Directory System Agent
Encyclopedia
A Directory System Agent (DSA) is the element of a X.500
directory service
that provides User Agent
s with access to a portion of the directory (usually the portion associated with a single Organizational Unit
). X.500 is an international standard developed by the International Organization for Standardization
(ISO) and the International Telecommunication Union
(ITU-T). The model and function of a directory system agent are specified in ITU-T Recommendation X.501.
's Active Directory
the DSA is a collection of server
s and daemon
process
es that run on Windows 2000 Server systems that provide various means for clients to access the Active Directory data store.
Clients connect to an Active Directory DSA using various communications protocol
s:
X.500
X.500 is a series of computer networking standards covering electronic directory services. The X.500 series was developed by ITU-T, formerly known as CCITT, and first approved in 1988. The directory services were developed in order to support the requirements of X.400 electronic mail exchange and...
directory service
Directory service
A directory service is the software system that stores, organizes and provides access to information in a directory. In software engineering, a directory is a map between names and values. It allows the lookup of values given a name, similar to a dictionary...
that provides User Agent
User agent
In computing, a user agent is a client application implementing a network protocol used in communications within a client–server distributed computing system...
s with access to a portion of the directory (usually the portion associated with a single Organizational Unit
Organizational Unit
In computing, an Organizational Unit provides a way of classifying objects located in directories, or names in a digital certificate hierarchy, typically used either to differentiate between objects with the same name , or to parcel out authority to create and manage objects In computing, an...
). X.500 is an international standard developed by the International Organization for Standardization
International Organization for Standardization
The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...
(ISO) and the International Telecommunication Union
International Telecommunication Union
The International Telecommunication Union is the specialized agency of the United Nations which is responsible for information and communication technologies...
(ITU-T). The model and function of a directory system agent are specified in ITU-T Recommendation X.501.
Active Directory
In MicrosoftMicrosoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
's Active Directory
Active Directory
Active Directory is a directory service created by Microsoft for Windows domain networks. It is included in most Windows Server operating systems. Server computers on which Active Directory is running are called domain controllers....
the DSA is a collection of server
Server (computing)
In the context of client-server architecture, a server is a computer program running to serve the requests of other programs, the "clients". Thus, the "server" performs some computational task on behalf of "clients"...
s and daemon
Daemon (computer software)
In Unix and other multitasking computer operating systems, a daemon is a computer program that runs as a background process, rather than being under the direct control of an interactive user...
process
Process (computing)
In computing, a process is an instance of a computer program that is being executed. It contains the program code and its current activity. Depending on the operating system , a process may be made up of multiple threads of execution that execute instructions concurrently.A computer program is a...
es that run on Windows 2000 Server systems that provide various means for clients to access the Active Directory data store.
Clients connect to an Active Directory DSA using various communications protocol
Communications protocol
A communications protocol is a system of digital message formats and rules for exchanging those messages in or between computing systems and in telecommunications...
s:
- LDAPLightweight Directory Access ProtocolThe Lightweight Directory Access Protocol is an application protocol for accessing and maintaining distributed directory information services over an Internet Protocol network...
version 3.0 — used by Windows 2000Windows 2000Windows 2000 is a line of operating systems produced by Microsoft for use on personal computers, business desktops, laptops, and servers. Windows 2000 was released to manufacturing on 15 December 1999 and launched to retail on 17 February 2000. It is the successor to Windows NT 4.0, and is the...
and Windows XPWindows XPWindows XP is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops and media centers. First released to computer manufacturers on August 24, 2001, it is the second most popular version of Windows, based on installed user base...
clients - LDAP version 2.0
- Security Account ManagerSecurity Account ManagerThe Security Accounts Manager is a registry file in Windows NT, Windows 2000, Windows XP, Windows Vista and Windows 7. It stores users' passwords in a hashed format...
(SAM) interface — used by Windows NTWindows NTWindows NT is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. It was a powerful high-level-language-based, processor-independent, multiprocessing, multiuser operating system with features comparable to Unix. It was intended to complement...
clients - MAPI RPCRemote procedure callIn computer science, a remote procedure call is an inter-process communication that allows a computer program to cause a subroutine or procedure to execute in another address space without the programmer explicitly coding the details for this remote interaction...
interface — used by Microsoft Exchange ServerMicrosoft Exchange ServerMicrosoft Exchange Server is the server side of a client–server, collaborative application product developed by Microsoft. It is part of the Microsoft Servers line of server products and is used by enterprises using Microsoft infrastructure products...
and other MAPI clients - A proprietary RPC interface — used by Active Directory DSAs to communicate with one another and replicateReplication (computer science)Replication is the process of sharing information so as to ensure consistency between redundant resources, such as software or hardware components, to improve reliability, fault-tolerance, or accessibility. It could be data replication if the same data is stored on multiple storage devices, or...
data amongst themselves