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Chapter 4. Using the JBoss Communications JAIN SLEE SIP Subscription Client Enabler

4.1. The Child's SbbLocalObject Interface
4.2. Creating And Retrieving The Child Sbb
4.3. Enabler configuration

In the last chapter we integrated the Enabler in the JAIN SLEE Service's Sbb, the Parent Sbb, in this chapter it is explained how to use the Enabler's Sbb, the Child Sbb.

Enabler performs following tasks:

manage subscription

send subscription events on behalf of Parent Sbb

automatic refresh

based on values exchanged between Enabler and Server, Enabler keeps track of subscription life time(expiration) and issues refresh requests to Server

JAIN SLEE SIP Subscription Client Enabler control flow

The JBoss Communications JAIN SLEE SIP Subscription Client Enabler Sbb, the Child Sbb, implements the org.mobicents.slee.enabler.sip.SubscriptionClientChildSbbLocalObject , which extends the javax.slee.SbbLocalObject and org.mobicents.slee.enabler.sip.SubscriptionClientChild interfaces, the latter declares the methods which can be used to interact with the SIP Event Server:



package org.mobicents.slee.enabler.sip;
public interface SubscriptionClientChild {
    public void setParentSbb(SubscriptionClientParentLocalObject parent);
    public String getSubscriber();
    public String getEventPackage();
    public String getNotifier();
    public void subscribe(String subscriber, String subscriberdisplayName
        , String notifier, String eventPackage, int expires, String content,
            String contentType, String contentSubtype) throws SubscriptionException;
    public void unsubscribe() throws SubscriptionException;
}
        
        

The Child Relation in the Parent Sbb Abstract Class is used to create and retrieve the Child Sbb, it is important to not forget to pass the Parent's SbbLocalObject to the Child after creation:



public SubscriptionClientChildLocalObject getPublicationClientChildSbb() {
    final ChildRelation childRelation = getSipPublicationClientChildRelation();
    if (childRelation.isEmpty()) {
        try {
            // creates new instance
            SubscriptionClientChildLocalObject sbb = 
                (SubscriptionClientChildLocalObject) childRelation.create();
            // passes the parent sbb local object to the child
            sbb.setParentSbb((SubscriptionClientParentLocalObject) 
                sbbContext.getSbbLocalObject());
            return sbb;
        } catch (Exception e) {
            tracer.severe("Failed to create child sbb", e);
            return null;
        }
    }
    else {
        return (SubscriptionClientChildLocalObject) 
            childRelation.iterator().next();
    }
}
        
        

The SbbLocalObject of the Child could also be stored in a CMP Field for the simplest retrieval, but unless you are going to reuse each instance several times it's better to have less state, specially in clustered environments.

Enabler can be configured with SLEE environment entries. Currently following entries are supported: