I seem to run into a lot of confusion over SOAs and ESBs.
I often meet people who think that an ESB is required in order to build an SOA. This is, of course, a load of rubbish – companies have been deploying SOAs from long before the ESB came to market. Others think that once they have implemented an ESB then they have an SOA. Once again, this is completely incorrect – a service-oriented architecture is about a lot more than just a messaging bus with a bit of mediation.
Having said this, there IS a good case for using ESB technology as part of an SOA implementation. After all, SOA requires some sort of communications pipe, and the sort of mediation facilities offered by ESBs, and there are other characteristics like standards adherence that add to the attraction of an ESB for SOAs. For those interested in a more detailed discussion of the relationship between SOAs and ESBs, take a look at the free Illuminatus Research report, ‘SOAs and ESBs’, which can be downloaded from www.illuminatusresearch.com.