SOAP 1.2, Introduction

University of Colorado at Boulder Department of Computer Science Software Engineering Research Laboratory Nathan D. Ryan

What Is SOAP?

 SOAP 1.1

 Simple Object Access Protocol SOAP 1.2

Huh? Us, work for Microsoft? No way!

XML Protocol (XMLP or XP)

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SOAP 1.2 Is…

 A “wrapper” protocol  Written in XML  Independent of the wrapped data  Independent of the transport protocol  Efficient (according to the W3C)  A uni-directional message exchange paradigm

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SOAP 1.2 Is

Not

…

   A transport protocol Written in

valid

XML Independent of the wrapped data  Independent of the transport protocol  Efficient (according to me)  A uni-directional message exchange paradigm

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Classification

 “Wrapper” protocol versus transport protocol  Data is placed in header blocks and body blocks, as desired  Transport is handled by another mechanism  HTTP 1.1 is the only binding specified, though others are possible

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Message Anatomy

SOAP Envelope SOAP Header Header Block ...

Header Block SOAP Body Body Block ...

Body Block

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Message Representation

...

...

...

...

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Independence

 Independent of the wrapped data  True, but…  Only text data is allowed  Some data structures are difficult to represent  Independent of the transport protocol  True, but…  The XML Protocol Working Group has requested additions to the HTTP 1.1 specification

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(In)Efficiency

HTTP Request HTTP Body XML Syntax SOAP Envelope SOAP Body SOAP Body Block Textual Integer 0x0b66 Sender

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Receiver

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Exchange Paradigm

 Point-to-point exchange  Sender, receiver, possible intermediaries  Uni-directional message exchange  True, but…  Specification includes semantics for dealing with faults   Faults cannot be ignored Faults must be reported to the sending node

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Uni-directional Exchange

Intermediary ???

Initial Sender

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Ultimate Receiver

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Bi-directional Exchange (Series)

Intermediary Initial Sender

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Ultimate Receiver

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Bi-directional Exchange (Series)

Intermediary Initial Sender

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Ultimate Receiver

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Bi-directional Exchange (Series)

Intermediary ???

Initial Sender

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Ultimate Receiver

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Processing Model

 Point-to-point (sender-to-receiver) exchange, possibly via intermediaries  Receivers assume “roles” as actors  Header blocks can be specific to actors  Body blocks are always specific to the ultimate receiver  Actors can be required to understand header blocks

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Nodes

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Actors

 Standard actors    none next Anonymous  Application-specific actors   Can be anything Semantics implied by a URI

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Actor-specific Header Blocks

...

...

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Intermediary Algorithm

 Receive message  Process appropriate header blocks  Processing possibly produces a fault  Remove processed headers  Add new headers  Send message

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Ultimate Recipient Algorithm

 Receive message  Process appropriate header blocks  Processing possibly produces a fault  Process all body blocks  Processing possibly produces a fault

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Higher-level Exchange Paradigms

 RPC   Fits well with HTTP 1.1 binding Current activity within the XML Protocol Working Group  Conversational  Fits well with general message passing, but awkward with HTTP 1.1 binding

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Normative References

        http://www.w3.org/2000/09/XML-Protocol-Charter http://www.w3.org/2002/ws/Activity.html

http://www.w3.org/TR/xmlp-reqs/ http://www.w3.org/TR/xmlp-am/ http://www.w3.org/TR/xmlp-scenarios/ http://www.w3.org/TR/soap12-part0/ http://www.w3.org/TR/soap12-part1/ http://www.w3.org/TR/soap12-part2/

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