It is necessary to examine each directory carefully before any attempt is made to deploy directory synchronization. A variety of data has to be obtained, including:

1. What value is, or what values are, to be used as the unique entry identifier or distinguished name for an entry? In an X.500 or LDAP directory each entry is guaranteed to have a uniquely identifying name, referred to as the distinguished name. Other directories can have their own uniquely identifying field, such as the user's "account" name. Yet other directories can have no single uniquely identifying field. For directory synchronization, each directory entry needs to be uniquely identifiable; PMDF-DIRSYNC uses the LDAP and X.500 term distinguished name for this unique identifier. (However, note that PMDF-DIRSYNC's distinguished name field does not need to literally be an X.500 distinguished name.) For directories whose entries do not have a single uniquely identifying field, you will have to either add some uniquely identifying field to that directory's entries, or select a collection of fields that in combination uniquely identify an entry.
2. What values are to be synchronized? Not all data held by one directory can be held by others, and even if it is possible, it might not be reasonable to attempt to synchronize pictures and other bulky data. The directory differencer has mechanisms to filter out extraneous data, but the rule should be to discard unnecessary data as early in the sequence as possible, for instance at the cook step. The only time the differencer should be discarding data is where you have some feature-rich directories (such as X.500, LDAP, or Lotus Notes), and one or more feature-poor directories such as cc:Mail.
3. What mechanism is to be used to extract and update the directory? PMDF-DIRSYNC has agents for most of the common directories and has general tools for assisting in building agents for other directories.
4. How are the directory agents to be scheduled? Most agents will require some external scheduling to run.
5. Each directory robot and most directory synchronization robots need to have their own PMDF channels defined. The only current exception to this is the Lotus Notes channel, where the LN channel used for e-mail also acts on directory information.