Using XML-RPC to combine Drupal and Wordpress on a site

This is really a set of notes for myself, so I can document what I'm trying to do and hopefully be able to reproduce it in the future.

The Idea

I have two sites right now - a Wordpress blog at /, and in /more, a Drupal site. I'm working on a new theme for both that includes content from each on the other, with some interesting ways to switch between them.

Starting Out

I have some ideas on grabbing Wordpress content from a Drupal page/template, so I'm concentrating on solving the other issues right now: starting Drupal and getting some content out of it. So far, I started a test.php file and have the folowing bits:

1. *Start Drupal:* Not too bad, Morbus helped me here.

    require_once (./includes/bootstrap.inc);
    drupal_bootstrap (DRUPAL_BOOTSTRAP_FULL);

2. *Grab some content to render:* I want to do as much config as possible in Drupal as to the content that appears on the Wordpress side, so I created new region in my theme, 'shared', and assigned a couple blocks to it. I then followed up the previous code with this:

    print theme('blocks', 'shared');

At this point I'm a bit stumped... I'm getting simply a blank page as the output. I suspect is has something to do with not having a template file to use, but I'm not at all certain, and I'd be open to any suggestions.

Cautious Success

Well, I figured out the problem I was experiencing in [Part I](/tech/franken-site-i) - I had misconfigured the blocks for the region I was attempting to use, so that's fixed. Using a chdir, my code now looked like this:

    $_DIR = 'more';
    chdir ($_DIR);
    require_once './includes/bootstrap.inc';
    drupal_bootstrap(DRUPAL_BOOTSTRAP_FULL);		
    return theme('blocks', $region);

And it worked! At least, from a plain php page in my Wordpress directory it did. As soon as I built it into a quick-and-dirty Drupal plugin for Wordpress, it went all to heck.

    Fatal error: Cannot redeclare timer_start() (previously 
    declared in /server/path/to/redmonk.net/wp-settings.php:57) 
    in /server/path/to/redmonk.net/more/includes/bootstrap.inc 
    on line 37

D'oh! Drupal and Wordpress were defining the same functions! To be expected, I suppose. I commented out the first few I found but kept running into more. Time to look for another solution.

Regroup and RPC

After my simple attempts at just including Drupal's bootstrap and using theme() to get what I wanted failed, I turned to a new pipe to get content from: Drupal's XML-RPC interface.

I have experience writing Drupal modules, so I did the required reading on hook_xmlrpc, and then got to work.

I added a custom module, redmonk.module. Then, I added a simple method to return the content I wanted (hard coded for now, later I'd make it a little more generic).

    function redmonk_shared () {
        return theme('blocks', 'shared');
    }

Then I implemented hook_xmlrpc:

    function redmonk_xmlrpc () {
        return array ("redmonk.shared"=>"redmonk_shared");
    }

Lastly, I built a quick Wordpress plugin, the expansively named drupal.php:

    include_once(ABSPATH . WPINC . '/class-IXR.php');

    function drupal_get_blocks ($region) {
        $ixrcli = new \
            IXR_Client('http://redmonk.net/more/xmlrpc.php', \
            false,80,15);
        $ret = "no response";
	if ($ixrcli->query('redmonk.shared')) {
            $ret = $ixrcli->getResponse();
        }
        
	return $ret;
    }

So now, I have an xml-rpc call that returns the chunk of HTML that I need for the Wordpress half of my franken-site. Next, I need to confirm that I can do something similar from Wordpress.

It's Alive!

After managing to fetch the content I wanted from Drupal into a Wordpress page via a custom XML-RPC call, I needed to figure out how to get recent posts out of Wordpress and onto a Drupal page.

Naturally RSS is a pretty decent way to accomplish this sort of thing, but I did not really want to mess with creating a custom feed just for this information. So I fell back to Wordpress's XML-RPC api. Wordpress supports the MetaWeblog api, which has an api which fitted my needs exactly:

metaWeblog.getRecentposts (n)

So, I added a couple methods to my redmonk.module for Drupal:

    function redmonk_monkinetic_posts_call ($num) {
        $rpc_result = xmlrpc ("http://redmonk.net/xmlrpc.php",
                              "metaWeblog.getRecentPosts",
                              "myblog","myusername","mypwd", $num);
        return $rpc_result;
    }

    function redmonk_monkinetic_posts ($num) {
        $posts = redmonk_monkinetic_posts_call ($num);
        $retstr = "<dl class='nodes'>\n";
        foreach ($posts as $post) {
            $retstr .= "<dt><a href='" . $post['link'] . "'>" .
                       $post['title'] . "</a></dt>\n";
            $retstr .= "<dd>" . $post['description'] . "</dd>\n";
        }
        $retstr .= "</dl>\n";
        return $retstr;
    }

The call goes into a Drupal template in the normal manner:

    print redmonk_monkinetic_posts (1);

Bingo!

So now all that remains is to clean up the plugin/module code on each side, and implement the new template. I *had* initially hoped for a more "integrated" way to work between the two, but the XML-RPC approach was remarkably simple, will be quite flexible, and will survive upgrades to both platforms.