TCP/IP Tutorial and Technical Overview - IBM Redbooks

12.4.7 LDAP and DCE
Additionally, search options can be specified in the URL. The following example
retrieves all the attributes for the DN ou=Accounting,c=US from the LDAP server
on host ldpserv.mydiv.mycorp.com. In this case, nonstandard port 4389 is
explicitly specified here as an example.
ldap://ldpserv.mydiv.mycorp.com:4389/ou=Accounting,c=US
The following example retrieves all the attributes for the DN
cn=JohnSmith,ou=Sales,o=myCorp,c=US. Note that some characters are
considered unsafe in URLs because they can be removed or treated as
delimiters by some programs. Unsafe characters such as space, comma,
brackets, and so forth need to be represented by their hexadecimal value
preceded by the percent sign:
ldap://ldpserv.mydiv.mycorp.com/cn=John%20Smith,o=myCorp,c=US
In this example, %20 is a space. More information about unsafe characters and
URLs in general are in RFC 4516.
In addition to options, the URL can specify what values attributes are to be
returned using the ? symbol. For example, assume we want to find the U.S.
address of myCorp. We use the following URL:
ldap://ldpserv.mydiv.mycorp.com:4389/o=myCorp,c=US?postalAddress
DCE has its own Cell Directory Service, or CDS (see 13.3.1, “DCE directory
service” on page 498). If applications never access resources outside of their
DCE cell, only CDS is required. However, if an application needs to communicate
with resources in other DCE cells, the Global Directory Agent (GDA) is required.
The GDA accesses a global (that is, non-CDS) directory where the names of
DCE cells can be registered. This global directory (GDS) can be either a Domain
Name System (DNS) directory or an X.500 directory. The GDA retrieves the
address of a CDS server in the remote cell. The remote CDS can then be
contacted to find DCE resources in that cell. Using the GDA enables an
organization to link multiple DCE cells together using either a private directory on
an intranet or a public directory on the Internet.
In view of LDAP's strong presence in the Internet, two LDAP projects have been
sponsored by The Open Group to investigate LDAP integration with DCE
technology.
Chapter 12. Directory and naming protocols 475