It’s a rare Ajax application that doesn’t need network access. To the despair of many a developer, though, there are almost as many ways of communicating with a server as there are servers. The usual alphabet soup applies (XML, JSON, SOAP, RPC, and others) but even once you pick one, you’re really just getting started. Designing your services for scalability and performance is an art in itself, regardless of which format you choose to represent your data. Fortunately, a few of us have lived this nightmare and survived to talk about it.