What does it mean that XML Web services are self-contained?
You are most likely referring to the common quote that Web services are "self-contained, self-describing, modular applications that can be published, located and invoked across the Web." Since most Web services today are based on XML, they are inherently capable of describing their operations and I/O requirements to interested parties. This allows client software to dynamically determine what a service does, the data types that a service uses, how to invoke operations on the service, and the responses that the service may return. Since Web services are remotely executed, they do not depend on resources residing on the client system that calls them. This autonomous nature of Web services is the primary factor that has lead to their being hyped as the new miracle of business-to-business connectivity and enterprise application integration.