[This documentation is preliminary and subject to change.]
ADAM is a complementary mode of Active Directory, minus infrastructure features, that provides directory services for applications.
ADAM provides dedicated directory services for applications. It provides a data store and services for accessing the data store. It uses standard application programming interfaces (APIs) for accessing the application data. The APIs include those of Active Directory, Active Directory Service Interfaces, Lightweight Data Access Protocol, and System.DirectoryServices.
ADAM operates independently of Active Directory and independently of Active Directory domains or forests. It operates either as a standalone data store, or it operates with replication. Its independence enables local control and autonomy of directory services for specific applications. It also facilitates independent, flexible schemas and naming contexts.
ADAM does not include directory services for the Windows operating system, so it concentrates on the requirements of specific applications. If ADAM operates in an Active Directory environment, it can use Active Directory for authentication. Because ADAM does not support the Messaging Application Programming Interface, Microsoft Exchange cannot use ADAM.
Although ADAM and Active Directory can operate concurrently within the same network, ADAM serves the requirements of specific applications. An instance of ADAM can be tailored for a specific application without concern for the dependencies required by Active Directory. More than one instance of ADAM, each supporting a separate application, can run on a server.