AMHS CONFORMANCE TEST TOOL

							                                                                          ACP – WG N/SG N3-WP/3-5 (IP)

                                                                                              24/Apr/2005

                  AERONAUTICAL COMMUNICATIONS PANEL (ACP)

                         WORKING GROUP N – NETWORKING

              SUBGROUP N3 – GROUND-GROUND APPLICATIONS




                                           th   th
                              Montreal, 12 – 13 May 2005 (third meeting)



                           Agenda Item 3 : ATS Message Handling Services



                             AMHS CONFORMANCE TEST TOOL




                                      Prepared by Klauspeter Hauf




                                                Summary

DFS started the project "AMHS conformance test tool" in August 2004 together with industry partners based
on experiences from the FIRST interoperability tests. The now available test tool interfaces an AMHS
implementation with a simulated AMHS/AFTN environment and can run test scripts created through a
graphical user interface.

Such conformance testing prepares AMHS implementation for subsequent interoperability testing and
reduces costs for co-ordination effort and communication services which are needed for the test performance
between distant sites.

The paper provides an outline of the concept and features of the AMHS conformance test tool. Its functions
have been successfully verified by conformance test exercises with AMHS implementations supplied by two
manufacturers.
AMHS CONFORMANCE TEST TOOL                                             ACP WGN05 (Montréal, 11th- 20th May 2005)




1.      INTRODUCTION
Generally, Conformance testing can be defined as the exhaustive testing of an implementation under test
(IUT) against functions and procedures defined in a Standard specification. A test tool provides the IUT with
defined inputs and observes the resulting behaviour of the IUT. Conformance testing should also allow to
"provoke" the IUT with an incorrect behaviour for study of the IUT´s stability (negative testing). Typically,
conformance testing is performed locally between the IUT and the test tool.

Conformance testing will not supersede, but prepare IUTs for subsequent interoperability testing, thereby
reducing the total costs that in particular interoperability tests impose concerning co-ordination effort and
needed communication services. - In this view, an AMHS conformance test tool is the equivalent facility to
the CIDIN test tool CITEST which was developed in support of the CIDIN implementation.

Initiated by the experience made during the FIRST interoperability tests, the DFS started in August 2004,
together with partners from the industry, the development of an AMHS conformance test tool. In particular,
the test tool should allow to perform such tests which had to be suspended from the FIRST interoperability
tests due to constraints that are inherent to interoperability tests with real systems.

The AMHS conformance test tool is now available and runs an initial set of conformance tests including
such test cases which had been defined for the FIRST interoperability tests. This set of tests addresses the
communications between AMHS users as well between AFTN and AMHS users by means of the
AFTN/AMHS Gateway. The technical concept behind the test tool provides a grade of flexibility which may
qualify the tool to run also conformance test which may be developed in the future by standardisation
bodies.


2.      CONCEPTUAL APPROACH
The conformance test tool interfaces the IUT with a simulated AMHS/AFTN environment consisting of a
number of adjacent ATS Message Servers (MTAs) and one adjacent AFTN/CIDIN Centre (see Figure 1).
Each of the ATS Message Servers in turn represents a number of AMHS users (UAs). Analogously, behind
the AFTN/CIDIN Centre there is a number of AFTN users.

For the simulated AMHS/AFTN environment the intended scope of test scenarios has been specified by
definition of test groups and test classes. Seven test groups were defined to provide a logical high-level
ordering in conformance tests: submission operations from AMHS users, AMHS transfer operations,
delivery operations to AMHS users, AFTN/AMHS Gateway operations, naming and addressing, AMHS
parameters (as the ATS Message Header), and traffic logging.

For each of the above test groups test classes were defined relating to normal communication and some
failure situations in terms of generated erroneous Messages, Report and Probes, and procedural errors.

The defined test groups and classes set up the requirements for the software design and operation of the
test tool. The concept was successfully verified by conformance test exercises with AMHS implementations
from two manufacturers.




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AMHS CONFORMANCE TEST TOOL                                              ACP WGN05 (Montréal, 11th- 20th May 2005)


                     Adjacent                                                 Adjacent
     AFTN                                                                                     ATS Message
                    AFTN/CIDIN                                              ATS Message
    Stations                                                                                  User Agents
                      Centre                                                  Servers


                   AFTN/CIDIN                                                AMHS                  AMHS
     AFTN                                                                                         User (1)
    User (1)
                                                     IUT                       Server (1)          AMHS
                                                                                                  User (2)

     AFTN
    User (2)                                        AMHS                                           AMHS
                    AFTN/CIDIN
                                                Communication                  Server (2)         User (3)
                      Centre
                                                  Functions
        
                                                                                   
                                                                                                  AMHS
                                                                                   
                                                                                                 User (4)
                                                                                   
                                                p
                                            1                                  Server (n)          AMHS
                                                 Local AMHS                                       User (5)
     AFTN
                                                User Terminals
    User (s)
                                                                                                   AMHS
                                                                                                  User (m)



                         Figure 1: AFTN/AMHS environment simulated for the IUT


1. 3. REALISATION OF THE TEST TOOL
The AMHS test tool (see Figure 2) simulates an operational environment for the IUT with three MTA
instances (representing three adjacent ATS Message Servers or three neighbour PRMDs) and one
AFTN/CIDIN source/sink (representing an adjacent AFTN/CIDIN environment).

The AMHS test tool was built on the basis of commercial off-the-shelf software products providing the
X.400 protocols and the MTA. Also, existing components supporting the CIDIN protocol and AFTN
functions were integrated. The TTMS (Test Tool for Messaging Systems) is the test control and evaluation
unit that implements test scripts, supports test step verification and maintains test result logs including the
records of messages exchanged with the IUT.

The test tool generates AMHS data at the X.400/P1 level. It sends and receives AMHS messages, reports
and probes via one or several AMHS transfer ports (see Figure 2). Whenever the IUT's gateway is involved
in the test, the test tool makes use of its AFTN/CIDIN interface in either direction.

The IUT is assumed to have a local attached AMHS user agent that can be used for AMHS
submission/delivery tests. Optionally, a local AFTN user terminal and a monitor and control position can be
used in the tests.




WG N/SG N3-WP/3-5 (IP)                              page 2                                             08/03/10
AMHS CONFORMANCE TEST TOOL                                             ACP WGN05 (Montréal, 11th- 20th May 2005)



                                IUT               AFTN/CIDIN                AMHS Test Tool
                                                   X.25 ports

 AFTN User
                           AFTN/AMHS                                  AFTN-




                                                                                 API
  Terminal
  (optional)                 Gateway                                 CIDIN IF




                                                                                                    Message Source/Sink
                                                                                          TTMS
                                                                                 API
                                                                      MTA-1
 AMHS User                      ATS
    (UA)




                                                                                 API
                             Message                                  MTA-2
                              Server
                               (MTA)




                                                                                 API
                                                                      MTA-3
                                                       AMHS
                                                      transfer
                                                        ports

                             Monitor &                                                        User
                                                                                            Interface
                           Control Position
                              (optional)


                                    Figure 2: Abstract test configuration


2. 4. FEATURES OF THE TEST TOOL
The test tool supports test data and script preparation, script-based execution and evaluation.

Test preparation

An AMHS editor is available to create messages, reports and probes. The user enters AMHS parameter
values in a graphical user interface, thereby making use of templates and a number of data samples.

Test scripts are created in a graphical user interface. There is no need to know any scripting language.

Test scripts can be combined to support complex scenarios. Messages can be sent to the IUT in a
controlled sequence.

The test tool can be configured to return a report (DR or NDR) or a notification (receipt or non-receipt)
response to any messages received from the IUT.

Test execution

Test scripts are presented in table-like format. Each line contains a test step with commands and
parameters for actions and queries.

Test scripts can run in full automatic mode or manually be controlled step by step. On-line modification is
possible to optimise a test script in the course of a test dry run.




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AMHS CONFORMANCE TEST TOOL                                                 ACP WGN05 (Montréal, 11th- 20th May 2005)

Test evaluation

The test tool analyses data captured from the IUT's interfaces and compares the received with the
expected AFTN or AMHS parameter values. Deeper analysis of captured AMHS data is possible with the
AMHS viewer.

Each executed test step indicates its success or failure with a green or red result field. All test results are
automatically stored.


3. 5. SUPPORTED TEST SCENARIOS
The test tool supports conformance tests for native AMHS communication and AMHS/AFTN gateway
functions in either direction. An initial set of test scripts has been implemented and already been verified
with two candidate implementations under test (IUTs) from different manufacturers.

The test tool is able to send
       Messages with ia5-text or general-text body containing correctly formatted ATS-message-header
        and ATS-message-text,
       Messages (IPMs) with ATS-message-header syntax errors or with (intentional) erroneous IPM
        heading,
       Notifications, reports and probes with user-provided values.

With the test tool the user (test personal) is able to view and evaluate
       AMHS parameter values of the envelope and content for every incoming/outgoing message,
       external/internal trace information conveyed in the envelope of messages received from the IUT,
       contents of delivery and non-delivery reports showing reason and diagnostic code in plain text.

With the test tool the user (test personal) is able to verify
       conversion of the ATS-message-header to correct AFTN format,
       translation from AFTN addresses to XF- or CAAS-addresses.




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