XML RPC via XMPP

Question

I'm currently trying to implement XML RPC via XMPP. I'm using Smack as client library and Vysper as XMPP server. Simplified, my setup looks as follows:

[client1] — [server] — [client2]

I want to invoke a method on Client 2 from Client 1. I create an IQ with type set, and from and to elements and the query content as described in [1]. Simplified example:

<iq type='set' from='client1@localhost' to='client2@localhost' id='1'>
  <query xmlns='jabber:iq:rpc'>
    <methodCall>
      <methodName>foo</methodName>
    </methodCall>
  </query>
</iq>

The problem is, when sending the IQ from client1 I receive back an error IQ, and nothing is submitted to client2. Investigating the problem, I came across this statement in the specs [2]:

A server MUST ignore any 'to' address on a roster "set", and MUST treat any roster "set" as applying to the sender. […]

Am I correct, that in this constellation Jabber-RPC is not possible between two clients? Or do I have a fundamental misunderstanding of Jabber-RPC?

[1] http://xmpp.org/extensions/xep-0009.html

[2] http://xmpp.org/rfcs/rfc3921.html#roster

Lance Stout Lance Stout · Accepted Answer · 2012-05-31T23:14:21

It looks like you are sending the Iq stanza to the client's bare JID instead of a full JID, i.e., [email protected] instead of [email protected]/resource.

Iq stanzas sent to a bare JID are handled by the server and are not routed to clients. You are in essence querying the user's account, not interacting with a particular connected agent. Typically, you always want to specify the recipient's full JID.

XML RPC via XMPP

1 Answers