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Correlation Table Mechanism for an IBM-X.400 Gateway

IP.com Disclosure Number: IPCOM000122157D
Original Publication Date: 1991-Nov-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 3 page(s) / 161K

Publishing Venue

IBM

Related People

Gering, MF: AUTHOR [+4]

Abstract

The International Telegraph and Telephone Consultative Committee (CCITT) X.400 Recommendations for Message Handling Systems (MHS) define a world-wide standard for electronic mail interchange. To enable users of current systems based on proprietary architectures to exchange messages with X.400 compatible systems, many vendors offer some form of gateway facility which performs a bidirectional conversion between the native system protocols and data streams and those defined by X.400. An inherent limitation of protocol conversions is that they are rarely without loss. The extent of the functional degradation depends on the specific semantic and syntactic mismatches between the respective architectures and protocols.

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Correlation Table Mechanism for an IBM-X.400 Gateway

      The International Telegraph and Telephone Consultative
Committee (CCITT) X.400 Recommendations for Message Handling Systems
(MHS) define a world-wide standard for electronic mail interchange.
To enable users of current systems based on proprietary architectures
to exchange messages with X.400 compatible systems, many vendors
offer some form of gateway facility which performs a bidirectional
conversion between the native system protocols and data streams and
those defined by X.400.  An inherent limitation of protocol
conversions is that they are rarely without loss.  The extent of the
functional degradation depends on the specific semantic and syntactic
mismatches between the respective architectures and protocols.

      This article considers such a gateway solution, whose function
is to map X.400 addresses, protocols and encoded information types
to/ from those supported by IBM's Document Interchange Architecture
(DIA) and SNA Distribution Services (SNADS), as implemented by
current IBM products.  It describes a correlation table technique to
enable such a gateway to correctly transform SNADS status
distributions to X.400 delivery and receipt notifications, and
vice-versa.

      Both the IBM architectures and X.400 have similar notions of
status feedback mechanisms at both the store-and-forward and User
Agent (UA) levels, as described below:
-    SNADS reports exceptions in the handling of a message within the
store-and-forward system via SNADS status distributions.  The X.400
Message Transfer System (MTS) accomplishes this via non- delivery
notifications.
-    If requested by the originator, the X.400 MTS reports successful
delivery of a message to a destination User Agent via a (positive)
delivery report.  A similar concept exists in SNADS, called
Confirmation of Arrival (COA).
-    Both DIA and the X.400 Interpersonal Messaging System (IPMS)
have the notion of returning a notification (if requested) when the
recipient end user has actually accessed a message in some way.  In
DIA, this event is called Confirmation of Delivery (COD), and is
generally triggered by the end user OBTAINing the document.  The
analogous function in the X.400 IPMS is called receipt notification.

      Note the different meaning of the term "delivery" in the DIA
sense from the X.400 usage above.  X.400 uses the term "delivery" to
mean that the message has successfully transferred through the MTS
(corresponding to SNADS "arrival"), whereas DIA "delivery" equates to
X.400 IPMS "receipt".  The two different usages of the term in the
respective architectures can easily cause confusion.
-    Similarly, both DIA and X.400 IPMS have the notion of reporting
exception events.  This is done via DIA notification codes in the
SNADS specific application status field, as above, and by X.400 IPMS
non-receipt notifications, respectively.

      Thus, there would seem to be a re...