SOAP Chandra Dutt Yarlagadda

Introduction  Why ?  What ?  How ?  Security Issues in SOAP  Advantages  Uses  Conclusion

Why Do We Need SOAP  Heterogeneous systems must be able to communicate  Need for a protocol that uses that already available resources  A firewall-friendly protocol  An extensible framework  KISS  Easy to Implement

WHAT IS SOAP  Simple Object Access Protocol  SOAP is a specification for defining... –an encoding style that uses XML to represent information graphs –a standard way to move XML with HTTP –rules for passing messages –error (fault) definition –a medium for performing Remote Procedure Calls (RPC) –one layer in a multi-layer architecture

What do we have to work with?  XML - An extensible framework that is easy-to-use and has a low-cost of entry  HTTP/SMTP - Industry accepted transport protocols that are already supported by Enterprise servers and are friendly with firewalls  In a simple equation SOAP = XML + HTTP

Where are we? Transport (e.g. HTTP) Application Envelope/Header/Body TCP/IP Message Encoding Transport (e.g. HTTP) Web Service Envelope/Header/Body TCP/IP Message Encoding Interface Semantics SOAP

 Envelope package  Header/Body pattern –Similar to how HTTP works How It Works Header Body

Header  Contains Information such as –Authentication information –Message routes –Logging –Transaction flow

Body  Contains Interface – Specific Information –RPC method name and parameters –Serialized objects (instances of types) –Messages

c = Add(a, b) A Simple Example

System Flow Response Request

Make Method Call Serialize Method Call Into a SOAP-XML Request De-serialize Method Call Into a SOAP-XML Response Extract SOAP-XML Response from HTTP Response Wrap SOAP-XML Request into HTTP Request Return value HTTP Response received from SOAP server HTTP Encoding/ Decoding SOAP Serialization/ De-serialization Client code 6 HTTP Request sent to SOAP server SOAP Package Client process Process at Client

Server Side Process

Actual SOAP Request <SOAP-ENV:Envelope xmlns:SOAP-ENV=“ SOAP-ENV:encodingStyle="

<SOAP-ENV:Envelope xmlns:SOAP-ENV=“ SOAP-ENV:encodingStyle=" Actual SOAP Response

Binding to HTTP (Request) POST /Calculator.pl HTTP/1.0 Host: Accept: text/* Content-type: text/xml Content-length: nnnn SOAPAction: “ <SOAP-ENV:Envelope xmlns:SOAP-ENV=“ SOAP-ENV:encodingStyle="

Binding to HTTP (Response) HTTP/ OK Content-type: text/xml Content-length: nnnn <SOAP-ENV:Envelope xmlns:SOAP-ENV=“ SOAP-ENV:encodingStyle="

Security  SOAP spec says nothing  Delegated to other levels –Transport (HTTPS/SSL)  Included in interface semantics  Needs standardization  Digital Signature

Uses of SOAP  Databases  Internetworking  E-Commerce Systems  Intelligent Devices

Advantages  Interoperability  Simplicity  Free from Firewalls  Industry Support  Easy to Implement

Conclusion :A Quick Comparison  COM – DCOM  CORBA – IIOP  JAVA - RMI

QUESTIONS