Inter-Process Communications Technologies:
Networking solutions enabled PCs to be able to communicate with each other. Inter-Process Communications Technologies are:
1. COM
2. DCOM
3. COM+
4. .NET FRAMEWORK
Microsoft originally designed COM to enable communications between components and applications running on the same computer.
COM was followed by DCOM (distributed COM), enabling applications to access components running on other computers over a network.
DCOM was itself followed by COM+. COM+ incorporated features such as integration with Microsoft Transaction Server, enabling applications to group operations on components together into transactions so that the results of these operations could either be made permanent (committed) if they were all successful, or automatically undone (rolled back) if some sort of error occurred. COM+ provided additional capabilities, such as automatic resource management (for example, if a component connects to a database, you can ensure that the connection is closed when the application finishes using the component), and asynchronous operations (useful if an application makes a request to a component that can take a long time to fulfill; the application can continue processing, and the component can alert the application by sending it a message when the operation has completed).
COM+ was followed in turn by the .NET Framework, which further extended the features available and renamed the technology as Enterprise Services. The .NET Framework also provided several new technologies for building networked components. One example was Remoting, which enabled a client application to access a remote object hosted by a remote server application as though it was running locally, inside the client application.
The Web Services
Technologies such as COM, DCOM, COM+, Enterprise Services, and .NET Framework Remoting all work well when applications and components are running within the same local area network inside an organization.
A Web service is an application or component that executes on the computer hosting the Web site rather than the user’s computer. A Web service can receive requests from applications running on the user’s computer, perform operations on the computer hosting the Web service, and send a response back to the application running on the user’s computer. A Web service can also invoke operations in other Web services, hosted elsewhere on the Internet. These are global, distributed applications.
WCF ( Windows Communication Foundation)
The purpose of WCF is to provide a unified programming model for many of technologies (Web Services, COM, Remoting, MSMQ etc..), enabling you to build applications that are as independent as possible from the underlying mechanism being used to connect services and applications together.
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