SOAP TECHNOLOGY What is SOAP SOAP is a

SOAP TECHNOLOGY What is SOAP ? • SOAP is a simple, lightweight XML protocol for exchanging structured and typed information on the Web • Extensible • No application semantics and no transport semantics

Who is drafting SOAP ? u User. Land, Ariba, Commerce. One, Compaq, Developmentor, HP, IBM, IONA, Lotus, Microsoft, SUN and SAP. u SOAP specification v 1. 1 already a W 3 C standard. v 1. 2 has recently been submitted.

Why SOAP? u Important need in Internet application development to allow communication between apps. u The politics of serialization : Several large factions each loyal to its own particular RPC ( remote procedure call ) protocol DCOM, CORBA , Java RMI u SOAP addresses the interoperability issue at the data serialization level

Bringing down the walls u These systems could interact using bridges but they add costs and hurt performance. u Made decisions to standardize on one or the other ; then used message-oriented middleware for integration. u If Web browsers can, why not remote services? u SOAP - simplicity, flexibility, platformneutrality and text-based.

RPC revisited u SOAP - a standard way of serializing the info. needed to invoke remote services into a format and transported across the wire, then recreated at destination. u To understand SOAP better : a look at DCOM’s RPC architecture. u Primary design goal of DCOM was “location transparency”.

DCOM Architecture u Location transparency in DCOM using the proxy/stub architecture. DCOM uses the NDR serialization scheme. u SOAP uses XML to structure the data serialization.

SOAP and. . . HTTP ? ! u More than a data serialization format to do real RPC…. transfer messages to the server and return the response. u DCOM and CORBA are incompatible when addressing endpoints, activating remote objects. . . u HTTP most conducive Internet Protocol for RPC via SOAP msgs : -URLs, Synch. Blocking, Scalable , Secure

The Firewall blues u DCOM and CORBA IIOP not firewall friendly, use oddly-numbered ports etc. u HTTP traffic over port 80 usually can talk through firewalls. u SOAP messages treated as a new MIME type to be carried in a HTTP payload : so HTTP headers indicate packet has SOAP request , better firewall control.

SOAP building block

SOAP Building block ( cont’d ) u. A SOAP message is an ordinary XML document. u The XML document contains the following XML elements: u- A SOAP envelope , defines message content u - A SOAP header(optional), contains header information u - A SOAP body, that contains call and response information

A SOAP Example u u u u u A SOAP request embedded in an HTTP Request: <SOAP-ENV: Envelope> < SOAP-ENV: Body> <xmlns: m=“http: //www. stock. org/stock”/> < m: Get. Stock. Price> < Stock. Name>IBM</Stock. Name> </m: Get. Stock. Price> </SOAP-ENV: Body> </SOAP-ENV: Envelope>

A SOAP Example (Cont’d ) u. A SOAP response embedded in an HTTP Response u u u u <SOAP-ENV: Envelope> < SOAP-ENV: Body> <xmlns: m=“http: //www. stock. org/stock”/> < m: Get. Stock. Price. Response> < Stock. Name>113. 81</Stock. Name> </m: Get. Stock. Price. Response> </SOAP-ENV: Body> </SOAP-ENV: Envelope>

SOAP Summary u SOAP is u - a lightweight comm. protocol u - is based on XML u - designed to communicate via HTTP u - not tied to any component technology or programming language. u - simple and extensible u - a W 3 C standard

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