In Patterns under Business Delegate pattern two proxys are created 1 on the client side called the stub and the other on the server side called the skeleton .But i have encountered another object called the model service(remote object) what is this and how come the stub communicates with this service instead of the skeleton Why is that ?
Please can any one clarify this, I might be confusing things if you could explain the whole thing .
Usually Business Delegate uses ServiceLocator to locate a JNDI,or other remote services. By doing so Business delegate obtains stub to a particular remote object on which the BusinessDelegate would perform subsequent method invocations. And that stub could be a client side representation of a remote "SessionFacade" , "Business Object" or an "Application Service" object. But It is very unlikely that Business Delegate invokes methods on remote BusinessObjects or an ApplicationService without a use of a proper Session Facade.
Also the stub, skeleton are supportive object to BusinessDelegate to invoke methods on a RemoteObject, For an example if you have a SessionFacade then the stub ,skeleton would help you calling the SessionFacade methods , or if the application uses BusinessObject without a SessionFacade then stub,skeleton are for that BusinessObject. Hence It looks like in the document that you referred could be talking about about one of the above implementations.Hope this helps a bit. And if there is a possibility please let me see the literature that you referred in the question.
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ths for your kind reply , i wanted to know what does model service mean .I am reading HFSJ and in the last chapter under business delegate pattern there is a mention of "model service" in the model component. It is also shown in a and drawn beside the model entity in the model component .
please if you can look in to the book and tell me from where is this service thing come from , because before this there was no mention of this in the book.
Model Service which is referred there is actually your Business Objects which contain Business Logic of the system.In an enterprise application you could possibly have three models, Domain Model , Data Model and possibly a Presentation Model too.
Domain model would be about the business logic of the system and this is most of the time comprises of Business Services provided by Business Objects plus Application Service objects.
Data model is about the representation of persistent data of the system, this would be given by an ER diagram.
Presentation Model is all about presenting information to the end user