Subject: Additional comments to Jeff's proposal

From: "Chung-Huy Chen (919)254-4827" <[email-masked]>
Date: Mon, 28 Feb 94 16:49:04 EST

(1) Map name.  Here is my view of a map name:

    From the user's perspective,
      - A map name is the name of a data map.
      - A data map is a description of application data which specifies
        each field of the data and the relations of the fields to each
        other.

    From the CRM's perspective,
      - A map name refers to a collection of routines.  These routines
        convert the outgoing data from the encoding used by the local
        system to that used by the network, and convert the incoming
        data from the encoding used by the network to that used by
        the local system.
      - These routines are referred to as the mapper in an LU 6.2 CRM,
        and as an U-ASE in an OSI TP CRM.

    *** This is a question:  Knowing that there is a map name
        for the incoming data as well as for the outgoing data,
        is a single characteristic map_name sufficient?
        Here is an example.  A program has two threads; one is sending
        data, and the other is receiving data.  Since both Set_ and
        Extract_Map_Name use the same characteristic map_name,
        is there a race condition in filling in or referencing the value
        of the map_name?
        If this is a problem, do we need to define two characteristics,
        incoming_map_name and outgoing_map_name, or to adopt an
        alternative solution?

    Scope:
      - When an LU 6.2 CRM is used, a map name is unique within that LU.
      - When an OSI TP CRM is used, a map name is unique within an
        application context.

  (2) Initialization data.  If this type of data is covered by the
      proposal, a description is needed in the data conversion
      section describing how the program can make use of data
      conversion facility for this type of data.

  (3) A working example.  Without a complete picture about how the
      proposed solution works from development time to runtime,
      I cannot tell how sound the solution is.
      For example, the question mentioned above can be detected in
      a complete walkthrough of the design.

      Note: The walkthrough has been a major part of the AD documents
      for those architectures which have advanced to their final
      status (CP).  The information is then incorporated into
      the spec. as part of the AP document.  However, some details
      are for implementers, and they may become a note to implementers
      in the spec. or just don't belong to the spec.

  Regards,
  Chung-Huy Chen