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Reprint 472
Expert Group Meeting on Internet Applications
For Agrometeorological Products
Washington DC, USA, 6-9 May 2002
Use of Web Server for International Exchange
of Public Forecasts and Warnings
of National Meteorological Services via the Internet
Dr H K Lam
Director of the Hong Kong Observatory
Permanent Representative of Hong Kong, China with WMO
Vice-President of WMO Regional Association II (Asia)
Tel: (852) 2926 8221
Fax: (852) 2721 6557
Telex: 54777 GEOPH HX
E-mail: dhko@hko.gov.hk
Abstract
Tasked by the Commission for Basic Systems (CBS), Hong Kong
Observatory (HKO), Hong Kong, China is taking the lead in the development of two
WMO-sponsored pilot websites, viz World Weather Information Service (WWIS)
and Severe Weather Information Centre (SWIC). This paper focuses on the technical
considerations in the development of the two pilot websites and their implementation
requirements.
The existing system setup of the two websites will be covered. Key factors
that are essential to the successful implementation and operation of a common
website for international exchange of public forecasts and warnings of National
Meteorological Services (NMSs) via Internet will also be discussed.
1. Introduction
Weather information is a much sought-after commodity – by the traveling
public, by the international media, etc. The rapidly expanding Internet with a
diversity of weather information from a wide array of information service providers
often bewilders the users and leads many governments to question the amount of
resources required to support National Meteorological Services (NMSs). WMO
Members, especially those from developing countries, have expressed concern on the
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impact of non-professionals on the public recognition of the weather services
provided by National Meteorological Services [1].
The meteorological community needs a collective official voice to
counteract the many spurious sources of weather information over the Internet. An
authentic and authoritative source of weather information on the web with the
backing of WMO Members will be a strategic step in elevating the public weather
services operated by NMSs to the international arena, enhancing the profile and
visibility of NMSs, leading to an appreciation that official and reliable forecasts come
from those who operate a highly regulated network of weather observations under the
auspices of WMO.
The Commission for Basic Systems (CBS) embraced these ideas and tasked
Hong Kong, China to take the lead in the development of two WMO-sponsored pilot
websites, viz World Weather Information Service (WWIS) and Severe Weather
Information Centre (SWIC).
The objectives for establishing the two websites are:
i. To develop a methodology for the international exchange of public forecasts
and warnings issued by NMSs via the Internet;
ii. To provide a centralized source of official weather information on the
Internet;
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iii. To encourage the international media and the public to make good use of
official weather information provided by NMSs; and
iv. To enhance the visibility of NMSs, especially those of developing countries,
so as to strengthen the public recognition of the weather services they
provide.
The websites are to be easily accessible and user-friendly to the public and
media. Collated information would also be used to generate an integrated set of
weather information for dissemination to the media, the public and back to the NMSs.
2. Recent Developments
The CBS Public Weather Services Expert Team on Warning and Forecast
Exchange Issues developed in July 2000 an initial framework for the exchange of city
forecasts among WMO Members. The addresses of the websites are: WWIS –
www.worldweather.org (Fig. 1) and SWIC – severe.worldweather.org or
typhoon.worldweather.org (Fig. 2). The WWIS website is being implemented in a
phased manner. In Phase I of the project, the website provides climatological
information for selected cities as well as links to the websites operated by the official
meteorological services of WMO Members. This phase is currently under
operational trial. Phase II will include city forecasts a few days ahead. City forecasts
are being added to the website as they become available. Phase II of the website will
undergo operational trial at the end of 2002. The SWIC website deals with severe
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weather warnings issued by Members. In the first instance, the website now covers
warnings of tropical cyclones in the western North Pacific provided by members of
the ESCAP/WMO Typhoon Committee. The website is also under operational trial
[2]. Both sites are currently operated in English only.
3. System Requirements
To meet the objectives of the pilot projects, a system to support the operation
of the websites needs to satisfy the following requirements:
i. Providing an appropriate resource management system to handle the
numerous weather information items supplied by WMO Members;
ii. Providing a high availability and reliability platform with automatic fail-over
and load-balancing features;
iii. Having sufficient storage capacity, system memory and computing power to
generate and manage the large number of web pages inside the two websites;
and
iv. Supporting a diversity of communication methods to facilitate exchange of
up-to-date weather information by WMO Members.
These requirements are to ensure that the system can provide a reliable and
capable platform for the exchange of public weather forecasts and warnings issued by
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NMSs. The diversity of communication methods would hopefully encourage all
WMO Members, including developing countries, to participate in the pilot projects.
4. System Configuration
A schematic diagram of the system is given in Figure 3. The web servers
and the backend processing system are part of a server farm which also hosts other
websites operated by the Hong Kong Observatory (HKO). To maintain high
availability and reliability, the server farm has automatic data backup facilities and
secondary power supplies. The system’s backend is connected to the Hong Kong
Observatory’s main computer system with a dedicated T1 (1.54 Mbps) leased line.
The front-end connection to the Internet backbone has a maximum capacity of 60
Mbps. Both connections are protected by firewalls as well as other system security
tools.
Two identical web servers forming a cluster are used to host the contents of
the two websites. They can simultaneously handle about 5,000 requests. The
resilience of the web servers is achieved by a pair of load balancers that constantly
monitor the serviceability of the servers and automatically divert traffic where the
situation warrants. To ensure data integrity across the web servers, web pages of the
websites are stored on a Network Attached Storage (NAS) device which is a high
availability data storage device and has automatic data backup capability.
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5. Content Management
The pilot websites are implemented based on a data-centric model. The web
contents are generated and updated based on the information stored in a relational
database management system (RDBMS), which is implemented in a two-tier fashion.
The “master” database is located at the Hong Kong Observatory’s main database
server. The “slave” database resides on the server farm. Data synchronization
between the “master” and “slave” database is achieved by using automatic data
replication. With this arrangement, the database is accessible by web applications
while a high security level for the data source can be maintained in the “master”
database at the same time.
In developing the content management software, open source system
development tools are used for better portability of the software. A combination of
Java Server Page (JSP), Java Database Connectivity (JDBC) and Perl module is
employed to manage the web contents. Backend processes are set up to regularly
monitor data updating in the RDBMS and, if necessary, update web pages
automatically by fetching data from the RDBMS using JDBC.
6. Weather Information Exchange Mechanism
In view of the diversity of capabilities and practices among WMO Members,
it would be important to allow a matching variety of communication means to
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facilitate the exchange of public forecasts and warnings in both coded and plain text
format. A system to receive and process information submitted by Members utilizing
a number of means is now under development. An array of communication methods
[3], including FTP, e-mail and web-form through the Internet in addition to sending
messages over the conventional GTS and AFTN, will be available for this purpose.
For example, the web-form (Figure 5) is a web interface to assist users in preparing
and submitting their forecasts manually. Users could choose the forecast periods,
weather elements and temperatures from pull-down menus. Upon confirmation, the
software residing on the HKO server would automatically process the message and
post the forecasts onto the pilot website.
A schematic diagram illustrating the workflow of weather information
exchange is depicted in Figure 4. A dedicated server is set up to receive forecasts via
FTP, e-mail and the tailor-made web-form. A software decoder is implemented to
automatically process and check the validity of the forecast bulletins submitted by the
participants. Deviations from the recommended format will be flagged to allow
manual intervention.
Forecasts submitted will be converted in eXtensible Markup Language
(XML). Using XML for information archival has the following advantages:
i. XML, a recommendation endorsed by the World Wide Consortium
(www.w3c.org), is now widely in use in the Internet community. Numerous
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tools, either commercial software or freeware, for processing XML data are
readily available. XML data can be easily converted into other format.
ii. XML is a highly extensible format. It is easy to incorporate new types of
information into the XML data structure.
In the near future, the XML data processing system will be used to support the web
server as an information distribution agent to allow Members to retrieve forecasts
available on the server via FTP for their own national applications.
For severe weather warnings and advisories, information is gathered
primarily from Members’ websites. A metafile format has been designed so as to
allow participating Members to decide the range of information to be presented in the
SWIC website. Metafiles created by participating Members in their websites are
fetched routinely by the data processing system and the corresponding web pages are
updated according to the contents in the metafiles. As a secondary channel, the
system is also capable of processing and posting onto the website warnings and
advisories available on the GTS.
7. Resources for Developing and Maintaining the Pilot Websites
Apart from technical considerations, a crucial factor for the successful
implementation is the availability of resources to support the setting up, the
continuous development and the day-to-day operation of the web servers. Hong
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Kong, China fully supports the concept of international exchange by Internet and
commits itself to providing the necessary resources required to run the pilot projects.
A summary of resources contributed by Hong Kong, China is in Annex I.
Human resources are second to none as the key element for success. A
project team has been set up in HKO to oversee liaison, system design and product
development. Two computer programmers are specifically assigned to handle the
numerous tasks on data processing and automation. It is likely that a number of staff
will still be required to maintain and update the system upon the full implementation
of the servers.
8. Observations to Date
The two pilot projects so far have demonstrated some success in using web
servers for international exchange of public forecasts and warnings of NMSs via the
Internet. By the end of April 2002, climatological information of 514 cities from 149
Members is included in the WWIS website. 25 participating Members are submitting
forecast bulletins either through GTS or e-mail to WWIS. Forecasts for more than
100 cities from these Members are now available in the website (Fig. 6). The
availability of e-mail submissions has made possible for some developing countries
to contribute to the pilot project.
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Visit statistics is a good measure to gauge the popularity of the websites.
By the end of March 2002, a total of about 300,000 page visits to the two websites
were recorded since their operational trial (Annex II). This is an encouraging sign
that the websites would grow to become a good means to promote Members’
visibility in the Internet community.
In the course of consulting participating Members regarding the
recommended form for the exchange of forecasts, language has emerged as a
potential issue. The pilot project is conducted in English. In order to encourage the
participation of Members whose native languages are not English, it would be
advantageous to strengthen the system to support the reception of information and the
generation of web pages in different languages.
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References
1. World Meteorological Organization 1999: Abridged Final Report with
Resolutions, Thirtheenth World Meteorological Congress. WMO-No. 902,
38.
2. World Meteorological Organization, 2001: Hong Kong Observatory and
WMO launch Trial Web Site WWW.WORLDWEATHER.ORG. Press release,
14 December 2001.
3. World Meteorological Organization, 2001: Weather on the Internet and
Other New Technologies. WMO/TD No. 1084.
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Figure 1: The World Weather Information Service website
Figure 2: The Severe Weather Information Centre website
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Figure 3: A schematic diagram of the system configuration
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Figure 4: Schematic diagram of the forecast collection and distribution system.
Figure 5: Web-form under development for Members to prepare and submit
weather forecasts to the WWIS website.
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Figure 6: Number of city forecasts available in the WWIS website from December 2001 to April 2002
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ANNEX I Summary of the resources for the development and management of the two pilot websites
(past and projected)
Manpower (Man-Month) Up to Dec. 2001 2002 2003
SWIC 12 12 8
WWIS 26 42 22
Total 38 54 30
Other Resources (US Dollars) Up to Dec. 2001 2002 2003
SWIC 1,400 7,600 7,300
WWIS 5,000 24,800 15,200
Total 6,400 32,400 22,500
SWIC – Severe Weather Information Center WWIS – World Weather Information Service Remarks (1) Estimates based on the assumption that no major change in scope would occur after operational trial. (2) “Other resources” include web hosting services and development software / hardware. (3) The recurrent cost for 2004 onwards for web hosting services is estimated to be around US$20,000 annually.
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ANNEX II
Visitor statistics of the two WMO pilot websites Monthly page visits to the SWIC and WWIS website since the operational trial: (SWIC: September 2001, WWIS: December 2001)
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
Sep 2001 Oct 2001 Nov 2001 Dec 2001 Jan 2002 Feb 2002 Mar 2002
Month
Pag
e V
isit
s
SWIC WWIS
Total and average daily page visits of SWIC and WWIS websites (up to 31 March 2002)
SWIC WWIS
Total page visits 87,000 214,000
Average daily page visits 300 1,800
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