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Posted by Jerry Stuckle on 09/16/07 17:48
FrobinRobin wrote:
> Hi I need to create a list that is updated whenever a change occurs in
> the database.
> I first used Ajax to poll a part of the page and query the database
> every 5-10 seconds, downloading the data every time... however as
> someone pointed out.. polling is bad practice and uses a lot of
> bandwidth.
>
> I've given it some thought and I'm wondering whether I can use polling
> more efficiently?
>
> For example:
> I have a function that querys the database and returns my results in a
> structured array - I assign this as $current_list.
> Then I poll a page that querys the database every 5-10 seconds and
> compares $current_list against $new_list ... if there is a difference,
> then it refreshes the $current_list array :)
>
> As I'm refreshing the array on the server side and only downloading
> when there is a change this should be much more bandwidth friendly
> right?
>
> Is there any point in only updating the part of the array which has
> changed it's fairly small data (The array will have a max of ten
> records (sub arrays) with 6 fields in each)
>
> Many Thanks
>
Downloading one row vs. 10 rows is probably an insignificant amount of
overhead compared to the polling involved (unless your database is
updated a lot).
Personally, I'd be looking at a different way of doing it - for
instance, a java applet. HTTP just isn't a good match for this type of
operation.
--
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Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
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