Programming Jabber

XML-RPC and SOAP

Realizing that if Jabber is an XML router that can carry XML-based custom payloads in synchronous and asynchronous modes, we can immediately start to imagine scenarios in which Jabber fits as a transport glue in other already established application domains.

The XML Remote Procedure Call (XML-RPC) specification and the Simple Object Access Protocol (SOAP) both formalize method calls and responses in XML. The XML-RPC specification describes the use of HTTP to carry those encoded calls and responses between endpoints, and SOAP can use HTTP too. What if we carry XML-RPC or SOAP payloads in Jabber? We immediately see the step-change increase in contextual richness; XML-RPC interactivity becomes part of a wider, all-encompassing conversation between applications and humans. Indeed, the breadth of that interactivity increases too; Jabber affords a network transparency across traditional firewalls and Network Address Translation (NAT) mechanisms that often defeat HTTP-based calls.

Traditional IM-based clients, applications using client stub libraries, and components can all make use of the power these technologies have to offer, without having to leave the comfort of their Jabber environment, which can serve as a messaging plasma between all sorts of entities and services.

We will look at embedding XML-RPC-encoded calls in Jabber messages in Section 10.2 in Chapter 10.