NetBase for MPE Reference Guide

The NetBase Components
1-7
NetBase Directory
The NetBase directory is used to define the NetBase environment. Entries in the directory tell
NetBase which files are on remote systems and which files are to be shadowed. The directory itself
is a hash file similar to an IMAGE master set. In fact, NetBase makes use of the IMAGE hashing
algorithm. This type of file is used because of its fast keyed access. A KSAM image of the file is
also maintained to facilitate the LIST command within the NBDIR directory maintenance program.
The directory files are created and maintained using NBDIR.
When entries are added to the NetBase directory, they take effect for all new processes on the
system. Anyone on the system may look at the NetBase directory entries, however, to add entries to
the directory requires either NM or SM capability. The default directory that is created when
NetBase is installed is called NBD.DATA.NETBASE. The associated KSAM file is
NBD0.DATA.NETBASE.
When making an entry in the NetBase directory, there are basically three ways to specify files:
• filename.group.account
• @.group.account
• @.@.account
This limited use of wildcards is for performance reasons. When the NetBase shell intercepts an
open of a file (FOPEN,DBOPEN), it must do a lookup in the directory to see if a NetBase service is
required for the file. To minimize the amount of time spent in the directory the use of wildcards is
limited. So, you can specify a specific file, all the files within a group, or all of the files within the
account. When NetBase searches the directory, it first looks for the specific file name. If it does not
find the specific filename, it looks for @.group.account. If it does not qualify here, it then searches
to for an @.@.account entry. If no match is found, the request is passed to MPE/iX. If a match is
found, the NetBase shell will do any necessary processing and then pass the request to MPE/iX.
When using the LIST commands in NBDIR, full use of the wildcard is supported. This is because
when doing a LIST command, the KSAM file associated with the directory is used for the listing.
For information about creating and maintaining the NetBase directory, turn to Chapter 4 “NBDIR”.