Low End Mac's Online Tech Journal

Creating an RSS News Feed with PHP and MySQL

Website Automation with PHP and MySQL, Part 16

Dan Knight - 2003.02.27

It's been a long time since I've added any automation to the site, although I have made a few tweaks to existing automation, but this week we added one more significant piece to our ongoing site automation project, an automatically generated RSS news feed.

What's RSS?

An RSS (Rich Site Summary) news feed is a text file that others can use to find out what's new on your website. There's a standard format for these documents, which includes things like the domain name and URL, email for the webmaster, when the latest update took place, along with article titles, their URL, and usually a brief description or teaser.

There's a good introduction to them in Using RSS News Feeds.

I've been generating RSS news feeds for Low End Mac for a long time. Quite frankly, it's a tedious business. I've been slacking off on doing them because of the time involved. What time I have, I'd rather spend writing, editing, designing, trying to keep on on email.

And after about an hour or so of coding and debugging, I don't have to manually create an RSS feed any longer. PHP uses the same MySQL database that already tracks site content to generate a news feed.

Here's a snippet of the last one I created manually:

<?xml version="1.0"?>
<!DOCTYPE rss SYSTEM "http://my.netscape.com/publish/formats/rss-0.91.dtd">
<rss version="0.91">
  <copyright>Copyright 1997-2004 Cobweb Publishing Inc</copyright>
  <pubDate>Fri, 14 Feb 2003 14:00:00 EDT</pubDate>
  <description>Resources for Mac users.</description>
  <title>Low End Mac</title>
  <title>Low End Mac</title>
  <webMaster>webmaster&#064;lowendmac.com (Dan Knight)</webMaster>
  <managingEditor>webmaster&#064;lowendmac.com (Dan Knight)</managingEditor>

  <title>Windows, Macs, OS X, and Real World Performance, Adam Robert Guha, 
Apple Archive</title>
  <description>As Mac OS X improves and hardware gets faster, complaints of 
sluggishness will become nothing but a memory.</description>

  <title>Safari Update, Mac OS X 10.2.4, a Neat Haxie, and How Mail Can 
Better Fight Spam, Dan Knight, 10 Forward</title>
  <description>Safari mostly improved but adds a glitch, 10.2.4 seems just 
fine, a better CPU monitor, and ways Apple can leverage Mail to better 
fight spam.</description>


The header only has one tricky part - the date. Everything else up there remains the same. The items change each day that we add new content. The tags pretty much explain the parts, which is a very nice feature of an RSS news feed.

The Program

I'm not going to give you the whole program. Program code will be set in monospace type and comments will be in regular type.


$db_server = "yourserver.com";
$db_username = "userID";
$db_password = "password";
$db_name = "mydata";
$connection = @mysql_connect($db_server,$db_username,$db_password);

$filepointer = fopen("/usr/local/apache/sites/mydomain.com/htdocs/rss.txt", "w");

This was one of the tricky parts. Since the RSS newsfeed file, rss.txt, is in the root directory, I had to find out from our system administrator just how to write the file to the correct spot. During testing, I wrote it to the same directory I was writing the script in. (The \r indicates a return.)

We also had to have things set up on the server so we had permission to write the file. Without that, none of this works.

fputs ($filepointer, "<?xml version='1.0'?>\r<!DOCTYPE rss SYSTEM 
'http://my.netscape.com/publish/formats/rss-0.91.dtd'>\r<rss version='0.91'>\r
<channel>\r   <copyright>Copyright 1997-2004 Cobweb Publishing Inc</copyright>
\r   <pubDate>");

The above line starts writing the text file with our news feed. This part only changes once a year as we update the copyright notice.

The next chunk of code is used to post the correct date and time in our file:

$rightnow = date(U);

$latestdate = mysql_fetch_array(mysql_query("SELECT * FROM links 
	WHERE timestamp <= $rightnow ORDER BY timestamp DESC LIMIT 1"));

fputs ($filepointer, date("D, d M Y h:i:s T", $latestdate[timestamp]));

The first line checks the current time and compares this with the latest timestamp in our MySQL database that's earlier than now. (We do this to assure that content scheduled for later release doesn't get posted in the news feed early.)

We then post the day, date, time, and time zone as the publication date. This will always match the moment when the most recent article went live.

UPDATE: The format we originally presented was incorrect and included am/pm between the time and time zone - h:i:s a T - which produces an invalid RSS feed. Please use <http://feeds.archive.org/validator/> to validate your feed before sharing it with the world.

Next we close the publication date, describe the site, provide the base URL for Low End Mac as well as the site's name, and provide the URL and dimensions for a site graphic.

fputs ($filepointer, "</pubDate>\r   <description>Resources for Mac users.
</description>\r   <link>http://lowendmac.com/</link>\r   <title>Low End Mac
</title>\r<image>\r   <link>http://lowendmac.com/</link>\r   <title>Low End 
Mac</title>\r   <url>http://lowendmac.com/88x31.gif</url>\r   <height>31
</height>\r   <width>88</width>\r</image>\r

Here we provide the email address for the webmaster and managing editor, which in our case is the same person. Someone having a problem with the news feed could use this to contact us and let us know about the problem.

<webMaster>webmaster@lowendmac.com (Dan Knight)</webMaster>\r   
<managingEditor>webmaster@lowendmac.com (Dan Knight)</managingEditor>\r

Low End Mac is published in English, and most of our writers use US English. So we cover that next.


We can tell what hours and days the site isn't updated, which is done in GMT. For those outside the UK, this can involve some head scratching. Basically we don't publish new articles between 9:00 p.m. and 6:00 a.m. (We try to have our publishing day done by noon Eastern Time to make time for lunch, email, and my other job.)

<hour>1</hour>\r   <hour>2</hour>\r   <hour>3</hour>\r   <hour>4</hour>\r   
<hour>5</hour>\r   <hour>6</hour>\r   <hour>7</hour>\r   <hour>8</hour>\r   
<hour>23</hour>\r   <hour>24</hour>\r   </skipHours>\r   <skipDays>\r   
<day>Saturday</day>\r   <day>Sunday</day>\r   </skipDays>\r");

The Meat

That's all header. Except for the time stamp, it doesn't change. From here on, we're creating content based on information in our MySQL database.

First up, get today's articles, starting with the most recently published:

$get_links = mysql_query("SELECT * FROM links 
	WHERE pubdate = '$latestdate[pubdate]' and timestamp <= $rightnow
      ORDER BY rank DESC");
while ($array = mysql_fetch_array($get_links))
	fputs ($filepointer, "<item>\r<title>$array[linktext]");
	if ($array[author]<>"")
	       {fputs ($filepointer, ", $array[author]");}
	if ($array[columnname]<>"")
	       {fputs ($filepointer, ", $array[columnname]");}
	fputs ($filepointer, "</title>\r<link>http://lowendmac.com

This is pretty similar to the code we use to display pages throughout the site. Instead of using just the title of the article as a link, we also include the name of the author and the column name as part of the title.

// This Date in LEM History

$thisdate = date(md);
$thisrecord = date(nd);
$today = date("F j");

$get_links = mysql_fetch_array(mysql_query("SELECT * FROM lemhistory
	WHERE datefield = '$thisrecord'"));

if ($get_links <> "")
	{fputs ($filepointer, "<item>\r<title>$today in LEM history</title>

Following the new articles, we check our database to see if we have an archive covering this date in Mac and LEM History. Most days we do, but about once a month there's a date we still haven't posted new content on. Except for holidays, most of those will disappear as we add content almost every weekday.

// Previous Day's Links
$previous_date = mysql_fetch_array(mysql_query("SELECT * FROM links
	WHERE pubdate < '$latestdate[pubdate]' ORDER BY timestamp DESC LIMIT 1"));
$previous_links = mysql_query("SELECT * FROM links
	WHERE pubdate = '$previous_date[pubdate]' ORDER BY clicks DESC");
while ($previous_array = mysql_fetch_array($previous_links))
	fputs ($filepointer, "<item>\r<title>$previous_array[linktext]");
	if ($previous_array[author]<>"")
	       {fputs ($filepointer, ", $previous_array[author]");}
	if ($previous_array[columnname]<>"")
	       {fputs ($filepointer, ", $previous_array[columnname]");}
	fputs ($filepointer, "</title>\r<link>http://lowendmac.com

The above code checks for the next previous date in our database, giving it the flexibility to work around holidays and weekends. It then lists that day's content ranked by popularity. The article that received the most traffic is listed first, working down to the best deals of the day, where we don't bother counting clicks.

We modify the above code once more to provide a third day in our feed, and then we close the text file.

fputs ($filepointer, "</channel>\r</rss>");
	fclose ($filepointer);

To read the current rss.txt file, click here. And if you're using OS X, download NetNewsWire Lite, add Low End Mac, and let software tell you when your favorite websites have new content.

As I write this, we're running the script manually, but the folks at BackBeat will be setting this up as a cron job that will automatically run every 5 minutes. This is the kind of tedium computers were designed for!

Other Updates

A couple weeks ago we changed the way we list our new content on the LEM home page. Instead of a bullet list, we display the article title using the term style (<dl>) in bold type, followed by the author, column name, and publication date in italic and a description in plain text. The latter two lines are styled as definition (<dd>).

We've received very positive feedback on the change. Here's an example from yesterday:

Switching from Mac to Windows, really clearing a hard drive, OS X and viruses, RAM disks, and more
Dan Knight, Low End Mac Mailbag, 02.26
More on replacing Claris Home Page, printing from a classic Mac, getting a CD-RW drive to work with a Performa, SpamBouncer, and why some G4s won't work in G3s.

We also discovered a problem one Sunday afternoon when we discovered Monday content was being displayed below Friday's content. Looking over the PHP script, we found that we were looking for the most recent date != (PHP's way of saying "not equal") to the most recent date matching or before today's date. Changing that to < solved the problem.

I'm still far from an expert on PHP, and I'd be lost without some assistance from Dave Hamilton at BackBeat Media (they handle our ads and our servers) and two of my sons. Brian and Stephen's help has been invaluable at finding typos and other problems to crop up so easily. You'll be able to check out their programming abilities soon when the launch their third virtual pet, second robotic virtual pet, and ultimate virtual robot pet site.

Next project: Using PHP and MySQL to generate our daily news releases.

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