Agenda What is SOAP? Characteristics SOAP message structure Header blocks Fault notification Exercises
What is SOAP? Provides the definition of the XML-based information which can be used for exchanging structured and typed information between peers in a decentralized, distributed environment Specification: http://www.w3.org/TR/soap/http://www.w3.org/TR/soap/ Initial Sender Intermediary Ultimate Receiver
Characteristics A SOAP message is formally specified as an XML infoset "on-the-wire" representation can be anything SOAP describes a stateless, one-way message exchange mechanism between a SOAP sender and a SOAP receiver But applications can create more complex interaction patterns on top of this one-way exchange mechanism request/response request/multiple responses back-and-forth conversations
Header Blocks Each header block may contain an optional “role” attribute Any URI can be the value Some predefined roles Next http://www.w3.org/2003/05/soap-envelope/role/next Ultimate Receiver http://www.w3.org/2003/05/soap-envelope/role/ultimateReceiver None http://www.w3.org/2003/05/soap-envelope/role/none Empty (“”)
Header Blocks (Cont.) A header block may contain “mustUnderstand” attribute true: Targeted node must process the header false: Targeted node may process the header A header block may contain “relay” attribute true: Header block targeted at the node must be relayed if it is not processed false: Header block targeted at the node is not forwarded if it is not processed
Fault Notification SOAP fault notification mechanism is based on fault details put inside SOAP body soapenv:Receiver Undeclared namespace prefix "ns1"
Fault Notification (Cont.) Nested fault details can be placed inside “Subcode”............
Fault Notification (Cont.) The node that generated the fault The role played by the node that generated the fault
Exercises In Module 01 (“Introduction to Web Services With Apache Axis2”), we used TCPMon to intercept and inspect SOAP messages between a SOAP client and server. Capture the communication between TemperatureConverterClient and Server. Attempt to resend the request and make sure server responds properly. Add an arbitrary SOAP header block and try. Set the “role” attribute of the header so that the message is targeted at the next SOAP node. Resend the message. Set the “mustUnderstand” attribute to “true” and try. Carefully note if there are differences between responses and HTTP headers in each case.