Distributed Computing Technology
The Web Services platform represents the evolution of past distributed component technologies like remote procedure calls (RPC), ORPC (DCOM, Corba, Java RMI), messaging (MSMQ, MQSeries), and even modern Web applications (like Google.com). Because RPC was so difficult, developers layered object facades over the RPC mechanism to hide complexity.
This led to the many flavors of object-oriented remote procedure calls (ORPC). Of course, not all application communication can be modeled with RPC, so other messaging paradigms (like those provided by MSMQ) were necessary. Then, over the years, as developers struggled with interoperability between the various ORPC and messaging systems, they turned to the evolving Web as a potential solution for these challenges.