Implement a simple rpc system

Servers can transmit their workload and jobstatus updates.

application/models/server.php

@@ -0,0 +1,40 @@
+<?php
+
+/**
+ * @author Karsten Heiken, karsten@disposed.de
+ */
+class Server extends CI_Model {
+
+	/**
+	 * Get a list of all available servers.
+	 *
+	 * @return array List of all available servers.
+	 */
+	public function get_all() {
+		return $this->db->get('servers')->result_array();
+	}
+
+	/**
+	 * Get a list of servers that could handle another job.
+	 *
+	 * @return array List of servers that could handle another job.
+	 */
+	public function get_idle() {
+		return $this->db->get_where('servers', 'workload <= 2')->result_array();
+	}
+
+	/**
+	 * Set a server's workload.
+	 *
+	 * In order to check if a server can handle another job we need to know
+	 * the workload of every server.
+	 *
+	 * @param type $secret The server's secret for basic authentication.
+	 * @param type $workload The server's workload.
+	 */
+	public function update_workload($secret, $workload) {
+		$this->db->query("UPDATE `servers` SET `workload`=".$this->db->escape($workload)
+				. ", `last_update`=NOW()"
+				. " WHERE `secret`=".$this->db->escape($secret));
+	}
+}