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

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

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

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?)

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?)

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

Security Issues

Firewalls allow only specific ports

HTTP,FTP

Most middleware dynamically assign ports

This is a real problem for internet applications

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

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

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’

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’

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

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

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

www.weather.com

float CurrentTemp(zip_code)

The process

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

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

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>

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

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

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

Size of Messages

Latency is key, not Bandwidth

High factors of Compression

Ascii + repetitive Tags

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

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

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

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

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

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

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

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

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

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

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

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

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

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

www.cs.utk.edu/~raman/soap/soap.html

links to whitepapers, spec, articles etc

link to this presentation

Questions???

Thank you