Lesson 1: COM Architecture

COM Features

A binary standard is a specification of how COM objects should be designed and constructed . It provides the structure necessary for interoperability between applications or other components . As long as the COM binary standard is adhered to, application and component objects can communicate with each other regardless of the language or development tool in which they were created.

Language Independent

Because COM objects must support a binary interface, developers can create COM objects with any programming language capable of supporting this interface. A client application or component object does not care what language a COM object was written in, only that it can communicate with the object through a standard binary interface.

COM technology is revolutionizing software development especially the development of component softwarewithout requiring changes to the architecture of networks, hardware, or programming tools.

Application Interoperability

COM enables interoperability among applications written in different languages. For example, a word processor application by one vendor can connect to a spreadsheet object written by another vendor. The word processor application could then be used to import data from the spreadsheet object. Additionally, the spreadsheet object could receive data through a COM object residing on a mainframe.

Figure 5.1 COM Features

As long as the objects support a standard interface for data exchange, the word processor, spreadsheet, and mainframe database do not have to know anything about each other's implementation. The word processor only needs to know how to connect to the spreadsheet; the spreadsheet only needs to know how to expose its services to anyone who wishes to connect.

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Note

Object Linking and Embedding (OLE) and ActiveX both use COM in their implementations . While the term ActiveX has replaced OLE, OLE is still used when referring to certain implementations such as OLE Structured Storage and OLE Automation.

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