Tim Bray writes

about an informative Nokia paper on WS/SOA.
Check out Nokia Web Services Framework for Devices – a Service-oriented Architecture. It’s a practical intro to how SOA might play in the mobile space, with some eminently sensible background work; there’s a section entitled What is a service-oriented architecture, and why is it good?

Heh, look, HTTP GET and POST being used (largely) RESTfully. Yeah.

The example exchange at the end is a bit concerning though. Anybody who’s done any amount of work in the mobile space quickly learns that network round trips are even more prohibitively expensive than on the land lines. You’re looking at at least a 500ms one-way over most networks, perhaps up to a second or more depending upon a number of factors, primarily signal strength (read; packet loss). At Idokorro, we had access to the first GPRS network in Canada (when nobody else was using them) and the first GPRS Blackberrys, and we were still getting 1.2 second hops to our BES.

So, any solution that requires two network round trips for doing what can be done in one, is a really horrible idea. They should scrap the PAOS stuff and just send the authentication information in the initial GET. It’s more self-descriptive, the net bandwidth consumption, at least in this example, is appreciably reduced (if auth info isn’t needed elsewhere, it might not be over time, though there’s still RESTful ways to manage that), and the user or app gets their data a second (or more) faster.


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