Tuesday, February 10, 2009

Victorian Bushfire Maps

Google have provided a Flash Map, using information from the Victorian Country Fire Authority (CFA) RSS Feed. The intention is to provide a better visual representation of the information and take the load off other web based information services. One of the services which was overloaded over the weekend was Geoscience Australia's national bushfire monitoring system "Sentinel". This was reporting "Service Temporarily Unavailable". This is the public version of the service and hopefully the separate password protected service provided to firefighters was operating. Even so it is unfortunate the public service was not able to cope with demand when needed.

The problem is that Sentinel tries to provide a very interactive and customized service to each user. As a result the system can become overloaded in periods of high demand. The web has features built in to reduce the load, but this would require a comprise of the interactive design.

In 2003 I suggested some changes to allow the Sentinel system to cope better with high demand. CSIRO, who at that time were maintaining the system, adopted some of the suggestions.

As an example, I suggested providing canned maps of major events, so that the general public would not need to use the interactive application. In the current version this is implemented as "Current Overview". The usefulness of this feature could be improved by moving the link up from tenth place in the menu to a more prominent position. Also the paragraph about it on the bottom of the page could be moved to the top of the page. More people would be likely to use the feature.

In addition the "Cache-Control" of "no-cache" could be removed from the maps provided in the overview. Maps at fixed points in time on unchanging web pages would then be created. When there was a new map, it would be placed on a newly created page. To get the latest map the user would be directed to the latest page, rather than refreshing the same page. This would allow caching of the maps and reduce the workload to the server. While this may made for a less interactive design, it would allow the system to cope with much higher loads.

Another option would be to supply the data to another system, such as that by Google. However, local network limitations could also hamper access, even if the server can cope with the load, so a more streamlined designed would still be a worthwhile improvement.

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