Generating XML Feeds (RSS, Atom) Using PHP

RSS/ATOM feeds are very common these days and almost all
Content Management Systems (CMS) can generate it. But in the case when
you want to generate it yourself or just want to learn how you can,
read on!


Both RSS and ATOM feeds are written in eXtensible Markup
Language (XML) standard markup. Not just standard markups, you
also need to be sure of what
and how you put data in those markup elements (tags). For all this
refer to the feed specifications of href="http://cyber.law.harvard.edu/rss/rss.html" target="_blank">RSS
and target="_blank">ATOM. XML itself is very strict
and
the standard specifications makes it even harder to generate valid
feeds. And moreover, why re-invent the wheel when we can have it –
ready-made.


The solution I'm referring to here is, to use a third-party
Library – Universal FeedWriter. FeedWriter is a PHP class written by
Anis uddin Ahmad that can dramatically  ease-off feeds (both
RSS and Atom) generation. You can download this library from  href="http://www.phpclasses.org/browse/file/22275.html"
target="_blank">here.


Every feed should have at least the following data:



  1. Feed title

  2. URL(of the website whose feed is it)

  3. Description

  4. Item


    1. Title

    2. Date

    3. URL (of the item, sometimes called permalink)

    4. Description (body of the item)




The RSS feed for this will look something like:


<?xml version="1.0" encoding="utf-8"?>
<rss version="2.0"
xmlns:content="http://purl.org/rss/1.0/modules/content/"
xmlns:wfw="http://wellformedweb.org/CommentAPI/">

<channel>
<title>RSS Title</title>
<link>URL of Website</link>
<description><![CDATA[Description]]></description>
<language>en-us</language>
<pubDate>Sat, 07 Mar 2009 06:55:15 +0530</pubDate>

<item>
<title>Item Title</title>
<link>Item URL (Permalink)</link>
<pubDate>Sat, 07 Mar 2009 06:55:15 +0530</pubDate>
<description><![CDATA[Item Description]]></description>
</item>
</channel>
</rss>

Using FeddWriter abstracts working with and generating XML
tags manually, you just tell FeedWriter what kind of Feed (RSS/Atom and
version) you want; give it the data you want your feed to have and
you’re done! The following code snippet shows you how exactly:


 style="color: rgb(0, 0, 187);"><?php
 style="color: rgb(255, 128, 0);">// Include the class
 style="color: rgb(0, 119, 0);">include( style="color: rgb(221, 0, 0);">"FeedWriter.php" style="color: rgb(0, 119, 0);">);

 style="color: rgb(255, 128, 0);">// Creating an instance of FeedWriter class.
// The parameter tell what type of
// feed you want.
 style="color: rgb(0, 0, 187);">$MyFeed  style="color: rgb(0, 119, 0);">= new  style="color: rgb(0, 0, 187);">FeedWriter style="color: rgb(0, 119, 0);">( style="color: rgb(0, 0, 187);">RSS2 style="color: rgb(0, 119, 0);">);

 style="color: rgb(255, 128, 0);">// Setting feed elements
 style="color: rgb(0, 0, 187);">$MyFeed style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">setTitle style="color: rgb(0, 119, 0);">( style="color: rgb(221, 0, 0);">'My RSS Feed' style="color: rgb(0, 119, 0);">);
 style="color: rgb(0, 0, 187);">$MyFeed style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">setLink style="color: rgb(0, 119, 0);">( style="color: rgb(221, 0, 0);">'http://www.example.com' style="color: rgb(0, 119, 0);">);
 style="color: rgb(0, 0, 187);">$MyFeed style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">setDescription style="color: rgb(0, 119, 0);">( style="color: rgb(221, 0, 0);">'Test feed generated by Universal FeedWriter.' style="color: rgb(0, 119, 0);">);
 style="color: rgb(0, 0, 187);">$MyFeed style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">setChannelElement style="color: rgb(0, 119, 0);">( style="color: rgb(221, 0, 0);">'pubDate' style="color: rgb(0, 119, 0);">,  style="color: rgb(0, 0, 187);">date style="color: rgb(0, 119, 0);">( style="color: rgb(0, 0, 187);">DATE_RSS style="color: rgb(0, 119, 0);">,  style="color: rgb(0, 0, 187);">time style="color: rgb(0, 119, 0);">()));

 style="color: rgb(255, 128, 0);">// Create a FeedItem.
 style="color: rgb(0, 0, 187);">$Item  style="color: rgb(0, 119, 0);">=  style="color: rgb(0, 0, 187);">$MyFeed style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">createNewItem style="color: rgb(0, 119, 0);">();

 style="color: rgb(255, 128, 0);">// Add elements to the feed item.
 style="color: rgb(0, 0, 187);">$Item style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">setTitle style="color: rgb(0, 119, 0);">( style="color: rgb(221, 0, 0);">'Item Title' style="color: rgb(0, 119, 0);">);
 style="color: rgb(0, 0, 187);">$Item style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">setLink style="color: rgb(0, 119, 0);">( style="color: rgb(221, 0, 0);">'http://www.example.com/item1.html' style="color: rgb(0, 119, 0);">);
 style="color: rgb(0, 0, 187);">$Item style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">setDate style="color: rgb(0, 119, 0);">( style="color: rgb(0, 0, 187);">mktime style="color: rgb(0, 119, 0);">( style="color: rgb(0, 0, 187);">10 style="color: rgb(0, 119, 0);">, style="color: rgb(0, 0, 187);">20 style="color: rgb(0, 119, 0);">, style="color: rgb(0, 0, 187);">0 style="color: rgb(0, 119, 0);">, style="color: rgb(0, 0, 187);">3 style="color: rgb(0, 119, 0);">, style="color: rgb(0, 0, 187);">6 style="color: rgb(0, 119, 0);">, style="color: rgb(0, 0, 187);">2008 style="color: rgb(0, 119, 0);">));
 style="color: rgb(0, 0, 187);">$Item style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">setDescription style="color: rgb(0, 119, 0);">( style="color: rgb(221, 0, 0);">'Item Description. Can contain <b>HTML</b>.' style="color: rgb(0, 119, 0);">);

 style="color: rgb(255, 128, 0);">// Now add the item to the feed.
 style="color: rgb(0, 0, 187);">$MyFeed style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">addItem style="color: rgb(0, 119, 0);">( style="color: rgb(0, 0, 187);">$Item style="color: rgb(0, 119, 0);">);

 style="color: rgb(255, 128, 0);">// Now genarate the feed.
 style="color: rgb(0, 0, 187);">$MyFeed style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">genarateFeed style="color: rgb(0, 119, 0);">();
 style="color: rgb(0, 0, 187);">?>

So you see how easy it is to generate a feed with the data we
had.


Feeds generally don’t just have one item so let’s see
something more
real. The following code will generate a feed having ten items:


 style="color: rgb(0, 0, 187);"><?php
 style="color: rgb(0, 119, 0);">include( style="color: rgb(221, 0, 0);">"FeedWriter.php" style="color: rgb(0, 119, 0);">);

 style="color: rgb(0, 0, 187);">$MyFeed  style="color: rgb(0, 119, 0);">= new  style="color: rgb(0, 0, 187);">FeedWriter style="color: rgb(0, 119, 0);">( style="color: rgb(0, 0, 187);">RSS2 style="color: rgb(0, 119, 0);">);

 style="color: rgb(0, 0, 187);">$MyFeed style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">setTitle style="color: rgb(0, 119, 0);">( style="color: rgb(221, 0, 0);">'My RSS Feed' style="color: rgb(0, 119, 0);">);
 style="color: rgb(0, 0, 187);">$MyFeed style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">setLink style="color: rgb(0, 119, 0);">( style="color: rgb(221, 0, 0);">'http://www.example.com' style="color: rgb(0, 119, 0);">);
 style="color: rgb(0, 0, 187);">$MyFeed style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">setDescription style="color: rgb(0, 119, 0);">( style="color: rgb(221, 0, 0);">'Test feed having Ten Items.' style="color: rgb(0, 119, 0);">);

 style="color: rgb(0, 0, 187);">$time  style="color: rgb(0, 119, 0);">=  style="color: rgb(0, 0, 187);">mktime style="color: rgb(0, 119, 0);">( style="color: rgb(0, 0, 187);">10 style="color: rgb(0, 119, 0);">,  style="color: rgb(0, 0, 187);">10 style="color: rgb(0, 119, 0);">,  style="color: rgb(0, 0, 187);">0 style="color: rgb(0, 119, 0);">,  style="color: rgb(0, 0, 187);">3 style="color: rgb(0, 119, 0);">,  style="color: rgb(0, 0, 187);">5 style="color: rgb(0, 119, 0);">,  style="color: rgb(0, 0, 187);">2009 style="color: rgb(0, 119, 0);">);
 style="color: rgb(0, 0, 187);">$MyFeed style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">setChannelElement style="color: rgb(0, 119, 0);">( style="color: rgb(221, 0, 0);">'pubDate' style="color: rgb(0, 119, 0);">,  style="color: rgb(0, 0, 187);">date style="color: rgb(0, 119, 0);">( style="color: rgb(0, 0, 187);">DATE_RSS style="color: rgb(0, 119, 0);">,  style="color: rgb(0, 0, 187);">$time style="color: rgb(0, 119, 0);">));

for( style="color: rgb(0, 0, 187);">$i style="color: rgb(0, 119, 0);">= style="color: rgb(0, 0, 187);">0 style="color: rgb(0, 119, 0);">;  style="color: rgb(0, 0, 187);">$i style="color: rgb(0, 119, 0);">< style="color: rgb(0, 0, 187);">10 style="color: rgb(0, 119, 0);">;  style="color: rgb(0, 0, 187);">$i style="color: rgb(0, 119, 0);">++)
{
     style="color: rgb(0, 0, 187);">$Item  style="color: rgb(0, 119, 0);">=  style="color: rgb(0, 0, 187);">$MyFeed style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">createNewItem style="color: rgb(0, 119, 0);">();

     style="color: rgb(0, 0, 187);">$Item style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">setTitle style="color: rgb(0, 119, 0);">( style="color: rgb(221, 0, 0);">'Item'  style="color: rgb(0, 119, 0);">. ( style="color: rgb(0, 0, 187);">$i  style="color: rgb(0, 119, 0);">+  style="color: rgb(0, 0, 187);">1 style="color: rgb(0, 119, 0);">) .  style="color: rgb(221, 0, 0);">' Title' style="color: rgb(0, 119, 0);">);
     style="color: rgb(0, 0, 187);">$Item style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">setLink style="color: rgb(0, 119, 0);">( style="color: rgb(221, 0, 0);">'http://www.example.com/item'  style="color: rgb(0, 119, 0);">. ( style="color: rgb(0, 0, 187);">$i  style="color: rgb(0, 119, 0);">+  style="color: rgb(0, 0, 187);">1 style="color: rgb(0, 119, 0);">) .  style="color: rgb(221, 0, 0);">'.html' style="color: rgb(0, 119, 0);">);
     style="color: rgb(255, 128, 0);">// Have different dates for each item
    // Each will have one day gap for the
    // publishing time
     style="color: rgb(0, 0, 187);">$Item style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">setDate style="color: rgb(0, 119, 0);">( style="color: rgb(0, 0, 187);">$time  style="color: rgb(0, 119, 0);">- ( style="color: rgb(0, 0, 187);">$i  style="color: rgb(0, 119, 0);">* ( style="color: rgb(0, 0, 187);">24  style="color: rgb(0, 119, 0);">* ( style="color: rgb(0, 0, 187);">60  style="color: rgb(0, 119, 0);">*  style="color: rgb(0, 0, 187);">60 style="color: rgb(0, 119, 0);">))));
     style="color: rgb(0, 0, 187);">$Item style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">setDescription style="color: rgb(0, 119, 0);">( style="color: rgb(221, 0, 0);">'Item '  style="color: rgb(0, 119, 0);">. ( style="color: rgb(0, 0, 187);">$i style="color: rgb(0, 119, 0);">+ style="color: rgb(0, 0, 187);">1 style="color: rgb(0, 119, 0);">) .  style="color: rgb(221, 0, 0);">' Description.' style="color: rgb(0, 119, 0);">);

     style="color: rgb(0, 0, 187);">$MyFeed style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">addItem style="color: rgb(0, 119, 0);">( style="color: rgb(0, 0, 187);">$Item style="color: rgb(0, 119, 0);">);
}

 style="color: rgb(0, 0, 187);">$MyFeed style="color: rgb(0, 119, 0);">-> style="color: rgb(0, 0, 187);">genarateFeed style="color: rgb(0, 119, 0);">();
 style="color: rgb(0, 0, 187);">?>

One thing to note here is why we are using the feed’s
generation time to be same as  that of the latest item rather
than the current time when it is generated well, it’s because the feed
gets updated only as and when new items are added (remains same at
other time) and at the very same time. Therefore just because the feed
is being generated dynamically at each request doesn’t mean it is
“generate” at that time.

Tags: , , , , , , , ,

Check out this stream