never started?
>> We have spend now a lot of time to find solutions for this problem
>> but they
>> all seem to be improvable.
>> Regards,
>> Eugen
>> _______________________________________________
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