[LINK] Victoria Bushfires

[Tom Worthington]

At 09:03 AM 9/02/2009, Stilgherrian wrote:
>I'll repeat a plea from the CFA yesterday for people to NOT 
>visit  their site unless there is a specific need ... overloaded by 
>the merely curious.   ...

Yes. Geoscience Australia's national bushfire monitoring system 
"Sentinel" was reporting  "Service Temporarily Unavailable" over the 
weekend. It appears the system was overloaded by high demand. This 
was the public version of the service and hopefully the separate 
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 <http://www.tomw.net.au/2003/enet.html>. 
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" <http://sentinel.ga.gov.au/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 
Google maps, which  appears to have been done.



Tom Worthington FACS HLM tom.worthington at tomw.net.au Ph: 0419 496150
Director, Tomw Communications Pty Ltd            ABN: 17 088 714 309
PO Box 13, Belconnen ACT 2617                      http://www.tomw.net.au/
Adjunct Senior Lecturer, Australian National University