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| <h1>XML-RPC and XML-RPC Server Classes</h1> | |
| <p>Code Igniter's XML-RPC classes permit you to send requests to another server, or set up | |
| your own XML-RPC server to receive requests.</p> | |
| <h2>What is XML-RPC?</h2> | |
| <p>Quite simply it is a way for two computers to communicate over the internet using XML. | |
| One computer, which we will call the <dfn>client</dfn>, sends an XML-RPC <strong>request</strong> to | |
| another computer, which we will call the <dfn>server</dfn>. Once the server receives and processes the request it | |
| will send back a <strong>response</strong> to the client.</p> | |
| <p>For example, using the MetaWeblog API, an XML-RPC Client (usually a desktop publishing tool) will | |
| send a request to an XML-RPC Server running on your site. This request might be a new weblog entry | |
| being sent for publication, or it could be a request for an existing entry for editing. | |
| When the XML-RPC Server receives this request it will examine it to determine which class/method should be called to process the request. | |
| Once processed, the server will then send back a response message.</p> | |
| <p>For detailed spcifications, you can visit the <a href="http://www.xmlrpc.com/">XML-RPC</a> site.</p> | |
| <h2>Initializing the Class</h2> | |
| <p>Like most other classes in Code Igniter, the XML-RPC and XML-RPCS classes are initialized in your controller using the <dfn>$this->load->library</dfn> function:</p> | |
| <p>To load the XML-RPC class you will use: | |
| <code>$this->load->library('xmlrpc');</code> | |
| <p>Once loaded, the xml-rpc library object will be available using: <dfn>$this->xmlrpc</dfn></p> | |
| <p>To load the XML-RPC Server class you will use: | |
| <code>$this->load->library('xmlrpcs');</code> | |
| <p>Once loaded, the xml-rpcs library object will be available using: <dfn>$this->xmlrpcs</dfn></p> | |
| <h2>Sending XML-RPC Requests</h2> | |
| <p>To send a request to an XML-RPC server you must specify the following information:</p> | |
| <ul> | |
| <li>The URL of the server</li> | |
| <li>The method on the server you wish to call</li> | |
| <li>The <em>request</em> data (explained below).</li> | |
| </ul> | |
| <p>Here is a basic example that sends a simple Weblogs.com ping to the <a href="http://pingomatic.com/">Ping-o-Matic</a></p> | |
| <code>$this->load->library('xmlrpc');<br /> | |
| <br /> | |
| $this->xmlrpc->server('http://rpc.pingomatic.com/', 80);<br /> | |
| $this->xmlrpc->method('weblogUpdates.ping');<br /> | |
| <br /> | |
| $request = array('My Photoblog', 'http://www.my-site.com/photoblog/');<br /> | |
| $this->xmlrpc->request($request);<br /> | |
| <br /> | |
| if ( ! $this->xmlrpc->send_request())<br /> | |
| {<br /> | |
| echo $xmlrpc->display_error();<br /> | |
| } | |
| </code> | |
| <h3>Explanation</h3> | |
| <p>The above code initializes the XML-RPC class, sets the server URL and method to be called (weblogUpdates.ping). The | |
| request (in this case, the title and URL of your site) is placed into an array for transportation, and | |
| compiled using the request() function. | |
| Lastly, the full request is sent. If the <dfn>send_request()</dfn> method returns false we will display the error message | |
| sent back from the XML-RPC Server.</p> | |
| <h2>Anatomy of a Request</h2> | |
| <p>An XML-RPC <dfn>request</dfn> is simply the data you are sending to the XML-RPC server. Each piece of data in a request | |
| is referred to as a <dfn>request parameter</dfn>. The above example has two parameters: | |
| The URL and title of your site. When the XML-RPC server receives your request, it will look for parameters it requires.</p> | |
| <p>Request parameters must be placed into an array for transportation, and each parameter can can be one | |
| of seven data types (strings, numbers, dates, etc.). If your parameters are something other than strings | |
| you will have to include the data type in the request array.</p> | |
| <p>Here is an example of a simple array with three parameters:</p> | |
| <code>$request = array('John', 'Doe', 'www.some-site.com');<br /> | |
| $this->xmlrpc->request($request);</code> | |
| <p>If you use data types other than strings, or if you have several different data types, you will place | |
| each parameter into its own array, with the data type in the second position:</p> | |
| <code> | |
| $request = array (<br /> | |
| array('John', 'string'),<br /> | |
| array('Doe', 'string'),<br /> | |
| array(FALSE, 'boolean'),<br /> | |
| array(12345, 'int')<br /> | |
| ); | |
| <br /> | |
| $this->xmlrpc->request($request);</code> | |
| The <a href="#datatypes">Data Types</a> section below has a full list of data types.</p> | |
| <h2>Creating an XML-RPC Server</h2> | |
| <p>An XML-RPC Server acts as a traffic cop of sorts, waiting for incoming requests and redirecting them to the | |
| appropriate functions for processing.</p> | |
| <p>To create your own XML-RPC server involves initializing the XML-RPC Server class in your controller where you expect the incoming | |
| request to appear, then setting up an array with mapping instructions so that incoming requests can be sent to the appropriate | |
| class and method for processing.</p> | |
| <p>Here is an example to illustrate:</p> | |
| <code>$this->load->library('xmlrpcs');<br /> | |
| <br /> | |
| $config['functions']['<var>new_post</var>']; = array('function' => '<dfn>My_blog.new_entry</dfn>');<br /> | |
| $config['functions']['<var>update_post</var>'] = array('function' => '<dfn>My_blog.update_entry</dfn>');<br /> | |
| <br /> | |
| $this->xmlrpcs->initialize($config);<br /> | |
| $this->xmlrpcs->serve();</code> | |
| <p>The above example contains an array specifying two method requests that the Server allows. | |
| The allowed methods are on the left side of the array. When either of those are received, they will be mapped to the class and method on the right. | |
| <p>In other words, if an XML-RPC Client sends a request for the <var>new_post</var> method, your | |
| server will load the <dfn>My_blog</dfn> class and call the <dfn>new_entry</dfn> function. | |
| If the request is for the <var>update_post</var> method, your | |
| server will load the <dfn>My_blog</dfn> class and call the <dfn>update_entry</dfn> function.</p> | |
| <p>The function names in the above example are arbitrary. You'll decide what they should be called on your server, | |
| or if you are using standardized APIs, like the Blogger or MetaWeblog API, you'll use their function names.</p> | |
| <h2>Processing Server Requests</h2> | |
| <p>When the XML-RPC Server receives a request and loads the class/method for processing, it will pass | |
| an object to that method containing the data sent by the client.</p> | |
| <p>Using the above example, if the <var>new_post</var> method is requested, the server will expect a class | |
| to exist with this prototype:</p> | |
| <code>class <kbd>My_blog</kbd> extends Controller {<br /> | |
| <br /> | |
| function <kbd>new_post</kbd>(<var>$request</var>)<br /> | |
| {<br /> | |
| <br /> | |
| }<br /> | |
| } | |
| </code> | |
| <p>The <var>$request</var> variable is an object compiled by the Server, which contains the data sent by the XML-RPC Client. | |
| Using this object you will have access to the <em>request parameters</em> enabling you to process the request. When | |
| you are done you will send a <dfn>Response</dfn> back to the Client.<p> | |
| <p>Below is a real-world example, using the Blogger API. One of the methods in the Blogger API is <dfn>getUserInfo()</dfn>. | |
| Using this method, an XML-RPC Client can send the Server a username and password, in return the Server sends | |
| back information about that particular user (nickname, user ID, email address, etc.). Here is how the processing | |
| function might look:</p> | |
| <code>class <kbd>My_blog</kbd> extends Controller {<br /> | |
| <br /> | |
| function <kbd>getUserInfo</kbd>(<var>$request</var>)<br /> | |
| {<br /> | |
| $username = 'smitty';<br /> | |
| $password = 'secretsmittypass';<br /><br /> | |
| $this->load->library('xmlrpc');<br /> | |
| <br /> | |
| $parameters = $request->output_parameters();<br /> | |
| <br /> | |
| if ($parameters['1'] != $username AND $parameters['2'] != $password)<br /> | |
| {<br /> | |
| return $this->xmlrpc->send_error_message('100', 'Invalid Access');<br /> | |
| }<br /> | |
| <br /> | |
| $response = array(array('nickname' => array('Smitty','string'),<br /> | |
| 'userid' => array('99','string'),<br /> | |
| 'url' => array('http://yoursite.com','string'),<br /> | |
| 'email' => array('jsmith@yoursite.com','string'),<br /> | |
| 'lastname' => array('Smith','string'),<br /> | |
| 'firstname' => array('John','string')<br /> | |
| ),<br /> | |
| 'struct');<br /> | |
| <br /> | |
| $this->xmlrpc->send_response($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. | |
| In the above example, the output parameters will be the username and password.</p> | |
| <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> | |
| <p>If the operation was successful, the client will be sent back a response array containing the user's info.</p> | |
| <h2>Formatting a Response</h2> | |
| <p>Similar to <em>Requests</em>, <em>Responses</em> must be formatted as an array. However, unlike requests, a response is an array | |
| <strong>that contains a single item</strong>. This item can be an array with several additional arrays, but there | |
| can be only one primary array index. In other words, the basic prototype is this:</p> | |
| <code>$request = array('Response data', 'array');</code> | |
| <p>Responses, however, usually contain multiple pieces of information. In order to accomplish this we must put the response into its own | |
| 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> | |
| <code> | |
| $request = array (<br /> | |
| array(<br /> | |
| 'first_name' => array('John', 'string'),<br /> | |
| 'last_name' => array('Doe', 'string'),<br /> | |
| 'member_id' => array(123435, 'int'),<br /> | |
| 'todo_list' => array(array('clean house', 'call mom', 'water plants'), 'array'),<br /> | |
| ),<br /> | |
| '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> | |
| <p>As with Requests, a response can be on of the seven data types listed in the <a href="#datatypes">Data Types</a> section.</p> | |
| <h2>Sending an Error Response</h2> | |
| <p>If you need to send the client an error response you will use the following:</p> | |
| <code>return $this->xmlrpc->send_error_message('123', 'Requested data not available');</code> | |
| <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> | |
| <p>To help you understand everything we've covered thus far, let's create a couple controllers that act as | |
| 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>. | |
| In it, place this code and save it to your <samp>applications/controllers/</samp> folder:</p> | |
| <textarea class="textarea" style="width:100%" cols="50" rows="32"><?php | |
| class Xmlrpc_client extends Controller { | |
| function index() | |
| { | |
| $this->load->helper('url'); | |
| $server_url = site_url('xmlrpc_server'); | |
| $this->load->library('xmlrpc'); | |
| $this->xmlrpc->server($server_url, 80); | |
| $this->xmlrpc->method('Greetings'); | |
| $request = array('How is it going?'); | |
| $this->xmlrpc->request($request); | |
| if ( ! $this->xmlrpc->send_request()) | |
| { | |
| 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>. | |
| In it, place this code and save it to your <samp>applications/controllers/</samp> folder:</p> | |
| <textarea class="textarea" style="width:100%" cols="50" rows="30"><?php | |
| class Xmlrpc_server extends Controller { | |
| function index() | |
| { | |
| $this->load->library('xmlrpcs'); | |
| $config['functions']['Greetings'] = array('function' => 'Xmlrpc_server.process'); | |
| $this->xmlrpcs->initialize($config); | |
| $this->xmlrpcs->serve(); | |
| } | |
| function process($request) | |
| { | |
| $parameters = $request->output_parameters(); | |
| $response = array( | |
| array( | |
| 'you_said' => $parameters['0'], | |
| 'i_respond' => 'Not bad at all.'), | |
| 'struct'); | |
| return $this->xmlrpc->send_response($response); | |
| } | |
| } | |
| ?></textarea> | |
| <h3>Try it!</h3> | |
| <p>Now visit the your site using a URL similar to this:</p> | |
| <code>www.your-site.com/index.php/<var>xmlrpc_client</var>/</code> | |
| <p>You should now see the message you sent to the server, and its response back to you.</p> | |
| <p>The client you created sends a message ("How's is going?") to the server, along with a reqest for the "Greetings" method. | |
| The Server receives the request and maps it to the "process" function, where a response is sent back.</p> | |
| <p> </p> | |
| <h1>XML-RPC Function Reference</h1> | |
| <h2>$this->xmlrpc->server()</h2> | |
| <p>Sets the URL and port number of the server to which a request is to be sent:</p> | |
| <code>$this->xmlrpc->server('http://www.sometimes.com/pings.php', 80);</code> | |
| <h2>$this->xmlrpc->timeout()</h2> | |
| <p>Set a time out period (in seconds) after which the request will be canceled:</p> | |
| <code>$this->xmlrpc->timeout(6);</code> | |
| <h2>$this->xmlrpc->method()</h2> | |
| <p>Sets the method that will be requested from the XML-RPC server:</p> | |
| <code>$this->xmlrpc->method('<var>method</var>');</code> | |
| <p>Where <var>method</var> is the name of the method.</p> | |
| <h2>$this->xmlrpc->request()</h2> | |
| <p>Takes an array of data and builds request to be sent to XML-RPC server:</p> | |
| <code>$request = array(array('My Photoblog', 'string'), 'http://www.yoursite.com/photoblog/');<br /> | |
| $this->xmlrpc->request($request);</code> | |
| <h2>$this->xmlrpc->send_request()</h2> | |
| <p>The request sending function. Returns boolean TRUE or FALSE based on success for failure, enabling it to be used conditionally.</p> | |
| <h2>$this->xmlrpc->set_debug(TRUE);</h2> | |
| <p>Enables debugging, which will display a variety of information and error data helpful during development.</p> | |
| <h2>$this->xmlrpc->display_error()</h2> | |
| <p>Returns an error message as a string if your request failed for some reason.</p> | |
| <code>echo $this->xmlrpc->display_error();</code> | |
| <h2>$this->xmlrpc->display_response()</h2> | |
| <p>Returns the response from the remote server once request is received. The response will typically be an associative array.</p> | |
| <code>$this->xmlrpc->display_response();</code> | |
| <h2>$this->xmlrpc->send_error_message()</h2> | |
| <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 | |
| is the error message.</p> | |
| <code>return $this->xmlrpc->send_error_message('123', 'Requested data not available');</code> | |
| <h2>$this->xmlrpc->send_response()</h2> | |
| <p>Lets you send the response from your server to the client. An array of of valid data values must be sent with this method.</p> | |
| <code>$response = array(<br /> | |
| array(<br /> | |
| 'flerror' => array(FALSE, 'boolean'),<br /> | |
| 'message' => "Thanks for the ping!")<br /> | |
| )<br /> | |
| 'struct');<br /> | |
| return $this->xmlrpc->send_response($response);</code> | |
| <a name="datatypes"></a> | |
| <h2>Data Types</h2> | |
| <p>According to the <a href="http://www.xmlrpc.com/spec">XML-RPC spec</a> there are seven types | |
| of values that you can send via XML-RPC:</p> | |
| <ul> | |
| <li><em>int</em> or <em>i4</em></li> | |
| <li><em>boolean</em></li> | |
| <li><em>string</em></li> | |
| <li><em>double</em></li> | |
| <li><em>dateTime.iso8601</em></li> | |
| <li><em>base64</em></li> | |
| <li><em>struct</em> (contains array of values)</li> | |
| <li><em>array</em> (contains array of values)</li> | |
| </ul> | |
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