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From Bulu <b...@romandie.com>
Subject Re: DependencyManager: notify third party object of changed adaptee properties
Date Thu, 16 Oct 2014 08:11:11 GMT
Hello Pierre

Thanks for coming up with this solution. I will try it out. The only 
downside I see, is that bundle-internal objects (the adapters) are 
published on the framework, so we lose a bit of encapsulation, but I can 
live with that.

About the usage of the DeviceManager:
I want to show devices with their properties in a Vaadin GUI, for this, 
they must be collected in a Container which is linked to the Widget (a 
Tree). So two things need to happen:
1. for each Device appearing, create a DeviceAdapter which is of a 
convenient form (a Bean) for the Vaadin framework to use, and which 
forwards calls to the actual Device
2. for each DeviceAdapter created, add it to the Container (and remove 
when disappearing...). The DeviceManager holds the Container and 
adds/removes the adapters in it.

For separation of concerns, I didn't want the DeviceAdapters to directly 
hold a reference to the deviceManager/container (ie. they should not 
add/remove themselves).

Now I also want to track changes in the properties (which do not destroy 
the adapter, its filter is still met), so that I can update the 
container (a typical property which might change is the "parent" node in 
the tree widget). So it is also the DeviceManager which needs to get 
these property change notifications.

I will file a Jira request. I guess the difficulty might lie in the fact 
that you will have to distinguish two case:
1. adaptee property change which make the adapter disappear (filter no 
longer met)
2. adaptee property change but adapter is kept - so call callbacks on 
itself or third party object

Regards Philipp

On 16.10.2014 08:50, Pierre De Rop wrote:
> Hello Philipp,
> I think that currently, it is not possible to specify a third party
> callback object to be notified when the adaptee services properties are
> changed, and only your adapter will be notified.
> One possible alternative could consist in letting the adapter impl provide
> an adapted interface and you could then track the adapted interface itself,
> because when the adaptee (Device) service properties are changed, the
> Device changed properties are then also propagated to the service
> properties provided by the adapter (if the adapter provides an adapted
> service).
> For example, when you create your adapter, you can manage to let it provide
> a service (like 'DeviceAdapter' service):
> mgr.add(createAdapterService(Device.class,null)
>         .setImplementation(DeviceAdapter.class)
>         .setInterface(DeviceAdapter.class, null)
>         .setCallbacks("init", "start", "stop", "destroy"));
> Then you could manage to define your "DeviceManager" as a DM component, and
> that component could listen to all DeviceAdapter services, including
> propagated service properties change events:
> mgr.add(createComponent()
>         .setImplementation(DeviceManager.class)
>         .add(createServiceDependency(DeviceAdapter.class).setRequired(true)
>                  .setCallbacks("added", "changed", "removed)));
> then your DeviceManager could be called back it its changed method when a
> DeviceAdapter propagates its adapted Device service properties change
> events.
> This should work, but I don't know if this would be compatible with your
> current application design ?
> (maybe you could describe a but what is doing your DeviceManager ?)
> Now unfortunately, regarding your last question, I think that the work
> around won't work, because when the adaptee services comes up, the first
> dependency (the one that your work around has modified) is removed and
> replaced by another dependency (see the AdapterServiceImpl.
> AdapterImpl.createService() method()).
> Now, if you really need to be able to specify a callback instance to be
> called when the adaptee service properties are changed (Device), then can
> you please create a Jira issue for it, and I will add a
> createAdapterService signature allowing to specify a callbackObject,
> similar to what is currently done int the createResourceAdapterService
> methods.
> (Marcel, would you be OK for this new feature ?)
> kind regards;
> /Pierre
> On Wed, Oct 15, 2014 at 2:52 PM, Bulu <bulu@romandie.com> wrote:
>> Addition to my own question:
>> I came up with the following, but the callbacks seem not to get called on
>> the deviceManager...
>> Component adapter = createAdapterService(Device.class,null)
>>    .setImplementation(DeviceAdapter.class)
>>    .setCallbacks(deviceManager, INIT_METHOD, START_METHOD, STOP_METHOD,
>> // Ugly: supposing the adapter has always the adaptee as first service
>> dependency
>> ServiceDependency dep = (ServiceDependency) adapter.getDependencies().get(
>> 0);
>> logger.debug("Dependency is {}", dep); // OK, in my tests it's the right
>> dependency
>> dep.setCallbacks(deviceManager, BIND_METHOD, CHANGED_METHOD,
>> mgr.add(adapter);
>> Is this the right way?
>> Regards Philipp
>> On 15.10.2014 14:12, Bulu wrote:
>>> Hello All
>>> Using Dependency Manager, I declare adapters like this:
>>> mgr.add(createAdapterService(Device.class,null)
>>> .setImplementation(DeviceAdapter.class)
>>>    .setCallbacks(deviceManager, "init", "start", "stop", "destroy"));
>>> So deviceManager gets notified when the adapters appear. Now I also want
>>> deviceManager to be notified when the properties of any of the adaptees
>>> (Device.class) change (need to update the UI).
>>> For normal ServiceDependency I can specify callbacks to be called on a
>>> third party object with
>>>    ServiceDependency.setCallbacks(Object instance, String added, String
>>> changed, String removed);
>>> For adapters and I can specify the callbacks, but only calling the
>>> adapter itself:
>>>    createAdapterService(Device.class.name, null, "add", "change",
>>> "remove")
>>> How can I tell the adapter to use callbacks on a third party object
>>> (deviceManager) when the adaptee's properties change?
>>> Thanks & regards
>>>    Philipp
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