Live Meter Data on the Web - Advice Please

[BCM]

I've been asked to display some meter data on the web and I need preliminary
advice.

We have several hundred meters on site, with a system that writes out xml
files at 10 second intervals containing their data. (These files are
overwritten every 10 seconds, not appended to.)

First, I need to display two numeric pieces of this data just as numbers in
a web page. Naturally that's easy enough: where I'm stumped is REFRESHING
that data when it's updated every 10 seconds. Of course I don't want to
refresh the whole page, but only update a particular number when its
associated xml file is updated.

I've seen this done client side with javascript, but it was pretty cludgey.
Can ASP.NET help me here with a kind of persistant connection to these xml
files? (I thought the DataSet did such business out of the box, but it
doesn't as far as I can tell.)

Second, I need to use this data later for graphic trend displays. In other
words, I need to show in graph or chart form how each of these meters is
performing over time. Since the xml files are overwritten, I obviously have
to persist each piece of data somehow. I can think of any number of ways to
do this, but none of them seem too elegant. Any advice anyone might have
will help me think this through.

 

[Hermit Dave]

well you can only refresh the whole page... but what you could do is put a
server side cache on parts that are not subject to frequent change.
for the part that displays your meter reading make sure its not cached.

unfortunately asp.net does not have a way to maintain a connection. if you
want sort of over the wire without refresh.. then you will have to go in for
a winforms control... or something like an applet.

for graphs you will need historical data. instead of writing reading to xml
file and over writing them each time.. why dont you insert them in the
database with a current timestamp. that way you can have your graph data as
well (you will need historical data for graph)

on graph components
http://www.google.co.uk/search?sourceid=navclient&ie=UTF-8&q=asp.net+chart

--

Regards,

Hermit Dave
(http://hdave.blogspot.com)