Re: [ecf-dev] Problem with SharedObject API

[Scott Lewis <slewis@xxxxxxxxxxxxx>]

Hi Pavel,

Samolisov Pavel wrote:
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> Thanks Scott.
>
> Tests works fine, my code works too. But I do not understand why this
> code is in TestSharedObject (in method initialize()):
>
> // This is a replica, so initialize the name from property
> name = (String) getConfig().getProperties().get(NAME_PROPERTY);
>
> Is this code a deserialization from Config to SharedObject? Why name do
> not replicate with SharedObject automaticaly?
>   

This code is only executed on the non-primary copy of the shared object 
(i.e. the replicas).  This code (run only on the primary copy), is 
responsible for serializing the state of the shared object (in this 
case, it's name):

   protected ReplicaSharedObjectDescription getReplicaDescription(ID 
receiver) {
       // Put primary state into properties and include in replica 
description
       final Map properties = new HashMap();
       properties.put(NAME_PROPERTY, name);
       return new ReplicaSharedObjectDescription(this.getClass(), 
getConfig().getSharedObjectID(), getConfig().getHomeContainerID(), 
properties);
   }

And then the code you quote above sets the name (for the replicas) to 
the value specified by the properties included in the 
ReplicaSharedObjectDescription.  The serialization/deserialization of 
shared object state is done explicitly rather than implicitly...so as to 
give the shared object programmer some control over the serialization.  
I was/have been thinking of adding some implicit serialization of shared 
object fields (perhaps through annotations processing or some such), but 
for the moment everything is explicitly done (via properties).

> And another question: Does SharedObject API have any listeners that
> calls when shared object has been added?
>   

Yes, indeed.  An IContainerEvent of sub-type ISharedObjectActivatedEvent 
is sent to any/all IContainerListeners before the shared object is 
activated, and similarly ISharedObjectDeactivatedEvent is sent before 
the shared object is deactivated.  The shared object itself is also 
asynchronously notified as well (the shared object has a message queue 
and a thread created for it to process it's messages...and that's how 
the initialize method gets called on the replicas).

Scott