Programming Jabber

The IQRPC classes

JabberBeans deals with Jabber element extensions—<query/> and <x/> tags—using individual helper classes. We’ve seen this in the HostAlive recipe in Section 8.2, where the IQAuthBuilder class is used to construct an authorization extension:

<query xmlns='jabber:iq:auth'>
  <username>alive</username>
  ...
</query>

The helper classes are oriented around namespaces. Because we have a new namespace to deal with (jabber:iq:rpc), JabberBeans needs to have helper classes to handle extensions in that namespace.

We need a minimum of two helper classes. We need a class that represents an extension—a <query/> tag—in the jabber:iq:rpc namespace. If we are going to construct IQ elements containing such Jabber-RPC extensions, we also need a class to build those extensions. The class that represents the jabber:iq:rpc extension is called IQRPC, and the class that is the builder for the extensions is called IQRPCBuilder.

For an example we’re already familiar with, look at the steps leading up to the authorization phase in the HostAlive script (and indeed our JabberRPCResponder script, which is shown in the next section); the authorization IQ element is constructed as follows:

InfoQueryBuilder iqb = new InfoQueryBuilder();
IQAuthBuilder iqAuthb = new IQAuthBuilder();

iqb.setType("set");

iqAuthb.setUsername(user);
iqAuthb.setPassword(pass);
iqAuthb.setResource(resource);

iqb.addExtension(iqAuthb.build());

If we bear in mind that this is what we want to end up with:

<iq type='set'> ...