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Lesson 2 Distributed object middleware
Objective Describe distributed object middleware.

Distributed Object Middleware

What is distributed object middleware?

Distributed object middleware enables the deployment and management of CORBA[1] and/or COM[2] objects across architectures. Also known as ORBs[3] or Object Wrappers[4], these products support the development of complex transactional systems.

For example, when an e-Commerce solution requires multi-phase commit logic of disconnected transactional systems that are each based on different object models, the architect may want to use distributed object middleware.
Let's say a Web-based customer service application developed in Java and running on Windows and needs to interoperate with an order management system developed in C++[5] running on Solaris inside of an Intranet. Object middleware could be used to synchronize the transactional commit process between both systems (that is, customer service users should be able to override and alter orders based on customers' wishes).
Object middleware allows the objects from both applications to interoperate and share functions, even though the objects were built in different languages, run on different operating systems, and are housed in different network domains.

Distributed object middleware considerations

Don't underestimate the complexity of distributed object solutions.
Despite attempts of vendors to hide the complex plumbing underlying distributed object processing, it remains one of the most difficult technologies to develop, deploy, and tune. Many object request broker (ORB)[6] based applications also take a heavy toll in terms of computing resources. Adopters of this type of middleware will trade flexibility and application power for a drain on machine and human resources. The expertise base in distributed object technology is slim and high-priced.

Judge by your buyer

To date, the majority of distributed object-based solutions designs have typically involved mission-critical applications. Many early adopting corporations have developed very sophisticated applications based on distributed object designs.
The architect should judge the buyer. The mainstream adopter and the laggard are probably not going to enjoy a project based on distributed objects at this time. Perhaps in a few years, when distributed object technology becomes easier to develop and manage, mainstream buyers will enjoy a greater level of comfort and success with distributed objects.

Consider Existing Component and Object Standards

Though relatively few e-Commerce solutions make active use of distributed objects, plenty of e-Commerce solutions take advantage of component and object standards (Enterprise JavaBeans[7] and COM[8] objects) which could be used in distributed object solutions.
Nonetheless, the design challenge for distributed object solutions remains an order of magnitude beyond basic component-based application designs.

Click the link below for information on distributed object middleware vendors and tools.
Distributed Object Middleware Vendors Tools
Verify your understanding of the concepts we have covered with a self-check quiz.
This quiz will provide you with valuable practice prior to taking the end of course test.
Object Middleware - Quiz

[1]Common Object Request Broker Architecture (CORBA): Enables pieces of programs, called objects, to communicate with one another regardless of what operating system they are running on or what programming language they were written in. To learn more about Corba visit Corba Fundamentals

[2] Component Object Model (COM): Microsoft's language independent component architecture intended to provide general purpose, object oriented means to encapsulate commonly used features and functions.

[3] Object Request Broker (ORB): A program that controls communication between clients and objects on servers.
[4] Object Wrapper: Object wrappers control communication between clients and objects on a server. They allow heterogeneous object environments to interoperate with or without a request broker.
[5] C++: A high level programming language primarily used for graphical applications.
[6] Object Request Broker (ORB): A program that controls communication between clients and objects on servers.

[7] Enterprise JavaBeans (EJB): Define how Java objects interact with other objects. It is actually possible to develop Enterprise JavaBeans in other languages, but they must be translated into Java byte codes, and organized as a EJB component. The EJB is executed within the context of a J2EE or J2SE virtual machine.
[8] Component Object Model (COM): Microsoft's language independent component architecture intended to provide general purpose, object oriented means to encapsulate commonly used features and functions.