Ray can you please explain a little more what you mean by 'manifest the 
schemas'? One thing I should have said is we don't know in advance of server 
startup as to what schemas will be needed. 

BTW I have read 
http://www.coding-dude.com/wp/java/liferay/liferay-multi-tenancy-setup-with-shards/
 

Tim 



From: "Raymond Auge" <raymond.a...@liferay.com> 
To: "OSGi Developer Mail List" <osgi-dev@mail.osgi.org> 
Sent: Wednesday, 25 January, 2017 11:20:37 AM 
Subject: Re: [osgi-dev] How to determine when a new service instance has been 
activated? 



On Tue, Jan 24, 2017 at 2:17 PM, Tim Jones < [ mailto:tim.jo...@mccarthy.co.nz 
| tim.jo...@mccarthy.co.nz ] > wrote: 



Actually the remote service still calls the same 'top level' component but it 
is this component that will make the choice as to which set of instance of 
services are ultimately exercised. At the risk of going too far off topic but 
to illustrate the requirement, the application is a multi-tenant system that 
needs to be able to create and access new db schemas on the fly. I don't wont 
the call to create the new db schemas and the associated services to return 
until they have been created. 



A nice way to do this is to flip the problem on it's head and manifest the 
schemas, once ready, as a services and have interested components declare 
references to those services. 

- Ray 



BQ_BEGIN


Tim 




From: "Christian Schneider" < [ mailto:ch...@die-schneider.net | 
ch...@die-schneider.net ] > 
To: "OSGi Developer Mail List" < [ mailto:osgi-dev@mail.osgi.org | 
osgi-dev@mail.osgi.org ] > 
Sent: Wednesday, 25 January, 2017 11:01:20 AM 

Subject: Re: [osgi-dev] How to determine when a new service instance has been 
activated? 

If the call is via jms then you should only start the route (and so the jms 
listener) once the service is injected. 
Christian 

2017-01-24 22:45 GMT+01:00 Tim Jones < [ mailto:tim.jo...@mccarthy.co.nz | 
tim.jo...@mccarthy.co.nz ] > : 

BQ_BEGIN

Yes the call is made by a component with the injected service and the service 
reference is mandatory but the initiating call to the component is from a 
remote system e.g. 

Remote system ---- (via Camel/JMS) ----> to component(s) which reference the 
newly created service 

Tim 



From: "Neil Bartlett" < [ mailto:njbartl...@gmail.com | njbartl...@gmail.com ] 
> 
To: "OSGi Developer Mail List" < [ mailto:osgi-dev@mail.osgi.org | 
osgi-dev@mail.osgi.org ] > 
Sent: Wednesday, 25 January, 2017 9:55:34 AM 

Subject: Re: [osgi-dev] How to determine when a new service instance has been 
activated? 

Who makes the call to the newly published service? If it is a component with an 
injected service, then just make the service reference mandatory. The component 
will then not be *able* to call the first service until it is actually 
published. 

Most of these timing and ordering problems disappear when you break the system 
down into components with injected service references. The DS runtime takes 
care of the underlying complexity and gives you a simple guarantee: for as long 
as your component is active, it can use its injected services without worrying 
about whether they are available yet and/or still available. 

Neil 




BQ_BEGIN

On 24 Jan 2017, at 20:42, Tim Jones < [ mailto:tim.jo...@mccarthy.co.nz | 
tim.jo...@mccarthy.co.nz ] > wrote: 

Thanks Neil and Christian, 

I may be going about this the wrong way but the service is ultimately injected 
into other components as you have suggested Christian. But, I don't want to 
return until the target service has been activated (and then hopefully fairly 
quickly referenced by other services) as the programatic call to 
ConfigurationAdmin.createFactoryConfiguration() is from a remote system and the 
next remote call will be to the services that have references to this newly 
published/activated service. If the next remote call is too soon the call would 
regularly fail as the service would not have been activated yet. While I 
acknowledge the next remote call can still fail I would rather this was the 
exceptional case. 

Tim 




From: "Neil Bartlett" < [ mailto:njbartl...@gmail.com | njbartl...@gmail.com ] 
> 
To: "OSGi Developer Mail List" < [ mailto:osgi-dev@mail.osgi.org | 
osgi-dev@mail.osgi.org ] > 
Sent: Monday, 23 January, 2017 11:18:54 PM 
Subject: Re: [osgi-dev] How to determine when a new service instance has been 
activated? 

I agree with Christian but would add an exception to his rule… using 
ServiceTracker.waitForService() is useful when writing unit tests. The other 
options such as adding fixed-length sleeps are unreliable and seriously damage 
the performance of your test runs. 

Neil 



BQ_BEGIN

On 23 Jan 2017, at 06:26, Christian Schneider < [ 
mailto:ch...@die-schneider.net | ch...@die-schneider.net ] > wrote: 

This exactly the expected behaviour. The @Activate method allows the component 
to configure itself. The service of the component will only be published when 
the @Activate method has finished. If it would be published earlier then the 
service might be in an invalid state. 
Btw. You should avoid using waitForService. Instead override the addedService 
method of ServiceTracker and continue your initialization only when the service 
is present. Even better just inject the servcie into another @Component. 

Christian 

2017-01-22 21:14 GMT+01:00 Tim Jones < [ mailto:tim.jo...@mccarthy.co.nz | 
tim.jo...@mccarthy.co.nz ] > : 

BQ_BEGIN

Hi, 
I am after some advice on the following. 

In general terms the problem is if a new instance of a service is created via a 
programatic call to ConfigurationAdmin.createFactoryConfiguration(), what 
options do I have to determine that this new service instance has been 
activated considering the call to .createFactoryConfiguration() returns 
immediately. 

I have tried setting up a service tracker with a filter for the specific 
instance of the service but I am not sure I understand the expected behavior of 
the .waitForService() method. For a small timeout period e.g. 1ms the call to 
.waitForService() returns with a null service as I would expect. For a longer 
timeout period e.g. 1000ms the call to .waitForService() returns with non null 
service and from the logs I can see that it seems to return only after the 
tracked service has returned from the @Activate method, is this the expected 
behavior? 
I also tried adding a sleep for 0.5 sec in the @Activate method of the tracked 
service and the .waitForService() still only returned after the @Activate 
method of that service had returned. Does the registration of a service have 
any dependency on its activation in the context of Declarative Services? Note 
the tracked service has @Component(immediate = true) 

Although the behavior is what I am after ie .waitForService() only seems to 
return after the tracked service has activated I am wondering if I am just 
getting lucky in this case. 
Regards, 
Tim Jones 


        

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[ http://www.liferay.com/web/raymond.auge/profile | Raymond Augé ] (@rotty3000) 
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(@Liferay) 
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