WCF, Win32 API, COM, DCOM

        The Windows Communication Foundation (or WCF), previously known as "Indigo", is a runtime and a set of APIs (application programming interface) in the .NET Framework for building connected, service-oriented applications.

WCF is used to design, implement and deploy distributed applications. It is a tool often used to implement a service-oriented architecture (SOA)

WCF is designed using service oriented architecture principles to support distributed computing where services have remote consumers. Clients can consume multiple services; services can be consumed by multiple clients. Services are loosely coupled to each other. Services typically have a WSDL interface (Web Services Description Language) that any WCF client can use to consume the service, regardless of which platform the service is hosted on.

The Windows API, informally WinAPI, is Microsoft's core set of application programming interfaces (APIs) available in the Microsoft Windows operating systems. It was formerly called the Win32 API; however, the name "Windows API" more accurately reflects its roots in 16-bit Windows and its support on 64-bit Windows. Almost all Windows programs interact with the Windows API; on the Windows NT line of operating systems, a small number (such as programs started early in the Windows startup process) use the Native API.

Developer support is available in the form of the Windows SDK, providing documentation and tools necessary to build software based upon the Windows API and associated Windows interfaces. Microsoft COM (Component Object Model) technology in the Microsoft Windows-family of Operating Systems enables software components to communicate. COM is used by developers to create re-usable software components, link components together to build applications, and take advantage of Windows services. COM objects can be created with a variety of programming languages. Object-oriented languages, such as C++, provide programming mechanisms that simplify the implementation of COM objects.

Microsoft provides COM interfaces for many Windows application programming interfaces such as Direct Show, Media Foundation, Packaging API, Windows Animation Manager, Windows Portable Devices, and Microsoft Active Directory (AD). COM is used in applications such as the Microsoft Office Family of products. For example COM OLE technology allows Word documents to dynamically link to data in Excel spreadsheets and COM Automation allows users to build scripts in their applications to perform repetitive tasks or control one application from another.

COM+ is the name of the COM-based services and technologies first released in Windows 2000. COM+ brought together the technology of COM components and the application host of Microsoft Transaction Server (MTS). COM+ automatically handles programming tasks such as resource pooling, disconnected applications, event publication and subscription and distributed transactions.

Microsoft Data Access Components (commonly abbreviated MDAC; also known as Windows DAC) is aframework of interrelated Microsoft technologies that allows programmers a uniform and comprehensive way of developing applications that can access almost any data store. Its components include: ActiveX Data Objects (ADO), OLE DB, and Open Database Connectivity (ODBC). There have been several deprecated components as well, such as the Microsoft Jet Database Engine, MSDASQL (the OLE DB provider for ODBC), and Remote Data Services (RDS). Some components have also become obsolete, such as the former Data Access Objects API and Remote Data Objects.