Object request broker

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In distributed computing, an object request broker (ORB) is a piece of middleware software that allows programmers to make program calls from one computer to another, via a network.

ORBs handle the transformation of in-process data structures to and from the byte sequence which is transmitted over the network. This is called marshalling or serialization.

Some ORBs, such as CORBA-compliant systems, use an Interface Description Language (IDL) to describe the data which is to be transmitted on remote calls. Before object-oriented programming (OOP) became mainstream, a similar technology called remote procedure call (RPC) was popular.

In addition to marshalling data, ORBs often expose many more features, such as distributed transactions, directory services or realtime scheduling.

In the object oriented languages, the ORB is an object, having methods to connect the objects being served. After such an object is connected to the ORB, the methods of that object become accessible for remote invocations. ORB must also have some means to obtain the network address of the object that has now become remote. The typical ORB also has many other methods.

[edit] See also

• Message broker

[edit] Implementations

• CORBA - the Common Object Request Broker Architecture.
• ORBexpress - real-time ORBs by Objective Interface Systems
• Orbix - An Enterprise-level CORBA ORB from IONA Technologies
• DCOM - the Distributed Component Object Model from Microsoft
• RMI - the Remote Method Invocation Protocol from SUN
• RPC - Remote Procedure Call
• SimpleORB - a small, non-CORBA ORB
• OmniORB - a CORBA-compliant ORB released under the GPL