a ‘weblogUpdates.ping’ - like interface for BritBlog

OK, I’ve been tinkering with this XML-RPC stuff for BritBlog. Basically, I want an interface the same as the Weblogs.Com XML-RPC weblogUpdates.ping method for BritBlog, as I mentioned earlier.

Acording to the documentation, I need to accept the following parameters:

weblogUpdates.ping (weblogname, weblogurl, changesurl=weblogurl, categoryname=”none”) returns struct

To tell Weblogs.Com that a weblog has changed, call weblogUpdates.ping on rpc.weblogs.com, port 80, path /RPC2.

It takes two required parameters, both strings, and two optional parameters, also strings. The first is the name of the weblog, the second is its URL. The third, changesurl, is the url of a page to be checked for changes. The fourth, categoryname, is the name of a category of pings, allowing the weblogs.com interface to be used to track RSS feeds, European weblogs, or whatever.

So I need a method that can accept two, three or four parameters (all strings).

Using the PEAR XML-RPC package I’ve created a framework that doesn’t actually do anything except tell me how many parameters I’ve sent (assuming they are of the correct type):

Listing 1: server.php

<?php
require_once 'XML/RPC/Server.php';

/*
** The 'update method'. This will do the work.
*/
function weblogUpdatePing($params)
{
   switch ($params->getNumParams())
   {
      case 2:
         $strReturn    = "Two params";
         $weblogname   = $params->getParam(0);
         $weblogurl    = $params->getParam(1);
         break;

      case 3:
         $strReturn    = "Three params";
         $weblogname   = $params->getParam(0);
         $weblogurl    = $params->getParam(1);
         $changeurl    = $params->getParam(2);
         break;

      case 4:
         $strReturn    = "Four params";
         $weblogname   = $params->getParam(0);
         $weblogurl    = $params->getParam(1);
         $changeurl    = $params->getParam(2);
         $categoryname = $params->getParam(3);
         break;

      default:
         /*
         ** Should never get here as the method
         ** signatures will prevent this
         */
         $strReturn = "Invalid parameter count.";
         break;
   }

   $val = new XML_RPC_Value($strReturn, 'string');
   return new XML_RPC_Response($val);
}

/*
** Create a server instance to handle the request.
*/
$server = new XML_RPC_Server(
   array(
      'weblogUpdates.ping' => array(
         'function'  => 'weblogUpdatePing',
         'signature' => array(array($XML_RPC_String,
                                    $XML_RPC_String,
                                    $XML_RPC_String),
                              array($XML_RPC_String,
                                    $XML_RPC_String,
                                    $XML_RPC_String,
                                    $XML_RPC_String),
                              array($XML_RPC_String,
                                    $XML_RPC_String,
                                    $XML_RPC_String,
                                    $XML_RPC_String,
                                    $XML_RPC_String))
      ),
   )
);
?>

To test this I used a simple client.

Listing 2 client.php:

<?php
require_once 'XML/RPC.php';
/*
You can call the method with two, three, or four parameters:

$params = array(new XML_RPC_Value('one', 'string'),
                new XML_RPC_Value('two', 'string'),
               );

$params = array(new XML_RPC_Value('one',   'string'),
                new XML_RPC_Value('two',   'string'),
                new XML_RPC_Value('three', 'string'),
               );
*/
$params = array(new XML_RPC_Value('one',   'string'),
                new XML_RPC_Value('two',   'string'),
                new XML_RPC_Value('three', 'string'),
                new XML_RPC_Value('four',  'string'),
               );

$msg = new XML_RPC_Message('weblogUpdates.ping', $params);

$cli = new XML_RPC_Client('/rpc/server.php', 'localhost');

//$cli->setDebug(1);

$resp = $cli->send($msg);

if (!$resp)
{
    echo 'Communication error: ' . $cli->errstr;
    exit;
}

if (!$resp->faultCode())
{
    $val = $resp->value();
    echo 'return message is ' . $val->scalarval();
}
else
{
    /*
     * Display problems that have been gracefully cought and
     * reported by the xmlrpc.php script.
     */
    echo 'Fault Code: ' . $resp->faultCode() . "n";
    echo 'Fault Reason: ' . $resp->faultString() . "n";
}
?>

So that seems to work as a simple framework. Now I’ve just got to add some logic to:

• check to see if the pings are from BritBlog members,
• check that they haven’t updated recently (say withing 24 hours) - we don’t want ping spammers,
• check that they have really updated their blog by getting their RSS feed,
• Update the ‘recently modified’ page/database stuff.

OK, that’s enough tonight. Anymore work and I’ll have to start to think, which after some Badger’s Tanglefoot and more Fuller’s Golden Pride is probably not possible. Still, time for another beer before bed, me thinks