24-12-2010, 12:30 PM
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Introduction to CORBA
Definition
The Common Object Request Broker Architecture (CORBA) is a standard defined by the Object Management Group (OMG) that enables software components written in multiple computer languages and running on multiple computers to work together, i.e. it supports multiple platforms.
CORBA-The Dominant Remoting Architecture
The CORBA defines the foundation of (OMG) Object Management Architecture. Version 2.2 of CORBA specification includes the following elements
CORBA IDL – Interface Definition Language used to describe the interfaces of CORBA objects
Dynamic Invocation – Invocation of CORBA object interfaces for client side and server side
Portable object adapter – creates portable CORBA server implementations
Interoperability – Interoperability between ORBs implemented between different vendors and platforms
CORBA bridging – defines how CORBA can be mapped to interoperability between two architecture
Multiple programming language mappings
ORB
For objects used across a network a client/server relationship must be established. For maintaining a relationship ORB can be used
Job of ORB
Intercept a call from client
Find the correct object
Pass the parameters
Invoke its method
Return the result to the client
ORB Job
Diagrammatical Representation
Step 1: Intercept the call from client
Cont…
Step 2,3,4
Find the correct object, pass it the parameters, invoke its method
Step 5: return result to the client
Why CORBA important in networked environment?
CORBA offers many benefits
Object reuse-allows wide-spread use of existing components
Flexibility –
operating System
Execution Environment
Programming Language
Processing speed and Scalable server-to- server infrastructure
History of Distributed Systems
In Beginning : Monolithic systems and mainframes
The Revolution: Client/Server architecture
The evolution: Multi client/server
The next generation: Distributed systems
Mainframes
In beginning there was the mainframe, along with it came hierarchical database systems and dumb terminals also known as green screens.
Capable of serving large number of users and centrally managed
Software systems on mainframes called monolithic (UI, business logic, data access functionality in one large application)
Because of monolithic the dumb terminals cannot do their own processing
Diagrammatical Representation of Mainframe
One large application
Two Tier Client/Server Architecture
Client and Server
Multi-tier Client/Server
Most popular multi-tier architecture is Three Tier
Distributed Systems
Achieves flexibility by enforcing component interfaces
The interface of a component specifies what services are offered by that component and how they are used
For example: customer information for company stored in relational database, The designers can make any number of changes to the component Implementation
Exploring CORBA Alternatives
When designing and implementing distributed applications using CORBA-there are number of alternatives for a developer to consider
Socket Programming
Remote procedure call
OSF Distributed computing environment
Microsoft DCOM
Java RMI