corba and soap

CORBA AND SOAP

Unmesh Kulkarnii2 Group

Ashish V. TendulkarDirectory Database integration group

(www.eusersolutions.com)

Persistent Systems Pvt. Ltd. Pune (www.pspl.co.in)

OUTLINE

• Introduction to middleware• CORBA Concepts• Problem Domain• SOAP• Synergies• Conclusion

What is Middleware?

Glue for Components Sits Between OS and

Applications Distributed Object Services CORBA, COM, DCE, Java/RMI … XML?

CORBA - Objectives

OS Independence Language Independence Remote Methods Static/Dynamic Invocations Distributed Services

Interoperability

Standardization of – Binary Formats : in-memory API’s : Programming Support IDL, Type Libraries, File Formats Data Representation – CDR/NDR Transfer Protocol

CORBA provides..

The PRO’s : IDL Stub-skeleton

generators Services API’s CDR IIOP

And The CON’s Complexity Vendor dependency Costly - large

volumes Behavior

marshalling Internet / Firewalls COM-CORBA Inter-

operability

The problem..

Client App.

Proxy Server

Server

Application Server

Firewall

Implications

Industry not shifted completely to either one

Vendor specific

Lack of interoperability

Require high-tech runtime environment

Why XML?

Simple text markup language

Platform, language and vendor agnostic

Easily extensible

Capable of solving interoperability problem

Why HTTP?

Ubiquitous

Supported by every web browser and server

Effective technology for transferring text, graphics and other information

XML + HTTP = SOAP

HTTP is used for transport

XML as encoding scheme

Endpoint HTTP based URL for the target

Object mapping: implementation specific

SOAP call anatomy

SOAP Component

HTTP Headers

SOAP method name

SOAP Envelope

SOAP Header

SOAP Body

Call element

Object Endpoint IDMethod/Interface ID

Extension Headers

Parameter Data

Uses of SOAP

SOAP greatly simplifies data exchange in B2B application over extranet

Enables web site to integrate services from other sites

Remote scripting more prevalent with SOAP

Non-browser client could seamlessly access a service across web

Example Message

POST /string_server/Object17 HTTP/1.1 Host: 209.110.197.2 Content-Type: text/xml Content-Length: 152 SOAPMethodName: urn:strings-com:IString#reverse <Envelope> <Body> <m:reverse xmlns:m='urn:strings-com:IString'>

<theString>Hello, World</theString> </m:reverse> </Body>

</Envelope>

Example Response

200 OK Content-Type: text/xml Content-Length: 162

<Envelope> <Body> <m:reverseResponse xmlns:m='urn:strings-

com:IString'> <result>dlroW ,olleH</result> </m:reverseResponse> </Body> </Envelope>

IOR : Object Reference

Interface Name /Method Name

Method Invocation with Parameters

POST/ObjectURI HTTP/1.1

SOAP:MethodName

SOAP:Envelope SOAP:Header SOAP:Body SOAP:CallElem

ent

CORBA vs SOAP

Advantages

Simplest Data Representation Hardware/Language Neutral No Vendor Dependencies Simple and Human-readable Typing Flexibility Firewall Issues

Then Why Not XML?

Distribution Support Resource location, control and

management Services – Transactions, Events, Security

etc. Error Handling Non-text data Quality of Service – Reliability Efficiency (Redundancy Elimination)

XML With CORBA

XML – Structure CORBA – Infrastructure XMI – Metadata Interchange XML Interfaces – Components

accepting/emitting XML documents

XML With CORBA….

Examples : XMI – Exchange of UML models

between Design tools and repositories

Persistent storage of components in IDE’s: JavaBean Persistence Resilience to versioning of libraries/VM’s Defaults/Redundancy elimination

Synergy

Conclusion

SOAP is platform independent, language neutral protocol

SOAP does not replace COM and CORBA SOAP works in place of DCOM and IIOP SOAP does not pose huge security risks Supports interoperation between

different vendor specific implementations

corba and soap

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