Description

   The CNBUILD utility compiles the textual configuration, option,
   mapping, security, conversion, system wide filter, and alias
   files into a single OpenVMS shareable image. The resulting image,
   PMDF_CONFIG_DATA (usually PMDF_EXE:CONFIG_DATA.EXE), can then be
   installed with the OpenVMS INSTALL utility.

   Whenever a component of PMDF (e.g., a channel program) must read
   any possibly compiled configuration component, it first checks
   to see if the PMDF_CONFIG_DATA image exists. If it does, the
   image is merged into the running program using the OpenVMS RTL
   routine LIB$FIND_IMAGE_SYMBOL. There are five exceptions to this
   rule. The first is CNBUILD itself, which for obvious reasons
   always reads the text files and never tries to load the image
   form of the configuration data. The remaining four exceptions are
   TEST/REWRITE, TEST/MAPPING, TEST/FAX_ROUTING, and TEST/X400 which
   can all be instructed with the /NOIMAGE_FILE qualifier to ignore
   any compiled image information. This facility in TEST/REWRITE is
   useful for testing changes prior to compiling them.

   The reason for compiling configuration information is simple:
   performance. The only penalty paid for compilation is the need
   to rebuild and reinstall the file any time the configuration or
   alias files are edited. Also, be sure to restart any channels or
   components which load the configuration data only once when they
   start up (e.g., the PMDF multithreaded TCP SMTP server, the POP
   or IMAP servers, FAX_RECEIVE, BITNET channels, or, if using PMDF-
   MR for MR TS replacement, the All-in-1 Sender, All-in-1 Fetcher,
   and MailWorks server).

   Once you begin to use a compiled configuration, it will be
   necessary to recompile the configuration every time changes are
   made to any of the following files: the PMDF configuration file,
   PMDF.CNF (or any files referenced by it); the system alias file,
   ALIASES.; the system mapping file, MAPPINGS.; the PMDF option
   file, OPTION.DAT; the conversions file, CONVERSIONS., the system
   wide filter file, PMDF.FILTER, the circuit check configuration
   file, CIRCUITCHECK.CNF, or the security configuration file,
   SECURITY.CNF. Until such time that the configuration is
   recompiled and reinstalled, changes to any of these files will
   not be visible to the running PMDF system.

   See the PMDF System Manager's Guide for further details on the
   use of compiled configurations.