Web Service Definitions Sanjoy Sanyal (Tech for NonGeek) UDDI Consortium definition: Self-contained, modular business application that have open, Internet-oriented, standards-based interfaces World Wide Web consortium (W3C) Software application identified by a URI, whose interfaces and bindings are capable of being defined, described and discovered as XML artifacts. A Web Service supports direct interactions with other software agents using XML-based messages exchanged via Internet-based protocols.
Each company exposes its functionality as a Web Service
B2B integration can run on standard Web technologies
Web services act as the entry point into local information systems
Web Services can also be used within the enterprise system or even a LAN to integrate enterprise applications
Sanjoy Sanyal (Tech for NonGeek)
Web Services Technologies Sanjoy Sanyal (Tech for NonGeek)
Service Description & Discovery Sanjoy Sanyal (Tech for NonGeek) Common base language interfaces business protocols properties and semantics Vertical standards directories Common meta-language used as a basis to describe the different aspects of a service. XML is used Interface definition in the absence of implicit context Web Services Description Language (WSDL) Set of rules supported by service that govern the conversations between clients and Web services. Emerging standards are Web Services Conversation Language (WSCL & Business Process Execution Langauge for Web Services (BPEL) Non functional properties (cost, quality), descriptions etc. associated with a service Universal Description Discovery and Integration (UDDI) Define specific interfaces, protocols, properties and semantics that services offered in certain applications should support Register services and Allow service users to search for & locate new services
Service Interactions Sanjoy Sanyal (Tech for NonGeek) transport basic and secure messaging protocol infrastructure (meta-protocols) middleware (horizontal) protocols Communication network is hidden behind a transport protocol HTTP is the most common Format and package the information to be exchanged. Simple Object Access Protocol (SOAP) Protocols which facilitate and coordinate the execution of business protocols WS-Coordination tries to standardize these protocols and the way WSDL and the way WSDL and SOAP should be used Provides properties like reliability and transaction WS-Transaction implements transactional properties
Software application identified by a URI, whose interfaces and bindings are capable of being defined, described and discovered as XML artifacts. A Web Service supports direct interactions with other software agents using XML-based messages exchanged via Internet-based protocols.
Service is a procedure, method or object with a stable published interface that can be invoked by client programs.
Two aspects of Web Services:
Allow Internal Operations to be exposed to the Web
Defines how Web Services discover and interact with each other
Standards are emerging to describe services, register and search services, format messages.
(the material in this topic is based on Web Services: Concepts, Architectures and Applications by Alonso, Casati, Kuno, Machiraju)