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Re: [ecf-dev] Problem with SharedObject API

Hi Pavel,

Thanks for the blogging. Any chance that we could get your blog posting converted to English and made available somehow? Are there Russion to English conversion services that would do the trick?



Samolisov Pavel wrote:
Hello All,

Scott, thanks for you reply. It works fine.
I had understood SharedObject API and blogged about it (on Russian).

Scott Lewis пишет:
Hi Pavel,

Samolisov Pavel wrote:
Hash: SHA1

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
       final Map properties = new HashMap();
       properties.put(NAME_PROPERTY, name);
       return new ReplicaSharedObjectDescription(this.getClass(),
getConfig().getSharedObjectID(), getConfig().getHomeContainerID(),

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 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).


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