The asynchronous web service is opposite to the synchronous request-response mechanism, as the asynchronous web services use a one-way mechanism. This type of invocation is recommended for long-running web services. The asynchronous web service invocation is especially handy in scenarios where we cannot expect the response in a reasonable time constraint such as the integration of payment systems between banks where confirmations are sent according to the contracts and can take from a few seconds to a few days. In this recipe, we will explore how to invoke the asynchronous web service from the BPEL process.
Before we start with the recipe, we need access to the asynchronous web service. Since the BPEL processes also have the possibility to be exposed as the web services endpoints, we will use the asynchronous BPEL process for this recipe. That way we will also show how to call one BPEL process from another BPEL process.