check date modified

Anonymous posted this at 16:45 — 18th October 2004.

Joined: Jan 1970

Hi guys,
I'm trying to find a way of checking the "date modified" of a particular page, and if it is equal to a certain value, then to redirect the browser to a different page. Basically, there's a page on someone's server that gets updated regularly. I would like to know as and when these updates have occured, so I want to create an asp page on my server that will keep checking the external webpage at regular intervals. When the "date modified" has changed, I need to know about it - so will redirect the open browser to a page that maybe has a sound file embedded to alert me. Any ideas? I've found a way to do it, but it can only retrieve the information if the target webpage is on the same server as the "checking script" page.
Cheers.
Jim.

Greg K posted this at 08:37 — 31st October 2004.

He has: 2,145 posts

Joined: Nov 2003

We use http://www.changenotes.com/ as one of the tools to monitor the competition. It will e-mail you when a site has any changes. The nice part, it's free!

-Greg

Renegade posted this at 10:09 — 31st October 2004.

He has: 3,022 posts

Joined: Oct 2002

You can try a "last updated" piece of code that I usually use:

$last_updated = $page_title . " was last updated: " . date ("F d Y", filemtime($page . ".php"));'

Found at my site

Mark Hensler posted this at 03:24 — 17th November 2004.

He has: 4,048 posts

Joined: Aug 2000

HTTP 1.0 (RFC 1945, section 10.10) and 1.1 (RFC 2616, section 14.29) have
an defined an optional "Last-Modified" header in the HTTP Response.
Syntax:
Last-Modified: Wed, 17 Nov 2004 03:08:16 GMT

If your (remote) server outputs this header, you can open a TCP connection
the remote server, send a HTTP Request, then read the HTTP Response.
From there, you can parse out the Last-Modified header and play your sound.

Example HTTP Request:

GET /showthread.php?t=26729 HTTP/1.0
Host: webmaster-forums.net

'
Example HTTP Response:

HTTP/1.1 200 OK
Date: Wed, 17 Nov 2004 03:16:41 GMT
Server: Apache/1.3.28 (Unix) mod_auth_passthrough/1.8 mod_log_bytes/1.2 mod_bwlimited/1.4 PHP/4.3.3 FrontPage/5.0.2.2634 mod_ssl/2.8.15 OpenSSL/0.9.7a
X-Powered-By: PHP/4.3.3
Expires: Mon, 26 Jul 1997 05:00:00 GMT
Last-Modified: Wed, 17 Nov 2004 03:16:41 GMT
Cache-Control: no-store, no-cache, must-revalidate
Cache-Control: private, post-check=0, pre-check=0
Pragma: no-cache
Set-Cookie: bblastvisit=1100661423; expires=Thu, 17-Nov-05 03:16:41 GMT; path=/
Set-Cookie: bblastactivity=1100660918; expires=Thu, 17-Nov-05 03:16:41 GMT; path=/
Set-Cookie: bbthread_lastview=ax1x-ix26729yix1100661423y_; path=/
Content-Length: 32646
Connection: close
Content-Type: text/html

*message body removed*

Note:
Each header line ends in \r\n (CR LF).
The header block is seperated from the body with an additional \r\n.

Mark Hensler
If there is no answer on Google, then there is no question.

Greg K posted this at 07:59 — 17th November 2004.

He has: 2,145 posts

Joined: Nov 2003

OFF TOPIC:

Renegade, thank you for posting the link to your site, as the last bit of code you had gave me a solution to something I had looked for in PHP: using the value of a variable to name a variable you want. (using the $$'s). I have been wanting to use that, I was used to being able to use "eval()" in another language.

(For those reading this and not knowing what I am talking about, try this example)

<?php
    $greg = \"This is Greg\";

    $varName = \"greg\";

    echo \"the variable '$varName' = {$$varName} \n\";

    // GIVE YOU:
    // the variable 'greg' = This is Greg 
?>