Expert Team on Enhanced Utilisation of Data Communication System
(a) Develop recommended practices and technical guidance material for the implementation of data communication facilities (GTS and Internet) at WWW centres, including security aspects, with a view to ensuring efficient and safe operations of information systems;
Reference material: Attachment II-15 of the Manual on the GTS (section 2)
On-line DCST information resources at:
tasked the ET-DCST to pursue the development of relevant guidance (on security and protection of GTS systems and centres from the Internet)
- It re-emphasized the critical importance of an appropriate level of security and protection of operational systems, and it urged all GTS centres to pay due attention to this important matter. It noted that the CBS/ISS/ET-EUDCS was tasked to pursue the development of relevant guidance for WWW centres and it underlined this urgent requirement for the whole range of GTS centres (NMCs and RTHs).
- It urged all RTHs on the MTN, as well as other centres, to provide the relevant information to be posted on the DCST information resources
comments: special attention should be given to guidance on implementation of GTS/data-communication systems, Internet access and security measures, at small NMCs (incl. developing countries).
Various meetings (Regions V, II):
Internet-based connections offer advantages to complement or even implement part of the GTS at a limited cost.
There are currently a number of NMCs and RTHs using TCP/IP socket connections via Internet between them, with access list control in each Centre’s routers. This does not provide adequate protection for operational systems, and a much greater level of security is possible by the use of Virtual Private Networks (VPN), with IP Security (IPSec). Requirement to develop guidelines for the implementation of Internet based VPNs as part of the GTS.
(b) Review current and anticipated telecommunication and information system requirements of the WWW and other WMO Programmes that can be effectively met by the Internet;
- Guidelines and procedures for the use of E-mail for the exchange of meteorological reports should also be developed.
- Several RTHs make extensive use of the Internet to retrieve both GTS and non-GTS data from other Meteorological Centres in non-real-time, and to collect observational bulletins from NMCs as a back-up or on a regular basis when dedicated telecommunication links are not economically affordable for the NMCs concerned. The meeting noted in this respect that various procedures had been developed by various centres (including Washington, Melbourne, Toulouse) for collecting observational reports or bulletins via the Internet, using FTP or e-mail (as attachment or as text of the message) or HTML forms. The meeting agreed that it would be helpful to identify a few recommended options taking benefit from the actual experience gained, with a view to facilitating a consistent implementation and operation by NMCs/RTHs interested. The meeting recommended that the ET-EUDCS and ICT-ISS consider this matter and develop guidelines and procedures; It invited RTHs/NMCs using such Internet procedures to provide contributions on their operational arrangements and experience.
Comments: Information (Questionnaire) and contributions were sought from NMCs/RTHs on the use of the Internet and procedures for collecting observational reports or bulletins from NMCs, and also for providing (or enabling access to) data and products from RTHs to NMCs. Develop guidance. (This matter is important for smaller centres, esp. developing countries)
(c) Review standard TCP/IP procedures and applications, including new developments (e.g. IPv6) that are relevant to WWW and other WMO programmes requirements, and develop recommended practices;
Reference material: Attachment II-15 of the Manual on the GTS
- Attachment II-15 of the Manual on the GTS should eventually only contain the fundamental elements of the recommended practices and procedures, and implementation guidance would be provided on DCST information resources to easily keep the information up-to-date.
Comments: Attachment II-15 should be reviewed accordingly; implementation guidance is posted on DCST information resources. Possibility of developing a guide on implementation of TCP/IP procedures and applications on the GTS.
- The file exchange procedure via FTP for new message types (without existing AHL) had not been tested yet on the GTS, and it requested the OPAG-ISS to further study the matter, in relation with the development of filenaming and metadata conventions.
- It re-affirmed the crucial importance of standard conventions for filenaming and metadata for WMO Programmes in general, and for the WWW in particular, in order to promote the transfer of information files other than traditional GTS messages on the GTS, and take full benefit of the improved GTS infrastructure.
Note: Metadata standards are being developed by the ET on Integrated Data Management
- It strongly stressed the urgent need for agreed WWW filenaming conventions. It noted with interest the file management, file server structure and filenaming mechanisms that were implemented at some RTHs for national and international operation on various data-communication services, including the GTS and the Internet. It noted in particular the push and pull file transfer procedures which were in operation at WMC/RTH Washington, Moscow and RTH Tokyo. It underlined that the different file server structure and filenaming mechanisms implemented by various centres had significantly complicated the operational access and retrieval of data and products by user centres. With a view to agreeing upon a limited number of possible options for future implementation and facilitating a co-ordinated development of file management within the WWW, the meeting invited the RTHs that are operating a file server system for global data, (i.e. Washington, Melbourne, Tokyo, Bracknell, Offenbach, Toulouse and ECMWF) to submit contributions on their file management, file server structure and filenaming mechanisms. These contributions should facilitate the task of the ET-EUDCS and be provided in advance to its forthcoming session planned for early 2002.
Comments: Guidance on filenaming and procedures for exchanging non-AHL files via FTP on the GTS (and on the Internet). Centres mentioned above will be invited to provide contributions.
- The mechanism for the transmission of ‘normal’ GTS messages (with Abbreviated Heading Line) batched in files exchanged via FTP, as described in Attachment II-15, was widely adopted for operational use by many centres, including on the MTN.
- It confirmed that the use of FTP on the GTS had achieved widespread acceptance amongst NMHSs, and that the mechanism for the transmission of ‘normal’ GTS messages (with Abbreviated Heading Line) batched in files exchanged via FTP, as described in Attachment II-15, was adopted for operational use by many centres, including on several MTN circuits. However, there were variable implementations of the messages batching procedures at various centres with regards to the frequency of transmission of batch-files (e.g. every minute), the maximum number of messages in one batch-file (e.g. 100), etc. Noting that these implementations can have an impact on the total transmission delay for the distribution of observational data, the meeting recommended that the ET-EUDCS review the matter and develop detailed guidelines for ensuring consistent and efficient implementation.
Comments: develop more detailed guidance on procedures for batching messages into files. Hiroyuki Ichijo (Japan) developed a questionnaire on this matter that he sent to some RTHs.
- The exchange mechanisms for processed products needed to be reviewed, taking into consideration the limited number of sources (WMCs and RSMCs) as well as different requirements from user centres. Downloading product files (data pull) would have a significant number of advantages, including the access to metadata. However, coordination and efficient management mechanisms should be in place to ensure a guaranteed level of quality of data-communication services on the GTS and to prevent a system overload, which might be inherent to data pull services (too many users accessing data at the same time). This matter should be carefully studied as a matter of urgency.
Comments: study possible procedures and management mechanisms, taking also into account the outcome of the Inter programme team on future WMO information systems. Last report:
(d) Develop recommendations on coordinated use of the Internet to meet in the relevant short term (1-3 years) requirements of all WMO Programmes and update the Guide on Internet Practices as required.
Reference material: Guide on Internet Practices at:
- The guide be "published" in HTML format on the Internet, and regular updates be done by the Secretariat in co-ordination with the ET-EUDCS.
Comments: Update the guide as required. Review and advise on the use of the Internet, taking also into account the outcome of the Inter programme team on future WMO information systems.
(e) Other matters
- In accordance with Attachment II-6 of the Manual on the GTS, the second part of the response to a request will be the transmission of the requested message(s). This will be a repeat of the originally sent messages, including the original sequence number(s). The resulting transmission will most likely put the ongoing transmission sequence numbers out of order. That rule unnecessarily complicates the automatic procedure for detecting gaps in the incoming sequence number stream and requesting the missing messages. The point is that the ongoing row of sequence numbers is broken again by the incoming requested messages, which may again trigger a further automatic request for repetition. The meeting recommended to amend Attachment II-6 (third line from bottom) as follows:
To replace the text:
", including the original sequence number(s). The resulting transmission will most likely put the ongoing sequence numbers out of order."
"that sequence numbers fit into the ongoing sequence numbers of outgoing messages."
Comments: the proposal should be reviewed and consolidated, and then submitted to the ICT-ISS meeting (September 2002).
Attachment II-15: http://www.wmo.ch/web/www/TEM/attII15rev.doc
ICM-MTN 2001: http://www.wmo.ch/web/www/TEM/ICMMTN2001/ICMMTN01rep.doc
ET-DCST (1999): ftp://www.wmo.ch/Documents/www/GTS/DCST99rep.doc