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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>Orbit</title>
<link rel="stylesheet" href="http://www.keplerproject.org/doc.css" type="text/css"/>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
</head>
<body>
<div id="container">
<div id="product">
<div id="product_logo">
<a href="http://www.keplerproject.org">
<img alt="Orbit" src="orbit.png"/>
</a>
</div>
<div id="product_name"><big><strong>Orbit</strong></big></div>
<div id="product_description">MVC for Lua Web Development</div>
</div> <!-- id="product" -->
<div id="main">
<div id="navigation">
<h1>Orbit</h1>
<ul>
<li><a href="index.html">Home</a>
<ul>
</ul>
</li>
<li><strong>Pages</strong>
<ul>
</ul>
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<li><a href="reference.html">Reference</a>
<ul>
</ul>
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<li><a href="example.html">Tutorial</a>
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<li><a href="license.html">License</a>
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<div id="content">
<h2>Orbit Pages</h2>
<p>Orbit Pages is a PHP-like programming environment built on top of Orbit. Orbit pages
are HTML pages (but using the extension .op in a typical Orbit installation) that
get dynamically converted into Orbit apps. They are launched by the op.cgi, op.fcgi
and ophandler.lua launchers, for CGI, FastCGI, and Xavante, respectively. A standard
Kepler installation includes support for Orbit pages by default.</p>
<p>An Orbit page is also a template that uses the <a href="http://cosmo.luaforge.net">Cosmo</a>
template language. The environment of this template is a sandbox that wraps the
global environment and is recreated on each request. The main variable in this
environment is the <code>web</code> variable, which is an Orbit request/response object.
Other variables of note:</p>
<p><strong>mapper</strong> - an instance of the default Orbit ORM</p>
<p><strong>model(<em>name</em>, <em>dao</em>)</strong> - same as mapper:new(<em>name</em>, <em>dao</em>), except that if <em>name</em>
is a tabel then calls mapper:new(<em>name[1]</em>, <em>name[2]</em>), so you can use this in the
template as <code>$model{ name, dao }</code></p>
<p><strong>app</strong> - the application's global environment, to be used as a session cache (for DB
connections, for example) for persistent launchers</p>
<p><strong>finish(<em>res</em>)</strong> - suspends the execution of the current page, and sends <em>res</em> as a
response <strong>instead</strong> of the page's contents</p>
<p><strong>redirect(<em>target</em>)</strong> - same as web:redirect(<em>target</em>) followed by finish(). If <em>target</em>
is a table does web:redirect(<em>target[1]</em>), so you can use this in the template as
<code>$redirect{ target }</code></p>
<p><strong>include(<em>page</em>, [<em>env</em>])</strong> - evaluates the Orbit page in the file <em>page</em> (relative to the
current page's path), optionally using the extra variables in <em>env</em> in the template's
environment. Can also be used in the template as <code>$include{ page, env }</code></p>
<p><strong>forward(<em>page</em>, [<em>env</em>])</strong> - aborts the execution of the current page and evaluates
and sends the page in file <em>page</em> instead; otherwise same as <strong>include</strong></p>
<p>There also a few more variables that should be used only in the template:</p>
<p><strong>$lua{ <em>code</em> }</strong> - runs <em>code</em> in the same environment as the page, so
<em>code</em> can change the template's variables and even define new ones</p>
<p><strong>$if{ <em>condition</em> }[[ <em>then-part</em> ]],[[ <em>else-part</em> ]]</strong> - if <em>condition</em> is true then
is replaced by the template evaluation of <em>then-part</em>, otherwise <em>else-part</em>. <em>else-part</em>
is optional, defaulting to blank</p>
<p><strong>$fill{ ... }[[ <em>template</em> ]]</strong> - replaced by the evaluation of <em>template</em> using the environment
passed to fill (<em>template</em> does <strong>not</strong> inherit the variables of the page)</p>
<p>Below is a very simple Orbit page that shows most of the concepts above (including Cosmo
concepts, see the Cosmo documentation for that):</p>
<pre><code> #!/usr/bin/env op.cgi
<html>
<body>
<p>Hello Orbit!</p>
<p>I am in $web|real_path, and the script is
$web|script_name.</p>
$lua{[[
if not web.input.msg then
web.input.msg = "nothing"
end
]]}
<p>You passed: $web|input|msg.</p>
$include{ "bar.op" }
</body>
</html>
</code></pre>
<p>The <code>bar.op</code> page it includes is this:</p>
<pre><code> #!/usr/bin/env op.cgi
<p>This is bar, and you passed $web|input|msg!</p>
</code></pre>
<p>The <a href="http://www.keplerproject.org">Kepler</a> distribution has a more complete example that has database
access, POST, and even some simple AJAX.</p>
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