Copyright © 2013 Curt Hill SOAP Protocol for exchanging data and Enabling Web Services

SOAP Simple Object Access Protocol Designed for applications to communicate with one another Uses Internet (TCP/IP and HTTP) Transferred data is in XML Platform and language independent Backed by W3C Copyright © 2013 Curt Hill

Previous Attempts Most of the previous attempts had problems Remote Procedure Calls raise security issues –DCOM or CORBA are two RPC standards –They are a lot more work XML cannot contain programs or viruses, so no security issues Will have no problems with a firewall or proxy server Copyright © 2013 Curt Hill

Messages SOAP messages are just XML documents Such a message contains –Envelope element –Header element –Body element –Fault element Copyright © 2013 Curt Hill

Envelope element Defines this XML document as a SOAP message This is the only element in the XML document Header and Body are within Envelope –Fault is within Body Copyright © 2013 Curt Hill

Header element Optional element Gives information not in the body Instructions for different roles may be specified here –For example the ultimate receiver may get different instructions than those nodes who only pass on the XML Copyright © 2013 Curt Hill

Body element The client puts the request here to send to the web service The service puts the response here to send back to the client The content of either is dependent on the web service Copyright © 2013 Curt Hill

Fault element Contains error information generated by the web service to be sent back to the client This should be checked to determine the validity or importance of the body Copyright © 2013 Curt Hill

WSDL Web Services Description Language Gives a description of the services offered by a particular web service provider WSDL uses XML to define the available services Copyright © 2013 Curt Hill

WSDL and SOAP An application can obtain the WSDL description of the services provided It may then generate a SOAP request for use of these services The provider responds with a SOAP response Copyright © 2013 Curt Hill

Pros and Cons SOAP uses XML which can be transmitted through HTTP and other protocols Platform independence Disadvantage: the XML is self describing, this makes it bulky –That is less of an issue than before Copyright © 2013 Curt Hill

UDDI Universal Description, Discovery and Integration One form of a directory service to register available web services and search for web services Uses WSDL to describe web services and SOAP to transmit them SOAP does not need UDDI to function –Any means of finding providers will suffice Copyright © 2013 Curt Hill