Soap xp-wg
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SOAP (Simple Object Access Protocol) is an XML-based protocol designed for exchanging information over the internet, primarily using HTTP. It allows for remote procedure calls (RPC) through a lightweight and extensible format, which includes a structured envelope, optional header, and body for containing call and response details. While it offers advantages like interoperability and firewall friendliness, it also has drawbacks such as reliance on HTTP and statelessness.
Soap xp-wg
- 1. SAFWAN HASHMI Introduction to SOAP
- 2. 2 Where did it come from? • Microsoft, UserLand, DevelopMentor, IBM, Ariba, Commerce One, Compaq, HP, IONA, Lotus, SAP ~ Submitted to W3C May 2000. • XML based protocol • Intended to be a simple wire-protocol for exchange of info. Largest use may be over Internet HTTP.
- 3. 3 Motivation • Many Distributed applications communicate using remote procedure calls (RPC) between distributed objects like DCOM and CORBA. • HTTP isn’t designed for those objects, so RPC calls aren’t easily adapted to the Internet. • Security problems exist for those methods of RPC, so most firewalls and proxy servers are set to block this traffic. • HTTP is supported by all Internet browsers and servers, so SOAP presents a nice protocol for doing RPC.
- 4. 4 What is SOAP? SOAP IS: • Lightweight communication protocol • For communication between applications one-way, request/response, multicast, etc.. • Designed to communicate via HTTP • Not tied to any component technology • Not tied to any programming language • Based on XML • Simple and extensible
- 5. 5 Basic Structure of Soap • Envelope Defines the content of the message • Header (optional) contains header information • Body contains call and response information
- 6. 6 SOAP Contains Four Parts: • An extensible envelope expressing (mandatory) • what features and services are represented in a message; • who should deal with them, • whether they are optional or mandatory. • A set of encoding rules for data (optional) • Exchange instances of application-defined data types and directed graphs • Uniform model for serializing abstract data models that can not directly be expressed in XML schema • A Convention for representation RPC (optional) • How to make calls and responses • A protocol binding to HTTP and HTTP-EF (optional)
- 7. 7 SOAP Envelope SOAP Example in HTTP HTTP Request SOAP-HTTP Binding SOAP Header SOAP Body POST /Accounts/Henrik HTTP/1.1 Host: www.webservicebank.com Content-Length: nnnn Content-Type: text/xml; charset="utf-8" SOAPAction: "Some-URI" <SOAP:Envelope xmlns:SOAP="http://schemas.xmlsoap.org/soap/envelope/" SOAP:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"> <SOAP:Header> <t:Transaction xmlns:t="some-URI" SOAP:mustUnderstand="1"> 5 </t:Transaction> </SOAP:Header> <SOAP:Body> <m:Deposit xmlns:m="Some-URI"> <m:amount>200</m:amount> </m:Deposit> </SOAP:Body> </SOAP:Envelope>
- 8. 8 SOAP Example in SIP SOAP Envelope SIP Request SOAP-SIP Binding SOAP Body SERVICE sip:broker.ubiquity.net SIP/2.0 To: sip:broker.ubiquity.net From: sip:proxy.ubiquity.net Call-ID:[email protected] CSeq: 1 SERVICE Via: SIP/2.0/UDP proxy.ubiquity.net Content-Type: text/xml Content-Length: 381 <SOAP:Envelope xmlns:SOAP="http://schemas.xmlsoap.org/soap/envelope” SOAP:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"> <SOAP:Body> <m:SetCreditStatus xmlns:m="http://www.ubiquity.net/sipservices"> <m:user>sip:[email protected]</m:user> <m:status>super</m:status> </m:SetCreditStatus> </SOAP:Body> </SOAP:Envelope>
- 9. 9 … or SOAP by Itself… <SOAP:Envelope xmlns:SOAP="http://schemas.xmlsoap.org/soap/envelope” SOAP:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"> <SOAP:Header> <m:MessageInfo xmlns:m="http://www.info.org/soap/message"> <m:to href="mailto:[email protected]"/> <m:from href="mailto:[email protected]"/> <m:contact href="mailto:[email protected]"> </m:MessageInfo> </SOAP:Header> <SOAP:Body> <msg:Message xmlns:m="http://www.info.org/soap/message"> <msg:subject>Your house is on fire!</msg:subject> <msg:feed href="ram://livenews.com/yourhouse"/> </msg:Message> </SOAP:Body> </SOAP:Envelope>
- 10. 10 Note Again: SOAP is a Protocol! • What does this mean? • It is not a distributed object system • It is not an RPC system • It is not even a Web application • Your application decides what your application is! • You can build a tightly coupled system …or… • You can build a loosely coupled system
- 11. 11 Why Not Roll My Own XML Protocol? • SOAP allows you to define your particular feature or service in such a way that it can co-exist with other features and services within a SOAP message • What is a feature or a service? • Authentication service • Payment service • Security service • Transaction management service • Privacy service • Not owning the message means easier deployment and better interoperability
- 12. 12 Syntax Rules • MUST be encoded using XML • MUST have a SOAP Envelope • CAN have a SOAP header • MUST have a SOAP Body • MUST use the SOAP Envelope namespace • MUST use the SOAP Encoding namespace • Must NOT contain a DTD reference • Must NOT contain XML Processing
- 13. 13 SOAP Fault Element • Error messages from a SOAP application are carried inside a Fault element. • Must appear as an element w/in the <Body> element and can only appear once in a SOAP message. • Fault sub elements: <faultcode> MUST: --code identifying the error, for use by the software <faultstring> MUST: --error as a string <faultactor> MUST(Apps not acting as ultimate destination of SOAP message) --who caused the error <detail> MUST(if contents of Body could not be successfully processed) --specific error information • Fault Codes: VersionMismatch Invalid namespace for the SOAP Envelope Element MustUnderstand A child element of the Header element, with the mustUnderstand attribute set to “1”, was not understood Client The message was incorrectly formed or contained incorrect information. Server There was a problem with the server so the message could not be process • Example: <env:Fault> <faultcode>env:MustUnderstand</faultcode> <faultstring>SOAP Must Understand Error</faultstring> </env:Fault>
- 14. 14 CORBA vs. SOAP CORBA (Common Object Request Broker Architecture) SOAP (Simple Object Access Protocol) CORBA provides a true object-oriented component architecture. Web services like (UDDI/WSDL/SOAP) are not providing true object-oriented component architecture. Fast Compared to SOAP Because of the verbose XML format, SOAP can be considerably slower than CORBA Can be difficult to use if server and/or client is behind a firewall or if network address translation is being used HTTP works well with network firewalls Problems with implementations It is XML based implementation compare to CORBA,SOAP Implementation is easy. It uses IIOP (Internet Inter ORB Protocol) Simple XML-based protocol to let applications exchange information over HTTP
- 15. 15 Advantages of SOAP are: • Portability • Firewall friendliness • Use of open standards • Interoperability • Universal acceptance. Language neutrality: SOAP can be developed using any language. • Interoperability and Platform Independence: SOAP can be implemented in any language and can be executed in any platform. SOAP messages are in very simple XML format. • Scalability: SOAP uses HTTP protocol for transport due to which it becomes scalable.
- 16. 16 Disadvantages of SOAP • – Too much reliance on HTTP • – Statelessness • – Serialization by value and not by reference
- 17. 17 Summary • SOAP envelope provides • SOAP can be used with many protocols • Easy to deploy with existing infrastructure • SOAP is fundamentally a one-way message • Supports request/response, RPC etc. • Your application decides what it is!
Editor's Notes
- #9: SIP (Session Initiation Protocol) is a text-based signaling protocol used to establish multimedia sessions on the Internet