Directory Assistance Service
Encyclopedia
The Directory Assistance Service (DAS) is an obsolete protocol
and service for accessing X.500
directory services. DAS was intended to provide a lightweight
means for clients to access X.500 directory services via a split-Directory User Agent model. Here the Directory User Agent (DUA) (the directory client) is split into a Directory Assistance (DA) client and a Directory Assistant. The directory user would interact with the DA-client, the DA-Client would communicate with the Directory Assistant using the DA protocol, and the Directory Assistant would communicate with the Directory Service using the X.500 Directory Access Protocol (DAP). That is, the Directory Assistant is a Directory Assistance protocol to DAP gateway. This design allows the DA-client to access the directory without requiring it to support the cumbersome Open Systems Interconnection
protocol stack.
The Directory Assistance Service was created in 1990 by Marshall T. Rose while at Performance Systems International, Inc., and formally specified in RFC 1202 (published in 1991).
These and related efforts, such as DIXIE
, lead to the development of the Lightweight Directory Access Protocol
. LDAP replaced the Directory Assistance Service.
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...
and service for accessing X.500
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 services. DAS was intended to provide a lightweight
means for clients to access X.500 directory services via a split-Directory User Agent model. Here the Directory User Agent (DUA) (the directory client) is split into a Directory Assistance (DA) client and a Directory Assistant. The directory user would interact with the DA-client, the DA-Client would communicate with the Directory Assistant using the DA protocol, and the Directory Assistant would communicate with the Directory Service using the X.500 Directory Access Protocol (DAP). That is, the Directory Assistant is a Directory Assistance protocol to DAP gateway. This design allows the DA-client to access the directory without requiring it to support the cumbersome Open Systems Interconnection
Open Systems Interconnection
Open Systems Interconnection is an effort to standardize networking that was started in 1977 by the International Organization for Standardization , along with the ITU-T.-History:...
protocol stack.
The Directory Assistance Service was created in 1990 by Marshall T. Rose while at Performance Systems International, Inc., and formally specified in RFC 1202 (published in 1991).
These and related efforts, such as DIXIE
DIXIE
DIXIE is an obsolete protocol for accessing X.500 directory services. DIXIE was intended to provide a lightweightmeans for clients to access X.500 directory services. DIXIE allowed TCP/IP clients to connect a DIXIE-to-DAP gateway which would provide access to the X.500 Directory Service...
, lead to the development of the Lightweight Directory Access Protocol
Lightweight Directory Access Protocol
The Lightweight Directory Access Protocol is an application protocol for accessing and maintaining distributed directory information services over an Internet Protocol network...
. LDAP replaced the Directory Assistance Service.