Python & XML

What About XML-RPC?

Before the first version of the SOAP specification was completed, a simpler specification for a remote procedure call mechanism employing XML over HTTP was created by Dave Winer of UserLand Software; this specification is known as XML-RPC. This specification builds in less support for complex data types, but has the advantage of simplicity. Uptake among the developer community has been very rapid, in part because it filled a void before SOAP was available, and in part because the simpler specification allowed implementations to be easy to work with.

The simplicity of XML-RPC comes largely from the willingness of the authors of the specification to nail down many of the details required to implement the specification. Where SOAP allows the use of alternate transport protocols and data serialization rules, XML-RPC specifies HTTP POST requests and a single set of serialization rules. Though the flexibility offered by SOAP can be valuable for some projects, many developers suspect that this will be used to bloat middleware components and achieve vendor lock-in, which is something many XML users are trying to avoid.

Fredrik Lundh’s xmlrpclib module, which will be part of the Python standard library as of Python Version 2.2, is available for older versions of Python at http://www.pythonware.com/. It presents a proxy interface very similar to that of SOAPy for clients to use, and provides support for basic server implementations as well.

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