Introduction to Web Services Presented by Sarath Chandra Dorbala

Outline Definitions Basic Standards SOAP WSDL UDDI

Definitions A Web Service is a software component that is described via WSDL and is capable of being accessed via standard network protocols such as but not limited to SOAP over HTTP. The W3C defines a Web service as a software system designed to support interoperable Machine to Machine interaction over a network. An Internet hosted application controlled through SOAP requests which returns results as SOAP responses.

Basic Standards XML – All web service documents are written in XML – XML Schemas are used to define elements used in Web Service communication SOAP – Communication is done over SOAP (typically) – Request and responses messages are encoded in SOAP – The body of the message is contained with in SOAP envelope – Binds the client to the web service

WSDL – Describes the web service and defines functions that are exposed in the web service – Defines SOAP message format UDDI – UDDI is used to register and look up services with a central registry – Service Providers can publish information about their business and the services that they offer – Service consumers can look up services that are available by Business Service category Specific service

SOAP Stands for Simple Object Access Protocol It is a platform independent, XML bases communication protocol for message exchanging between applications

Elements of SOAP message SOAP is a XML document with the following elements Envelope – Used to identify the SOAP message Header (Optional) – This element contains header. For this course this part is important for incorporating security into web services Body – This element contains call and response information Fault (Optional) – This element contains details about processing errors

Skeleton SOAP Message

Sample SOAP Message SOAP Request POST /InStock HTTP/1.1 Host: Content-Type: application/soap+xml; charset=utf-8 Content-Length: nnn IBM

SOAP Response HTTP/ OK Content-Type: application/soap+xml; charset=utf-8 Content-Length: nnn 34.5

WSDL WSDL stands for Web Service Description Language It is an XML Document that describes a web service It specifies the location of the service and operations it exposes

Elements of WSDL – It describes a web service, the operations that can be performed, and the messages that are involved. – Defines the data elements of an operation. Eg, Parameters to the function call parameters – Defines the data types used by the web service – Defines the message format and protocol bindings for each port

Skeleton WSDL Document definition of types definition of a message.... definition of a port definition of a binding....

WSDL Binding to SOAP

UDDI UDDI stands for Universal Description, Discovery and Integration UDDI is a platform-independent framework for describing services, discovering businesses, and integrating business services by using the Internet.

Advantages of UDDI Finding the right business from millions Defines how to enable e-commerce once business is found Describing services and business processes programmatically in a single, open and secure environment.

Basic Mechanism

Conclusions We have seen the essential components of a Web Service. We have seen the brief overview of these components that form the building blocks of a web service

Recommendations Examine the real WSDL documents and realize its components Here is a sample WSDL Tutorials for creating web services both in.NET and in Java are available

References

Questions