/jquery_spy/out.php

The thing I don't get about AJAX is how it queries the databse on the fly.

The requested script my be something:

[psudocode]
$row = query("select * from articles where timestamp > $POST['timestamp'] order by timestamp desc limit1");
printhtml($row);
[/psduocode]

The AJAX part is done in the browser, just calling your script and processing the output - and in the simplest case, adding the HTML to the page.

Zac - yep - I certainly don't expect Digg to switch to this any time quickly ;-) but it would be interesting to look in to throttling the processing.

http://leftlogic.com/jquery_spy/out.php.txt

As for a push function for the RSS, I'll post a follow up soon (I'm on hols soon - so next week).

Is this available in PHP or so?

What I'd like to do with this, is show what page of a blog people are viewing - so as ppl click you can view what pages are being viewed. Problem is that my blog is flatfile with server side.. so i don't use a database which makes it more difficult.

Any ideas?

Great tutorial regardless! Thanks a lot.

Wait for a new joomla module for this! Perhaps next week. Check out www.webpr.gr/joomla for updates.

@Remy Sharp

Excellent work. When our Joomla implementation is finished, I will send you a link, if it's OK with you.

That's what I was curious about too, but after examining the source code, I realized how the concept works. What happens is the JavaScript code sends a timestamp among other things to a script you've created in the language of your choice (I used Perl) as often as you specify (in this case abut a second or two) and for the example I created, the Perl code selects the row from a field in a table that has a timestamp later than the one sent by the JavaScript and sends that back to the spy page. Hope this helps.

Thanks for the reply Henry, I figured it out and basically did the same as you but in PHP.

http://programming-designs.com

So, this makes it somewhat difficult to apply this script in a real situation, in a CMS. It is practical only for RSS feeds or sites with huge input, like Digg. You cannot use it to display in cyclic order the 10 most latest items in your website!

What is nice about the script -and I guess everyone agrees on that- is the effect produced. So why not modify it to "read" several items at a time and display them in some order (by date, alphabetical etc.)...

So at the moment I can't find a practical implementation of the script -although I'd love to!!- inside Joomla, as I previously rushed in to do.

Don't get me wrong, it's very good what you did, but unless it has practical applications you won't be seeing it implemented in many websites.

Even the "demo" site you provide (Arsenal-Now) seems to fail to deliver (e.g. it displays double items)...

How is this possible with the script?

Thanks, Jack.

Two ideas I had were to query the database once every 5-10 minutes with a PHP script to get the last 150 posts (5 minutes at 2 seconds each) and put that into either a flat file or populate a small database. Then each user would either access the flat file via the "out.php" file or query this much smaller db in the "out.php" file. The only downside is that the only way to "cycle" through the results would be to keep a cookie on the users system to tell the out.php file what row of the db or file it last saw, so the out.php can grab the next one.

Do you see any other options for that?

Well, that sounds like what I want to do, but I can't seem to get it to work. Where should the script code go? In the "out.php" file or in the "spy.html" file? And what is "#spyContainer"? Does that need to be renamed to something? And do the div's need to be named something with an index? (it has "div:gt(4)" there).

thanks for any help!

Though I've replied to most of these comments directly via email - I thought I might summarise my suggestions/feedback:

@Simon - here's the source to the json example:

http://leftlogic.com/jqueryspy/outjson.php.txt

@Jack + @Ryan - you should pre-populate the page as if you didn't have the spy functionality. So long as each item is in a container div (the spy ignores the class or ids) and the collection of items is in a single container div that has an ID that you pass to the spy function it will work correctly (see the 'spy detail' code example).

You don't need any naming on the item divs - the 'div:gt(4)' means all the divs after the 5th one.

@Fotis - you've got my long reply! But for those who had similar questions - I will be looking at a version of the spy that reads several items in at once in the near future.

Could you please share how did you achieve this.... I am having a real hard time querying the DB. the bugger just dosen't work. Displays the first listing and then nothing after that.

If you can help out, that would be great!
my email is:
Matt55_22@Yahoo.com

thanks.

I did a simple example of out_json.php only in perl/cgi. It had three different lines of text which it randomly selected and print. Now to my problem, it printed the same line of text two times in a sequence.

That shouldn't be possible should it?

Only one problem, the spy must support more than one row, that's the only thing left.

I was trying to grab more than one row at a time and find out that the $_POST timestamp give me this value 1155370514 (08/12/06)and the timestamp php function 1158059700 (09/12/06) in the same moment.

Is this a problem in my server configuration? Really don't know, but I can't grab more than one row because the timestamp is one month behing the real date.

I don't understand much about JS, that's why I can't modify the code, but the timestamp() in PHP is different than the $_POST["timestamp"] value.

Hope you can help me in this one, greetings.

$_POST['timestamp'] + that number of seconds will give you the actual timestamp, just substract the refresh time and you have the correct time.

Something like this (in a 5 seconds refresh period):

$correct = $POST['timestamp'] + ((time() - $POST['timestamp']) - 5);

$correct will be the actual time minus your refresh time. You can put just $correct = time() - 5 and the result will be the same.

It's not the right way to do it, but well, just have to wait for the creator answer. At least now I can load any number of rows at a time =)

var timestamp = Date.parse(now) / 1000;

That timestamp is the same that the time() function of PHP.

var epoch = new Date(1970, 1, 1);

with

var epoch = new Date(1970, 0, 1);

It works on me! Thanks for the great plugin :)

Thanks for pointing the bug in the timestamp. I'll update the source code on this site very shortly.

I've also been working on a new version of the spy that support multiple rows from the AJAX request and also supports custom timestamp functions.

It also supports collecting multiple items from the AJAX, and showing them at the specified timeout interval - giving the appearance of 'real-time'.

I'm just ironing out the last of the bugs in the timeout "thread" and then I'll release it.

It does use the version 1+ of jQuery - you will need to upgrade.

I'll be in touch soon!

I'm working on that but in other script, if everything goes right soon I'll post it here.

Greetings.

There must be something else. If you use a one-row system it's impossible for you to notice, 'cause the script don't repeat the last row, but in a multiple system (like the one that I'm trying to do) gives 3hs ago results with the epoch fix.

Crazy, uh?

The solution is to store the last timestamp sended by spy.php (the database timestamp) and in the next query send the newest compared to it. Never use the client time, always the database one, just store the last time sended to the client.

Help would reeeally be appreciated. Thanks in advance!

“Too many requests to the db.. solution – Two ideas I had were to query the database once every 5-10 minutes with a PHP script to get the last 150 posts (5 minutes at 2 seconds each) and put that into either a flat file or populate a small database. Then each user would either access the flat file via the “out.php” file or query this much smaller db in the “out.php” file”

please help me!

ps – email me the response if easier for you seeing as its probably really indepth.

Let me know if you get stuck, I might be able to help.

$(document).ready(function() {
$('#text1').spy({'ajax': '/get.php'})
});