Java Message Service, 2nd Edition

Foreword

Ted Neward

Principal Consultant,ThoughtWorks

For close to a decade now, I’ve been a fan of messaging-based systems. They offer a degree of reliability, flexibility, extensibility, and modularity that a traditional RPC or distributed object system simply cannot. Working with them takes a bit of adjustment, because they don’t quite behave the same way that an architect or designer expects a traditional n-tier system to behave. This is not to say that they’re better or worse; they’re just different. Instead of invoking methods on objects directly, where the object can hold conversational state or context, now the message itself has to be self-contained and state-complete.

Which raises an important point.

For any given developer with respect to any given technology, there are four distinct stages.

The first is the Ignorant. We may know the technology exists, or not, but beyond that we remain entirely ignorant about its capabilities. It’s a collection of letters, at best, often mentioned in conjunction with other technologies that may or may not matter to what we’re doing on a daily basis.

The second is the Explorer. Something piques our curiosity, voluntarily or not. We begin some initial forays into the jungle, perhaps downloading an implementation or reading a few articles. We begin to understand the basic framing of where this thing sits in the broad scheme of things and maybe how it’s supposed to work, but our hands-on experience is generally limited to the moral equivalent of ...