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Note: This page dates from 2005, and is kept for historical purposes.

How this site works

Templates | Comments | Working Code

Templates

Apache's URL rewriting engine, mod_rewrite, is used to send all URL's to an index.php file. This is the mod_rewrite used on this site.

RewriteEngine on Options +FollowSymlinks RewriteBase / # Allow subdirectories RewriteRule ^(.*/.*) - [L] # Allow plain index.php?blah addresses RewriteRule ^(index.php.*) - [L] # Replace blah with index.php?blah RewriteRule ^(.+)$ index.php?$1

The URL's are parsed by the PHP file, and split around any periods in the URL and stored in an array.

if ($_SERVER['QUERY_STRING']) { $array = explode(".",$_SERVER['QUERY_STRING']); }

Care must always be taken to ensure that anything able to be externally passed into a file isn’t malicious. This function attempts to find PHP and HTML files, and returns a default PHP file if none are found. This can prevent anyone attempting to access anything unusual.

function verify_file($file) { switch(true) { case file_exists($file.'.php'): return $file.'.php'; case file_exists($file.'.html'): return $file.'.html'; default: return 'default.php'; } }

Files are stored as XHTML or XML. XHTML files are parsed for their body, style and title tags and these tags are then included into the resulting output. This allows a simple template system where the content can be created with any XHTML capable editor. I have found this to be the simplest way of creating a consistent and easily updateable style across a site.

// Parse $file for tags function include_tag($tag, $file) { if (!file_exists($file)) { $file = verify_file($file); } $data = file_get_contents($file); preg_match( "/<$tag.*>(.+)<\/$tag>/sU", $data, $matches ); eval('?>'.$matches[1]); } // Title print '<title>n e d m a r t i n - UNI - '; include_tag('title',$file); print '</title>'; // Style if ($type == 'default') { print '<style type="text/css">'; include_tag('style',$file); print '</style>';

There are several advantages and limitations to this approach.

Disadvantages include:

• Slightly more processing is required to parse a file, rather than serving straight HTML
• Initial design is more complex

Advantages include:

• Easily updateable
• Easy to maintain
• Consistent across an entire site
• Content generation possible with the majority of “webpage” HTML editors, as well as by hand
• Foreign content assumes a consistent style after parsing
• Possible to create complex file hierarchies without the user being aware
• Allows the logical file system to change without affecting existing URL’s
• Does not limit URL’s to HTML, PHP or any fixed extension. In fact, using this-site, this-site.html, this-site.php and even this-site.no-known-file.extension as links will not affect the page that is displayed.
• Allows an easy upgrade from existing non-template sites, as existing “legacy” URL’s will continue to work alongside the newer URL’s, and not all existing pages need be updated at the same time as various sections can simply be parsed out of those pages and into the new template.

Comments

This site uses an XSL based comments system.

PHP is used to run an XSL processor, as below. The comment, author and various other information is passed to this processor, which in turn applies a style sheet to it, producing an XML output file.

// create array containing comment information $params = array ( 'page' => $page, // page information 'ip' => $ip, // author's IP 'author' => $author, // author's name 'comment' => $comment, // the comment 'date' => $date // the time and date ); // create an xslt processor $xp = xslt_create(); if ( xslt_process ( $xp, // xslt processor 'saved-comments.xml', // input file 'save-comments.xsl', // xslt stylesheet 'temporary.xml', // output file array(), // dummy array $params // input information ) ) { // rename output file over the top of input file, performing // atomic update and ensuring two users don't overwrite each other rename('temporary.xml', 'saved-comments.xml'); // print success message $print = 'Your comment has been saved and your IP logged as '.$ip; } // print error if it failed else $print = 'Error: An unknown error has occurred while processing your comment.'; // free the xslt processor xslt_free($xp);

This is a slightly simplified version of the XSLT style sheet used to save comments.

<?xml version="1.0" encoding="utf-8"?> <!-- Copyright © 2002 Ned Martin http://copyright.the-i.org/ Saves XML comments file --> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:output method="xml" encoding="utf-8"/> <xsl:param name="page">page</xsl:param> <xsl:param name="ip">ip</xsl:param> <xsl:param name="author">author</xsl:param> <xsl:param name="comment">comment</xsl:param> <xsl:param name="date">date</xsl:param> <xsl:template match="comments"> <comments> <xsl:for-each select="comment"> <xsl:copy-of select="."/> </xsl:for-each> <comment> <xsl:attribute name="page"> <xsl:value-of select="$page"/> </xsl:attribute> <xsl:attribute name="ip"> <xsl:value-of select="$ip"/> </xsl:attribute> <xsl:attribute name="author"> <xsl:value-of select="$author"/> </xsl:attribute> <xsl:attribute name="date"> <xsl:value-of select="$date"/> </xsl:attribute> <xsl:value-of select="$comment"/> </comment> </comments> </xsl:template> </xsl:stylesheet>

A very similar process is used to display comments. PHP is once again used to run an XSLT processor, and the page information passed to that processor. Once again, an XSLT style sheet is applied to this information, using the previously stored XML comments file, and the output displayed in the browser.

// Parse comments file for comments $params = array ( 'page' => $page, // page information ); // create xslt processor $xp = xslt_create(); $result = xslt_process ( $xp, '_src/comments.xml', // input file '_src/show-comments.xsl', // xslt stylesheet NULL, array(), // dummy array $params // page information ); // evaluate and print out the results eval('?>'.$result); // free xslt processor xslt_free($xp);

This is a simplified version of the XSLT style sheet used to display comments.

<?xml version="1.0" encoding="utf-8"?> <!-- Copyright © 2003 Ned Martin http://copyright.the-i.org/ Shows comments --> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:output method="html" encoding="utf-8"/> <xsl:param name="page">blah/blah2.php</xsl:param> <xsl:template match="comments"> <xsl:if test="comment[@page = $page]"> <dl title="Comments"> <xsl:for-each select="comment[@page = $page]"> <dd> <xsl:value-of select="."/> </dd> </xsl:for-each> </dl> </xsl:if> </xsl:template> </xsl:stylesheet>

Working Code

Update from the year 2011… Sadly, XSLT is annoying and not especially useful for anything particularly complex. I no longer use it, and have had to remove the below links.

Journal Site Code
Working examples of XSLT style sheets used in my journal can be viewed here.

Amused Site Code
Several examples of the working code used to generate my amused site are available.

• PHP template and comment supporting code
• XSLT to save a new comment
• XSLT to show a single per-page comment as at the bottom of here
• XSLT to display and sort all comments as shown here
• XML comments file that stores the comments
• Comments file schema
• Temporary XML comments file

Please remember that this code is © Copyright