How to reload 4 pages at exactly the same time

Femke

Hello,

I once made this work: http://www.geuzen.org/anxiety -- simply using 4 frames and meta http-equiv="Refresh". For an exhibition in a gallery, I now need to divide this single pages over 4 separate screens/machines.

I started with simply splitting up the page in 4 individual urls, and have each of the 4 pages reload every 11 seconds, displaying another word from a list.

But... I would need to synchronize the reloads so that they run simultaneously, i.e. when the 3rd word from list A is shown on screen A, than the 3rd word from list B is shown on screen B.

I looked at forking, crontab, microtime() but I am really lost. I'm sorry if this is actually really simple, but I can't figure out where to start and your help would be much appreciated.

Thanks a lot in advance,

Femke

leatherback

Ha Femke,

I am not sure how crucial the EXACT synchronisation would be.. :

What I would probably do, is work with a simple table on the server: You store whichever word is served at that time, and until what time that is valid. Then, you start the pages. Whenever the time has expired, the new word is placed in the table, with new time.
Each page -as it reloads- check the table. If it sees a new word? Then loads that page, but your meta-refresh time you set to e.g., 1 second less than the time left for this word to be displayed. That way, the page will come back and check the current word around the time that the time is expired.
If it sees the word is expired: It loads the new word in the database, and builds the new page.

bradgrafelman

Is there a need for frames? Why not use AJAX? Obviously I don't know the design, but it sounds like you could just have 4 different containers on the page and use AJAX to refresh all of them with new content from the server.

leatherback

bradgrafelman wrote:
Is there a need for frames? Why not use AJAX? Obviously I don't know the design, but it sounds like you could just have 4 different containers on the page and use AJAX to refresh all of them with new content from the server.

Brad: Sounds like she is moving away from the current setup (Which works) towards a setup where each 'page' loads individually on seperate machines. Probably a wall of displays, each display their own language

Femke

Thanks, leatherback and bradgrafelman!

There's indeed no need for frames in the split-screen version, and I am looking for a way to keep 4 translations lining up, so I guess synchronization does not need to be exact. I'll have a try at your approach, leatherback, though have to confess that I feel like an absolute newbie when it comes to 'work with a simple table on the server' ...

will report later about progress.

🙂

Femke

Roger_Ramjet

A very interesting project Femke (have you other guys had a look at her link?).

How does that existing page work? Because my instinct is to use what you already have with as little modification as possible.

Femke

okay... I think I figured it out. The project/screens do not run completely sync -- moment of loading varies a bit per page, but this is corrected with every reload, and actually works in favor of the project (it comes to life somehow).

Also happy to know that I can predict what word will be searched in a weeks time ;-)

//VARIABLES
$interval = 11;
$num_items = 29;

//GET AMOUNT OF SECONDS PASSED SINCE EPOCH
$total_seconds = mktime();

//DECIDE IN WHICH SLOT WE ARE
$clean_slot = floor($total_seconds/$interval);

//DECIDE WHICH WORD TO PICK / WHERE WE ARE ON THE DIAL
$cur_word = $clean_slot%$num_items;

//RETRIEVE FRACTIONS THAT WERE CLEANED OFF THE SLOT
$slot = ($total_seconds/$interval) - $clean_slot;

//FIND OUT HOW MUCH TIME IS LEFT BEFORE NEXT RELOAD SHOULD HAPPEN
$slot_remain = ($interval - ($slot*$interval));

Than in the of the header 4 files which display the searches, I have put this line:

<meta http-equiv="Refresh" content="<?php echo $slot_remain+1; ?>">

I needed to add a second to compensate for 'floating'; otherwise reloads are sometimes scheduled after half a second or so.

Time to celebrate + call it a night

best,

Femke