[9] WHY USE DISTRIBUTED OBJECTS
(Part of the CORBA FAQ, Copyright © 1996-99)

[9.1] WHAT IS A DISTRIBUTED OBJECT?

A distributed object is an object that can be accessed remotely. This means that a distributed object can be used like a regular object, but from anywhere on the network. An object is typically considered to encapsulate data and behavior. The location of the distributed object is not critical to the user of the object. A distributed object might provide its user with a set of related capabilities. The application that provides a set of capabilities is often referred to as a service. A Business Object might be a local object or a distributed object. The term business object refers to an object that performs a set of tasks associated with a particular business process.

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[9.2] ARE ALL DISTRIBUTED OBJECTS CORBA OBJECTS?

No.

A CORBA object is an object that obeys certain rules and which can be accessed via a particular protocol. A CORBA object is frequently also a distributed object, but it doesn’t have to be.

A distributed object is not necessarily a CORBA object. A distributed object might be a C++ object that can be accessed via a socket, RPC, or telephony. In order for a distributed object to be a CORBA object, it must be declared in IDL. The object can be implemented in a variety of programming languages.

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[9.3] WHY SHOULD I DEVELOP APPLICATIONS WITH DISTRIBUTED OBJECTS?

[Recently did some wordsmithing (12/1998). Click here to go to the next FAQ in the “chain” of recent changes]

For lots of reasons:

1. Distributed objects might be used to share information across applications or users.
2. Distributed objects might be used to synchronize activity across several machines.
3. Distributed objects might be used to increase performance associated with a particular task.
4. Distributed objects might be used to connect applications running on PCs with information managed by UNIX processes or mainframes databases.
5. Distributed objects might be used to allow people in different cities to contributed to a particular business process.
6. Distributed objects can allow business processes to be modified or re- implemented without altering applications that use the distributed objects.
7. Distributed objects are a way to distribute computing horsepower across a network of computers, which makes it easier to accommodate unpredictable growth. Centralized approaches frequently fail in such environments.

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[9.4] HOW ARE DISTRIBUTED OBJECTS ACTUALLY IMPLEMENTED?

[Recently did some wordsmithing (12/1998). Click here to go to the next FAQ in the “chain” of recent changes]

Typically a company will start by modeling their business processes. Next, the company will determine which business processes should be implemented as local objects and which should be implemented as distributed objects. Usually, the company will leverage a tool-kit that simplifies the distribution of those objects. There are many issues associated with simplifying distribution of objects. The tool-kit might also enhance the distribution with a robust set of communication features. A company might select a particular CORBA implementation, and build their distributed objects on top of the third party package. The CORBA vendor simplifies distribution by implementing all low-level network development. An IDL compiler will process interface definition files into client and server side base classes. These base classes use low level network APIs (such as TCP/IP) to communicate. The vendor will most likely provide daemon processes that facilitate communication, the spawning of processes, the spawning of objects, and the storage of IDL used by a running system. A number of other utilities might also be provided. These could include debuggers, interface browsers or communication monitors.

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[9.5] SHOULD ALL MY OBJECTS BE DISTRIBUTED?

Nope.

Not every business object should be distributed. Distribution implies network overhead and management overhead. Distribution of all business objects can lead to severe performance problems. Distribution can provide many benefits, but should only be used where specific goals are achieved. You must first ask why you need to do distributed objects.

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