Table of contents

Appendices

2 Predefined Message Exchange Patterns

Web Services Description Language (WSDL) message exchange patterns (hereafter simply 'patterns') define the sequence and cardinality of abstract messages listed in an operation. Message exchange patterns also define which other nodes send messages to, and receive messages from, the service implementing the operation. WSDL message exchange patterns describe the interaction at the abstract (interface) level, which may be distinct from the pattern used by the underlying protocol binding (e.g. SOAP Message Exchange Patterns).

By design, WSDL message exchange patterns abstract out specific message types. Patterns identify placeholders for messages, and placeholders are associated with specific message types by the operation using the pattern.

Unless explicitly stated otherwise, WSDL message exchange patterns also abstract out binding-specific information like timing between messages, whether the pattern is synchronous or asynchronous, and whether the message are sent over a single or multiple channels.

Like interfaces and operations, WSDL message exchange patterns do not exhaustively describe the set of messages exchanged between a service and other nodes; by some prior agreement, another node and/or the service may send other messages (to each other or to other nodes) that are not described by the pattern. For instance, even though a pattern may define a single message sent from a service to one other node, the Web Service may multicast that message to other nodes.

To maximize reuse, WSDL message exchange patterns identify a minimal contract between other parties and Web Services, and contain only information that is relevant to both the Web Service and another party.

This specification defines several message exchange patterns for use with WSDL Version 2.0 Part 1: Core Language [WSDL-PART1].