TT AvData Discussion 2025 May 14 - wmo-im/iwxxm GitHub Wiki

Details

2025-May-14, 12:00-14:00 UTC, Microsoft Teams

Agenda

  1. IWXXM 2025-2:
    • Review the preparation of IWXXM 2025-2RC2:
      • IWXXM 2025-2RC2, proposed revision to the code lists and proposed amendments to WMO No.306 Vol. I.3
        • Model:
          • Inclusion of digital signature (see Issue #348)
        • Code lists:
          • Migration from 306, 49-2 and common to iwxxm (see Issue #355).
          • Enhancement to the code lists (Issue #354).
      • Proposed addition of new WMO Abbreviated Headings for exchange of VONA reports over ICAO AFS (Issue #321) and hosting such information on WMO Community Website (Issue #353)
        • Draft text to be put onto the WMO Community Website - AHL-pagev2.docx
        • Jun raised at the WG-MIE telecon on 13 May 2025 that a discussion between the secretariats of WMO and ICAO is required to confirm the workflow to approve the proposals made by TT-AvData as this may touched on the WMO-ICAO working arrangement.
  2. Ad hoc teams:
    • The removal of reference to WMO No. 49-II in all IWXXM documentation (Boonchai as lead).
    • The consolidation and management of code lists used by IWXXM (Dirk as lead).
  3. AOB:
    • Guidance on coding (and decoding)
      • Use of gml:identifier in new report types (see Issue #346).
      • The need to specify interpolation method in gml:PolygonPatch.
      • Shall we formalize TAC-to-XML-Guidance.txt and make it an online document?
    • Use of the WMO Codes Registry for operational preparation, exchange and consumption of IWXXM. Invest or leave it behind?
    • Technical challenges on operational use of different versions of IWXXM.
    • Activities on development of IWXXM to support future MET information services on SWIM.

Notes

  • Choy opened the meeting with welcome to all and noted that Mark Oberfield has retired
  • The team discussed the following:
    • digital signatures #348
      • Choy told the team that iwxxm:ReportType was designed to bring in metadata to describe the report itself. That means this is the natural place for digital signatures to reside
      • Choy also mentioned that XMLDSig is pretty old and its success depends on the "XML canonicalization" algorithm used to reformat the XML document for creation of the "signature" which almost always carries a hash of the document. He hadn't touch on this topic for many years and invited all to advise if there is any updates to XMLDSig and similar technologies (block chain?) that can be use to sign a document
      • The team noted that digitally sign documents may have value in (1) authenticating digitally a document as well as its contents especially if it has to be passed through providers with varying degree of IT security levels (c.f. AFS where the "nodes" are managed by States convened by PIRGS), and (2) it could be the basis for cost recovery. The team has consensus that there is no urgent need to pursue with its development but could be considered in the development of a technical suite also for AMOIS, AMFIS and HWIS.
    • code lists #355 and #354
      • Choy mentioned that he has revised the TTL files creation script from CSV sources to also generate RDF files which are being used in validation with iwxxm.sch. This means that there is no longer a need to employ the WMO Codes Registry for conversion code lists from TTL to RDF formats.
      • Choy has also showed the consolidation of code lists grouped under 306, 49-2 and common under iwxxm. The team discussed whether it is time to reveal consolidated code lists under iwxxm in 2025-2 but needs time to thing about (Jan mentioned that a cut over (e.g. increasing the major and/or minor version number of packages) to consolidated iwxxm is good enough but Choy thought a more gradual arrangement with transition periods allowing people to use either 306, 49-2 and common as well as consolidated iwxxm for a period could be smoother). This will be revisited in next meeting.
      • Choy also showcased a possible way to attach applicable IWXXM version(s) (through the use of namespaces) to individual entity of a code list in CSV sources, converted to RDF files and then be used to valid the code list entries in instances with schematron rules. If this works this may be able to solve the old problem of versioning code lists for validation. He will continue working on this for demonstration in next meeting.
  • Choy will make RC2 available for team review as soon as possible.
  • Anna presented the draft page of abbreviated headings. What roles and responsibilities of TT-AvData regarding preparation of proposed changes to the headings, submission for approval as well as subsequent implementations will be determined after the discussion between WMO and ICAO Secretariats.
    • Jan mentioned information on the use of BBBs was missing which is required for issuance of correction messages of METAR and TAF and less likely for retard messages. Choy to add this back into the draft page.
  • Choy will undertake the lead on the work in the ad hoc teams (WMO-No. 49 references) and code lists management.
  • The team discussed guidance:
    • Choy noted that more questions were being asked on encoding recently. Traditionally this information is included in TAC-to-XML-Guidance.txt that comes with the examples in the schemas.
    • While the team believe it would be nice to have an online version on the WMO Community Website, team members' anticipation for easy editing should also be addressed.
    • The team agreed to manage AsciiDoc files on GitHub IWXXM repository. Choy will create an initial version based on TAC-to-XML-Guidance.txt. Dirk will provide inputs on gml:PolygonPatch and Choy will also say something regard the use of gml:identifier in newer products as a start.
  • Choy asked about the use of the WMO Codes Registry. Jan said that they are using RDF files from the schemas directory but it is also important to have access to the codes.wmo.int to check if the URIs are the latest ones. Choy confirmed that iwxxm.sch will only validates with local RDF files. To validate with online resource, the server will need to response to URIs like http://codes.wmo.int/306/4678/DZ in XML files [Post meeting note: Choy found such a discussion back in 2013. See TT-AvXML-3-Doc17-final.pdf]. Currently, the WMO Codes Registry only response with webpages. Choy invite all to bring back use cases for online code list resources, so as to better understand the need of the service.
  • Anna reminded all that the WMO Codes Registry is never intended for "operational use".
  • Choy mentioned the effort on the development of IWXXM for MET information services on SWIM, noting that a RC will be required next year to showcase the establishment, operation and provision of such information services. Albert asked about if the development will include provision of space weather advisories through SWIM information services. Dirk noted that the existing schema should work.
  • Dirk mentioned Europe's upcoming development work on AMOIS, AMFIS and HWIS, and asked if private collaboration is necessary to kick-start relevant activities. Choy mentioned that since these information services have been discussed in METP/6 and received general consensus for a go, the METP/6 minutes could be taken as a request coming from ICAO which also means the full team can participate their development. Dirk to suggest which section(s) of the METP/6 minutes is relevant.

Actions

  • Once ready Choy will invite all to review the new RDFs with applicable IWXXM versions for individual code list entity and try out the enhanced iwxxm.sch
  • Choy will make available draft IWXXM 2025-2RC2 for review
  • Choy has invited Sunny to make available initial documentation, based on TAC-to-XML-Guidance.txt etc., in an AsciiDoc for others to contribute
  • Anna to report as appropriate outcome of the discussion on authorization of changes to abbreviated headings
  • Choy and Dirk will come back with more information on the development of AMOIS, AMFIS and HWIS and anticipated action of TT-AvData to support the associated activities

Next Meeting

4 June 12 - 14 UTC

Invitees / Attendance

Name Country/Affiliation Attendance
Boon-leung CHOY (Chair) Hong Kong, China X  
Wilberforce KIKWASI (Member) Tanzania  
Jan KOROSI (Member) HMEI/IBL  X
Mark OBERFIELD (Member) USA  (Retired)
Raquel SALAZAR (Member) Costa Rica  
Boonchai TEPYOSE (Member) Thailand  
Dirk ZINKHAN (Member) Germany  X
Albert MOLOTO (Member) South Africa  X
Shan CAO (Member) China X
Sunny CHAN (Guest) Hong Kong, China X  
Paul HERSHBERG (Guest) USA  X
Anna MILAN (Secretariat) WMO X
Martin Michalek (Guest) HMEI/IBL X