522 lines
14 KiB
HTML
Executable File
522 lines
14 KiB
HTML
Executable File
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<meta name="generator" content="HTML Tidy, see www.w3.org">
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<title>LuaXMLRPC: XML-RPC interface to the Lua programming
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language</title>
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<style type="text/css">
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ul { list-style-type: disc };
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</style>
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</head>
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<body bgcolor="#FFFFFF">
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<hr>
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<center>
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<table border="0" cellspacing="2" cellpadding="2">
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<tr>
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<td align="center"><a href=
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"http://www.keplerproject.org/luaxmlrpc"><img border="0" alt=
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"LuaXMLRPC logo" src="luaxmlrpc.png"></a> </td>
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</tr>
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<tr>
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<td align="center"><big><b>LuaXMLRPC Reference Manual</b></big>
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</td>
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</tr>
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<tr>
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<td align="center" valign="top">XML-RPC interface to the <a href=
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"http://www.lua.org">Lua</a> programming language</td>
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</tr>
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</table>
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</center>
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<center><small><a href="index.html">home</a> · <a href=
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"#introduction">introduction</a> · <a href=
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"#data_types">data types</a> · <a href="#basic">basic</a>
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· <a href="#client">client</a> · <a href=
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"#server">server</a> · <a href="#examples">examples</a>
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· <a href="#related_docs">related docs</a></small></center>
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<hr>
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<a name="introduction"></a>
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<h2>Introduction</h2>
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<p>LuaXMLRPC is a <a href="http://www.lua.org">Lua</a> library to
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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 having to deal with
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XML code</li>
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<li>Transform Lua objects into XML-RPC data types and
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vice-versa</li>
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</ul>
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<p>LuaXMLRPC provides a simple API and an abstraction layer over
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XML avoiding manipulation of string representation of data
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structures.
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<!--It also offers ways to express everything when needed.-->
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</p>
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<p>LuaXMLRPC is based on <a href=
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"http://www.keplerproject.org/luaexpat">LuaExpat</a> and on <a
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href="http://www.lua.org">Lua 5.0</a>.<br>
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The abstraction layer over HTTP depends on <a href=
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"http://www.tecgraf.puc-rio.br/luasocket">LuaSocket 2.0</a>.<br>
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<a name="data_types"></a></p>
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<h2>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. <a name=
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"xr2lua"></a></p>
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<h3>From XML-RPC to Lua</h3>
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<p>When converting from XML-RPC element to a Lua object, a table
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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 border="1">
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<tr>
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<td>XML-RPC data type</td>
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<td>Lua object</td>
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</tr>
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<tr>
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<td>double<br>
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int<br>
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i4</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>struct<br>
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arrray</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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{
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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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}
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</pre>
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</td>
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</tr>
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</table>
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<a name="lua2xr"></a>
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<h3>From Lua to XML-RPC</h3>
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<p>A conversion from a Lua object to an XML-RPC can be made
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automatically or explicitly. The automatic conversion rules
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are:</p>
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<table border="1">
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<tr>
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<td>Lua object</td>
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<td>XML-RPC data type</td>
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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><i>val</i></value>
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</member>
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</struct>
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</pre>
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<small><i>val</i> 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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In 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. <!--
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Explicit conversions can be forced by the creation of <i>typed values</i>
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(see function <code><a href="#newtypedvalue">newTypedValue</a></code>).
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-->
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<a name="basic"></a>
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<h2>Basic support</h2>
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<p>The file <code>xmlrpc.lua</code> implements all basic support
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for encoding and decoding XML-RPC messages and for transforming
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data types between the two representations. Following is the list
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of functions.</p>
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<ul>
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<li style="list-style: none"><a name="clEncode"></a></li>
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<li><b><code>clEncode (method_name, params*) =>
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method_call</code></b><br>
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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. <a name="clDecode"></a></li>
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<li><b><code>clDecode (method_response) => ok,
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results</code></b><br>
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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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<i>faultString</i> and the <i>faultCode</i>. This values are
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extracted from the <code>fault</code> element. <a name=
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"srvDecode"></a></li>
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<li><b><code>srvDecode (method_call) => method_name,
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list_params</code></b><br>
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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. <a name=
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"srvEncode"></a></li>
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<li><b><code>srvEncode (object, is_fault) =>
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method_response</code></b><br>
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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 <i>one</i> value so a
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Lua function that returns more than one value has to <i>pack</i>
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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>. <!--
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<a name="newtypedvalue"></a>
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<li> <b><code>newTypedValue (object, type) => object</code></b> <br>
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Build a Lua object with the XML-RPC representation of the Lua
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<code>object</code> given according to the given <code>type</code>.
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<a name="newarray"></a>
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<li> <b><code>newArray (elemtype) => type</code></b> <br>
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Build an array type for use with
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<a href="newtypedvalue">newTypedValue</a>
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function.
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The <code>elemtype</code> can be one of the basic XML-RPC types or
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a constructed one.
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-->
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<a name="srvMethods"></a></li>
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<li><b><code>srvMethods (tab_or_func)</code></b><br>
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Register the methods on the server. The parameter can be a table
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or a dispatching function. If a <i>table</i> is given it can have
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one level of objects with the corresponding methods. If a
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<i>function</i> is given, it will replace the dispatcher. <a name=
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"dispatch"></a></li>
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<li><b><code>dispatch (method_name) => function</code></b><br>
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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.</li>
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</ul>
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<a name="client"></a>
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<h2>Client side</h2>
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<p>The file <code>xmlrpc.http.lua</code> implements a simple
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stand-alone client based on <a href=
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"http://www.tecgraf.puc-rio.br/luasocket">LuaSocket 2.0</a>. The
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following function is provided:</p>
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<ul>
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<li style="list-style: none"><a name="call"></a></li>
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<li><b><code>call (url, method, params*)</code></b><br>
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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 <i>faultString</i> and the
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<i>faultCode</i> (if the call fails). <!--
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The result is a boolean indicating whether the call was successful or
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not, followed by the response value (if successful) or by the faultString
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and the faultCode (if the call fails).
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-->
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</li>
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</ul>
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<a name="server"></a>
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<h2>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 file <code>xmlrpc.cgi.lua</code> implements a simple XML-RPC
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server using the package <code>post</code> that can parse 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.</p>
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<p>The main goal of this file is to give a starting point for other
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real implementations.</p>
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<a name="examples"></a>
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<h2>Examples</h2>
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<a name="client_example"></a>
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<h3>Client example</h3>
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Below is a small sample code displaying the use of the library in a
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client application.
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<blockquote>
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<pre>
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require "xmlrpc.http"
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local ok, res = xmlrpc.http.call ("http://www.oreillynet.com/meerkat/xml-rpc/server.php", "system.listMethods")
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print (ok)
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for i, v in pairs(res) do print ('\t', i, v) end
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</pre>
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</blockquote>
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<a name="types_example"></a>
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<h3>Type conversion example</h3>
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The next example shows how to force the conversion of types from
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Lua to XML-RPC.
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<blockquote>
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<pre>
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require "xmlrpc"
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double_array_type = xmlrpc.newArray ("double")
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double_array = xmlrpc.newTypedValue ( { 1.1, 2, 3, 4 }, double_array_type)
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double_array_array_type = xmlrpc.newArray (double_array_type)
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double_array_array = xmlrpc.newTypedValue (
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{
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{ 11, 12, 13, },
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{ 21, 22, 23, },
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{ 31, 32, 33, },
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}, double_array_array_type)
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</pre>
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</blockquote>
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The table <code>double_array_array</code> will be:
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<blockquote>
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<pre>
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<array>
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<data>
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<value>
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<array>
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<data>
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<value><double>11</double></value>
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<value><double>12</double></value>
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<value><double>13</double></value>
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</data>
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</array>
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</value>
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<value>
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<array>
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<data>
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<value><double>21</double></value>
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<value><double>22</double></value>
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<value><double>23</double></value>
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</data>
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</array>
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</value>
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<value>
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<array>
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<data>
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<value><double>31</double></value>
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<value><double>32</double></value>
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<value><double>33</double></value>
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</data>
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</array>
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</value>
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</data>
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</array>
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</pre>
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</blockquote>
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<a name="server_example"></a>
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<h3>Server example</h3>
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Follow a small example of a server based on a cgi launcher.
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<blockquote>
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<pre>
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require "xmlrpc.cgi"
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local kepler_home = "http://www.keplerproject.org"
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local kepler_products = { "luasql", "lualdap", "luaexpat", "luaxmlrpc", }
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local kepler_sites = {
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luasql = kepler_home.."/luasql",
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lualdap = kepler_home.."/lualdap",
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luaexpat = kepler_home.."/luaexpat",
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luaxmlrpc = kepler_home.."/luaxmlrpc",
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}
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-- Register methods
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xmlrpc.srvMethods {
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kepler = {
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products = function (self) return kepler_products end,
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site = function (self, prod) return kepler_sites[prod] end,
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}
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}
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-- Parse POST data
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local doc = {}
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post.parsedata (doc)
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-- Decode method call
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local method, arg_table = xmlrpc.srvDecode (doc[1])
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local func = xmlrpc.dispatch (method)
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local ok, result, err = pcall (func, unpack (arg_table or {}))
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if ok then
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result = { code = 3, message = result, }
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end
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respond (xmlrpc.srvEncode (result, not ok)
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</pre>
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</blockquote>
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Note that the package <code>post</code> and the function
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<code>respond</code> should be provided by the cgi launcher. <a
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name="related_docs"></a>
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<h2>Related documentation</h2>
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Here is a list of related documentation:
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<ul>
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<li><a href="http://www.xmlrpc.com">http://www.xmlrpc.com</a></li>
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</ul>
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<a name="contents"></a>
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<h2>Contents</h2>
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<ul>
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<li><a href="#introduction">Introduction</a></li>
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<li><a href="#data_types">Data types</a>
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<ul>
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<li><a href="#xr2lua">From XML-RPC to Lua</a></li>
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<li><a href="#lua2xr">From Lua to XML-RPC</a></li>
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</ul>
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</li>
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<li><a href="#basic">Basic support</a>
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<ul>
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<li><a href="#clEncode">clEncode</a></li>
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<li><a href="#clDecode">clDecode</a></li>
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<li><a href="#srvEncode">srvEncode</a></li>
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<li><a href="#srvDecode">srvDecode</a></li>
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<li><a href="#newtypedvalue">newTypedValue</a></li>
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<li><a href="#newarray">newArray</a></li>
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<li><a href="#srvMethods">srvMethods</a></li>
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<li><a href="#dispatch">dispatch</a></li>
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</ul>
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</li>
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<li><a href="#client">Client side</a>
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<ul>
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<li><a href="#call">call</a></li>
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</ul>
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</li>
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<li><a href="#server">Server side</a></li>
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<li><a href="#examples">Examples</a>
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<ul>
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<li><a href="#client_example">Client example</a></li>
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<li><a href="#types_example">Type conversion example</a></li>
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<li><a href="#server_example">Server example</a></li>
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</ul>
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</li>
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<li><a href="#related_docs">Related documentation</a></li>
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</ul>
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<br>
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<br>
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<center><small><a href="index.html">home</a> · <a href=
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"#introduction">introduction</a> · <a href=
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"#data_types">data types</a> · <a href="#basic">basic</a>
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· <a href="#client">client</a> · <a href=
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"#server">server</a> · <a href="#examples">examples</a>
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· <a href="#related_docs">related docs</a></small></center>
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<hr>
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<small>$Id: manual.html,v 1.7 2004/01/12 10:43:39 tomas Exp
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</html>
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