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Web services

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Balas Kandhan
Balas Kandhan

Web services use SOAP, WSDL, and UDDI to enable communication between systems. SOAP defines an XML format for messages, WSDL describes available services and operations, and UDDI provides a directory for services to publish themselves. Services communicate by exchanging SOAP messages, with requests and responses defining common operations, and faults handling errors.

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Web Services simplesourcecodes@live.com
? SOAP (Simple Object Access Protocol) is a simple protocol for exchange of information. ? UDDI (Universal Description, Discovery, and Integration) is a specification designed to allow businesses of all sizes to benefit in the new digital economy. ? WSDL (Web Services Description Language) defines the XML grammar for describing services as collections of communication endpoints capable of exchanging messages. simplesourcecodes@live.com
Communication between Web-Service and heterogeneous clients simplesourcecodes@live.com
Introduction ? A Web service is a method of communication between two electronic devices over the web (internet). ? It has an interface described in a machine-processable format (WSDL) ? Other systems interact with the Web service using SOAP messages Features of Web Services ? Language Independent ? Operating System Independent 4
WSDL ? WSDL is written in XML ? used to describe & locate Web services WSDL Ports ? The <portType> element is the most important WSDL element. ? It defines a web service, the operations that can be performed, and the messages that are involved. simplesourcecodes@live.com
PortType <portType name="glossaryTerms"> <operation name="setTerm"> <input name="newTerm" message="newTermValues"/> </operation> </portType > simplesourcecodes@live.com
Operation Types The request-response type is the most common operation type, but WSDL defines four types: Type Definition One-way The operation can receive a message but will not return a response Request-response The operation can receive a request and will return a response Solicit-response The operation can send a request and will wait for a response Notification The operation can send a message but will not wait for a response simplesourcecodes@live.com
UDDI ? Universal Description, Discovery and Integration (UDDI) ? UDDI is a directory for storing information about web services ? UDDI is a directory of web service interfaces described by WSDL ? UDDI communicates via SOAP ? UDDI uses WSDL to describe interfaces to web services simplesourcecodes@live.com
SOAP-based communication Waiting for Waiting for Sending Sending requests requests Data in XML format requests, requests, (known location, (known location, known port) getting getting known port) results results ? SOAP: ¨C Data in a well-defined XML format ¨C Transport over various protocols ? HTTP, SMTP are the most used, perhaps because they are firewall-friendly ¨C server side: either an RPC call or a message delivered
SOAP Elements ? Envelope (mandatory) ¨C Top element of the XML document representing the message. ? Header (optional) ¨C Determines how a recipient of a SOAP message should process the message ¨C Adds features to the SOAP message such as authentication, transaction management, payment, message routes, etc¡­ ? Body (mandatory) ¨C Exchanges information intended for the recipient of the message. ¨C Typical use is for RPC calls and error reporting.
SOAP Request <SOAP-ENV:Envelope xmlns:SOAP-ENV=¡°http://schemas.xmlsoap.org/soap/envelope/¡± SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/¡±> <SOAP-ENV:Header> <t:transId xmlns:t=¡°http://a.com/trans¡±>345</t:transId> </SOAP-ENV:Header> <SOAP-ENV:Body> <m:Add xmlns:m=¡°http://a.com/Calculator¡±> <n1>3</n1> <n2>4</n2> </m:Add> </SOAP-ENV:Body> </SOAP-ENV:Envelope>
SOAP Response <SOAP-ENV:Envelope xmlns:SOAP-ENV=¡°http://schemas.xmlsoap.org/soap/envelope/¡± SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/¡±> <SOAP-ENV:Header> <t:transId xmlns:t=¡°http://a.com/trans¡±>345</t:transId> </SOAP-ENV:Header> <SOAP-ENV:Body> <m:AddResponse xmlns:m=¡°http://a.com/Calculator¡±> <result>7</result> </m:AddResponse> </SOAP-ENV:Body> </SOAP-ENV:Envelope>
SOAP Fault ? Used to carry error and/or status information within a SOAP message ? Appears within the SOAP body ? Defines the following: ¨C faultcode (mandatory) ? algorithmic mechanism for identifying the fault ? defined in the SOAP spec ¨C Faultstring (mandatory) ? human readable explanation of the fault
SOAP Fault ¨C faultactor (optional) ? information about who caused the fault to happen ? URI value identifying the source ¨C Detail ? error information related only to the Body element. ? if not present then indicates that the fault is not related to the Body element.
SOAP Fault Example <SOAP-ENV:Envelope xmlns:SOAP-ENV=¡°http://schemas.xmlsoap.org/soap/envelope/¡± SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/¡±> <SOAP-ENV:Body> <SOAP-ENV:Fault> <faultcode>SOAP-ENV:Server</faultcode> <faultstring>Internal Application Error</faultstring> <detail xmlns:f=¡°http://www.a.com/CalculatorFault¡±> <f:errorCode>794634</f:errorCode> <f:errorMsg>Divide by zero</f:errorMsg> </detail> </SOAP-ENV:Fault> </SOAP-ENV:Body> </SOAP-ENV:Envelope>
XML Messaging Using SOAP

More Related Content

Web services

  • 1. Web Services simplesourcecodes@live.com
  • 2. ? SOAP (Simple Object Access Protocol) is a simple protocol for exchange of information. ? UDDI (Universal Description, Discovery, and Integration) is a specification designed to allow businesses of all sizes to benefit in the new digital economy. ? WSDL (Web Services Description Language) defines the XML grammar for describing services as collections of communication endpoints capable of exchanging messages. simplesourcecodes@live.com
  • 3. Communication between Web-Service and heterogeneous clients simplesourcecodes@live.com
  • 4. Introduction ? A Web service is a method of communication between two electronic devices over the web (internet). ? It has an interface described in a machine-processable format (WSDL) ? Other systems interact with the Web service using SOAP messages Features of Web Services ? Language Independent ? Operating System Independent 4
  • 5. WSDL ? WSDL is written in XML ? used to describe & locate Web services WSDL Ports ? The <portType> element is the most important WSDL element. ? It defines a web service, the operations that can be performed, and the messages that are involved. simplesourcecodes@live.com
  • 6. PortType <portType name="glossaryTerms"> <operation name="setTerm"> <input name="newTerm" message="newTermValues"/> </operation> </portType > simplesourcecodes@live.com
  • 7. Operation Types The request-response type is the most common operation type, but WSDL defines four types: Type Definition One-way The operation can receive a message but will not return a response Request-response The operation can receive a request and will return a response Solicit-response The operation can send a request and will wait for a response Notification The operation can send a message but will not wait for a response simplesourcecodes@live.com
  • 8. UDDI ? Universal Description, Discovery and Integration (UDDI) ? UDDI is a directory for storing information about web services ? UDDI is a directory of web service interfaces described by WSDL ? UDDI communicates via SOAP ? UDDI uses WSDL to describe interfaces to web services simplesourcecodes@live.com
  • 9. SOAP-based communication Waiting for Waiting for Sending Sending requests requests Data in XML format requests, requests, (known location, (known location, known port) getting getting known port) results results ? SOAP: ¨C Data in a well-defined XML format ¨C Transport over various protocols ? HTTP, SMTP are the most used, perhaps because they are firewall-friendly ¨C server side: either an RPC call or a message delivered
  • 10. SOAP Elements ? Envelope (mandatory) ¨C Top element of the XML document representing the message. ? Header (optional) ¨C Determines how a recipient of a SOAP message should process the message ¨C Adds features to the SOAP message such as authentication, transaction management, payment, message routes, etc¡­ ? Body (mandatory) ¨C Exchanges information intended for the recipient of the message. ¨C Typical use is for RPC calls and error reporting.
  • 11. SOAP Request <SOAP-ENV:Envelope xmlns:SOAP-ENV=¡°http://schemas.xmlsoap.org/soap/envelope/¡± SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/¡±> <SOAP-ENV:Header> <t:transId xmlns:t=¡°http://a.com/trans¡±>345</t:transId> </SOAP-ENV:Header> <SOAP-ENV:Body> <m:Add xmlns:m=¡°http://a.com/Calculator¡±> <n1>3</n1> <n2>4</n2> </m:Add> </SOAP-ENV:Body> </SOAP-ENV:Envelope>
  • 12. SOAP Response <SOAP-ENV:Envelope xmlns:SOAP-ENV=¡°http://schemas.xmlsoap.org/soap/envelope/¡± SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/¡±> <SOAP-ENV:Header> <t:transId xmlns:t=¡°http://a.com/trans¡±>345</t:transId> </SOAP-ENV:Header> <SOAP-ENV:Body> <m:AddResponse xmlns:m=¡°http://a.com/Calculator¡±> <result>7</result> </m:AddResponse> </SOAP-ENV:Body> </SOAP-ENV:Envelope>
  • 13. SOAP Fault ? Used to carry error and/or status information within a SOAP message ? Appears within the SOAP body ? Defines the following: ¨C faultcode (mandatory) ? algorithmic mechanism for identifying the fault ? defined in the SOAP spec ¨C Faultstring (mandatory) ? human readable explanation of the fault
  • 14. SOAP Fault ¨C faultactor (optional) ? information about who caused the fault to happen ? URI value identifying the source ¨C Detail ? error information related only to the Body element. ? if not present then indicates that the fault is not related to the Body element.
  • 15. SOAP Fault Example <SOAP-ENV:Envelope xmlns:SOAP-ENV=¡°http://schemas.xmlsoap.org/soap/envelope/¡± SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/¡±> <SOAP-ENV:Body> <SOAP-ENV:Fault> <faultcode>SOAP-ENV:Server</faultcode> <faultstring>Internal Application Error</faultstring> <detail xmlns:f=¡°http://www.a.com/CalculatorFault¡±> <f:errorCode>794634</f:errorCode> <f:errorMsg>Divide by zero</f:errorMsg> </detail> </SOAP-ENV:Fault> </SOAP-ENV:Body> </SOAP-ENV:Envelope>

Editor's Notes

  1. A basic scenario of a distributed computing. RPC based communications. Various protocols.