an intermediate buffer exists between a service and its service consumer

temporary message storage is provided in case either the service or service consumer are unavailable

periodic re-transmission of a message is supported until it is successfully delivered

enforcement of consistent, uninterrupted, synchronous communication between service and service consumer are guaranteed

Schema Centralization, XML schemas

Message Metadata, SOAP message headers

Decoupled Contract, WSDL definitions

Policy Centralization, WS-Policy definitions

a service, acting as a publisher, issues event notification messages to an event management program that is responsible for broadcasting the messages

a service consumer, acting as a subscriber, can selectively subscribe to specific events

an intermediate event management program enters the role of subscriber when accepting event subscriptions

upon receiving a message associated with an event that a service consumer subscribed to, the service consumer enters the publisher role