Web Services at W3C

Philippe Le Hégaret,
W3C Architecture Domain

January 2005

Web Service

A Web service is a software system designed to support interoperable machine-to-machine interaction over a network. It has an interface described in a machine-processable format (specifically WSDL). Other systems interact with the Web service in a manner prescribed by its description using SOAP messages, typically conveyed using HTTP with an XML serialization in conjunction with other Web-related standards.

from Web Services Architecture,
11 February 2004

Architecture

Web Services Architecture (completed in January 2004)

common minimal characteristic of Web Services
define a scope for each technology and their relationships
promotes an interoperability architecture
glossary for Web Services
usage scenarios

Web Services

Web Services Protocol
Core Protocol
- Messaging Framework: SOAP 1.2
- Web Services Addressing
- Message Transmission Optimization Mechanism: MTOM
Protocol extension
- Resource Representation SOAP Header Block
Web Services Description
- Web Services Description: WSDL 2.0
- Web Services Choreography Description: WS-CDL 1.0

Web Services Protocol

Messaging Framework

SOAP 1.2:

basic XML Framework for exchanging structured and typed information in machine-to-machine interaction
necessitate the use of a transport protocol, such as HTTP/1.1
improved interoperability, processing model, and protocol independence since SOAP 1.1
already deployed in all major toolkits and several Web Services extensions

W3C Recommendation since June 2003

Addressing (1/2)

Addressing (2/2)

Web Services Addressing 1.0:

define service endpoint references
direct messages to the service endpoints, including replies or faults.
relates messages using URIs

Working Group started in October 2004

Message Transmission Optimization Mechanism (1/2)

Message Transmission Optimization Mechanism (2/2)

SOAP Message Transmission Optimization Mechanism (MTOM):

enables the optimization, at the transport protocol level, of the transmission and wire format used to transfer binary data in a SOAP message.
ideal for large binary attachments:
- save bandwith: binary files are sent as-is on the wire (33% gain)
- better performance: no conversion binary-to-XML and XML-to-binary for the transmission
compatible with specifications built on top of the Infoset, such as XML Signature

W3C Recommendation since January 2005.

Resource Representation SOAP Header Block

Resource Representation SOAP Header Block (RRSHB):

allows SOAP messages to embed cached representations of external resources.

W3C Recommendation since January 2005.

Web Services Description

Description

WSDL 2.0: Define a basic description of a Web Service

the interface and its operations, including the types of the data being exchanged
the transport protocol binding(s) associated with the operations
the endpoints associated with each transport protocol bindings

Working Group started in January 2002

Choreography Description

WS-CDL 1.0: Describe interaction among atomic Web Services

Complex messages exchanges
Composition of Web Services: linking business via Web Services