One of the things I like about XML-RPC is that is really is astonishingly easy to implement. I like to be able to understand the code I write - and that includes the things I reuse from elsewhere. And with XML-RPC, it's even better - it's normally possible to parse the XML that comes back by eye.
Contrast that with the monstrosity that SOAP has evolved into - a huge morass of complexity, massive code size, bloat everywhere, and it's really turned into a right mess. There's been nothing simple about SOAP for a long time now.
The snag with XML-RPC is that there are a couple of rather crippling limitations. In particular, you're stuck with 32-bit integers. I've had to enable vendor extensions in order to use 64-bit longs, and while that's fine for my client code, it makes the JKstat server far less useful for clients using other frameworks and languages.
So I'm stuck in a hole. I'm going to stick with XML-RPC for now, as it will be good enough to test with and is really easy to develop against. (And the way I've implemented the remote access makes it trivial to put in new or replacement access services.)
What's the way forward? I'm not at all keen on building a full web-services stack - that defeats the whole object of the exercise. There has been some discussion recently of exposing the kstat hierarchy via SNMP, but that's clunky and depends on SNMP (great if you use SNMP already, less great if you don't). I've been looking at things like JSON-RPC and RESTful web services as alternatives. The simplest approach may just be to encode everything as Strings and convert back.