how to create rss feed in php

// How to create RSS feed for site in php
// Check your rss is correct or not @ http://validator.w3.org/feed/


$a='<?xml version="1.0" encoding="UTF-8"?>';
$a .='<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">';
$a.='<channel>';
$a.= '<atom:link href="http://www.anydomain.com?feed=xml" rel="self" type="application/rss+xml" />';
$a.='<title>Your Site Title</title>';
$a.='<link>http://www.yourdomain.com</link>';
$a.='<description>Your site Details here</description>';
$a.='<language>en-us</language>';
$a.='<docs>http://blogs.law.harvard.edu/tech/rss/</docs>';
$a.='<item>';
$a.='<title>Title For Item1</title>';
$a.='<link>http://www.linktoitem1.com</link>';
$a.='<guid>http://www.linktoitem1.com</guid>';
$a.='<description>Item1 Description Here</description>';
$a.='<pubDate>'.date("D, d M Y H:i:s T",UNIX_TIMESTAMP).'</pubDate>';
$a.='</item>';
$a.='<item>';
$a.='<title>Title For Item2</title>';
$a.='<link>http://www.linktoitem2.com</link>';
$a.='<guid>http://www.linktoitem2.com</guid>';
$a.='<description>Item2 Description Here</description>';
$a.='<pubDate>'.date("D, d M Y H:i:s T",UNIX_TIMESTAMP).'</pubDate>';
$a.='</item>';
$a.='</channel>';
$a.='</rss>';

echo trim($a);