The second instalment of the WebSphere Process Server and WebSphere ESB deployment patterns series is now available. This describes in considerable detail the steps required to configure a simple Process Server cluster. By removing the parts that are plainly not applicable, you are left with a set of good instructions for creating a simple WebSphere ESB cluster. You should, however, refer back to the first article to review when using this simple topology is valid. In particular, you should note that co-locating the SCA modules and messaging engines is generally only possible when you are not using asynchronous SCA i.e. the module imports are not using JMS. If you do use asynchronous SCA then the partitioning of destinations on the SCA.SYSTEM bus that occurs as a result of clustering the messaging engines can become a problem, with responses no longer guaranteed to get back to a partition that is accessible by the instance of the module waiting for it.