Web services concepts, protocols and development

Web services concepts, protocols and development

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  Web Services: Concepts, Protocolsand development Prepared By: Mehta Ishani
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  Outline • What isa web service? • Why web service? • Web Services Model • Web Services Stack • What is UDDI? • What is WSDL? • What is SOAP?
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  What is aweb service? • Application components accessible over internet • Once deployed, can be used by other applications • XML is the basis for Web services
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  Standard definitions • IBM ▫“A Web service is an interface that describes a collection of operations that are network accessible through standardized XML messaging” • Microsoft: XML Web Services ▫ “.. provide a way to describe their interfaces in enough detail to allow a user to build a client application to talk to them”
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  History • Structured programming •Object-oriented programming • Service oriented programming Hewlett-Packard's e-Speak in 1999 was an enabler for e-services. Microsoft introduced the name "web services" in June 2000
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  Why web services? •Application and data integration (provides interoperability) • Versatility (Any platform, Any Language) • Code re-use (provides flexibility) • Cost savings (Open Standards)
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  How does itwork? The basic Web services platform is XML + HTTP. • SOAP (Simple Object Access Protocol) • UDDI (Universal Description, Discovery and Integration) • WSDL (Web Services Description Language)
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  Web services model Registry (UDDI) Service Requestor Service Provider FindPublish Bind (SOAP) (SOAP) (WSDL)
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  Web services stack
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  What is UDDI? •Universal Description, Discovery and Integration • UDDI is a directory service where businesses can register and search for Web services. • Sponsored by OASIS • Uses W3C and IETF Internet standards such as XML, HTTP, and DNS protocols.
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  What is UDDI? •UDDI registry • Search for Web service to obtain WSDL • For ex. Travel agency can use air line reservation interface • UDDI Community
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  What is WSDL? •Web Services Description Language • XML-based language for describing Web services and how to access them. • WSDL is maintained by the W3C.
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  Major elements • Porttype - describes the operations performed • Port - specifies an address for a binding • Message – describes name and format of message • Types - defines the data types • Binding - defines the communication protocols • Service - specifies the address URL
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  What is SOAP? •Simple Object Access Protocol • SOAP is a simple XML-based protocol that allows applications to exchange information over HTTP. • SOAP will be developed as a W3C standard
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  Why SOAP? • RPCdoes not support HTTP • compatibility and security problem, firewalls and proxy servers issues • HTTP is supported by all Internet browsers and servers.
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  Major elements • Envelope–encloses the message itself. • Header (optional) – contains information relevant to the message • Body – includes the message payload. • Fault (optional) – carries information about a client or server error within a SOAP message.
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  namespace • default namespacefor the SOAP envelope: http://www.w3.org/2001/12/soap-envelope • default namespace for SOAP encoding and data types is: http://www.w3.org/2001/12/soap-encoding
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  SOAP HTTP Binding •HTTP + XML = SOAP • A SOAP request could be an HTTP POST or an HTTP GET request. • Contains two headers • Content-Type - defines the MIME type • Content-Length - number of bytes in the body