Introduction to WSDL presented by Xiang Fu

Source WSDL 1.1 specification WSDL 1.1 specification – WSDL 1.2 working draft WSDL 1.2 working draft – W3C School Tutorial W3C School Tutorial –

What is WSDL Web Service Description Language. Web Service Description Language. An XML language used to describe and locate web services. An XML language used to describe and locate web services. –Written in XML. –Describe functionality of a web service –Specify how to access the service (binding protocol, message format, and etc.) Not a W3C standard yet. Not a W3C standard yet. –Version 1.1 released March 2001 –Working draft of Version 1.2 released July 2003

Related Standards Type System: XML Schema Type System: XML Schema Name space: XML namespaces Name space: XML namespaces Binding: SOAP, HTTP, MIME and etc. Binding: SOAP, HTTP, MIME and etc.

The Main Structure of WSDL xschema types xschema types … … a set of operations a set of operations communication protocols communication protocols a list of binding and ports a list of binding and ports <definition>

Types define types used in message declaration define types used in message declaration XML Schema, DTD, and etc. XML Schema, DTD, and etc. XML Schema must be supported by any vendor of WSDL conformant products. XML Schema must be supported by any vendor of WSDL conformant products.

<types> <element name="tickerSymbol" type="string“ <element name="tickerSymbol" type="string“ minOccur = “1” maxOccur=“10”/> minOccur = “1” maxOccur=“10”/> </types>

WSDL Messages The element defines the data elements of an operation. The element defines the data elements of an operation. Each messages can consist of one or more parts. The parts can be compared to the parameters of a function call in a traditional programming language. Each messages can consist of one or more parts. The parts can be compared to the parameters of a function call in a traditional programming language.

WSDL Ports The element is the most important WSDL element. The element is the most important WSDL element. It defines a web service, the operations that can be performed, and the messages that are involved. It defines a web service, the operations that can be performed, and the messages that are involved. The defines the connection point to a web service, an instance of. The defines the connection point to a web service, an instance of. It can be compared to a function library (or a module, or a class) in a traditional programming language. Each operation can be compared to a function in a traditional programming language. It can be compared to a function library (or a module, or a class) in a traditional programming language. Each operation can be compared to a function in a traditional programming language.

Operation Types The request-response type is the most common operation type, but WSDL defines four types: The request-response type is the most common operation type, but WSDL defines four types: One-way: The operation can receive a message but will not return a response Request-response:The operation can receive a request and will return a response Solicit-response:The operation can send a request and will wait for a response Notification:The operation can send a message but will not wait for a response -- v 1.2 addition request – multiple response …

One way and Notification Example

Binding Binding defines how message are transmitted, and the location of the service. Binding defines how message are transmitted, and the location of the service.

<soap:binding style ="document" transport ="

My first service

WSDL and UDDI Description of web service. Description of web service. Discovery of web service? Discovery of web service? UDDI – yellow page. UDDI – yellow page.

What is UDDI UDDI is a platform-independent framework for describing services, discovering businesses, and integrating business services by using the Internet. UDDI is a platform-independent framework for describing services, discovering businesses, and integrating business services by using the Internet. UDDI stands for Universal Description, Discovery and Integration UDDI stands for Universal Description, Discovery and Integration UDDI is a directory for storing information about web services UDDI is a directory for storing information about web services UDDI is a directory of web service interfaces described by WSDL UDDI is a directory of web service interfaces described by WSDL

How can UDDI be Used If the industry published an UDDI standard for flight rate checking and reservation, airlines could register their services into an UDDI directory. If the industry published an UDDI standard for flight rate checking and reservation, airlines could register their services into an UDDI directory. Travel agencies could then search the UDDI directory to find the airline's reservation interface. Travel agencies could then search the UDDI directory to find the airline's reservation interface. When the interface is found, the travel agency can communicate with the service immediately because it uses a well- defined reservation interface. (by WSDL) When the interface is found, the travel agency can communicate with the service immediately because it uses a well- defined reservation interface. (by WSDL)

What’s missing? Quality of service. (how fast, how reliable?) Smart Searching (currently business code match) DAML-S project. DAML-S project. –DARPA Agent Markup Language for web Services. Describes control flow Describes control flow Quality of service. Quality of service. Support smart discovery of service Support smart discovery of service –Ontology based technology. A big dictionary defining the relations between concepts. A big dictionary defining the relations between concepts. e.g. vehicle – car – truck …

Problems Complex long running web services. Complex long running web services. Communication infrastructure – Communication infrastructure – –Asynchronous communication Analysis and verification Analysis and verification Automatic composition of complex services. Automatic composition of complex services. …