source: branches/fscctrl_safety_limits/www/smartfact/struct/help-introduction.page@ 18340

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1Introduction
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3The idea of SmartFACT++ is simple. A backend (<I>smartfact</I>) updates some
4data-files continously which can then be retrieved from a web-server
5and the data is displayed in your browser. To keep the network traffic
6low the data is not encapsulated in html, but transmitted <I>as is</I>.
7A JavaScript, running client side, <I>i.e.</I> on the machine running
8the browser is then creating the html around it dynamically which is then
9displayed by the browser. The backend writing the data-files can be basically
10everything. In case of FACT it is a program called <I>smartfact</I> which
11subscribes to all dim-services in the dim-network which are needed.
12Whenever a service is updated, the corresponding files are also updated.
13The disadvantage is that it is difficult to mix information which is
14not updated together in a single file and display it on a single page.
15This, <I>e.g.</I>, means that a file which is only updated every two
16hours (because new information is only available every two hours) cannot
17reasonably store information which can change every minute, <I>e.g.</I>
18general warnings. Every page is restricted to reload a single file, to
19keep network traffic low. A simple solution would be a php which concatenates
20information before the information is transfered, but this is (not yet?)
21available. Consequently, all pages which are not updated frequently or
22are guranteed to be updated frequently will not show fats updateing
23information as warning. Some pages, <I>e.g.</I>, the main page are
24updated once every seconcd or few seconds rather than updated
25event-driven by the reception of a new service. These pages will then
26show informations like the current warning status of the system.
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28The page description is reloaded whenver a page has been clicked to
29avoid a lot of network traffic at startup. The disadvantage is a little
30network traffic (in the order of a few hundred bytes) whenever a page
31is changed.
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