Hi, I will complete a little Richard's answer :-): The temporal dependency accepts several arguments: - timeout : setting the timeout time - onTimeout : defines the action to do when the timeout occurs.
When requesting a temporal dependency, the thread is stopped until the service appears or the timeout is reached (3s by default, set the timeout to -1 to wait forever). When the timeout is reached, you can define an action. By default a RuntimeException is thrown. But, you can set the onTimeout action to do: - null: injects null - nullable: injects a fake service object that does nothing - empty-array: injects an empty array (only for aggregate dependencies) - a class name : this class name is used as default-implementation. So, an instance of this class is created. This class must implement the service interface and you can implement your own behavior. So, with this temporal dependency you can create a smart proxy delegating call to the service and managing the dynamism. Clement -----Original Message----- From: Richard S. Hall [mailto:[EMAIL PROTECTED] Sent: vendredi 17 octobre 2008 15:26 To: [email protected] Subject: Re: Dependency Injection with annotations Miroslav Nachev wrote: > Hello Clement, > > In traditional way if I have some OSGi Service which have to be used > in some class (POJO Bean) I MUST pass this service to one or more > classes as parameter. Then when the time for using of that service is > on the service can be unavailable. Similar problem I will have when I > want to stop my bundle. That's why if iPOJO Annotations allow some > service to be used inside of the bundle will be perfect. This can be > done with Proxy. When I create some new object with new JavaClass(...) > and in that object I am declared some OSGi Service using iPOJO > Annotation, that service will point to some Proxy which proxy will try > to get the service on request. This will guarantee that the service is > actual independently how much the service is restarted and updated. In > traditional way the application must track all service states and etc. > Passing the service as parameter complicate the things. > > Did you have some plans iPOJO to support the above scenario? I am not totally sure I understand your scenario, but it sounds like you want a proxy that only tries to get the service when someone tries to use it. iPOJO does not support this type of scenario automatically, but it is fairly easy to achieve. Assume you have the following service: public interface Foo { void doFoo(); } You could create a component like this: import org.apache.felix.ipojo.temporal.Requires; public class MyFooProxy implements Foo { @Requires private Foo m_foo; public void doFoo() { m_foo.doFoo(); } } The dependency on m_foo is declared to be temporal, which means that it will only try to get the service when it is used. If one is not available, it will eventually timeout and throw an exception. Now you should be able to pass this "proxy" component to you components and they will be able to use the service on demand. -> richard > > > Regards, > Miro. > > > clement escoffier wrote: >> 2008/10/14 Stuart McCulloch <[EMAIL PROTECTED]> >> >> >>> 2008/10/14 Miroslav Nachev <[EMAIL PROTECTED]> >>> >>> >>>> Hi, >>>> >>>> This is very interesting and I will try it but this answer is half >>>> of my >>>> question. I am interesting how to get some service in my code, not in >>>> another service. For example: >>>> >>>> public class SomePOJOBean >>>> { >>>> >>>> @Requires >>>> ??? how to pass some parameters to the service (passive, dynamics) >>>> private FooService foo; >>>> >>>> } >>>> >>>> How can be implemented the above scenario? >>>> >> >> So, as I understand, you don't want (global) services but your own >> (customized) service. As you're configuring the service, this service >> should >> not be available to other consumers. In iPOJO you can do this by using >> composites (the new documentation is coming soon). Composites assert >> that >> your service is isolated. However, composites does not allows you to >> declare >> those services in your code. >> >> >> >>> Well, iPOJO injects components - but these are not necessarily >>> services. >>> >>> Clement's example happened to provide a service, but this isn't >>> mandatory. >>> You do need to tell iPOJO about your code somehow, and in iPOJO this is >>> done >>> by marking them as components which iPOJO injects as necessary. (I'm >>> sure >>> Clement can explain this better than me!) >>> >> >> >> Service providing is (of course) not necessary. Your component can be a >> component that does not provide a service (like a GUI). >> >> >> Clement >> >> >> >>> There are also alternative ways to inject OSGi services, using >>> (non-OSGi) >>> dependency injection frameworks: >>> >>> * Spring has the Spring-DM extension, but I don't know if it fully >>> supports >>> configuration via annotation. >>> >>> http://www.springframework.org/osgi/ >>> >>> * Guice has the peaberry extension, which I work on - in this case the >>> service configuration is done in the binding module, not the >>> annotation (I >>> did look at doing annotation configuration, but this rapidly becomes a >>> management nightmare) >>> >>> http://code.google.com/p/peaberry/ >>> >>> HTH >>> >>> Regards, >>> >>>> Miro. >>>> >>>> >>>> >>>> clement escoffier wrote: >>>> >>>> >>>>> Hi, >>>>> >>>>> iPOJO provides such annotations as: >>>>> @Component >>>>> @Provides // Provides a service >>>>> public class Foo implements Service { >>>>> @Requires // Service dependency >>>>> private HelloService hello; >>>>> >>>>> >>>>> ... >>>>> } >>>>> >>>>> You can find further info at >>>>> http://felix.apache.org/site/how-to-use-ipojo-annotations.html >>>>> >>>>> About parameters, the iPOJO's way is to inject instance property. >>>>> Those >>>>> fields will be set before the execution of your constructor >>>>> (between the >>>>> super constructor invocation and the constructor code), and your >>>>> constructor >>>>> can use those fields, such as in: >>>>> >>>>> @Component >>>>> @Provides // Provides a service >>>>> public class Foo implements Service { >>>>> >>>>> @Property >>>>> private String myString; >>>>> >>>>> @Requires // Service dependency >>>>> private HelloService hello; >>>>> >>>>> public Foo() { >>>>> // Can use myString here as well as hello >>>>> } >>>>> ... >>>>> } >>>>> >>>>> Regards, >>>>> >>>>> Clement >>>>> >>>>> >>>>> 2008/10/14 Miroslav Nachev <[EMAIL PROTECTED]> >>>>> >>>>> >>>>> >>>>> >>>>>> Hi, >>>>>> >>>>>> I would like to ask you about some way in Felix to export >>>>>> services in >>>>>> more >>>>>> easy way only with annotation like in EJB3.x: @Stateful, @Stateless, >>>>>> @Remote, @Local, @EJB, etc. >>>>>> In my opinion the best way this to be done is inside of the OSGi >>>>>> framework. >>>>>> Then all resources (services) can be exported to the framework just >>>>>> >>> with >>> >>>>>> annotation. The same for needed services. What about if before to >>>>>> get >>>>>> some >>>>>> service we have to pass some parameters to the constructor? >>>>>> >>>>>> >>>>>> Regards, >>>>>> Miro. >>>>>> >>>>>> --------------------------------------------------------------------- >>>>>> >>>>>> To unsubscribe, e-mail: [EMAIL PROTECTED] >>>>>> For additional commands, e-mail: [EMAIL PROTECTED] >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>> >>>> --------------------------------------------------------------------- >>>> To unsubscribe, e-mail: [EMAIL PROTECTED] >>>> For additional commands, e-mail: [EMAIL PROTECTED] >>>> >>>> >>>> >>> -- >>> Cheers, Stuart >>> >>> >> >> > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
