SGN2-07 WP 7/12
July3rd, 2006
AERONAUTICAL COMMUNICATIONS PANEL
(ACP)
SUB-GROUP N/2 (A/G APPLICATIONS) – 7th MEETING
Brussels (Belgium), 3rd – 7thJuly 2006
CURRENT STATUS OF PM-FIS VALIDATION PROJECT
Prepared bySofréavia for Eurocontrol
Presented by F. Picard
This paper provides information on the status of the Eurocontrol PM-FIS validation project and reports preliminary results.
The GG/N is invited to note the progress of the validation activity performed on the PM-FIS specification.
1Introduction
1.1Scope
This paper provides information on the status of the Eurocontrol PM-FIS validation project and reports preliminary results.
1.2Abbreviations
ASEApplication Service Element
CHARMEDSNA ATN End System
PM-FISProtected-Mode FIS
RRI/ASERouter Reference Implementation / Application Service Element
DSNADirection des Services de la Navigation Aérienne
1.3References
[1] PM-FIS Specification – Version 0.4 – Input SGN2 Brussels Meeting – June 2006.
[2] PM-FIS-CommentTable.doc
1.4Background
The Protected Mode Controller Pilot Data Link Communication (PM-FIS) application defines an alternative FIS protocol for use in air/ground applications that demand a stronger proof against corruption than provided by Standard Mode FIS (as defined in ICAO Doc 9705, Volume II, Part 4). The PM-FIS specification was developed at the initiative of AIRBUS France and reviewed at the SGN/5 December 2005 meeting (Toulouse, France) and SGN/6 March 2006 meeting (Atlantic City, USA).
The project launched by Eurocontrol aims at validating this draft specification. It consists in the development of two prototypes implementing the PM-FIS specification and the accomplishment of inter-operability tests between both prototypes.
To ensure the confidence of the inter-operability tests, the two prototypes were to be developed by two independent teams and from two independent SARPs V1 compliant ATN End Systems, namely the Sofréavia End System (RRI/ASE) and the DSNA CHARME End System.
The DSNA, Direction des Services de la Navigation Aérienne, was involved in the validation activity by providing access to the source of the CHARME End System and allowing the use of its ATN Laboratory for performing the inter-operability tests.
Preliminary Results
Two independent implementations of the PM-FIS ASEs have been developed in the scope of the project. This is believed to be the first complete implementations of the PM-FIS ATN application.
A two-step approach was followed. First locally in each development site, the CHARME and RRI/ASE implementations acting each as both air and ground systems have run the validation test scenarios. The scenarios were defined in order to cover all the new aspects introduced by the protected mode in FIS. Then, interoperability testing has been performed in the DSNA ATN laboratory with a dual configuration where the CHARME and the RRI/ASE end systems inter-operate.
Note. The second step described above has not been performed at the time of the writing of this document.
A number of specification defects have already been identified and tested corrections are proposed to ACP WG/N SG/N2 for approval. The defect reports are summarized in section 4.2 of this paper.
Prototype implementation
Architecture
Both the CHARME and the RRI/ASE PM-FIS prototypes are implemented to run on DEC workstations, under the UNIX operating system DEC ALPHA 0.4d.
The test of the PM-FIS prototypes focused on the behavior of the PM-FIS air and ground ASEs and users, as described in the draft specifications.
Use for SARPs Validation
The validation activity comprises the following steps:
-Paper analysis of the PM-FIS draft specification,
-Identification of the impacts on the existing FISsoftware code,
-Implementation,
-Development of the associated test tools,
-Stand-alone tests,
-Interoperability tests.
The two implementation teams have worked independently.
The two PM-FIS prototype come with a test software tool specially developed for the validation of the PM-FIS protocol. This tool has been ported over the PM-FIS application programmatic interfaces (API) provided by the RRI/ASE and the CHARME ATN End Systems. It allows to run all the validation exercises defined for the validation. The test software tool is based on interpreted command scenarios, each command driving the emission or reception of a PM-FIS service primitive. A specific scenario in mode "listener" allows automatic pre-defined responses to incoming messages.
Thistool support two checksum procedures: the default ATN 32 bit checksum algorithm and the password algorithm where a string of characters is passed along the messages.
Implementation of Defect Resolutions
During the lifetime of the project, several defects have been identified in the draft SARPs specification.
A project forum using internet means has been set up to discuss each of these defects and to decide of the best technical approach to fix them. When an agreement was found, the defect resolution was implemented in the PM-FIS prototypes for formal validation. The validation results of this report assume the implementation of the defect results.
The defects and associated solutions are being presented to ACP WG/N SGN/2 for discussion.
Interoperability test Scenarios
Functions to be tested
Interoperability test scenarios have been defined to cover all the specifics introduced by the PM-FIS mode over the standard FIS mode. These variants are the following:
- Support by the PM-FIS users of the checksum algorithm identification mechanism, the checksum computation procedure and the checksum verification procedure ;
- Notification to the peer PM-FIS user of errors during checksum identification, computation and verification ;
- Coding and decoding by the PM-FIS-user of both the FIS and the PM-FIS messages ;
- Detection of decoding error and notification to the peer PM-FIS users ;
- Coding and decoding by the PM-FIS ASE of the PM protocol data units ;
- Transparent transfer by the PM-FIS ASEs of the FIS messages.
Test scenario description
58 test scenarios have been defined and are spread over 9 families. A coverage matrix was built to check that all the requirements impacted by the PM-FIS functionality were tested by at least one test. The test families are listed below:
- PM-FIS Demand Contract Service scenarios,
- PM-FIS Update Contract Service scenarios,
- PM-FIS Report Service scenarios,
- PM-FIS Cancel Update Contract Service scenarios,
- PM-FIS Cancel Contracts Service scenarios,
- PM-FIS User Abort Service scenarios,
- PM-FIS Provider Abort Service scenarios,
- ASN.1 compilation scenarios,
- Checksum Algorithm change scenarios.
Contribution to Draft SARPS Validation
Draft SARPs Verification
The main contribution of the PM-FIS Validation project to SARPs validation has been to demonstrate that the new PM-FIS functionality are well-defined in the PM-FIS draft specification, i.e. that the requirements are clear, consistent and unambiguous, no specification hole nor redundancy was found.
The results give a high level of confidence in the draft PM-FIS specification.
Defect Identification and Resolution
During the development of the PM-FIS prototypes, technical questions have been raised on, the draft SARPs. Some of those have caused the generation of defect reports (DR) sent for consideration to WG/N SGN/2. The defects are documented in the maintenance file for the PM-FIS managed by the editor of the document [2].
Both PM-FIS prototypes have been modified according to these defect reports.
An upgrade of the draft specification including the resolution of the here above Defect Reports is provided to SGN/2 for review [see 1].
Current Status
In June 2006, independent test sessions have been performed on each PM-FIS implementation. The interoperability test session between the two implementations have started the 24th of June. Half of the tests have been passed successfully.The final results will be made available at the end of summer 2006 and presented at the next SGN2/WGN meeting..
Conclusion
The SG/N is invited to note the progress of the validation activity performed on the PM-FIS specification.
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