This webapp demonstrates the advantages of calling webservices using Asynchronous APIs. In this case it calls the EBay REST API using the jetty async HTTP Client and Jetty Continuations to free the servlet thread while waiting for the response. The results are compared to a normal synchronous call and both the total and thread times are charted below.
It can be seen that for the synchronous case, the thread is held for the entire waiting time and that multiple requests are performed serially. For the asynchronous case, the thread is only held for a short periods and multiple requests can be handled in parallel.