A few years ago, I wrote a book with a colleague about open source ESBs (Enterprise Service Buses), Open Source ESBs in Action (Manning, 2008). In that book we wrote about using open source tools to integrate applications and expose legacy systems as services. In the years that followed, ESBs were seen as one of the cornerstones of developing Service Oriented Architectures (SOAs). In 2008, when people talked about SOA, especially in the enterprise world, they meant the traditional SOAP-over-HTTP-based services. Everyone was doing this, the big vendors promoted it, and it finally looked like we had a way to create services that could be used by.
