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Re: [ecf-dev] OSGi Container bundles for Eclipse Remote Service tutorial

Hi Wim and All,

One thing to note about the ECF implementation WRT the 'service.imported' OSGi service property...

For ECF's impl the following code

Object o = serviceReference.getProperty("service.imported");

will result in Object o being of type 'IRemoteService'...see javadocs here

http://www.eclipse.org/ecf/org.eclipse.ecf.docs/api/org/eclipse/ecf/remoteservice/IRemoteService.html

So code like this can be written (if desired...Wim's code below will work just fine as well):

IRemoteService rs = (IRemoteService) serviceReference.getProperty("service.imported");
// use rs if non-null
if (rs != null) {
rs.callAsync(remoteCall,listener);
}


I just mention this because this is a feature unique to ECF...as the OSGi remote services spec only defines that a remote service will have a non-null value for "service.imported" service property...but does not say what type that value will be (and IRemoteService allows easy access to...e.g. asynchronous/non-blocking remote invocation).

Scott


Wim Jongman wrote:
Hi Nicholas,

There are a few ways to deal with discovered services but here is one that uses the OSGi framework.

Please take a look at the modified Activator.start method of the o.e.e.examples.remoteservices.quotes.consumer bundle . Replace the start method with this code and then connect to the yazafatutu.com <http://yazafatutu.com> server.

The code will extract all services in the framework every 10 seconds and will print a list of all services and a list with remote services.

It extracts the services from the framework with /Activator.getContext().getAllServiceReferences(null, null);/
the null, null can be replaced by your specific class and filter requirements.


It then extracts the actual service from the service reference (/Activator.getContext().getService(serviceReference)/) and prints the class name.

The next loop only prints services with the property "service.imported" not equal to null. This indicates that the service is a remote property.

Is it useful to know if the service is a remote service? In one way, yes. You have to adapt your programming style to be "remote aware" and realize that calls can be delayed.

On the other hand, there is no difference in remote and local services from an OSGi point of view. With the discovery in place, services are "just there" to be used.

Best regards,

Wim


public void start(BundleContext bundleContext) throws Exception { Activator.context = bundleContext;

Runnable runner = new Runnable() {
public void run() {
try {
ServiceReference[] services = Activator.getContext().getAllServiceReferences(null, null);
System.out.println("All Services");
System.out.println("------------");
for (ServiceReference serviceReference : services) {
Object obj = Activator.getContext().getService(serviceReference);
System.out.println(obj.getClass().getSimpleName());
}


services = Activator.getContext().getAllServiceReferences(null, null);
System.out.println();
System.out.println("Remote Services");
System.out.println("------------");
for (ServiceReference serviceReference : services) {
if (serviceReference.getProperty("service.imported") != null) {
Object obj = Activator.getContext().getService(serviceReference);
System.out.println(obj.getClass().getSimpleName());
}
}

} catch (InvalidSyntaxException e) {
e.printStackTrace();
}

try {
Thread.sleep(10000);
} catch (InterruptedException e) {
}

new Thread(this).start();
}
};

new Thread(runner).start();

}

On Tue, Aug 17, 2010 at 11:27 AM, Nicholas Loulloudes <loulloudes.n@xxxxxxxxxxxx <mailto:loulloudes.n@xxxxxxxxxxxx>> wrote:

    Hi Wim,

    The listener in the consumer example you have provided me, as far
    as i understand tracks for services changes and based on
    the event (i.e Registration) it shows some service details. In my
    case, how can i first get a list of all the available services?

    Thanks.

Wim Jongman wrote:
    Hi,

    The service will already be available/published as a local
    service. Why not get a list of all services and display that to
    the user. You can also filter all remote services by specifying
    the remote service property in the filter.

    Look at the listener code in [1] to see an approach on publications.

    Best regards,

Wim

    [1] http://dev.eclipse.org/viewcvs/index.cgi/org.eclipse.ecf/examples/bundles/org.eclipse.ecf.examples.remoteservices.quotes.consumer/src/org/eclipse/ecf/examples/remoteservices/quotes/consumer/Application.java?view=markup&root=RT_Project
    <http://dev.eclipse.org/viewcvs/index.cgi/org.eclipse.ecf/examples/bundles/org.eclipse.ecf.examples.remoteservices.quotes.consumer/src/org/eclipse/ecf/examples/remoteservices/quotes/consumer/Application.java?view=markup&root=RT_Project>


On Tue, Aug 17, 2010 at 8:01 AM, Markus Alexander Kuppe <ecf-dev_eclipse.org <http://ecf-dev_eclipse.org>@lemmster.de <http://lemmster.de>> wrote:

        On 08/17/2010 07:58 AM, Nicholas Loulloudes wrote:
        > Hi Markus,
        >
        > I am experimenting with the Zookeeper code rom Wim's
        tutorial, and one
        > of the things i would like to do is to obtain a list of the
        services
        > provided by a host.
        > I tried to use the IDiscoveryLocator interface as suggested
        in the
        > Zoodiscovery wiki, but when calling the getServices()
        method, an empty
        > array is returned.
        >
        > Could the discovery part in OSGi assist me in getting a
        list of the
        > published services? If yes, could you direct me on how to
        achieve this?

        Question is, what is supposed to happen with the list of
        services once
        retrieved. Do you want your distribution provider to create
        endpoints
        and connect to each of to invoke services? Or do you just want to
        display the results and e.g. let a user choose a service
        manually?

        Markus
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--

    ________________________________________________________
    Nicholas Loulloudes
    PhD Candidate,

    High Performance Computing Systems Laboratory (HPCL)
    University of Cyprus,
    Nicosia, Cyprus

    Tel: +357-22892663
    Email: loulloudes.n[at]cs.ucy.ac.cy <http://cs.ucy.ac.cy>
    Web: www.cs.ucy.ac.cy/~nickl <http://www.cs.ucy.ac.cy/%7Enickl>
    ________________________________________________________

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