Publication and Maintenance of the ICAO Register of AMHS MDs

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					                                                                                       ACP WGN02-WP27

                                                                                        ACP/SGN3 WP/2-3

                                                                                                  30/07/12

                  AERONAUTICAL COMMUNICATIONS PANEL(ACP)

                         WORKING GROUP N - NETWORKING

             SUBGROUP N3 – GROUND-GROUND APPLICATIONS




                   Montréal, April 2003 (SGN3 second meeting, WGN third meeting)

                           Agenda Item 3 : ATS Message Handling Services



                   Publication and Maintenance of the ICAO Register of AMHS MDs




                                    Presented by Jean-Marc Vacher




                                                Summary

The ICAO Secretariat has collected from ICAO Member States and Organizations information aimed at
building the “ICAO Register of AMHS MDs and addressing information”.

The goal of this paper is to propose a set of practices and procedures aimed at publication and
maintenance of the Register by the ICAO Secretariat, in co-operation with States continuing to provide up-
to-date information.
Publication and Maintenance of the ICAO Register of AMHS MDs                                          ACP/WGN and SGN3 meetings (Montreal, May 2004)




                                                               TABLE OF CONTENTS
1      INTRODUCTION ................................................................................................................................................. 3

2      GOAL OF THE REGISTER ................................................................................................................................ 3

3      ROLE OF THE ICAO SECRETARIAT ............................................................................................................. 4
    3.1        ROLE AND TASKS .............................................................................................................................................. 4
    3.2        ISSUES TO BE CONSIDERED ............................................................................................................................... 4
4      REGISTER LIFECYCLE .................................................................................................................................... 5

5      EXAMPLES OF PUBLICATION FORMAT ..................................................................................................... 6

6      PROCEDURES FOR REGISTER MAINTENANCE........................................................................................ 7

7      RECOMMENDATIONS TO THE MEETING .................................................................................................. 8

8      APPENDIX A: DESCRIPTION OF PROCEDURES ........................................................................................ 9
    8.1     SCHEDULE: GENERAL DESCRIPTION.................................................................................................................. 9
    8.2     NOTATION ........................................................................................................................................................ 9
    8.3     DESCRIPTION OF PROCEDURES........................................................................................................................ 11
       8.3.1    Proposed update .................................................................................................................................... 11
       8.3.2    Actors..................................................................................................................................................... 12
       8.3.3    Purpose of the procedure ...................................................................................................................... 12
       8.3.4    Description ............................................................................................................................................ 12
       8.3.5    Trigger ................................................................................................................................................... 12
       8.3.6    List of tasks ............................................................................................................................................ 13
       8.3.7    Pro forma............................................................................................................................................... 13



                                                                        REFERENCES


[1]          Manual of Technical Provisions for the Aeronautical Telecommunication Network (ATN), ICAO Doc 9705,
             Third Edition - Sub-Volume III, Ground-Ground Applications

[2]          Manual of Technical Provisions for the Aeronautical Telecommunication Network (ATN), ICAO Doc 9705,
             Third Edition - Sub-Volume VII, ATN Directory Services

[3]          Comprehensive ATN Manual (CAMAL), ICAO Document 9739, Second Edition (draft to be published)

[4]          RFC2849 The LDAP Data Interchange Format (LDIF) - Technical Specification




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1    INTRODUCTION

The ICAO Secretariat has collected from ICAO Member States and Organizations information aimed at building the
“ICAO Register of AMHS MDs and addressing information”.

The ACP Working Group N and its subgroup N3 (ground applications) are committed to provide support to the ICAO
Secretariat in the establishment of this Register.

The goal of this paper is to make use of the collected information, and to propose a set of practices and procedures
aimed at publication and maintenance of the Register by the ICAO Secretariat, in co-operation with States continuing
to provide up-to-date information.



2    GOAL OF THE REGISTER

The goal of the Register is to facilitate the implementation of the ATS Message Handling System (AMHS), and the
migration from AFN/CIDIN to AMHS, through the official publication of up-to-date information needed to construct
the AMHS addresses of users in this new messaging system.

The published Register shall be the collection of addressing information provided by each ICAO Member State or
Organization. This will enable each State or Organization to determine the most appropriate addressing scheme and
address attributes for its own AMHS Management Domain, within the framework defined by the ICAO Manual of
Technical Provisions for the Aeronautical Telecommunications Network (Document 9705, Edition 3).

Each AMHS user or user system (ATS Message User Agent, AFTN/AMHS gateway) will construct a recipient AMHS
address using on the one hand the AFTN addressee indicator of the considered user, and on the other hand the
Register information to derive additional MHS address attributes (e.g. PRMD-name, organization-name).

It will be possible to use the published information in different ways:

-   human AMHS users will be able to directly use the published information to manually construct AMHS addresses
    of the recipients to whom they wish to send AMHS messages. They will derive AMHS addresses from former
    AFTN (or CIDIN) address indicators, based on detailed AMHS address attributes retrieved from the Register;

-   AMHS system operators and/or administrators will also be able to facilitate the above task for AMHS users, up to
    the point of making it completely invisible if desired. For this purpose, the information published in the Register
    may be entered in three main ATN/AMHS system categories belonging to each AMHS Management Domain:

          the preferred option is to enter the Register information into a Directory Server implementing the
           Document 9705 requirements for Directory support of AMHS. The entered directory information may in
           turn be retrieved by ATS Message User Agents or by AFTN/AMHS Gateways, e.g. using AFTN
           addressee indicators as an input to construct AMHS addresses, as explained in the ICAO Comprehensive
           ATN        Manual      (Document       9739   Edition   2,  draft   available     electronically from
           http://www.icao.int/anb/panels/atnp/misc/Doc9739/ , part 3, sections 6.2.1.5.10 to 6.2.1.5.20).
           Other (i.e. non-ATN) directory systems may also be used for the same purpose provided that they also
           facilitate the users’s task of constructing AMHS addresses;

          the same information may also be entered directly into ATS Message User Agents, to be used locally as
           part of a “local address book”. However the task of maintaining the information up-to-date might be more
           difficult than if it is stored in a central directory server as suggested above;




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            this information is also required in AFTN/AMHS gateways, to populate the address look-up tables that
             are an essential function of such gateways. Direct input of the Register information into the gateway look-
             up tables is possible, but retrieval from a Directory Server is also a valid option.

AMHS addresses are subject to changes, additions and withdrawals, as in any communication system. Therefore the
ICAO Register of AMHS MDs and addressing information should not be seen as a static document (or collection of
information), but rather as an evolutive database. This is particular true in the initial time of AMHS deployment, in
which changes are likely to occur, e.g. because of States migrating from an XF addressing scheme to a CAAS
addressing scheme when starting up operational AMHS services.

For each of these changes, the Register will have to be updated. It is suggested that the update frequency be in
accordance with the AIRAC cycle (every 28 days). This means that the information entered in AMHS systems, as
described above, will have to be updated accordingly.



3     ROLE OF THE ICAO SECRETARIAT


3.1       ROLE AND TASKS

The ICAO Secretariat should play a central role in the registration and publication process of the Register of AMHS
MDs and addressing information, in the same way as ICAO manages and publishes ICAO Location Indicators in
Document 79101. This would be in continuation with the work that was started with the publication of State Letter
referenced SP 54/1-03/39 concerning the establishment of the Register.

In general terms, the tasks that are required from the Secretariat in this area are the following:

          collection of updates to the Register proposed by ICAO Member States,

          verification of the proposed updates, to ensure that they are institutionally and technically valid,

          input of the validated updates in the publishable, electronic version of the Register,

          publication of the Register.


3.2       ISSUES TO BE CONSIDERED

The issues to be considered appear to be related to two main aspects, in conjunction with the fact that the Register
information is made available to Member States for operational purposes (creation of AMHS addresses by systems
contributing to the Aeronautical Fixed Service):

          The management of the Register information represents a workload, which is likely to be low but cannot be
           neglected. Cyclic publication dates will have to be met, in accordance with the lifecycle described in
           section 4 below. This is critical to States because they will require up-to-date information, in accordance with



1
          Doc 7910 is a good example of similar practice. It provides information of a similar nature to that included in the
Register. It is published by ICAO both in written and electronic format.




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         the AIRAC cycle, for proper message routing and delivery in the AMHS. It should be ensured that resources
         are available so that publication date constraints can be met;

        Integrity of Register information is essential, because of the operational nature of this addressing information.
         Accidental or intentional corruption of the Register information would lead to AMHS dysfunctions. This
         implies that exchanges between Member States and ICAO for the collection of updates are secured, either
         technically or procedurally. This also implies that the ICAO publication medium for the Register be protected
         from loss of integrity.

However, it should be noted that there is no “real-time” constraint associated with the Register update and publication,
given that the publication cycle is based on a 28 days period. Likewise, there is no strong availability constraint placed
on the Register publication. The service could incur e.g. maintenance disruptions of up to one day, provided that the
proposed cycle milestones described in section 4 are met.

Finally, the question of confidentiality of the Directory information should be discussed, particularly in view of the
intention to publish the Register on the ICAO web site.



4    REGISTER LIFECYCLE

The Register lifecycle, including the publication, utilization and maintenance processes is illustrated below.




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                       PUBLICATION (by ICAO Secretariat)
                    AND UTILIZATION (by ATSOs / AMHS MDs)
                                 PROCESS
                                                                 MAINTENANCE
                                                                     PROCESS
                                                               (by ICAO Secretariat)

                                     (web) publication of           Storage of register
                                     Register Version N            Engineering version N




                                         input of Register
                    One full          Version N information
                    AIRAC            in AMHS MDs’ systems
                    Cycle
                                                                         Reception of
                                                                       Reception of a
                                                                      Reception of aa
                                                                         proposed update
                    (28 days)   14 days                                 proposed update
                                                                      proposed update
                                                                       to Version N


                                       applicability of
                  AIRAC Date          Register Version N

                                                                      Verification of
                                                                     proposed updates


                                14 days
                                                                         Updates      No
                                                                          OK ?              Reject or co-
                                                                                        ordination procedure
                                                                        Yes

                                                                  Entry/formatting of
                                                                    validated updates
                                                               into Engineering version N
                                    (web) publication of
                                    Engineering Version N
                                    as Register Version N+1




               Figure 1: Lifecycle of the ICAO Register of AMHS MDs and addressing information



5    EXAMPLES OF PUBLICATION FORMAT

The tools and publication formats depend upon ICAO web publication standards. There is consequently no intention
to constrain such formats in this paper.

Nevertheless, principles can be established, and examples given, to show how the Register could be easily
implemented.




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The Register needs to be posted on the ICAO web site in at least two, and ideally three forms:
        an easily readable, user-friendly format for web publishing (e.g. HTML or LDAP browsing), and
        an electronic file (or a set of) that can be imported into an AMHS system or a Directory system. LDIF
         (LDAP Data Interchange Format, specified in RFC 2849) should be preferred for the latter. For importation
         into other AMHS systems not including a standard directory function, formats such as tab-separated or CSV
         text files could be easier to manage for systems not implementing LDAP.
        ideally an ICAO-managed electronic directory database, X.500 or LDAP-based would also enable the
         creation of a central Register consistent with States technical systems. However it is uncertain whether the
         operation of such a database fits into the terms of reference of the ICAO Secretariat (or of another central
         ICAO body).

Apart from recommending a directory format if feasible, the format used for storage of the Register internally to ICAO
is not a matter for recommendation. At present, the working file building the Register is a Microsoft Excel  folder, but
many other options can be envisaged. The only constraint is that creation of the formats for posting should be as
simple as possible. The Excel format meets this goal, with native HTML and CSV storage functions.

A software tool enabling export of data from the ICAO internal storage format to the LDIF format should be either
procured (preferably using freeware or Open Source software) or developed.



6    PROCEDURES FOR REGISTER MAINTENANCE

The procedures to be developed for the maintenance of the Register, in accordance with the lifecycle described above,
are listed in the table below.

The “initiator” is the entity that takes the initiative of starting the procedure. The “trigger” is the main event that
causes the procedure to be started. In some cases, calendar considerations related to the AIRAC cycle may also
participate in the triggering decision. Work optimization to perform the procedure on a set of proposed updates (rather
than on a single one as described below) may also be taken into consideration.



procedure name         initiator    involved parties                 description                          trigger
proposed update      State         originating State, action by which a State submits to         State decision to amend
                     (AMHS         ICAO Secretariat ICAO a Register update reflecting an         its AMHS address space
                     MD)                              intended amendment of the State’s          in    accordance    with
                                                      AMHS address space                         ICAO      Global    and
                                                                                                 Regional practices

verification of a ICAO             ICAO Secretariat verification by the ICAO Secretariat reception of proposed
proposed update   Secretariat                       that the amended address information update
                                                    is valid from an institutional and
                                                    technical viewpoint and can be
                                                    published

co-ordination     of ICAO          originating State, action by which the ICAO Secretariat       diagnostic by ICAO
update               Secretariat   ICAO Secretariat co-ordinates with the submitting State       Secretariat    that   the
                                                      to modify the proposed update, so as       initially proposed update
                                                      to make it valid in case of initial non-   is invalid




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                                                       validity

entry of validated ICAO            ICAO Secretariat actual update by the ICAO Secretariat   diagnostic by ICAO
update             Secretariat                      of the Register engineering version     Secretariat    that   the
                                                    with the (validated) amended address    initially proposed update
                                                    information provided by the State       is valid

web publication ICAO               ICAO Secretariat replacement by the ICAO Secretariat AIRAC date + 14 days
of Register     Secretariat                         of the published version of the
                                                    Register with the engineering version
                                                    that includes the validated updates

input of Register AMHS             AMHS MDs            action by which AMHS MDs and publication of a Register
information       MDs                                  organizations operating Directory update
                                                       Systems in support of AMHS update
                                                       (but do not activate) the Register
                                                       information entered in their systems

application     of AMHS            AMHS MDs            activation of updated information in AIRAC date (next cycle)
Register update    MDs                                 operational AMHS systems




If this principle is agreed, each of these procedures should be described in a more detailed fashion. An example of
detailed description for the “proposed update” procedure is given in Appendix A to this paper.



7    RECOMMENDATIONS TO THE MEETING

The meeting is invited to provide comments, if any, about the publication principles and maintenance procedures
described above, and to recommend their adoption, after amendment as appropriate, by the ICAO Secretariat, for the
purpose of managing and operating the ICAO Register of AMHS MDs and addressing information.

The meeting is further invited to task SGN3 with the continuation of this work so as to provide the ICAO Secretariat
with a detailed set of procedures at the earliest opportunity.




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8     APPENDIX A: DESCRIPTION OF PROCEDURES

Publication and Maintenance Procedures are sequences of operations which are specified in detail in this section and
which involve the use of the ICAO Register of AMHS MDs and addressing information, both in its officially web-
published version and in its engineering version maintained by the ICAO Secretariat..


8.1     SCHEDULE: GENERAL DESCRIPTION

Procedures are executed on a fixed schedule. This schedule is based on a fixed cycle of exactly 28 days, each cycle
being fixed by a so-called “AIRAC Date” which is always a Thursday. In this cycle, specified actions shall be
performed on given days or within a range of days.

The days in a cycle are numbered 1, 2, …, 27, 28. Day 28 is always an AIRAC Date – see Figure 2.




            AIRAC Date                                              AIRAC Date




                   27 28 1 2 3                  15 16           27 28 1 2       

                cycle n-1                             cycle n                           cycle n+1




                                          Figure 2: Illustration of the 28-day cycle


8.2     NOTATION

Procedures are specified formally in Section 8.3. At present section 8.3 contains only the description of the “proposed
update” procedure, as an example, but it is intended to complement it with other descriptions. This section describes
the notation used for the specifications.

A procedure is a single action or a set of actions performing a well-defined task which has a unique starting and a
unique end point.

An actor is an organization involved in the procedure.

A task is a unit of work performed by an actor.

A trigger is an event which causes an action to be started, e.g. a fixed time, an external event or an event created by
another procedure.

A procedure description consists of the following parts:

-     a graphic defining the elements of the procedure,




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-   a list of the actors,

-   a description of the purpose of the procedure,

-   a verbal description of the procedure,

-   a list of triggers,

-   a list of tasks and decisions and

-   a set of proforma (where appropriate).

The following additional elements are used in the procedure definition:

A delay is a scheduled time period between the commencement of two sequential actions.

In a decision the operator shall select among alternatives according to given criteria.

END indicates the end of the procedure.

A Goto, e.g. Goto x, is an unconditional jump to the indicated connector in another part of the graphical description.

Figure 3 illustrates the use of these graphic elements.




                                           trigger
                                                                           action




                                                                           delay




                                             END          terminate       decision



                                                                          continue


                                                                           goto
                                                                            x



                            Figure 3: Example of graphical notation used to specify procedures




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8.3     DESCRIPTION OF PROCEDURES

8.3.1    Proposed update




               decision to amend
               AMHS addressing                                  internal specification of
                     space                                     new addressing scheme




                                                                   retrieve update
                                                                submission form from
                                                                   ICAO web site




                                                                      prepare update
                                                                     submission forms




                                                                     wait publication of
                                                                     Version N (day 1)



                                                                    check applicability of
                                                                    update to Version N



                                                           securely send proposed
                                                               update to ICAO
                                                           Secretariat before day 14




                                                                           END




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8.3.2    Actors

There are two actors involved in the “proposed update” procedure:

        the single active actor of the “proposed update” procedure is the State / ATSO implementing an AMHS MD
         and willing to amend its AMHS address space,

        the ICAO Secretariat is present as a passive actor, being the recipient of the proposed update developed by
         the ATSO.

8.3.3    Purpose of the procedure

The purpose of this procedure is to provide a framework for the submission of an update to the address space of an
AMHS MD, to be applicable within one AIRAC cycle from submitting the update to ICAO. This means that the
update refers to Version N of the Register, and is applicable from the applicability date of Version N+1.

Potential updates include:

        the modification of the PRMD-name used by the considered AMHS MD (this should be as unfrequent as
         possible since PRMD-names as required to be stable);

        modification of the addressing scheme selection (from XF to CAAS – recommended) and from CAAS to XF
         (not recommended);

        modification of the CAAS detailed table;

        addition of an entry in the Register to deal with specific cases (e.g. Kosovo recently);

        deletion of an entry in the Register (this is unlikely to happen but it should still be envisaged for efficient
         Register maintenance).

8.3.4    Description

Upon the decision to amend the AMHS address space of a State / ATSO, the specification of the amended addressing
scheme is developed by the staff in charge of managing the considered AMHS MD. Changes in the information
already published by ICAO as part of the Register version currently published are specifically identified, and the
update is formulated using a submission form provided by ICAO (retrieved from the ICAO web site).

Upon publication of Version N of the Register, the proposed update (if prepared in advance) is checked for
applicability before being submitted. This is to make sure that changes between Version N-1 (available when the
update was being prepared) and Version N (to which the update shall apply) do not compromise the proposed update.

After this verification the proposed update is formally sent to the ICAO Secretariat before day 14 following the
publication of Version N. Security measures must guarantee the integrity of the proposed update transmission from the
State / ATSO to ICAO.

8.3.5    Trigger

The trigger for the “proposed update” procedure is the decision to amend the AMHS address space of the AMHS MD
implemented (or to be implemented) by a State / ATSO. Such a decision may result from internal (e.g. MD-topology




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reorganization) or external (e.g. ICAO Regional decision for a new system being operationally started) events. The
identification of such events is beyond the scope of this procedure.

8.3.6    List of tasks

    1.   internal specification of new addressing scheme. The details of this task are a matter local to the considered
         State / ATSO. This task must be performed at any time between the trigger and at the latest 29 days (one
         AIRAC cycle + one day) before the intended applicability of the new scheme, as part of Register Version
         N+1;

    2.   retrieve update submission form from ICAO web site. [Add URL]. This task should be performed at any time
         between the trigger and the submission of the proposed update;

    3.   prepare update submission forms. This task consists in entering in the update form retrieved from ICAO the
         intended changes specified as part of task 1 above. It must be performed at any time between completion of
         task 1 and at the latest 29 days (one AIRAC cycle + one day) before the intended applicability of the new
         scheme, as part of Register Version N+1;

    4.   wait publication of Register Version N. This task is a passive self-explanatory task;

    5.   check applicability of update to Version N. This is in case the proposed update has been prepared in tasks 1
         and 3 upon the basis of the published ICAO Version N-1 (or earlier) of the Register. In this case official
         changes may have been made between Version N-1 and Version N, and it is necessary to check that they do
         not compromise the proposed update. This task must be performed between publication of Version N and the
         submission of the proposed update, occurring at the latest 29 days before the intended applicability of the
         update;

    6.   securely send proposed update to ICAO. This must be performed between day 1 of publication of Version N
         and day 14 after this publication.

8.3.7    Pro forma

[to be developed on the basis of the pro forma attached to State Letter referenced SP 54/1-03/39 concerning the
establishment of the Register]




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