For an application to use another application's functionality on any platform, the application must use a universal language to communicate called SOAP (Simple Object Access Protocol). SOAP is an XML-based protocol that you can use to write messages to send and receive web service requests and responses over the Internet.
The following figure shows how web services work with ColdFusion:
Figure 1. Web services working with ColdFusion
When using ColdFusion, you don’t have to learn how to write SOAP messages to communicate with other servers; you can use simple ColdFusion tags to publish and consume web services. ColdFusion writes the SOAP messages for you.