Implementing and managing synchronous design pattern is easy in middle-ware. Because most of retry and error handling is taken care of source application itself. It has many benefits and drawbacks. One of the drawback is that thread is blocked until  it gets response back from ESB. Other  is  that , web service invocation may results in a timeout when ESB layer takes longer time to reply back to source application. This will have impact on performance. Sometimes it is hidden from our view that many applications are participating in this chain of invocation to complete the web service invocation loop. Following might be the typical scenario.

Source application is invoking a web service to the ESB and wait for ESB to complete the process. ESB in-turn calls target application and wait for response. Target waits for response from database. The database waits for synch up with DR site before responding.

In the above example entire chain is spread over five applications.  So source application waits till all the 5 applications complete their tasks. It take considerable amount of time.  It may results in time-out, duplicate message issue etc.  In this context, asynchronous invocation is a better option.