[xdm]

Hello

I trying to implement the model view controller pattern using IceStorm to deliver messages or events fron model objects to client views. in oder to do it I add a new interface to my base object derived from Ice::Object, create and Event class to emcapsulate events that are send and create a listener inteface that must be implemented or agreate by View objects the definitios as are follow

           module Oz
           {
              module Base
              {
                 class Event
                  {
                          // the id of the object that send the event
                          Ice::Identity objectId;
                          // a name used for diference events
                          string name; 
                  };
                  inteface EventPublisher
                  {
                         void eMit(Oz::Base::Event e);
                  };
                  
                  interface EventListener
                  {
                       // this operation create a Ices::Storm subcriber 
                       // for topic named objectId.name
                       idempotent void suscribe(Ice::Identity objectId);

                       // this operation unsuscribe object 
                       // for topic objectId.name
                       idempotent void unsuscribe(Ice::Identity objectId);
                       
                       // this opeartion is the contract betwen publisher 
                       // and subscriber object
                       idempotent void notify(Event e);
                   };
               };
            };

my problem is that i need a diferent topic for each object and this topics must be created on demand with object creation like topics are not persistent and objects are persistents. I think to diferents ways to manage this situation are

1) try to retrive a topic in objectInitializer and if topic not exist creating it the code can be as folow

void 
Oz::Base::ObjectInitializer::initializer(
       const Ice::ObjectAdapterPtr&,
       const Ice::Identity& objId,
       const std::string& ,
       const Ice::ObjectPtr& obj)
{

         /** heare I initilize topic manager code not show for simplicy **/
        try
        {
          obj->topic=topicManagerPx->retrieve(obj->getId().name);
        }
        catch(const IceStorm::NoSuchTopic& ex)
        {
                  obj->topic=topicManagerPx->create(obj->getId().name);
        }
}

2) can be a better aproach to do it this in the eMit operation if ObjectNoExistException is throw whe try to a call an operation on topic object

               void Oz::Base::eMit(Oz::Base::Event e)
                {
                           try
                           {
                                topic->notify(e);
                           }
                           catch(ObjectNoExistException& e)
                           {
                                  /*retrive topic manager code not show*/
                                 topic=topicManagerPx->create(id.name);
                                 topic->notify(e);
                           }
                }

In the client side i create a subscriber Proxy for each view and sucribe it to the correspoding model proxy.

My subscriber implementation can hold a pointer to the view object a when notifiy
operation is invoked in the subscriber in dispach the envet to the view.



can you say me if this a correct usage for IceStorm service?

what aproach can be better to ensure that s exist a topic for each object, or
any sugestion for do it in a diferent way?


In other to subscribe objects be accessible by IceStorm service is neceary configuring Glacier or Glacier2 are both valid?

it is posible to adquire topic manager via IcePack::Query i think yes but i'm not sure.

Thanks in advantage