In a chapter like this, it makes sense to discuss the difference between components and services.

Components are first-class deployable units packaged into standard artifacts. Components live in some container; there is component-container interaction for component lifecycle management and event notification. Thus, components are physical units. Components will also assume explicitly about the protocol and format of data sent over the wire, since most of the time they are technology-dependent.

Services on the other hand have URL addressable functionality, accessible over the network. At least from the consumer perspective, there are no lifecycle activities associated with the service, since services are stateless and idempotent. Between any two service invocations, there is no state maintained at the provider-level (of course, there are stateful services too). Thus services are virtual distributed components, which are neutral about the protocol and format of sending...