Enterprise service buses (ESBs) are a wonderful example of the evolving state of SOA technology, and the confusion it causes. In April of 2005, there was a somewhat fractious debate about whether an ESB was even a product. Sonic Software, self-proclaimed inventors of the ESB, of course took the product side, while IBM argued that it was a "concept" that would be implemented within various applications.
In December of 2005, Sonic attempted to deal with market confusion by publishing what it hoped would become an official definition. The company at that time felt that many of its competitors -- or competitor wannabes -- were abusing the term because it was so hot.
In August of 2005, the former CTO of a company called YouthStream Media Networks proposed that it was time for the ESB to evolve to an ESP -- "event stream processing," meaning that the bus would actually act on messages.
This week, we have the ISB -- the "information service bus," which is based on the notion that the types of adapters used to connect data sources differ considerably from ESB adapters. In fact, it may be that three different types of buses are required.
These developments -- in some cases, non-developments -- are typical growing pains for any new technology. Unfortunately, developers still have to track them -- and that's what we're here for.