HomePHP Page 6 - Plugging RDF Content Into Your Web Site With PHP
Nesting Time - PHP
A Web site which dynamically updates itself with the latestnews and information? Nope, it's not as far-fetched as it sounds. Asthis article demonstrates, all you need is a little imagination, acouple of free RDF files and some PHP glue.
Now, the previous example was just fine for illustrative purposes - but if you're serious about plugging content into your Web site, you're going to need something a lot prettier. So take a look at this evolution of the previous script, which makes a few additions to simplify the task of formatting the RDF data.
<html>
<head>
<basefont face="Verdana">
</head>
<body>
<table border="0" cellspacing="5" cellpadding="5">
<tr>
<td><b>New releases on freshmeat.net today:</b></td>
</tr>
<?php
// XML file
$file = "http://www.freshmeat.net/backend/fm-releases.rdf";
// set up some variables for use by the parser
$currentTag = "";
$flag = "";
$count = 0;
// this is an associative array of channel data with keys ("title",
"link",
"description")
$channel = array();
// this is an array of arrays, with each array element representing an
<item> // each outer array element is itself an associative array
// with keys ("title", "link", "description")
$items = array();
// opening tag handler
function elementBegin($parser, $name, $attributes)
{
global $currentTag, $flag;
$currentTag = $name;
// set flag if entering <channel> or <item> block
if ($name == "ITEM")
{
$flag = 1;
}
else if ($name == "CHANNEL")
{
$flag = 2;
}
}
// closing tag handler
function elementEnd($parser, $name)
{
global $currentTag, $flag, $count;
$currentTag = "";
// set flag if exiting <channel> or <item> block
if ($name == "ITEM")
{
$count++;
$flag = 0;
}
else if ($name == "CHANNEL")
{
$flag = 0;
}
}
// character data handler
function characterData($parser, $data)
{
global $currentTag, $flag, $items, $count, $channel;
$data = trim(htmlspecialchars($data));
if ($currentTag == "TITLE" || $currentTag == "LINK" ||
$currentTag ==
"DESCRIPTION")
{
// add data to $channels[] or $items[] array
if ($flag == 1)
{
$items[$count][strtolower($currentTag)] .=
$data;
}
else if ($flag == 2)
{
$channel[strtolower($currentTag)] .= $data;
}
}
}
// create parser
$xp = xml_parser_create();
// set element handler
xml_set_element_handler($xp, "elementBegin", "elementEnd");
xml_set_character_data_handler($xp, "characterData");
xml_parser_set_option($xp, XML_OPTION_CASE_FOLDING, TRUE);
xml_parser_set_option($xp, XML_OPTION_SKIP_WHITE, TRUE);
// read XML file
if (!($fp = fopen($file, "r")))
{
die("Could not read $file");
}
// parse data
while ($xml = fread($fp, 4096))
{
if (!xml_parse($xp, $xml, feof($fp)))
{
die("XML parser error: " .
xml_error_string(xml_get_error_code($xp)));
}
}
// destroy parser
xml_parser_free($xp);
// now iterate through $items[] array
// and print each item as a table row
foreach ($items as $item)
{
echo "<tr><td><a href=" . $item["link"] . ">" . $item["title"] .
"</a><br>" . $item["description"] . "</td></tr>"; }
?>
</table>
</body>
</html>
The major difference between this iteration and the previous
one is that this one creates two arrays to hold the information extracted during the parsing process. The $channel array is an associative array which holds basic descriptive information about the channel being processed, while the $items array is a two-dimensional array containing information on the individual channel items. Every element of the $items array is itself an associative array, with named keys for the item title, URL and description; the total number of elements in $items is equal to the total number of <item> blocks in the RDF document.
Note also the change to the $flag variable, which now holds two values depending on whether a <channel>...</channel> or <item>...</item> block is being processed. This is necessary so that the parser puts the information into the appropriate array.
Once the document has been fully parsed, it's a simple matter to iterate through the $items array and print each item as a table row. Here's what the end result looks like:
PHP 
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An Introduction to XUL Part 4
