source: branches/FACT++_part_filenames/www/smartfact/struct/help-traffic.page@ 20115

Network traffic
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This interface is optimized for slow network connection and low network
traffic. It is not advisable to reload the pages manually because you
would just reload the JavaScript. The traffic should be <B>less than
1kB/s</B> and hence suitable also for mobile connections. The layout is
optimized for small windows and mobile phones. 

The data displayed is refreshed once every three seconds, <I>i.e.</I>
the file is reloaded from the server. The graphics display is refreshed
once every five seconds. A new refresh is only started if the old one
has been finished, either successfully for with an error or timeout,
<I>i.e.</I> that slow or faulty network connection can significanly
increase the refresh time. Whenever a refresh was performed, the color
of the dots around the title is changed (one for the data and one for
the graphics) to indicate that the JavaScript is still running and
requesting data from the server. Also the time stamp at the footer is
updated. The time-stamp of the retrieved data is displayed at the top.
If no updated could be performed within sixty seconds or the data is
older than sixty seconds the time stamp is displayed in red. If the
time-stamp of the graphics is older than sixty seconds the graphics is
grayed.

In case of errors or broken connections, the time interval for
retrieval is  increased to ten seconds, and decreased again if valid
data was received.

The timer is not newly started if a new page is loaded, hence, it might
take a few seconds before the values will be displayed. 

The typical size of a camera display is about 350 bytes, the typical
size of the ascii data is about 100 bytes. Adding the HTML header
which is in the order of 200 bytes, this yields an average transmission
rate of aprroximately 200 bytes per second. This is less than one
mega-byte in one hour, plus the data loaded for each page switch.
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