SOAP provides a standard way to exchange data over HTTP by encoding information as XML. It uses XML for encoding data and HTTP as the transport medium. While not a revolutionary technology, SOAP is a step in the right direction by providing a common language for data exchange and leveraging XML to solve problems of interoperability between heterogeneous systems.

1. SOAP:Simple Object Access Protocol XML-RPC Ganapathy Raman GRA-Netsolve Group ICL

2. SOAP: Introduction XML - last week talk MathML, SMIL, VML Distributed Computing is here to stay Computation thro Communication Resource Heterogenity Common Language for Data exchange Leverages XML to solve the above problem

3. SOAP:Is this Hype? Lack of standard - Hurts Interoperability In-memory representation On-the-wire representation DCOM - DCE/NDR CORBA - IIOP/CDR JAVA - RMI/JRMP Netsolve - XDR Tied to a single middleware (Monopoly?)

4. SOAP:Is this Hype? Security Issues Firewalls allow only specific ports HTTP,FTP Most middleware dynamically assign ports This is a real problem for internet applications

5. Possible solutions Use Ascii fprintf/fscanf instead of fwrite/fread flat stream of data not rich enough to represent structure producer and consumer forced to ‘know’ each other Use CGI http + ascii

6. XML to the rescue XML is not about content XML is about structure of content XML + DTD provides a standard way for anyone to understand data using the same set of tools Producer and consumer can be ‘strangers’

7. SOAP in a Nutshell 1. XML for encoding data LANGUAGE OF COMMUNICATION 2. HTTP as transport MEDIUM OF COMMUNICATION Do not let Microsoft Hype fool you!! “Simplicity over Complexity” Surely a step in the right direction Deserves a detailed look

8. An example www.weather.com float CurrentTemp(zip_code) The process Application Middleware SOAP HTTP Application Middleware SOAP HTTP icl.cs.utk.edu www.weather.com Request Reply Error

9. REQUEST Example POST /Temperature HTTP/1.1 Host: www.weather.com Content-Type: text/xml Content-Length: <whatever> SOAPMethodName: <some-URI>#CurrentTemp <SOAP:Envelope xmlns:SOAP=&quot;urn:schemas-xmlsoap-org:soap.v1&quot;> <SOAP:Body> <m:CurrentTemp xmlns:m=&quot;some-URI&quot;> <zip_code>37919</zip_code> <m:CurrentTemp> </SOAP:BODY> <SOAP:Envelope> URI- Uniform Resource Identifier some-URI -> www.netsolve.com or www.globus.com Http Header Xml Payload Soap Extensions

10. RESPONSE Example HTTP/1.1 200 OK Content-Type: text/xml Content-Length: <whatever> <SOAP:Envelope xmlns:SOAP=&quot;urn:schemas-xmlsoap-org:soap.v1&quot;> <SOAP:Header> <t:Transaction xmlns:t=&quot;some-URI&quot;> 5 </t:Transaction> </SOAP:Header> <SOAP:Body> <m:CurrentTempResponse xmlns:m=&quot;some-URI&quot;> <return>42</return> </m:CurrentTempResponse> </SOAP:Body> </SOAP:Envelope> Http Header Xml Payload

11. SOAP: What it’s NOT Object Activation who invokes CurrentTemp function? Bi-directional Communications Distributed Garbage Collection Language Bindings unspecified good for interoperability Perl,C,java Source of xml-rpc payload is immaterial

12. SOAP: Analysis Size of Messages Latency is key, not Bandwidth High factors of Compression Ascii + repetitive Tags Client Server Client Server 100 bytes 1000 bytes 100 bytes 200 bytes No compression Compression

13. SOAP:Analysis Strings - no conversion needed Floating Point - sprintf,sscanf “ e-commerce” applications --- GOOD text + integers “ grid” applications --- BAD numeric intensive There is always a tradeoff involved encode decode In-memory In-memory xml-rpc

14. SOAP: What the Grid needs A standard that can find a balance between performance and inter-operability XDR,NDR,CDR - possible candidates Ability to represent structure is key Maybe an extension to xml-rpc Will enable grid infrastructures to inter-operate

15. SOAP: Analysis Stateless Nature - Independent transactions Most distributed applications are stateful Programming model is different State info with every transaction Size of state info need “ A cookie may not satisfy hunger”!! Good for scalability

16. SOAP: Analysis Programming complexity Standards are in flux Maturity of tools Need open-source xml parsers xml.apache.org xerces : parsers in xml,perl,c++ A minor obstacle at best

17. SOAP: Birds-eye-view DCOM OTHER CORBA JAVA Islands of in-compatibility interconnected by SOAP bridges Philosophy of “Do one thing and do it well” Focus on Interoperability

18. SOAP: What can it teach us? Use XML for data exchange can define our own xml-rpc if needed the idea of encoding is what is important can use TCP as transport HTTP tunneling Would be a short-sight on our part to ignore because of Microsoft tag

19. SOAP: Summary Its not something path-breaking “Right mix of technology at the right time” Structure more important than content XML - ASCII of the future Holds lot of promise Step in the right direction

20. SOAP: Resources www.cs.utk.edu/~raman/soap/soap.html links to whitepapers, spec, articles etc link to this presentation Questions??? Thank you