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The drawaing contained in this Recommendation have been done in Autocad
Recommendation T.300
GENERAL PRINCIPLES OF TELEMATIC INTERWORKING
The establishment in various countries of telematic services,
computer-based store-and-forward message services and other services creates a
need to produce standards to facilitate international message exchange between
subscribers to such services.
The CCITT,
considering
(a) the need to transfer messages of different types having a large
varietry of formats;
(b) that within the X Series of Recommendations services and optional user
facilities for public data networks are defined;
(c) that the F Series of Recommendations defines telematic services and
that the T Series of Recommendations defines terminal equipment and control
procedures for telematic services;
(d) that a set of Recommendations describes various aspects of message
handling systems: X.400 Series,
unanimously declares
that this Recommendation describes the general principles for telematic
interworking.
CONTENTS
0 Introduction
1 Scope and field of application
2 References
3 Definitions
4 Symboles and abbreviations
5 Conventions
6 Telematic interworking model
6.1 Overview
6.2 Telematic interworking involving the MTS
6.3 Telematic interworking not involving the MTS
6.4 Physical configuration - Definition of the telematic interworking
facility (TIF)
7 The telematic interworking system
7.1 Definition of the TISs
7.2 TIS involving the MTS
7.3 TIS not involving the MTS
8 Refinement of the TLMA principles of telematic access protocol
0 Introduction
This Recommendation is the first in a series of Recommendations dealing
with telematic interworking.
Telematic interworking is the generic name for a set of applications
provided to telematic users. Each of these applications is called a telematic
interworking application (TIA), and involves a subset of the following:
- allowing efficient interchange of information between telematic
terminals which cannot interact directly;
- providing additional features to standardized telematic services, such
as document storage and multiaddressing;
- providing access to or participation in CCITT defined services such as
telex, interpersonnal messaging, directory services, etc.
Two TIAs are defined in the present set of Recommendations, namely:
- participation of telematic users in the IPM service;
- teletex to telex interworking.
Other TIAs are for further study.
Some TIAs may be defined to be operated on a standalone basis, e.g.
teletex to telex interworking.
1 Scope and field of application
This Recommendation defines the general principles for telematic
interworking. It defines the principles of the telematic access protocols as the
protocols used by the telematic terminal to participate in telematic interworking
applications.
This Recommendation makes use of the concepts defined for message
handling. The architectural basis and foundation for message handling is defined
in the X.400 Series of Recommendations.
Fascicle VII.5 - Rec. T.300 PAGE1
The other Recommendations in the T.300 Series define the telematic
interworking applications and the protocols used by telematic terminals to make
these applications available to their users. Only the protocols dealing with the
telematic access to CCITT-defined services are being considered.
2 References
This Recommendation cites the documents listed below:
- Rec. T.330: Telematic access to interpersonal messaging system
- Rec. X.400: Message handling systems: System and service overview
- Rec. X.402: Message handling systems: Overall architecture
- Rec. X.420: Message handling systems: Interpersonal messaging system.
3 Definitions
This Recommendation makes use of terms defined in Recommendations X.400,
X.402 and X.420.
4 Symbols and abbreviations
AU Access unit
C Conditional/consumer
CF Conversion facility
IPM Interpersonal messaging
IPMS Interpersonal messaging system
IPM-UA Interpersonal messaging user agent
M Multiple
MS Message store
MTA Message transfer agent
MTS Message transfer system
PDS Physical delivery system
PTTXAU Public teletex access unit
TIA Telematic interworking application
TIAS Telematic interworking abstract service
TIU Telematic interworking unit
TLM Telematic
TLMA Telematic agent
TLMAU Telematic access unit
TLM-TER Telematic terminal
TTX Teletex
UA User agent
5 Conventions
This Recommendation makes use of no specific convention.
PAGE8 Fascicle VII.5 - Rec. T.300
6 Telematic interworking model
6.1 Overview
The telematic interworking model serves as a tool to aid in the
development of Recommendations on telematic interworking. It depicts different
interworking scenarios, and the use of the message handling model for telematic
interworking.
The model is applicable in two cases, the first one involving the MTS, the
second one not involving the MTS. The model provides only a functional
description and does not mandate any specific implementation or interfaces.
6.2 Telematic interworking involving the MTS
Figure 1/T.300 depicts the telematic interworking model when the MTS is
involved.
It allows:
a) telematic to telematic interworking, through the use of the MTS for
relaying the telematic information;
b) participation of a telematic user in the IPM service (telematic to
IPM-UA interworking through the MTS);
c) participation of a telematic user in any other CCITT-defined
application in the field of message handling (telematic to other UA
interworking);
d) telematic to other CCITT-defined services interworking through the MTS
and the appropriate access units.
Fascicle VII.5 - Rec. T.300 PAGE1
Fig. 1/T.300/T0801060-87 = 13 cm
6.3 Telematic interworking not involving the MTS
Figure 2/T.300 depicts the telematic interworking model when the MTS is
not involved.
Fig. 2/T.300/T0801071-89 = 7 cm
In this case, TLMAUs and AUs are the same as in S 6.2. The TIU may provide
the appropriate subset of the MTS service that will enable information to be
conveyed between TLMAUs, or between TLMAUs and AUs. The TIU performs, when
necessary, the relevant conversion and dispatching functions.
6.4 Physical configurations - Definition of the telematic interworking
facility (TIF)
A telematic interworking facility (TIF) is a real system incorporating a
valid combination of functional units within telematic interworking. The present
clause defines the valid combinations.
6.4.1 TIF involving the MTS
In the case of telematic interworking involving the MTS, valid
combinations of functional units are depicted in Table 1/T.300.
TABLE 1/T.300
Physical confirgurations of a TIF involving the MTS
Functional units
M 1 [M] [M] [M] [1] [M]
T
I
F
M Multiple
[ ] Optional
MS Message store
Two rules apply to define a TIF in this case:
- At least one TLMAU is present.
- TLMAUs are necessarily co-resident with the MTA they are in relation
with.
PDAUs,
PDAUs, other AUs) and their relations with the MTA is outside the scope of the
T.300 Series of Recommendations.
6.4.2 TIF not involving the MTS
This case corresponds to a standValone TIF, that is a realVsystem
interacting with telematic terminals, and optionally with other CCITTVdefined
systems (e.g. telex system), but not with MHS nor with other TIFs.
The valid combinations of functional units are depicted in Table 2/T.300.
TABLE 2/T.300
Physical configurations of a TIF not involving the MTS
Functional units
PAGE8 Fascicle VII.5 - Rec. T.300
TLMAU TIU TLXAU Other AU
TIF M 1 [M] [M]
M Multiple
[ ] Optional
7 The telematic interworking system
Every TIA is provided to the user by a system called telematic
interworking system (TIS). This clause provides an abstract model of the TIS.
7.1 Definition of the TISs
The TIS and associated users are modelled as objects, as depicted in
Figure 3/T.300.
Fig. 3/T.300/T0803950-89 = 7 cm
A user and the TIS are paired through the use of one or more ports. At
each of these ports, one or more abstract operations are made available to the
user. The collection of these abstract operations will define the
abstract-service (called telematic interworking abstract service - TIAS) provided
by the TIS.
All ports and operations are application-dependent, and thus are described
in appropriate (application-specific) Recommendations.
One application of TIS that is defined is the IPMS. IPM-ports and
operations are described in Recommendations X.420 and T.330.
The refinement of the TISs leads to two cases, the first one involving the
MTS, the second one not involving the MTS.
7.2 TIS involving the MTS
The TIS may be refined according to Figure 4/T.300.
Fascicle VII.5 - Rec. T.300 PAGE1
Fig. 4/T.300/T0803960-89 = 10 cm
The refinement or the TIS exposes the following component objects:
- The MTS, as defined in Recommendations X.402 and X.411.
- The TLMA, providing the user of a telematic terminal with the telematic
interworking abstract service (TIAS).
- The UA, which provide TIAS to users not using a telematic terminal. One
application is the IPM-UA, in Recommendation X.420.
- The AUs, which allow intercommunication with other CCITT-defined
services. An example of such an AU is the PDAU, defined in the X.400
Series of Recommendations.
The description of UAs and AUs is outside the scope of the T.300 Series of
Recommendations.
The ports and operations between the MTS and the other objects listed
above are defined in the X.400 Series of Recommendations.
7.3 TIS not involving the MTS
This case is for further study.
8 Refinement of the TLMA principles of telematic access protocols
The refinement of a TLMA exposes two component objects: the telematic
terminal (TLM) and the telematic access unit (TLMAU).
A TLM is functional object corresponding to a terminal as defined in the
relevant T Series of Recommendations.
The TLMAU is defined in Recommendation T.330 in the case of telematic
access to IPMS.
The TLM and TLMAU are linked together through one or more port and a set
of operations describing them.
Ports and operations are application-dependent and thus are described in
appropriate (application-specific) Recommendations.
The realization of these operations involves some transfer of information
between the TLM and the TLMAU. It is called a telematic access protocol (see
Figure 5/T.300).
Fig. 5/T.300/T0803970-89 = 8 cm
PAGE8 Fascicle VII.5 - Rec. T.300
