CORBA

Catalysis has been central to the component-specification standards defined by Texas Instruments and Microsoft, the CBD-96 standards from Tl/Sterling, and services and products from Platinum Technology it has been adopted by several companies as their standard approach for UML-based development. It fits the needs of Java, JavaBeans, COM+, and CORBA development and supports the approach of RM-ODP. It also supports systematic development based on use cases. 

Directed actions may be implemented in CORBA, in COM, as method calls in an OO programming language, or as a set of calling conventions in some other style the directed actions are mapped based on technical architecture choices.20 There is still a dialog at some level (such as call and return), but this is set by the architecture and local conventions rather than being specific to the participants. 

The choice of technology (CORBA, function calls, and so on) for connecting components. 

These objections are met by building an appropriate adapter a layer of design that translates object references and messages to and from bits on wires (such as CORBA) or to pixels and from keystrokes and mouse clicks (the GUI). An adapter is a fagade with strong translation capabilities. 

In simple cases, persistence can be achieved by a protocol by which a component instance serializes itself into a stream that is managed by its container. For larger, server-side components, each component can manage its own persistent storage and transactions effective composition now requires that the container be able to coordinate nested transactions that cross its subcomponent boundaries. Enterprise JavaBeans, CORBA, Microsoft Transaction Server, and COM+ provide their own versions of this... 

CORBA (Common Object Request Broker Architecture) was designed by the Object Management Group (OMG) to support open distributed communication between objects across a wide variety of platforms and languages. Interestingly, despite the Object in its name, CORBA does not directly expose the notion of object identity it could more properly be considered a distributed component framework. 

CORBA bus The base level of IDL-based interface definitions, the interface and server repositories, and the request broker... 

CORBA Services A variety of largely infrastructure services ranging from events to transactions, relationship, naming, life cycle, licensing, and extemalization... 

CORBA Facilities (horizontal) Printing, e-mail, compound documents, structured storage, workflow, and so on... 

CORBA Facilities (vertical) Standards for business objects in vertical domains, including health care, telecomm, financials, and so on... 

CORBA recently defined mappings for the Java language and aligned closely with Jav-aBeans and Enterprise JavaBeans for its component model. In fact, the Java Transaction Service is defined based on the CORBA model. 

To us, a component architecture defines the schemes of how components can be plugged together and interact. This definition may vary from one project or component library to another and includes schemes such as CORBA, DCOM, JavaBeans, database interface protocols such as ODBC, and lower-level protocols such as TCP/IP as well as simpler sets of conventions and rules created for specific projects. 

The answers to these questions are common across any set of components that can work together (see Section 10.2.2, Components and Standardization). Together, they form a set of definitions and rules called a component architecture. Microsoft s DCOM, the Object Management Group s CORBA, and Sun s JavaBeans are examples. Project teams often devise their own component architecture either independently or (more sensibly) as specializations of these types. Highly generalized architectures cannot provide, for example, a common model of a Bank Customer, but this would be a sensible extension within a bank. 

There are an infinite number of interesting architectures, and the principles of component-based design we discuss apply regardless of specifics. Components can be connected in a great variety of ways—using CORBA, COM, or even a daily manual FTP transfer—but all of them can be seen as examples of the basic notion of self-contained components coupled together using a set of connectors. The kinds of components and connectors and the way they are implemented vary from one architecture to another for example, JavaBeans (see Section 10.3) offers a specific set. 

Connector Any means of communication between components we call a connector. A connector can be something as simple as a function call or a group of calls that provide for a collaboration, or it can be something more complex such as a dialog across an API. Or it might be a message sent via CORBA or COM or a file transfer, a pipe, or even the delivery of a deck of punched cards by courier. And of course, a GUI is a connector, just as a user is a component. 

Use CORBA for all distribution, using CORBA event channels for notification and the CORBA relationship service. 

Distribution mechanisms COM, CORBA, RMI, TCP/IP, and other technology (but consider which component is run on which machine)... 

Decide How Objects, Links, and Actions Are Implemented. This is highly dependent on the answers to the preceding question. Each component may have its own internal representation of objects as C structures, as Java or C++ objects, or as files or database records. Links may be memory addresses, URLs, CORBA identifiers, database keys, or customer reference numbers, or they may be refined to further objects. Actions may be further refined and ultimately be function calls, Ada rendezvous, signals, or Internet messages. 

Use standard frameworks for distribution, including CORBA, Active-X, and COM+. 

Among current component technologies, CORBA technology is described at the OMG Web site [CORBA] COM at Microsoft s Web site [COM] and JavaBeans at the Java-Beans Web site [EJB],... 

CORBA] Common Object Request Broker Architecture. See www.omg.oig. 

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One of the drawbacks of JADE framework is that it does not support Ml mobility of agents. By default, JADE agents communicate with each other using Java Remote Method Invocation (RMI, [5]) or Common Object Request Broker Architecture (CORBA, [6]). However, a mobile agent can be created and it can travel between hosts within the same agent platform but not between different platforms. Currently, there is a research work on going to enhance JADE to support mobility between different agent platforms. 

Facchiano A, A Weisz Internet tools for the analysis of gene expression by database integration, Proceedings of the NETTAB 2001 Workshop CORBA and XML—Toward a bioinformatics integrated network environment , Italy, 2001, pp. 99-102. 

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