Microsoft® Windows® DNA is a platform for developing n-tier applications. Windows DNA unifies the services available on personal computers, application servers, and mainframes. The following diagram summarizes the categories of technology that make up Windows DNA.
The section of the diagram labeled "Applications" models the prototypical application that the BackOffice® Developer's Guide offers in each of its scenarios. Microsoft's Component Object Model (COM) technology serves as the glue that binds the various systems and services that are engaged in n-tier applications. COM enables developers to build applications from binary software components that can be deployed at any tier of the application model. It allows an application developer to use components by encapsulating any type of code or application functionality, such as a user interface control or a business object. A component has one or more interfaces that expose a set of methods and properties, which in turn can be accessed by other components and applications. For example, a component that represents a customer might expose properties such as name, address, and telephone number, and methods that update orders and transactions.
With Microsoft Windows DNA, using components reduces the complexity of building multitier applications. Component-based applications rely on a common set of infrastructure and network services provided in the Windows application development platform. These services include the transactions and other component services provided by Microsoft Transaction Server, the Web services provided by Internet Information Server, and the messaging services provided by Microsoft Message Queue Server. Other common services include systems management, directory services, networking, and hardware support.
For more information about Windows DNA, see the site http://www.microsoft.com/dna.