SOAP

Simple Object Access Protocolby Vinubalaji Gopal (Vinu)

What is SOAP?

W3C Recommendation Simple Object Access Protocol XML based Can use SMTP or HTTP transport Can be used for RPC or Message exchange Works through Firewall Platform Independent

SOAP Participants

SOAP Message

<?xml version='1.0' ?><env:Envelope

xmlns:env="http://www.w3.org/2003/05/soap-envelope">

<env:Header> .... </env:Header> <env:Body> ..... </env:Body></env:Envelope>

SOAP Message

Header isOptional meantfor SOAP Intermediary

SOAP Message Example

SOAP Sender

<?xml version='1.0' ?><env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope"> <env:Body> <flight xmlns:env=”urns”> list </flight> </env:Body></env:Envelope>

SOAP Receiver

SOAP Message Example

SOAP Receiver now

<?xml version='1.0' ?><env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope"> <env:Body> <flightresponse xmlns:env=”urns”> <type>Singapore Airlines</type>

<type>United Airlines</type> </flightresponse> </env:Body></env:Envelope>

SOAP Sender now

What about RPC?

Messaging model is extensible SOAP defines additional elements that

facilitates RPC SOAP is very flexible and lets you define any

method signature. A unique URI needs to be passed which

identifies the SOAP Node that contains or supports the RPC.

SOAP RPC Example Request

<?xml version="1.0"?><env:Envelopexmlns:env="http://www.w3.org/2003/05/soap-

envelope"><env:Body> <m:GetPrice

xmlns:m="http://urwebsite/prices"> <m:Item>Apples</m:Item> </m:GetPrice></env:Body></env:Envelope>

SOAP RPC Example Reply

<?xml version="1.0"?><env:Envelopexmlns:env="http://www.w3.org/2003/05/soap-

envelope"><env:Body> <m:GetPriceResponse

xmlns:m="http://urwebsite/prices"> <m:Price>1.90</m:Price> </m:GetPriceResponse></env:Body></env:Envelope>

SOAP Fault Message

env:Fault – a Subelement of env:Body two mandatory sub-elements - env:Code (which mandates env:Value) - env:Reason – Human Readable Optional env:Detail subelement element Optional env:Node subelement Optional env:Role subelement

SOAP RPC Fault ExampleEnvelope and Body headers.....

<env:Fault> <env:Code>

<env:Value>env:Sender</env:Value> </env:Code><env:Reason> <env:Text xml:lang="en-US">Processing

error</env:Text></env:Reason></env:Fault> End of headers

SOAP HTTP Bindings

Relates the HTTP Response codes with SOAP responses.

Provides a mechanism to specify the URI which identifies the SOAP node which “contains” or “supports” RPC.

HTTP Request Example

GET/travelcompany.example.org/reservations?code=FT35ZBQ HTTP/1.1

Host: travelcompany.example.orgAccept: text/html;q=0.5, application/soap+xml

HTTP Response

HTTP/1.1 200 OKContent-Type: application/soap+xml; charset="utf-8"Content-Length: nnnn

<?xml version='1.0' ?><env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-

envelope"> <env:Body> <flightresponse xmlns:env=”urns”> <type>Singapore Airlines</type> <type>United Airlines</type> </flightresponse> </env:Body></env:Envelope>

HTTP SOAP Fault Example Associated with a HTTP Post

HTTP/1.1 500 Internal Server ErrorContent-Type: application/soap+xml;

charset="utf-8"Content-Length: nnnn<?xml version='1.0' ?><env:Envelope.........<env:Body> <env:Fault>............

Where is it used?

Key component of .Net Architecture Google services through SOAP Amazon store SOAP API Flickr Services SOAP with AJAX (Eg: W3C validator through Soap)

Alternatives

REST – Representative State Transfer JSON RPC XML RPC WDDX – Web Distributed Data eXchange LDO – Lightweight Distributed Objects HTTP EXT (RFC 2744)

Links

SOAP Links: http://www.w3.org/TR/soap/ http://searchwebservices.techtarget.com/searchWebServices/dow

nloads/what_is_soap.swf http://www.soaprpc.com/faq.html http://www.w3schools.com/soap/Soap Implementations: Apache SOAP - http://ws.apache.org/soap/ SOAP:Lite