home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Internet Standards
/
CD2.mdf
/
ccitt
/
1992
/
f
/
f410.asc
< prev
next >
Wrap
Text File
|
1994-01-30
|
28KB
|
676 lines
Recommendation F.410
MESSAGE HANDLING SERVICES:
THE PUBLIC MESSAGE TRANSFER SERVICE
The establishment in various countries of message handling
services in association with public networks creates the need to
produce Recommendations covering the aspects of public message
handling services.
The CCITT,
considering
(a) the need for public message handling services;
(b) the strategic and commercial importance of
standardization of message handling services;
(c) the urgent need for intercommunication arrangements for
existing telematic services, and other services with public message
handling services;
(d) the need for a clear distinction between the
responsibilities to be allocated to service providers and those of
subscribers and/or users;
(e) the need for establishing international compatibility
between different messaging systems;
(f) the growth of the installed base of terminals and
personal computers with the ability to access message handling
systems;
(g) that several F series Recommendations describe public
message handling services;
(h) that certain X and T series Recommendations cover
relevant aspects of systems used for the provision of messaging
services,
unanimously declares
the view that the requirements specified in this
Recommendation should be applied for the provision of the public
message transfer service internationally.
CONTENTS
1 Purpose and scope
1.1 General
1.2 Message handling systems used in the provision of MT
service
2 MT service
2.1 General service requirements
2.2 Message transfer service features
2.2.1 Introduction
2.2.2 The basic message transfer service
2.2.3 Optional user facilities in the MT service
2.2.4 Naming and addressing
3 Operation of the service
3.1 General
3.2 Message transfer
4 Quality of service
4.1 Message status
4.2 Responsibility for messages
4.3 Model of delivery and notification times
4.4 Message transfer time targets
4.5 Delivery notification time targets
4.6 Error protection
4.7 Availability of service
4.8 Minimum storage capacity
5 Networks requirements
5.1 General
5.2 Network requirements for international interconnection
5.3 Network requirements for service access
6 Use of MT service within CCITT defined telematic services
Annex A - Abbreviations
Annex B - MT elements of service for 1984 systems
1 Purpose and scope
1.1 General
This Recommendation specifies the general, operational and
quality of service aspects of the public international message
transfer service.
This type of message handling service is an international
telecommunication service offered by Administrations, enabling
subscribers' user agents to submit standardized classes of messages
to message transfer agents for their transfer to another message
transfer agent in the same Administration's domain, in another
Administration's domain, or to private domains, via
telecommunication networks using store and forward techniques.
The message transfer service also may transfer messages
submitted through a message store, and delivered to a message
store, and to and from access units to other services.
Locally provided functions, for which communication with other
user agents or message transfer agents is not required, are nor
covered by CCITT Recommendations.
The message transfer (MT) service enables subscribers to
request a variety of features to be performed during the transfer
of messages.
Some features are inherent in the basic MT service. Other non-
basic features may be selected by the subscriber, either on a per-
message basis, or for an agreed contractual period of time, if they
are provided by Administrations.
Elements of service belonging to the basic message transfer
service and essential optional user facilities are to be made
available internationally by Administrations.
MT service may be provided using any physical network. MT
service may be offered separately or in combination with various
telematic or data communication services. It can be obtained by
making appropriate arrangements.
Technical specifications and protocols, to be used in the MT
service are defined in the X.400 series of Recommendations.
The service definition is contained in ñ 2. Sections 3 and 4
describe the operation of the service and quality of service, and
network requirements are given in ñ 5.
1.2 Message handling systems used in the provision of MT service
1.2.11984 implementations
This Recommendation assumes that the message handling systems
implemented to provide the service outlined herein are based on the
1988 version of the X.400 series of technical Recommendations. It
is recognized however that for some time after the publication of
this Recommendation, the majority of implementations of MT service
will be based on the 1984 X.400 series of Recommendations.
Administrations are encouraged to adopt the latest CCITT
Recommendations; however, in the interim, they may make use of this
Recommendation with 1984 implementations as outlined below.
1.2.2Elements of service
The elements of service available for message handling
services are listed and classified in Recommendation F.400. Annex
B/F.400 provides a list of all the elements of service (called
Service Elements in 1984) for MT service from the 1984 X.400
Recommendation. In addition the classifications of each element of
service, as they were in 1984 in Recommendation X.401, are shown.
In the 1988 X.400 Recommendation, there are many new elements of
service representing new functionality that were not present in
1984. Most of these have been classified as additional, meaning
that they do not have to be supported, hence the 1984
implementations can make use of this service Recommendation in most
cases. Other differences between 1988 and 1984 are of two types,
new elements of service that are classified as essential, and old
(meaning 1984) elements of service that have been re-classified as
essential for 1988. Annex C of Recommendation F.400 lists both the
new elements of service in 1988 as well as changes in
classification to any 1984 elements of service. In both cases to
allow for 1984 implementations to be used for the provision of
pubic MT service as described in this Recommendation, a grace
period of 8 years is provided for Administrations to upgrade their
implementations in this respect to the 1988 technical
Recommendations.
1.2.3Name forms
The specifications of the name forms in the 1988
Recommendations have been enhanced and postal O/R addresses have
been added. The name forms and the mandatory components of the 1984
Recommendations have their equivalence in the new framework and are
aligned in principle.
1.2.4Interworking
In order to protect the investment of Administrations who have
implemented 1984 systems for the provision of MT service, 1988 ADMD
implementations must be able to interwork to 1984 ADMDs as outlined
in Recommendation X.419, Annex B.
Interworking from 1988 ADMDs to 1984 PRMDs is a national
matter.
2 MT service
2.1 General service requirements
2.1.1 The fundamental ability of the MT Service is to provide for
the transfer of messages submitted by other services subscribing to
the MT service. These other services may submit messages from their
user agents, if they are services that follow the X.400 series of
Recommendations. Services may also access the MT service from
standardized access units. Messages may also be transferred to and
from message stores. The access units and message stores are not
part of the MT service. Conversion of messages when different
codings and other formats are used may be provided by the MT
service.
2.1.2 The public MT service will be provided by Administrations
using systems that conform to the X.400 series Recommendations.
Management domains (MDs) are defined for the purpose of
responsibilities boundaries. The MD managed by an Administration is
called an Administration Management Domain (ADMD). The MD managed
by an organization is called a Private Management Domain (PRMD).
2.1.3 International exchange of messages are performed between
administation management domains through CCITT standardized public
data transmission services. Each Administration will designate one
or more MTAs in its management domain as international access
points to the MT service.
2.1.4 Different classes of messages may be exchanged through this
service. Some classes of messages may be standardized by CCITT
Recommendations, such as F.420. Other classes of messages may also
be transferred, provided that the format adheres to the appropriate
X.400 series or Recommendations.
2.1.5 An Administration may provide different methods of access
to the MT service. The possible methods are:
1)from a subscribing service's user agent, message store, or
access unit;
2)from an MTA in a private management domain.
2.1.6 Each Administration is responsible for the national access
to its management domain.
2.1.7 The characteristics of the direct interfaces to the MT
service, or between a private domain and the MT service are a
national matter, although they should generally conform to the
X.400 series of Recommendations. Interworking with postal systems,
or other physical delivery systems, should be in accordance with
F.415.
2.1.8 The national implementation of the MT service may provide
intercommunication of subscribing services with other telematic
services such as telex, teletex, facsimile and videotex. When
implemented, the interface between the MT service and the other
services shall be according to relevant CCITT Recommendations.
Intercommunication may also be provided to a physical delivery
system.
2.1.9 As the service is providing indirect communication, cases
of non-delivery of the message to the intended recipient may occur.
The MT service provides for non-delivery notification and, as an
optional user facility, for delivery notification.
2.1.10 Due to the intermediate storage of the message, the service
may provide conversion optional user facilities: speed, access
procedures, networks, and coding of message contents.
2.1.11 The message belongs to the originator until delivery has
taken place. After delivery the message belongs to the recipient.
2.1.12 Where sender and recipient have different and conflicting
requirements, the sender's requirements shall take precedence
(e.g., content type conversion or redirection control).
2.1.13 Management domains shall relay messages even if some
additional optional user facilities are not supported by that
domain.
2.2 Message transfer service features
2.2.1Introduction
Recommendation F.400, ñ 19, defines elements of service which
are available in the MT service and are classified as either
belonging to the basic service or as MT optional user facilities.
Elements of service comprising the basic MT service are inherently
part of the service, and are always provided and available. The
optional user facilities that are classified as essential are
always provided and those classified as additional may be available
nationally or internationally on the basis of bilateral agreement.
In the MT service there is the following grouping of elements
of service:
1)basic service which corresponds with the basic elements of
service listed in Table 4/F.400;
2)optional user facilities, which correspond to the MT
optional user facilities listed in Table 5/F.400.
Basic features are inherent in the service. Optional user
facilities may be selected on a per-message basis or for an agreed
contractual period of time.
2.2.2The basic message transfer service
The basic MT service shall be implemented according to the
requirements of CCITT Recommendation X.411. The basic MT service
enables UAs to access and be accessed by the MTS in order to
exchange messages. Each message is assigned a unique message
reference identification. If a message cannot be delivered, the
originating UA is informed. To facilitate meaningful communication,
a UA may specify the types of encoded information that can be
contained in messages delivered to it. The content type, the
original encoded information types, the time of submission and
delivery and whether conversion occurred are indicated for each
message. The elements of service comprising the basic MT service
are listed in Recommendation F.400, Table 4/F.400.
2.2.3Optional user facilities in the MT service
Two classes of optional user facilities are available in the
MT services. The first class is selectable on a per-message basis.
The second class may be provided to the subscribing service when
agreed to over a contractual period of time. The classes are
described and cited in Recommendation F.400 (ñ 19.3, and Table
5/F.400) and are available in the service based on the MT service.
2.2.4Naming and addressing
Naming and addressing as used in the MT service is described
in overview in Recommendation F.400, ñ 12. The rules for naming and
addressing in an Administration Management Domain are given in
Recommendation F.401.
3 Operation of the service
3.1 General
3.1.1 The MT service provides that messages can be sent,
transferred, delivered and received using fully automatic
procedures.
Manual delivery of messages can be provided in the case of
interworking with postal systems, and is described in
Recommendation F.415.
3.1.2 Messages are prepared by subscribers services User
Agents/Access Units or by User Agents/Access Units in other
management domains.
3.1.3 Each Administration providing the MT service should
validate its subscribers identities, at the time of access. It
should also validate the identity of other Management Domains at
their points of access.
3.1.4 Connectivity of the MT service to message transfer in
private management domains, which will allow users of these systems
to exchange messages, is desirable. This is recognized to be a
national matter. If these interconnections are provided, they
should take place between management domains in accordance with
CCITT Recommendations.
3.1.5 When implicit conversion is provided by the Administration
via the message transfer service, the message will be converted if
necessary, unless prohibited by the originator. The conversion will
be in accordance to the rules specified in Recommendation X.408.
3.2 Message transfer
Message transfer is initiated when a message is received from
a User Agent/Message Store or access unit. Delivery is attempted to
the address of the message. The body part of the message will be
transferred in the form in which it was received unless conversion
has been performed.
The results of the transfer attempt may be conveyed by two
notifications.
- non-delivery notification;
- delivery notification.
Delivery notification may be given to the originating domain
by the destination domain to indicate successful delivery. This
delivery notification should be provided if requested.
Non-delivery notification is automatically originated by the
MTS, while delivery notification will be generated by the
recipients MTA on request of the originator. If non-delivery
notification is prevented, and delivery notification is not
requested, no notification is possible. In the case of a message to
a teletex terminal, (auto) receipt notification may be returned by
the TTXAU.
4 Quality of service
4.1 Message status
The unique identification of messages conforming to the
requirements of CCITT X.400 series Recommendations enables the
system to provide information about e.g., the status of an IP-
message or other class of message.
In the event of system failure all accepted and non-delivered
messages should be traceable. If messages cannot be delivered, the
originator must be informed by a non-delivery notification.
4.2 Responsibility for messages
The subscribers to the service using the MTS are responsible
for the messages in their User Agents/Message Stores. The service
using the MT service is responsible for the transfer between the
UAs/MSs in that service and the MT service.
The Administration providing the MT service is responsible for
the message transfer and the optional user facilities performed
within its management domain and for messages coming from or
directed to private management domains connected to its management
domain, unless other national regulations apply. In international
interconnection of ADMDs, the responsibility to deliver passes from
managements domains with the message.
Administrations should provide assistance to their
subscribers, with regard to status and tracing of non-delivered
messages.
Note - The international implications of this are for further
study.
4.3 Model of delivery and notification times (see Figure 1/F.410)
Figure 1/F.410
4.4 Message transfer time targets
The recipient ADMD should force non-delivery notification if
it has not been able to transfer the message to the receiving UA
before x hours after submission to the originating MTA (or after
date and time indicated for deferred delivery), the value of x
being dependent on the grade of delivery requested by the
originator as shown in Table 1/F.410.
TABLE 1/F.410
Grade of 95% delivered Non-delivery
delivery before forced after x
Urgent 0.75 hours 4 hours
Normal 4.0 hours 24 hours
Non-urgent 24.0 hours 36 hours
Note - Intercommunication with PRMDs is not included in the
calculation of the time targets.
To be able to meet these time targets, a message has to
transit a transitting ADMD within y hours, the value of y being
dependent on the grade of delivery requested by the originator as
shown in Table 2/F.410.
TABLE 2/F.410
Grade of 95% transitted
delivery before y
Urgent 0.45 hours
Normal 2.5 hours
Non-urgent 14.5 hours
Note 1 - Time Targets assume that receiving UA is continuously
available and excludes cases of Hold for Delivery.
Note 2 - Intercommunication with PRMDs is not included in the
calculation of the time targets.
4.5 Delivery notification time targets
Non-delivery notifications or requested delivery notifications
should be returned on a per-recipient basis, in order not de delay
notifications for those messages in a multi-addressed message which
have already been delivered, to enable the originating management
domain either to return per-recipient notifications or to batch
notifications to its subscribers (see Table 3/F.410).
TABLE 3/F.410
Type 95% returned
before
ND-notification 0.75 hours
D-notification 0.75 hours
Note - Time Targets assume that receiving UA is continuously
available and excludes cases of Hold for Delivery.
4.6 Error protection
Error protection on transmission is provided by the MHS and
underlying protocols used in the provision of the MT service.
4.7 Availability of service
In principle the MT service should be available continuously.
User agents or message stores connected to the MT service should be
available for submission or delivery continuously (unless hold for
delivery is invoked).
4.8 Minimum storage capacity
The storage capacity of the message transfer agent shall be
sufficient to provide a high grade of service.
Note - This is for further study.
5 Network requirements
5.1 General
The MT service is network independent, that is, the basic
service and the essential optional user facilities are provided
independently of the type of network used for service access.
Additional optional user facilities chosen by an Administration to
offer may vary.
5.2 Network requirements for international interconnection
For an interim period (8 years) in the interest of ease of
interconnection of the public international message transfer
service between Administrations public packet switching connections
shall be used. This does not preclude Administrations from using
different means for this interconnection on a bilateral basis.
5.3 Network requirements for service access
Access to the public message transfer service is a national
matter.
6 Use of the MT service within CCITT defined telematic services
See relevant F series Recommendations.
ANNEX A
(to Recommendation F.410)
Abbreviations
The following abbreviations are used in this Recommendation.
A Additional Optional User Facility
ADMD Administration Management Domain
E Essential Optional User Facility
IP Interpersonal
MD Management Domain
MHS Message Handling System
MS Message Store
MT Message Transfer
MTA Message Transfer Agent
MTS Message Transfer System
PDS Physical Delivery System
PRMD Private Management Domain
TTXAU Teletex Access Unit
UA User Agent
Note 1 - For a glossary of terms see Annex A of Recommendation
F.400.
Note 2 - For references see Recommendations F.400 and F.401.
ANNEX B
(to Recommendation F.410)
MT elements of service for 1984 systems
Classification
Element of service Basic Optional
Per Contract
message ual
Access management X
Alternate recipient E
allowed
Alternate recipient A
assignment
Content type X
indication
Conversion prohibition E
Converted indication X
Deferred delivery E
Deferred delivery E
cancellation
Delivery notification E
Delivery time stamp X
indication
Disclosure of other E
recipients
Explicit conversion A
Grade of delivery E
selection
Hold for delivery A
Implicit conversion A
Message identification X
Multi-destination E
delivery
Non-delivery X
notification
Original encoded X
information types
indication
Prevention of non- A
delivery notification
Probe E
Registered encoded X
information types
Return of content A
Submission time stamp X
indication