Web Services - WSDLDr. Schahram Dustdar

Overview

What is WSDL?WSDL alternatives?WSDL discussion: pro‘s & con‘sWSDL structure

What is WSDL?

Web Services Description LanguageAn XML format for describing network services as a set of endpoints operating on messages containing either document-oriented or procedure-oriented informationBindings are described in conjunction with SOAP 1.1, HTTP GET/POST and MIME data and protocol formatsWSDL documents provide

documentation for distributed systems to communicateA recipe for automating the details involved in applications communication

WSDL documents don‘t provideSecurity informationQoS information

What is WSDL?

WSDL 1.1 submitted to W3CDescribes

TypesMessagesPort Types (Groups of operations)

Bindings (port type associated with protocol)Ports (associations of bindings with network address)Services (groups of ports)

WSDL alternatives?

e-speak (Hewlett Packard)Rosetta-netRDF

WSDL pro‘s

Fits with SOAP (but not tied to it)Flexible and layered

Example:WSDL & WebSphere Application Server

WSDL Structure

WSDL identifies 4 elements of a service description

Reuseable DescriptionsType/Message DefinitionsAbstract Interface DescriptionsReuseable Protocol Bindings

Service DeploymentEndpoints of Deployed Services

WSDL Dokumentaufbau

Message Patterns - Overview

Message Patterns One-Way

Analog zu Fire- and- ForgetDie Message wird vesendet; es wird keine Antwort erwartet.

Request/ResponseAnalog zu RPCDer Sender sendet eine Message der Receiver sendet eine Antwort darauf.

Solicit Response (noch offen)Ein Request ohne Daten für eine Response.Das Inverse einer One- Way Message

Notification (noch offen)Mehrere Empfänger für eine Message (broadcast ähnlich)Analog zu Publish/ Subscribe

Message Patterns 1/2

Message Patterns 2/2

Scenario

WSDL tags

WSDL Structure

Abstract Description

ConcreteDescription

Simple Web Service example

WSDL for example 1/3

WSDL for example 2/3

WSDL for example 3/3

Reuseable WSDL Specs as tModels (WSDL und UDDI)

UDDI tModels provide a base for technical service descripionsWSDL provides an XML schema for defining reuseable technical specificationsA tModel that references a WSDL provides a mechanism (via UDDI) by which compliant services can be located and invoked