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Posted to users@felix.apache.org by Pierre De Rop <pi...@alcatel-lucent.fr> on 2008/03/25 21:48:07 UTC

SCR: How to reconfigure Service Components

Hello every one;

I am wondering if it's possible to reconfigure a Service Component 
without restarting it at all !
Here is my use case: I have a Service Component which is activated by 
the Declarative Service. The corresponding DS xml is:

    <?xml version="1.0" encoding="utf-8"?>
    <component name="hello">
      <implementation class="test.HelloComponent"/>
    </component>

Now, my HelloComponent's activate method is defined as this:

    public class HelloComponent {
      protected void activate(ComponentContext ctx) {
        // initialize our HelloComponent using ctx.getProperties()
      }
    }

if I create a Configuration using the Config Admin Service with a pid 
equals to the
HelloComponent's name (that is: "*hello*"), then my HelloComponent will 
retrieve its
properties from the *ComponentContext.getProperties*() method. So far, 
all is working like a charm.

Now here is my question: Is there a way for my HelloComponent to 
register a ManagedService in order
to be notified when properties are updated by the Configuration Admin 
Service ?
I ask this question because I have observed that SCR *REACTIVATES* the 
HelloComponent, when the
properties are updated by the Config Admin Service. That is: when Config 
Admin updates the
configuration, my HelloComponent is deactivated (it is removed from the 
OSGi servide registry), and
then re-activated (my activate method is invoked again).
The problem here is that my HelloComponent is actually a "crutial" 
component which must not be *shutdown* when
properties are modified (because I don't wan't to interrupt the service 
while re-activating my
HelloComponent).

/Pierre

Re: SCR: How to reconfigure Service Components

Posted by Felix Meschberger <fm...@gmail.com>.
Hi Pierre,

Am Dienstag, den 25.03.2008, 23:19 +0100 schrieb Pierre De Rop:
> Ok, now it's clear to me.
> Thanks a lot for your quick response.

You are welcome ;-)

Regards
Felix

> 
> /Pierre
> 
> Felix Meschberger wrote:
> > Hi Pierre,
> >
> > According to the spec, the component must be cycled (deactivate -
> > activate) when the configuration is updated. The Configuration itself
> > should not register a ManagedService for its own PID.
> >
> > You could of course create another PID and from within your component
> > register a ManagedService with that new PID. You then update the
> > configuration for that PID, get it in the ManagedService and may update
> > your component with this configuration.
> >
> > However, I am not sure, whether your requirements are so hard, that it
> > justifies this overhead.
> >
> > Alternatively, you might want to not create an SCR component at all and
> > create your component from a bundle activator and just register it as a
> > ManagedService directly and act upon the update method call.
> >
> > Hope this helps.
> >
> > Regards
> > Felix
> >
> > Am Dienstag, den 25.03.2008, 21:48 +0100 schrieb Pierre De Rop:
> >   
> >> Hello every one;
> >>
> >> I am wondering if it's possible to reconfigure a Service Component 
> >> without restarting it at all !
> >> Here is my use case: I have a Service Component which is activated by 
> >> the Declarative Service. The corresponding DS xml is:
> >>
> >>     <?xml version="1.0" encoding="utf-8"?>
> >>     <component name="hello">
> >>       <implementation class="test.HelloComponent"/>
> >>     </component>
> >>
> >> Now, my HelloComponent's activate method is defined as this:
> >>
> >>     public class HelloComponent {
> >>       protected void activate(ComponentContext ctx) {
> >>         // initialize our HelloComponent using ctx.getProperties()
> >>       }
> >>     }
> >>
> >> if I create a Configuration using the Config Admin Service with a pid 
> >> equals to the
> >> HelloComponent's name (that is: "*hello*"), then my HelloComponent will 
> >> retrieve its
> >> properties from the *ComponentContext.getProperties*() method. So far, 
> >> all is working like a charm.
> >>
> >> Now here is my question: Is there a way for my HelloComponent to 
> >> register a ManagedService in order
> >> to be notified when properties are updated by the Configuration Admin 
> >> Service ?
> >> I ask this question because I have observed that SCR *REACTIVATES* the 
> >> HelloComponent, when the
> >> properties are updated by the Config Admin Service. That is: when Config 
> >> Admin updates the
> >> configuration, my HelloComponent is deactivated (it is removed from the 
> >> OSGi servide registry), and
> >> then re-activated (my activate method is invoked again).
> >> The problem here is that my HelloComponent is actually a "crutial" 
> >> component which must not be *shutdown* when
> >> properties are modified (because I don't wan't to interrupt the service 
> >> while re-activating my
> >> HelloComponent).
> >>
> >> /Pierre
> >>     
> >
> >
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: users-unsubscribe@felix.apache.org
> > For additional commands, e-mail: users-help@felix.apache.org
> >
> >   
> 


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Re: SCR: How to reconfigure Service Components

Posted by Pierre De Rop <pi...@alcatel-lucent.fr>.
Ok, now it's clear to me.
Thanks a lot for your quick response.

/Pierre

Felix Meschberger wrote:
> Hi Pierre,
>
> According to the spec, the component must be cycled (deactivate -
> activate) when the configuration is updated. The Configuration itself
> should not register a ManagedService for its own PID.
>
> You could of course create another PID and from within your component
> register a ManagedService with that new PID. You then update the
> configuration for that PID, get it in the ManagedService and may update
> your component with this configuration.
>
> However, I am not sure, whether your requirements are so hard, that it
> justifies this overhead.
>
> Alternatively, you might want to not create an SCR component at all and
> create your component from a bundle activator and just register it as a
> ManagedService directly and act upon the update method call.
>
> Hope this helps.
>
> Regards
> Felix
>
> Am Dienstag, den 25.03.2008, 21:48 +0100 schrieb Pierre De Rop:
>   
>> Hello every one;
>>
>> I am wondering if it's possible to reconfigure a Service Component 
>> without restarting it at all !
>> Here is my use case: I have a Service Component which is activated by 
>> the Declarative Service. The corresponding DS xml is:
>>
>>     <?xml version="1.0" encoding="utf-8"?>
>>     <component name="hello">
>>       <implementation class="test.HelloComponent"/>
>>     </component>
>>
>> Now, my HelloComponent's activate method is defined as this:
>>
>>     public class HelloComponent {
>>       protected void activate(ComponentContext ctx) {
>>         // initialize our HelloComponent using ctx.getProperties()
>>       }
>>     }
>>
>> if I create a Configuration using the Config Admin Service with a pid 
>> equals to the
>> HelloComponent's name (that is: "*hello*"), then my HelloComponent will 
>> retrieve its
>> properties from the *ComponentContext.getProperties*() method. So far, 
>> all is working like a charm.
>>
>> Now here is my question: Is there a way for my HelloComponent to 
>> register a ManagedService in order
>> to be notified when properties are updated by the Configuration Admin 
>> Service ?
>> I ask this question because I have observed that SCR *REACTIVATES* the 
>> HelloComponent, when the
>> properties are updated by the Config Admin Service. That is: when Config 
>> Admin updates the
>> configuration, my HelloComponent is deactivated (it is removed from the 
>> OSGi servide registry), and
>> then re-activated (my activate method is invoked again).
>> The problem here is that my HelloComponent is actually a "crutial" 
>> component which must not be *shutdown* when
>> properties are modified (because I don't wan't to interrupt the service 
>> while re-activating my
>> HelloComponent).
>>
>> /Pierre
>>     
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@felix.apache.org
> For additional commands, e-mail: users-help@felix.apache.org
>
>

Re: SCR: How to reconfigure Service Components

Posted by Felix Meschberger <fm...@gmail.com>.
Hi Pierre,

According to the spec, the component must be cycled (deactivate -
activate) when the configuration is updated. The Configuration itself
should not register a ManagedService for its own PID.

You could of course create another PID and from within your component
register a ManagedService with that new PID. You then update the
configuration for that PID, get it in the ManagedService and may update
your component with this configuration.

However, I am not sure, whether your requirements are so hard, that it
justifies this overhead.

Alternatively, you might want to not create an SCR component at all and
create your component from a bundle activator and just register it as a
ManagedService directly and act upon the update method call.

Hope this helps.

Regards
Felix

Am Dienstag, den 25.03.2008, 21:48 +0100 schrieb Pierre De Rop:
> Hello every one;
> 
> I am wondering if it's possible to reconfigure a Service Component 
> without restarting it at all !
> Here is my use case: I have a Service Component which is activated by 
> the Declarative Service. The corresponding DS xml is:
> 
>     <?xml version="1.0" encoding="utf-8"?>
>     <component name="hello">
>       <implementation class="test.HelloComponent"/>
>     </component>
> 
> Now, my HelloComponent's activate method is defined as this:
> 
>     public class HelloComponent {
>       protected void activate(ComponentContext ctx) {
>         // initialize our HelloComponent using ctx.getProperties()
>       }
>     }
> 
> if I create a Configuration using the Config Admin Service with a pid 
> equals to the
> HelloComponent's name (that is: "*hello*"), then my HelloComponent will 
> retrieve its
> properties from the *ComponentContext.getProperties*() method. So far, 
> all is working like a charm.
> 
> Now here is my question: Is there a way for my HelloComponent to 
> register a ManagedService in order
> to be notified when properties are updated by the Configuration Admin 
> Service ?
> I ask this question because I have observed that SCR *REACTIVATES* the 
> HelloComponent, when the
> properties are updated by the Config Admin Service. That is: when Config 
> Admin updates the
> configuration, my HelloComponent is deactivated (it is removed from the 
> OSGi servide registry), and
> then re-activated (my activate method is invoked again).
> The problem here is that my HelloComponent is actually a "crutial" 
> component which must not be *shutdown* when
> properties are modified (because I don't wan't to interrupt the service 
> while re-activating my
> HelloComponent).
> 
> /Pierre


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