321 lines
11 KiB
HTML
321 lines
11 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html>
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<head>
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<title>Lua XML-RPC: XML-RPC interface to the Lua programming language</title>
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<link rel="stylesheet" href="http://www.keplerproject.org/doc.css" type="text/css"/>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
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</head>
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<body>
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<div id="container">
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<div id="product">
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<div id="product_logo">
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<a href="http://www.keplerproject.org">
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<img alt="Lua XML-RPC logo" src="luaxmlrpc.png"/>
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</a>
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</div>
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<div id="product_name"><big><strong>Lua XML-RPC</strong></big></div>
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<div id="product_description">XML-RPC interface to the Lua programming language</div>
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</div> <!-- id="product" -->
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<div id="main">
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<div id="navigation">
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<h1>Lua XML-RPC</h1>
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<ul>
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<li><a href="index.html">Home</a>
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<ul>
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<li><a href="index.html#overview">Overview</a></li>
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<li><a href="index.html#status">Status</a></li>
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<li><a href="index.html#download">Download</a></li>
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<li><a href="index.html#history">History</a></li>
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<li><a href="index.html#credits">Credits</a></li>
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<li><a href="index.html#contact">Contact</a></li>
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</ul>
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</li>
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<li><strong>Manual</strong>
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<ul>
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<li><a href="manual.html#introduction">Introduction</a></li>
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<li><a href="manual.html#installation">Installation</a></li>
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<li><a href="manual.html#data_types">Data types</a></li>
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<li><a href="manual.html#functions">Library functions</a></li>
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<li><a href="manual.html#client">Client side</a></li>
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<li><a href="manual.html#server">Server side</a></li>
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<li><a href="manual.html#references">References</a></li>
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</ul>
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</li>
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<li><a href="examples.html">Examples</a></li>
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<li><a href="license.html">License</a></li>
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</ul>
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</div> <!-- id="navigation" -->
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<div id="content">
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<h2><a name="introduction"></a>Introduction</h2>
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<p>Lua XML-RPC is a <a href="http://www.lua.org">Lua</a> library that can be used
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to build <a href="http://www.xmlrpc.com">XML-RPC</a> clients and
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servers. It enables a Lua program to:</p>
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<ul>
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<li>Encode and decode XML-RPC messages without handling XML code</li>
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<li>Transform Lua data structures into XML-RPC data types and vice-versa</li>
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</ul>
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<p>Lua XML-RPC provides a simple API and an abstraction layer over XML avoiding
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manipulation of string representation of data structures.</p>
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<p>Lua XML-RPC is based on
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<a href="http://www.keplerproject.org/luaexpat">LuaExpat</a> and on
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<a href="http://www.lua.org">Lua 5.1</a>.
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The abstraction layer over HTTP depends on
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<a href="http://w3.impa.br/~diego/software/luasocket/">LuaSocket 2.0.2</a>.</p>
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<h2><a name="installation"></a>Installation</h2>
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<p>Lua XML-RPC is composed by three Lua files:
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<dl>
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<dt><code>init.lua</code></dt>
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<dd>Main source file providing the API</dd>
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<dt><code>http.lua</code></dt>
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<dd>API to call XML-RPC via HTTP</dd>
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<dt><code>server.lua</code></dt>
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<dd>Server side API</dd>
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</dl>
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</p>
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These files should be copied to a directory named <code>xmlrpc</code> created in your
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<code>LUA_PATH</code>.</p>
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<p>Lua XML-RPC follows the
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<a href="http://www.keplerproject.org/compat/">package model</a>
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for Lua 5.1, therefore it should be "installed". Refer to
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<a href="http://www.keplerproject.org/compat/manual.html#configuration">
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Compat-5.1 configuration</a> section about how to install the module.</p>
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<h2><a name="data_types"></a>Data types</h2>
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<p>XML-RPC elements are usually represented by the simplest
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correspondent Lua object. When the correspondance is not obvious, a
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Lua table is used with a field specifying the element.</p>
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<h3><a name="xr2lua"></a>From XML-RPC to Lua</h3>
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<p>When converting from XML-RPC element to a Lua data item or table,
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a table with a field <code>tag</code> is used. The child elements are
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stored at numbered indexes and white space is ignored.</p>
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<table>
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<tr>
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<th>XML-RPC data type(s)</th>
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<th>Lua object</th>
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</tr>
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<tr>
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<td>
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double<br />
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int<br />
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i4
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</td>
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<td>number</td>
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</tr>
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<tr>
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<td>string</td>
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<td>string</td>
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</tr>
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<tr>
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<td>boolean</td>
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<td>boolean</td>
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</tr>
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<tr>
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<td>
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struct<br />
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arrray
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</td>
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<td>table</td>
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</tr>
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<tr>
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<td>other elements</td>
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<td>
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<pre>{
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tag = "element name",
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[1] = <first child>,
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[2] = <second child>,
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[3] = ...,
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}</pre>
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</td>
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</tr>
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</table>
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<h3><a name="lua2xr"></a>From Lua to XML-RPC</h3>
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<p>A conversion from a Lua data item or table to an XML-RPC element
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can be made automatically or explicitly. The automatic conversion rules
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are:</p>
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<table>
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<tr>
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<th>Lua object</th>
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<th>XML-RPC data type</th>
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</tr>
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<tr>
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<td>number</td>
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<td>int or double</td>
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</tr>
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<tr>
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<td>string</td>
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<td>string</td>
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</tr>
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<tr>
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<td>boolean</td>
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<td>boolean</td>
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</tr>
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<tr>
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<td><code>{ key = val }</code></td>
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<td>
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<pre>
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<struct>
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<member>
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<name>key</name>
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<value><em>val</em></value>
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</member>
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</struct>
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</pre>
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<small><em>val</em> is converted according to the same rules.</small>
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</td>
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</tr>
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</table>
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<p>Ifn case of a table that has numeric keys, the resulting struct will
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have the string representation of these numbers as keys (e.g.
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<code>"1"</code> instead of <code>1</code>). The library tries to
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convert integral numbers to integer types, otherwise converting
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them to floating point numbers.</p>
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<h2><a name="functions"></a>Library functions</h2>
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<p>The <code>xmlrpc.lua</code> file implements the functions that encode and decode XML-RPC messages and transform
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data types between the Lua and XML-RPC. The functions are:</p>
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<dl>
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<dt><a name="clEncode"></a><strong><code>clEncode (method_name [, params]) => method_call</code></strong></dt>
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<dd>Build a XML-RPC document containing a <code>methodCall</code>
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element. It receives a string with the method's name and an
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optional list of parameters. The result is a string containing the
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XML-RPC document.</dd>
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<dt><a name="clDecode"></a><strong><code>clDecode (method_response) => ok, results</code></strong></dt>
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<dd>Disassemble the server response into a Lua object. It receives a
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string containing the XML-RPC document representing the
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<code>methodResponse</code> element. The result is a boolean
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indicating wether the call was successful or not followed by the
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resulting objects (typically a methodResponse has only one value so
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only one Lua object will be returned). In case of error the
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<code>false</code> value is followed by the XMLRPC
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<em>faultString</em> and the <em>faultCode</em>. This values are
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extracted from the <code>fault</code> element.</dd>
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<dt><a name="srvDecode"></a><strong><code>srvDecode (method_call) => method_name, list_params</code></strong></dt>
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<dd>Disassemble the client request into a method's name and a table
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with the list of parameters. It receives a string containing the
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XML-RPC document representing the <code>methodCall</code> element.
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The result is a string with the name of the method to be called and
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a Lua table with the arguments to the call.</dd>
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<dt><a name="srvEncode"></a><strong><code>srvEncode (object, is_fault) => method_response</code></strong></dt>
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<dd>Build a XML-RPC document containing a <code>methodResponse</code>
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element. It receives a Lua object (a number, a string, a table, a
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"created typed value" etc.) with the return value of the call. The
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result is a string containing the XML-RPC document. Note that
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XML-RPC defines that a response only returns <em>one</em> value so a
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Lua function that returns more than one value has to <em>pack</em>
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them into a table to guarantee that all of them will be returned.
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The second parameter (<code>is_fault</code>) can be used to force a
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<code>fault</code> element to be generated instead of a
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<code>params</code>. In this case, the Lua object must be a table
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with the members <code>faultCode</code> and
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<code>faultString</code>.</dd>
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<dt><a name="srvMethods"></a><strong><code>srvMethods (tab_or_func)</code></strong></dt>
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<dd>Register the methods on the server. The parameter can be a table
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or a dispatching function. If a <em>table</em> is given it can have
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one level of objects with the corresponding methods. If a
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<em>function</em> is given, it will replace the dispatcher.</dd>
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<dt><a name="dispatch"></a><strong><code>dispatch (method_name) => function</code></strong></dt>
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<dd>Returns a Lua function that implements the method call. Note that
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the object is encapsulated into that function so that the call will
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be turned into a real method call.</dd>
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</dl>
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<h2><a name="client"></a>Client side</h2>
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<p>The <code>http.lua</code> file implements a simple
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stand-alone client based on
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<a href="http://w3.impa.br/~diego/software/luasocket/">LuaSocket 2.0.2</a>. The
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following function is provided:</p>
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<dl>
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<dt><a name="call"></a><strong><code>call (url, method [, params])</code></strong></dt>
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<dd>Execute the call to <code>method</code> at location
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<code>url</code> with the given <code>params</code> (if any). The
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<code>method</code> and <code>params</code> parameters will be just
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passed to <a href="#clEncode">clEncode</a> function. The result is
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the same as <a href="#clDecode">clDecode</a> function: a boolean
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indicating whether the call was successful or not, followed by the
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response value (if successful) or by the <em>faultString</em> and the
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<em>faultCode</em> (if the call fails).</dd>
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</dl>
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<h2><a name="server"></a>Server side</h2>
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<p>The distribution also offers a simple XML-RPC server implemented
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over a CGI launcher. This launcher just have to offer a way to
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decode POST data and to send data back to the client.</p>
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<p>The <code>tests</code> directory contains a file named
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<code>cgi.lua</code>, which implements an example of a simple XML-RPC
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server using the package <code>post</code> (which parses incoming
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POST data from the http server). An appropriate environment for
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writing Lua functions is implemented; a new <code>assert</code>
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function generates a XML-RPC fault in case of a false condition; a
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<code>respond</code> function creates the correct header for the
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responses. The main goal of <code>cgi.lua</code> is to give a
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starting point for other implementations.</p>
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<h2><a name="references"></a>References</h2>
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<p>Related documentation can be found at: <a href="http://www.xmlrpc.com">http://www.xmlrpc.com</a>.</p>
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</div> <!-- id="content" -->
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</div> <!-- id="main" -->
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<div id="about">
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<p>
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<a href="http://validator.w3.org/check?uri=referer">
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<img src="http://www.w3.org/Icons/valid-xhtml10" alt="Valid XHTML 1.0!" height="31" width="88" />
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</a>
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</p>
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</div> <!-- id="about" -->
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</div> <!-- id="container" -->
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</body>
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</html>
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