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<h1>XML-RPC and XML-RPC Server Classes</h1>

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<p>CodeIgniter's XML-RPC classes permit you to send requests to another server, or set up

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your own XML-RPC server to receive requests.</p>

<p>Quite simply it is a way for two computers to communicate over the internet using XML.

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One computer, which we will call the <dfn>client</dfn>, sends an XML-RPC <strong>request</strong> to

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another computer, which we will call the <dfn>server</dfn>. Once the server receives and processes the request it

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will send back a <strong>response</strong> to the client.</p>

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<p>For example, using the MetaWeblog API, an XML-RPC Client (usually a desktop publishing tool) will

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send a request to an XML-RPC Server running on your site. This request might be a new weblog entry

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being sent for publication, or it could be a request for an existing entry for editing.

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When the XML-RPC Server receives this request it will examine it to determine which class/method should be called to process the request.

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Once processed, the server will then send back a response message.</p>

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<p>For detailed specifications, you can visit the <a href="http://www.xmlrpc.com/">XML-RPC</a> site.</p>

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<h2>Initializing the Class</h2>

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<p>Like most other classes in CodeIgniter, the XML-RPC and XML-RPCS classes are initialized in your controller using the <dfn>$this->load->library</dfn> function:</p>

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<p>To load the XML-RPC class you will use:</p>

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<code>$this->load->library('xmlrpc');</code>

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<p>Once loaded, the xml-rpc library object will be available using: <dfn>$this->xmlrpc</dfn></p>

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<p>To load the XML-RPC Server class you will use:</p>

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<code>

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$this->load->library('xmlrpc');<br />

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$this->load->library('xmlrpcs');

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</code>

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<p>Once loaded, the xml-rpcs library object will be available using: <dfn>$this->xmlrpcs</dfn></p>

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<p class="important"><strong>Note:</strong>  When using the XML-RPC Server class you must load BOTH the XML-RPC class and the XML-RPC Server class.</p>

<h2>Sending XML-RPC Requests</h2>

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<p>To send a request to an XML-RPC server you must specify the following information:</p>

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<ul>

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<li>The URL of the server</li>

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<li>The method on the server you wish to call</li>

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<li>The <em>request</em> data (explained below).</li>

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</ul>

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<p>Here is a basic example that sends a simple Weblogs.com ping to the <a href="http://pingomatic.com/">Ping-o-Matic</a></p>

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<code>$this->load->library('xmlrpc');<br />

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<br />

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$this->xmlrpc->server('http://rpc.pingomatic.com/', 80);<br />

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$this->xmlrpc->method('weblogUpdates.ping');<br />

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<br />

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$request = array('My Photoblog', 'http://www.my-site.com/photoblog/');<br />

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$this->xmlrpc->request($request);<br />

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<br />

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if ( ! $this->xmlrpc->send_request())<br />

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{<br />

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    echo $this->xmlrpc->display_error();<br />

}</code>

<h3>Explanation</h3>

<p>The above code initializes the XML-RPC class, sets the server URL and method to be called (weblogUpdates.ping). The

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request (in this case, the title and URL of your site) is placed into an array for transportation, and

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compiled using the request() function.

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Lastly, the full request is sent. If the <dfn>send_request()</dfn> method returns false we will display the error message

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sent back from the XML-RPC Server.</p>

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<h2>Anatomy of a Request</h2>

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<p>An XML-RPC <dfn>request</dfn> is simply the data you are sending to the XML-RPC server. Each piece of data in a request

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is referred to as a <dfn>request parameter</dfn>. The above example has two parameters:

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The URL and title of your site. When the XML-RPC server receives your request, it will look for parameters it requires.</p>

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<p>Request parameters must be placed into an array for transportation, and each parameter can be one

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of seven data types (strings, numbers, dates, etc.). If your parameters are something other than strings

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you will have to include the data type in the request array.</p>

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<p>Here is an example of a simple array with three parameters:</p>

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<code>$request = array('John', 'Doe', 'www.some-site.com');<br />

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$this->xmlrpc->request($request);</code>

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<p>If you use data types other than strings, or if you have several different data types, you will place

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each parameter into its own array, with the data type in the second position:</p>

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<code>

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$request = array (<br />

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                   array('John', 'string'),<br />

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                   array('Doe', 'string'),<br />

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                   array(FALSE, 'boolean'),<br />

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                   array(12345, 'int')<br />

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                 );

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<br />

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$this->xmlrpc->request($request);</code>

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The <a href="#datatypes">Data Types</a> section below has a full list of data types.

<h2>Creating an XML-RPC Server</h2>

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<p>An XML-RPC Server acts as a traffic cop of sorts, waiting for incoming requests and redirecting them to the

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appropriate functions for processing.</p>

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<p>To create your own XML-RPC server involves initializing the XML-RPC Server class in your controller where you expect the incoming

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request to appear, then setting up an array with mapping instructions so that incoming requests can be sent to the appropriate

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class and method for processing.</p>

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<p>Here is an example to illustrate:</p>

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<code>

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$this->load->library('xmlrpc');<br />

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$this->load->library('xmlrpcs');<br />

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<br />

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$config['functions']['<var>new_post</var>'] = array('function' => '<dfn>My_blog.new_entry</dfn>'),<br />

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$config['functions']['<var>update_post</var>'] = array('function' => '<dfn>My_blog.update_entry</dfn>');<br />

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$config['object'] = $this;<br />

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<br />

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$this->xmlrpcs->initialize($config);<br />

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$this->xmlrpcs->serve();</code>

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<p>The above example contains an array specifying two method requests that the Server allows.

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The allowed methods are on the left side of the array. When either of those are received, they will be mapped to the class and method on the right.</p>

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<p>The '<var>object</var>' key is a special key that you pass an instantiated class object with, which is necessary when the method you are mapping to is not

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part of the CodeIgniter super object.</p>

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<p>In other words, if an XML-RPC Client sends a request for the <var>new_post</var> method, your

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server will load the <dfn>My_blog</dfn> class and call the <dfn>new_entry</dfn> function.

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If the request is for the <var>update_post</var> method, your

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server will load the <dfn>My_blog</dfn> class and call the <dfn>update_entry</dfn> function.</p>

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<p>The function names in the above example are arbitrary. You'll decide what they should be called on your server,

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or if you are using standardized APIs, like the Blogger or MetaWeblog API, you'll use their function names.</p>

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<h2>Processing Server Requests</h2>

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<p>When the XML-RPC Server receives a request and loads the class/method for processing, it will pass

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an object to that method containing the data sent by the client.</p>

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<p>Using the above example, if the <var>new_post</var> method is requested, the server will expect a class

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to exist with this prototype:</p>

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<code>class <kbd>My_blog</kbd> extends Controller {<br />

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<br />

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    function <kbd>new_post</kbd>(<var>$request</var>)<br />

    {<br />

<br />

    }<br />

}

</code>

<p>The <var>$request</var> variable is an object compiled by the Server, which contains the data sent by the XML-RPC Client.

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Using this object you will have access to the <em>request parameters</em> enabling you to process the request. When

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you are done you will send a <dfn>Response</dfn> back to the Client.</p>

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<p>Below is a real-world example, using the Blogger API. One of the methods in the Blogger API is <dfn>getUserInfo()</dfn>.

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Using this method, an XML-RPC Client can send the Server a username and password, in return the Server sends

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back information about that particular user (nickname, user ID, email address, etc.). Here is how the processing

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function might look:</p>

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<code>class <kbd>My_blog</kbd> extends Controller {<br />

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<br />

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    function <kbd>getUserInfo</kbd>(<var>$request</var>)<br />

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    {<br />

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        $username = 'smitty';<br />

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        $password = 'secretsmittypass';<br /><br />

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        $this->load->library('xmlrpc');<br />

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    <br />

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        $parameters = $request->output_parameters();<br />

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    <br />

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        if ($parameters['1'] != $username AND $parameters['2'] != $password)<br />

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        {<br />

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            return $this->xmlrpc->send_error_message('100', 'Invalid Access');<br />

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        }<br />

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    <br />

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        $response = array(array('nickname'  => array('Smitty','string'),<br />

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                                'userid'    => array('99','string'),<br />

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                                'url'       => array('http://yoursite.com','string'),<br />

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                                'email'     => array('jsmith@yoursite.com','string'),<br />

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                                'lastname'  => array('Smith','string'),<br />

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                                'firstname' => array('John','string')<br />

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                                ),<br />

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                         'struct');<br />

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<br />

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        return $this->xmlrpc->send_response($response);<br />

    }<br />

}

</code>

<h3>Notes:</h3>

<p>The <dfn>output_parameters()</dfn> function retrieves an indexed array corresponding to the request parameters sent by the client.

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In the above example, the output parameters will be the username and password.</p>

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<p>If the username and password sent by the client were not valid, and error message is returned using <dfn>send_error_message()</dfn>.</p>

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<p>If the operation was successful, the client will be sent back a response array containing the user's info.</p>

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<h2>Formatting a Response</h2>

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<p>Similar to <em>Requests</em>, <em>Responses</em> must be formatted as an array. However, unlike requests, a response is an array

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<strong>that contains a single item</strong>. This item can be an array with several additional arrays, but there

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can be only one primary array index. In other words, the basic prototype is this:</p>

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<code>$response = array('Response data', 'array');</code>

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<p>Responses, however, usually contain multiple pieces of information. In order to accomplish this we must put the response into its own

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array so that the primary array continues to contain a single piece of data. Here's an example showing how this might be accomplished:</p>

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<code>

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$response = array (<br />

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                   array(<br />

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                         'first_name' => array('John', 'string'),<br />

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                         'last_name' => array('Doe', 'string'),<br />

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                         'member_id' => array(123435, 'int'),<br />

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                         'todo_list' => array(array('clean house', 'call mom', 'water plants'), 'array'),<br />

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                        ),<br />

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                 'struct'<br />

                 );

</code>

<p class="important">Notice that the above array is formatted as a <dfn>struct</dfn>. This is the most common data type for responses.</p>

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<p>As with Requests, a response can be one of the seven data types listed in the <a href="#datatypes">Data Types</a> section.</p>

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<h2>Sending an Error Response</h2>

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<p>If you need to send the client an error response you will use the following:</p>

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<code>return $this->xmlrpc->send_error_message('123', 'Requested data not available');</code>

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<p>The first parameter is the error number while the second parameter is the error message.</p>

<h2>Creating Your Own Client and Server</h2>

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<p>To help you understand everything we've covered thus far, let's create a couple controllers that act as

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XML-RPC Client and Server. You'll use the Client to send a request to the Server and receive a response.</p>

<h3>The Client</h3>

<p>Using a text editor, create a controller called <dfn>xmlrpc_client.php</dfn>.

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In it, place this code and save it to your <samp>applications/controllers/</samp> folder:</p>

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<textarea class="textarea" style="width:100%" cols="50" rows="32"><?php

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class Xmlrpc_client extends Controller {

function index()

{

$this->load->helper('url');

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$server_url = site_url('xmlrpc_server');

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$this->load->library('xmlrpc');

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$this->xmlrpc->server($server_url, 80);

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$this->xmlrpc->method('Greetings');

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$request = array('How is it going?');

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$this->xmlrpc->request($request);

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if ( ! $this->xmlrpc->send_request())

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{

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echo $this->xmlrpc->display_error();

}

else

{

echo '<pre>';

print_r($this->xmlrpc->display_response());

echo '</pre>';

}

}

}

?></textarea>

<p>Note: In the above code we are using a "url helper". You can find more information in the <a href="../general/helpers.html">Helpers Functions</a> page.</p>

<h3>The Server</h3>

<p>Using a text editor, create a controller called <dfn>xmlrpc_server.php</dfn>.

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In it, place this code and save it to your <samp>applications/controllers/</samp> folder:</p>

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<textarea class="textarea" style="width:100%" cols="50" rows="30"><?php

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class Xmlrpc_server extends Controller {

function index()

{

$this->load->library('xmlrpc');

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$this->load->library('xmlrpcs');

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$config['functions']['Greetings'] = array('function' => 'Xmlrpc_server.process');

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$this->xmlrpcs->initialize($config);

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$this->xmlrpcs->serve();

}

function process($request)

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{

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$parameters = $request->output_parameters();

$response = array(

array(

'you_said' => $parameters['0'],

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'i_respond' => 'Not bad at all.'),

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'struct');

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return $this->xmlrpc->send_response($response);

}

}

?></textarea>

<p>Now visit the your site using a URL similar to this:</p>

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<code>example.com/index.php/<var>xmlrpc_client</var>/</code>

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<p>You should now see the message you sent to the server, and its response back to you.</p>

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<p>The client you created sends a message ("How's is going?") to the server, along with a request for the "Greetings" method.

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The Server receives the request and maps it to the "process" function, where a response is sent back.</p>

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<h2>Using Associative Arrays In a Request Parameter</h2>

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<p>If you wish to use an associative array in your method parameters you will need to use a struct datatype:</p>

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<code>$request = array(<br />

array(<br />

// Param 0<br />

array(<br />

'name'=>'John'<br />

),<br />

'struct'<br />

),<br />

array(<br />

// Param 1<br />

array(<br />

'size'=>'large',<br />

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'shape'=>'round'<br />

),<br />

'struct'<br />

)<br />

);<br />

$this->xmlrpc->request($request);</code>

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<p>You can retrieve the associative array when processing the request in the Server.</p>

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<code>$parameters = $request->output_parameters();<br />

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$name = $parameters['0']['name'];<br />

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$size = $parameters['1']['size'];<br />

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$size = $parameters['1']['shape']; </code>

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<h1>XML-RPC Function Reference</h1>

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<h2>$this->xmlrpc->server()</h2>

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<p>Sets the URL and port number of the server to which a request is to be sent:</p>

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<code>$this->xmlrpc->server('http://www.sometimes.com/pings.php', 80);</code>

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<h2>$this->xmlrpc->timeout()</h2>

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<p>Set a time out period (in seconds) after which the request will be canceled:</p>

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<code>$this->xmlrpc->timeout(6);</code>

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<h2>$this->xmlrpc->method()</h2>

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<p>Sets the method that will be requested from the XML-RPC server:</p>

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<code>$this->xmlrpc->method('<var>method</var>');</code>

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<p>Where <var>method</var> is the name of the method.</p>

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<h2>$this->xmlrpc->request()</h2>

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<p>Takes an array of data and builds request to be sent to XML-RPC server:</p>

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<code>$request = array(array('My Photoblog', 'string'), 'http://www.yoursite.com/photoblog/');<br />

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$this->xmlrpc->request($request);</code>

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<h2>$this->xmlrpc->send_request()</h2>

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<p>The request sending function. Returns boolean TRUE or FALSE based on success for failure, enabling it to be used conditionally.</p>

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<h2>$this->xmlrpc->set_debug(TRUE);</h2>

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<p>Enables debugging, which will display a variety of information and error data helpful during development.</p>

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<h2>$this->xmlrpc->display_error()</h2>

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<p>Returns an error message as a string if your request failed for some reason.</p>

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<code>echo $this->xmlrpc->display_error();</code>

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<h2>$this->xmlrpc->display_response()</h2>

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<p>Returns the response from the remote server once request is received. The response will typically be an associative array.</p>

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<code>$this->xmlrpc->display_response();</code>

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<h2>$this->xmlrpc->send_error_message()</h2>

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<p>This function lets you send an error message from your server to the client. First parameter is the error number while the second parameter

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is the error message.</p>

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<code>return $this->xmlrpc->send_error_message('123', 'Requested data not available');</code>

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<h2>$this->xmlrpc->send_response()</h2>

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<p>Lets you send the response from your server to the client. An array of valid data values must be sent with this method.</p>

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<code>$response = array(<br />

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                 array(<br />

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                        'flerror' => array(FALSE, 'boolean'),<br />

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                        'message' => "Thanks for the ping!")<br />

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                     )<br />

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                 'struct');<br />

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return $this->xmlrpc->send_response($response);</code>

<h2>Data Types</h2>

<p>According to the <a href="http://www.xmlrpc.com/spec">XML-RPC spec</a> there are seven types

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of values that you can send via XML-RPC:</p>

<ul>

<li><em>boolean</em></li>

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<li><em>string</em></li>

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<li><em>double</em></li>

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<li><em>dateTime.iso8601</em></li>

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<li><em>struct</em> (contains array of values)</li>

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<li><em>array</em> (contains array of values)</li>

</ul>

</div>

<p>

Previous Topic:  <a href="validation.html">Validation Class</a>

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   ·  

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<a href="#top">Top of Page</a>   ·  

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<a href="../index.html">User Guide Home</a>   ·  

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Next Topic:  <a href="zip.html">Zip Encoding Class</a>

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</p>

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