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This is a 
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A PHP script to get the contents of a remote file
Since Ajax is restricted to calling local files on the server, we need a PHP
script to at least grab the contents of the remote RSS file and feed it to our
JavaScript on the other side. Furthermore, the script must cache the RSS file locally on the server and only make
periodic requests to the actual RSS feed for updates if we know what's good for
us. Here it is:
<?
/*
======================================================================
Get, cache, and output contents of a RSS XML file
Author: George at JavaScriptKit.com/ DynamicDrive.com
Created: Feb 1st, 2006. Updated: Feb 1st, 2006
======================================================================
*/
header('Content-type: text/xml');
// -------------------------------------------------------------------
// Enter list of possible RSS feeds to fetch inside array:
// -------------------------------------------------------------------
$rsslist=array(
"CNN" => "http://rss.cnn.com/rss/cnn_topstories.rss",
"BBC" => "http://newsrss.bbc.co.uk/rss/newsonline_uk_edition/front_page/rss.xml",
"news.com" => "http://news.com.com/2547-1_3-0-5.xml",
"slashdot" => "http://rss.slashdot.org/Slashdot/slashdot",
"dynamicdrive" => "http://www.dynamicdrive.com/export.php?type=new"
);
$cachefolder="cache"; //path to cache directory. No trailing "/". Set
dir permission
to read/write!
// -------------------------------------------------------------------
// Determine which RSS file to actually fetch
// Based on the value of the "id" parameter of the URL string mapping to the RSS
array's key
// -------------------------------------------------------------------
$rssid=$_GET['id'];
$rssurl=isset($rsslist[$rssid])? $rsslist[$rssid] : die("Error: Can't find
requested RSS in list.");
$localfile=$cachefolder. "/" . urlencode($rssurl); //Name cache file based on
RSS URL
// -------------------------------------------------------------------
// Get the minutes to cache the local RSS file based on "cachetime" parameter of
URL string
// -------------------------------------------------------------------
$cacheminutes=(int) $_GET["cachetime"]; //typecast "cachetime" parameter as
integer (0 or greater)
// -------------------------------------------------------------------
// fetchfeed() gets the contents of an external RSS feed,
// and saves its contents to the "cached" file on the server
// -------------------------------------------------------------------
function fetchfeed(){
global $rssurl, $localfile;
$contents=file_get_contents($rssurl); //fetch RSS feed
$fp=fopen($localfile, "w");
fwrite($fp, $contents); //write contents of feed to cache file
fclose($fp);
}
// -------------------------------------------------------------------
// outputrsscontent() outputs the contents of a RSS feed using the cached local
RSS file
// It checks if a cached version of the RSS feed is available, and if not,
creates one first.
// -------------------------------------------------------------------
function outputrsscontent(){
global $rssurl, $localfile, $cacheminutes;
if (!file_exists($localfile)){ //if cache file doesn't exist
touch($localfile); //create it
chmod($localfile, 0666);
fetchfeed(); //then populate cache file with contents of RSS feed
}
else if (((time()-filemtime($localfile))/60)>$cacheminutes) //if age of cache
file great than cache minutes setting
fetchfeed();
readfile($localfile); //return the contents of the cache file
}
outputrsscontent();
?>
Click here to see a sample
output by the script based on the parameters passed into it.
Don't be intimated by the length of the script, a good chunk of it is
comments and spacing. :) All this PHP script does is grab the contents of a
remote RSS file and return its content unparsed back to the browser as a XML
file (specified using header()).. The script will cache the contents of the file
after the initial request to it by creating a duplicate file on the server, and
update the later based on the user specified cache time. Be sure that the cache
directory specified (ie: "cache") has read/write permission set, via FTP for
example. Both the exact remote
RSS file to grab and the cache duration is controlled by passing in the
appropriate parameter to the script via GET (URL string). This design is to
facilitate what comes next- using Ajax coupled with JavaScript to pull this
PHP's strings and do what they want, on demand!
Ok, time for the real magic to occur- using Ajax to get the XML file, and
JavaScript to pound it into something legible and dynamic.
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