webmcp

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Updated year + version in documentation
author jbe
date Wed Apr 28 12:54:38 2021 +0200 (2021-04-28)
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jbe@566 85 <title>WebMCP 2.2.1 Documentation</title>
jbe/bsw@0 86 </head>
jbe/bsw@0 87 <body>
jbe@566 88 <h1>WebMCP 2.2.1 Documentation</h1>
jbe/bsw@0 89 <p>
jbe@278 90 WebMCP is a web development framework based on the Lua programming language (read more about Lua <a href="http://www.lua.org/about.html">here</a>).
jbe/bsw@0 91 </p>
jbe/bsw@0 92 <h2>Requirements</h2>
jbe/bsw@0 93 <p>
jbe@387 94 WebMCP has been developed on Linux and FreeBSD. Using it with Mac&nbsp;OS&nbsp;X is untested as of yet; Microsoft Windows is not supported. Beside the operating system, the only mandatory dependencies for WebMCP are the <a href="http://www.lua.org/">programming language Lua</a> version 5.2 or 5.3, the <a href="http://www.public-software-group.org/moonbridge">Moonbridge Network Server for Lua Applications</a> version 1.0.1 or higher, <a href="http://www.postgresql.org/">PostgreSQL</a> version 8.2 or higher, and a C compiler.
jbe/bsw@0 95 </p>
jbe/bsw@0 96 <h2>Installation</h2>
jbe/bsw@0 97 <p>
jbe@525 98 Please read the following instructions carefully to avoid problems during installation.
jbe@507 99 </p>
jbe@525 100 <ol>
jbe@525 101 <li>Download and compile the <a href="http://www.public-software-group.org/moonbridge">Moonbridge Network Server for Lua Applications</a> (follow the README file of Moonbridge).</li>
jbe@525 102 <li>Optional: Ensure that the <tt>moonbridge</tt> binary is within the search path for binaries.</li>
jbe@525 103 <li>Optional: Ensure that the <tt>moonbridge_http.lua</tt> file is covered by Lua's <a href="https://www.lua.org/manual/5.3/manual.html#pdf-package.path">package path</a> (see Lua's <a href="https://www.lua.org/manual/5.3/manual.html#pdf-package.searchpath">search path documentation</a> on how to format the <tt>LUA_PATH</tt> environment variable).</li>
jbe@525 104 <li>Download <a href="http://www.public-software-group.org/webmcp">WebMCP</a>.</li>
jbe@525 105 <li>Enter WebMCP's unpacked source code directory and execute the command "<tt>make</tt>".</li>
jbe@525 106 <li>If you experience problems during step&nbsp;3, edit the <tt>Makefile.options</tt> file and repeat step&nbsp;3.</li>
jbe@525 107 <li>The <tt>framework/</tt> directory (or the <tt>framework.precompiled</tt> directory if you want to use precompiled code) is WebMCP's framework base directory now. It may be copied to any other directory of your choice (but make sure to follow links, e.g. using <tt>cp -L -R</tt>, when copying the directory to a different place).</li>
jbe@525 108 <li>If optional step&nbsp;3 has been skipped, ensure that Moonbridge's <tt>moonbridge_http.lua</tt> file is soft-linked or copied to the <tt>lib/</tt> directory of the framework's base directory.</li>
jbe@525 109 </li>
jbe@525 110 </ol>
jbe@507 111 <h2>Configuration, initializers, and request handling</h2>
jbe@507 112 <p>
jbe@526 113 A WebMCP application may consist of several (sub-)applications. Each application sharing the same base directory also shares the database models but may provide different views and actions. The views and actions of an application are found within the "<tt>app/</tt><i>application_name</i><tt>/</tt>" directory, relative to the application base path. When starting WebMCP, the application's base path as well as the desired application name must be provided.
jbe@526 114 </p>
jbe@526 115 <p>
jbe@526 116 In addition to selection of an application, a config file must be chosen when starting the application. This enables to run an application in different contexts, e.g. you may have one configuration file for development purposes and one for productive use. Configuration files are found in the "<tt>config/</tt>" directory, relative to the application base path.
jbe@526 117 </p>
jbe@526 118 <p>
jbe@526 119 WebMCP uses the <a href="http://www.public-software-group.org/moonbridge">Moonbridge Network Server</a> to handle HTTP requests. The Moonbridge Network Server listens to a TCP port and passes control to WebMCP (by invoking <tt>bin/mcp.lua</tt> in the framework's base directory), eventually resulting in a call of <a href="#request.handler"><tt>request.handler(...)</tt></a> for each request. However, before any request is processed, WebMCP will initialize the environment. This initialization includes tasks such as
jbe@507 120 </p>
jbe@507 121 <ul>
jbe@507 122 <li>loading libraries,</li>
jbe@507 123 <li>configuring the database connection or the application,</li>
jbe@507 124 <li>connecting to the database,</li>
jbe@507 125 <li>etc.</li>
jbe@507 126 </ul>
jbe@507 127 <p>
jbe@507 128 For each request, it is also possible to execute filters. Filters can be used to
jbe@278 129 </p>
jbe@507 130 <ul>
jbe@507 131 <li>
jbe@521 132 restrict access for certain requests, e.g. by performing redirects or raising errors,
jbe@507 133 </li>
jbe@507 134 <li>
jbe@507 135 perform tasks that are common for different requests, e.g.
jbe@507 136 <ul>
jbe@521 137 <li>execute certain database requests,</li>
jbe@507 138 <li>prepare a menu on the website,</li>
jbe@507 139 <li>&hellip;</li>
jbe@507 140 </ul>
jbe@507 141 </li>
jbe@507 142 </ul>
jbe@278 143 <p>
jbe@526 144 Filters and initializers are created by adding files in the application's directory structure. The filename determines the execution order (lexicographical order). It is a common idiom to start the filename of a filter or initializer with a two digit number to be easily able to change the execution order when desired. Filters and initializers are wrapping requests, i.e. part of them is executed before and part after the remaining request handling.
jbe@526 145 </p>
jbe@526 146 <p>
jbe@526 147 When an initializer or filter calls <a href="#execute.inner"><tt>execute.inner()</tt></a>, execution of the initializer or filter is suspended and the remaining initializers and/or filters or the requested view or action are executed. Afterwards, the interrupted filters and initializers are resumed in reverse order (from where they called <tt>execute.inner()</tt>). Most often, <tt>execute.inner()</tt> is the last line in an initializer or filter, resulting in all code to be executed prior to request handling (and nothing to be executed afterwards).
jbe@507 148 </p>
jbe@507 149 <p>
jbe@507 150 The Moonbridge server creates forks (i.e. clones) of the application server process (i.e. the whole Lua engine including all libraries and variables) in order to handle concurrent requests. Certain initializations may be performed before forking, other initializations must be performed after forking. For this purpose, WebMCP allows an application to provide so-called "pre-fork" and "post-fork" initializers. The application's configuration files as well as its pre-fork initializers are executed before forking. The application's post-fork initializers are executed after forking. In particular, any libraries that open file or network handles during initialization must not be loaded before the server process is forked. Opening database connections must be performed after forking as well. WebMCP follows the following execution order (directory structure is explained further down):
jbe@278 151 </p>
jbe@278 152 <ol>
jbe@278 153 <li>
jbe@520 154 Initialization code of <tt>mcp.lua</tt> in the <tt>bin/</tt> directory of the framework, including:
jbe@520 155 <ul>
jbe@520 156 <li>Initialization of WebMCP's autoloader in <tt>mcp.lua</tt> (in the <tt>bin/</tt> directory of the framework),</li>
jbe@520 157 <li>Execution of <tt>env/__init.lua</tt> (both relative to the framework and, if existent, relative to the application base directory)</li>
jbe@520 158 <li>Loading of most of WebMCP's libraries (excluding "multirand" library, which must not be loaded prior to forking);</li>
jbe@520 159 </ul>
jbe@278 160 </li>
jbe@278 161 <li>
jbe@520 162 Executing the selected configuration file: <tt>config/</tt><i>configuration_name</i><tt>.lua</tt>;
jbe@278 163 </li>
jbe@278 164 <li>
jbe@520 165 Executing all pre-fork initializers (both those in the <tt>app/_prefork/</tt> and those in the <tt>app/</tt><i>application_name</i><tt>/_prefork/</tt> directory) until call of <tt>execute.inner()</tt> within each initializer;
jbe@278 166 </li>
jbe@278 167 <li>
jbe@520 168 The Moonbridge Network Server forks the process (i.e. cloning the whole Lua machine);<br />
jbe@278 169 <span style="color: red">Note: no file handles or network connections must be opened prior to this point!</span>
jbe@278 170 </li>
jbe@278 171 <li>
jbe@520 172 Loading WebMCP's "multirand" library;
jbe@281 173 </li>
jbe@281 174 <li>
jbe@520 175 Executing all post-fork initializers (both those in the <tt>app/_postfork/</tt> and those in the <tt>app/</tt><i>application_name</i><tt>/_postfork/</tt> directory) until call of <tt>execute.inner()</tt> within each initializer;
jbe@278 176 </li>
jbe@278 177 <li>
jbe@278 178 For each request:
jbe@278 179 <ul>
jbe@278 180 <li>
jbe@520 181 Execution of all applicable filters until call of <tt>execute.inner()</tt> within each filter,
jbe@278 182 </li>
jbe@278 183 <li>
jbe@520 184 Handling of the request by calling the appropriate view or action,
jbe@278 185 </li>
jbe@278 186 <li>
jbe@520 187 Resuming execution of all filters in reverse order from that position where <tt>execute.inner()</tt> had been called;
jbe@278 188 </li>
jbe@278 189 </ul>
jbe@278 190 </li>
jbe@278 191 <li>
jbe@520 192 Resuming execution of all post-fork initializers in reverse order from that position where <tt>execute.inner()</tt> had been called;
jbe@278 193 </li>
jbe@278 194 <li>
jbe@520 195 Resuming execution of all pre-fork initializers in reverse order from that position where <tt>execute.inner()</tt> had been called.
jbe@278 196 </li>
jbe@278 197 </ol>
jbe/bsw@0 198 </p>
jbe@439 199 <p>
jbe@509 200 As a minimum configuration, the used configuration file or pre-fork initializer should at least contain a <a href="#listen"><tt>listen{...}</tt></a> call, e.g.:
jbe@439 201 </p>
jbe@439 202 <pre>
jbe@439 203 listen{
jbe@439 204 { proto = "tcp", host = "::", port = 8080 },
jbe@439 205 { proto = "tcp", host = "0.0.0.0", port = 8080 }
jbe@439 206 }
jbe@507 207 execute.inner() -- only use this line if done in pre-fork initializer</pre>
jbe/bsw@0 208 <h2>Using the atom library</h2>
jbe/bsw@0 209 <p>
jbe/bsw@0 210 Lua itself has only very few built-in data types. The atom library gives support for extra data types. Currently the following extra data types are provided:
jbe/bsw@0 211 </p>
jbe/bsw@0 212 <ul>
jbe@509 213 <li><a href="#atom.fraction:new">atom.fraction</a></li>
jbe@509 214 <li><a href="#atom.date:new">atom.date</a></li>
jbe@509 215 <li><a href="#atom.time:new">atom.time</a></li>
jbe@509 216 <li><a href="#atom.timestamp:new">atom.timestamp (date and time combined in one data type)</a></li>
jbe/bsw@0 217 </ul>
jbe/bsw@0 218 <p>
jbe/bsw@0 219 In addition the following pseudo-types are existent, corresponding to Lua's base types:
jbe/bsw@0 220 </p>
jbe/bsw@0 221 <ul>
jbe/bsw@0 222 <li>atom.boolean</li>
jbe/bsw@0 223 <li>atom.string</li>
jbe/bsw@0 224 <li>atom.integer</li>
jbe/bsw@0 225 <li>atom.number</li>
jbe/bsw@0 226 </ul>
jbe/bsw@0 227 <p>
jbe/bsw@0 228 Both atom.integer and atom.number refer to Lua's base type &ldquo;number&rdquo;.
jbe/bsw@0 229 </p>
jbe/bsw@0 230 <p>
jbe@514 231 New values of atom data types are created by either calling <tt>atom.</tt><i>type</i><tt>:load(string_representation)</tt> or by calling <tt>atom.</tt><i>type</i><tt>{...}</tt>, e.g. <tt>atom.date{year=1970, month=1, day=1}</tt>. Note that <tt>atom.date{...}</tt> is a shortcut for <tt><a href="#atom.date:new">atom.date:new</a>{...}</tt>. You can dump any atom value as a string by calling <a href="#atom.dump"><tt>atom.dump(value)</tt></a> and later reload it with <tt>atom.</tt><i>type</i><tt>:load(string)</tt>.
jbe/bsw@0 232 </p>
jbe/bsw@0 233 <h2>Using the Object-Relational Mapper &ldquo;mondelefant&rdquo;</h2>
jbe/bsw@0 234 <p>
jbe@278 235 The library &ldquo;mondelefant&rdquo; shipping with WebMCP can be used to access PostgreSQL databases. It also serves as an Object-Relational Mapper (ORM). The database connection is usually configured in the config file (e.g. in <tt>config/devel.lua</tt>):
jbe@278 236 </p>
jbe@278 237 <pre>
jbe@439 238 config.db = { engine="postgresql", dbname="webmcp_demo" }</pre>
jbe@278 239 <p>
jbe@278 240 In addition to configuring the database, it must be opened within a post-fork initializer (e.g. in <tt>app/_postfork/01_database.lua</tt>):
jbe/bsw@0 241 </p>
jbe/bsw@0 242 <pre>
jbe@509 243 _G.db = assert(<a href="#mondelefant.connect">mondelefant.connect</a>(config.db))
jbe@509 244 function mondelefant.class_prototype:<a href="#db_class:get_db_conn">get_db_conn</a>() return db end
jbe@439 245 execute.inner()</pre>
jbe/bsw@0 246 <p>
jbe@515 247 The parameters for <tt>mondelefant.connect</tt> are directly passed to PostgreSQL's client library libpq. See PostgreSQL's documentation for information about <a href="https://www.postgresql.org/docs/9.6/static/libpq-connect.html#LIBPQ-PARAMKEYWORDS">supported parameters</a>.
jbe/bsw@0 248 </p>
jbe/bsw@0 249 <p>
jbe/bsw@0 250 To define a model to be used within a WebMCP application, create a file named with the name of the model and <tt>.lua</tt> as extension in the <tt>model/</tt> directory of your application. The most basic definition of a model (named &ldquo;movie&rdquo; in this example) is:
jbe/bsw@0 251 </p>
jbe/bsw@0 252 <pre>
jbe@509 253 Movie = <a href="#mondelefant.new_class">mondelefant.new_class</a>()
jbe/bsw@0 254 Movie.table = 'movie'</pre>
jbe/bsw@0 255 <p>
jbe/bsw@0 256 Note: Model classes are always written CamelCase, while the name of the file in <tt>model/</tt> is written lower_case.
jbe/bsw@0 257 </p>
jbe/bsw@0 258 <p>
jbe/bsw@0 259 To select objects from the database, the mondelefant library provides a selector framework:
jbe/bsw@0 260 </p>
jbe/bsw@0 261 <pre>
jbe@509 262 local s = Movie:<a href="#db_class:new_selector">new_selector</a>()
jbe@509 263 s:<a href="#db_selector:add_where">add_where</a>{ 'id = ?', param.get_id() }
jbe@509 264 s:<a href="#db_selector:single_object_mode">single_object_mode</a>() -- return single object instead of list
jbe@509 265 local movie = s:<a href="#db_selector:exec">exec</a>()</pre>
jbe/bsw@0 266 <p>
jbe/bsw@0 267 A short form of the above query would be:
jbe/bsw@0 268 </p>
jbe/bsw@0 269 <pre>
jbe/bsw@0 270 local movie = Movie:new_selector():add_where{ 'id = ?', param.get_id() }:single_object_mode():exec()</pre>
jbe/bsw@0 271 <p>
jbe/bsw@0 272 For more examples about how to use the model system, please take a look at the demo application.
jbe/bsw@0 273 </p>
jbe/bsw@0 274 <h2>The Model-View-Action (MVA) concept</h2>
jbe/bsw@0 275 <p>
jbe/bsw@0 276 As opposed to other web application frameworks, WebMCP does not use a Model-View-Controller (MVC) concept, but a Model-View-Action (MVA) concept.
jbe/bsw@0 277 </p>
jbe/bsw@0 278 <h3>Models</h3>
jbe/bsw@0 279 <p>
jbe@513 280 The models in MVA are like the models in MVC; they are used to access data, which is stored in a relational database (PostgreSQL), in an object oriented way. Methods provided by the corresponding classes can be used to alter stored objects or execute any other associated program code. Models are usually defined in a file with a lowercase filename ending with "<tt>.lua</tt>" in the <tt>models/</tt> directory of the application. The corresponding model name (i.e. class name) must be written in CamelCase, e.g. "<tt>models/my_model.lua</tt>" should define a model class named "<tt>MyModel</tt>". The simplest model is created by calling <a href="#mondelefant.new_class"><tt>mondelefant.new_class()</tt></a> and subsequently setting the <a href="#db_class.table"><tt>table</tt></a> attribute of the returned class.
jbe@509 281 </p>
jbe@509 282 <pre>
jbe@509 283 -- filename: model/customer_receipt.lua
jbe@509 284 CustomerReceipt = mondelefant.new_class()
jbe@509 285 CustomerReceipt.table = "custreceipt"</pre>
jbe@509 286 <p>
jbe@509 287 Methods such as <a href="#db_class:add_reference"><tt>:add_reference(...)</tt></a> can be used to further modify or extend the class.
jbe/bsw@0 288 </p>
jbe/bsw@0 289 <h3>Views</h3>
jbe/bsw@0 290 <p>
jbe@513 291 The views in the MVA concept are different from the views in the MVC concept. As WebMCP has no controllers, the views are responsible for processing the GET/POST parameters from the webbrowser, fetching the data to be displayed, and creating the output by directly writing HTML to slots of a layout (see <a href="#slot.select"><tt>slot.select(...)</tt></a>, <a href="#slot.put"><tt>slot.put(...)</tt></a>, and <a href="#slot.put_into"><tt>slot.put_into(...)</tt></a> or by calling helper functions for the user interface (those functions beginning with "<tt>ui.</tt>"). Views are stored in files with the file path "<tt>app/</tt><i>application_name</i><tt>/</tt><i>module_name</i><tt>/</tt><i>view_name</i><tt>.lua</tt>". When their corresponding URL, e.g. "<tt>http://</tt><i>hostname</i><tt>:</tt><i>port</i><tt>/</tt><i>module_name</i><tt>/</tt><i>view_name</i><tt>.html</tt>", is requested, the code in that file gets executed (after calling appropriate filters). After the execution of the view has finished (and after all filters have finished their execution too), the slot data will be inserted into placeholder sections in the selected layout file. The layout file defaults to "<tt>app/</tt><i>application_name</i><tt>/_layout/default.html</tt>" but may be changed using the <a href="#slot.set_layout"><tt>slot.set_layout(...)</tt></a> function.
jbe/bsw@0 292 </p>
jbe/bsw@0 293 <h3>Actions</h3>
jbe/bsw@0 294 <p>
jbe@509 295 Actions are similar to views, but supposed to change data in the database, hence only callable by HTTP POST requests. They are also responsible for processing the POST parameters from the webbrowser. They can modify the database, but instead of rendering a page to be displayed, they just return a status code string (via Lua's <tt>return</tt> statement, where <tt>true</tt> can also be used instead of "<tt>ok</tt>", and <tt>false</tt> instead of "<tt>error</tt>"). Depending on the status string there will be an internal forward or an HTTP 303 redirect to a view. When calling an action via a POST request, additional POST parameters, which are usually added by hidden form fields, determine the view to be displayed for each status string returned by the action. See the <tt>routing</tt> parameter to the <a href="#ui.form"><tt>ui.form{...}</tt></a> function for further details.
jbe/bsw@0 296 </p>
jbe@510 297 <h2>Layouts</h2>
jbe@510 298 <p>
jbe@510 299 Templates for HTML documents to be returned by views are stored at the path "<tt>app/</tt><i>application_name</i><tt>/_layout/</tt><i>layout_name</i><tt>.html</tt>", relative to the application base path. The default layout name is "<tt>default</tt>". For system errors, the layout name "<tt>system_error</tt>" is used. A sample layout is given as follows:
jbe@510 300 </p>
jbe@510 301 <pre>
jbe@510 302 &lt;!DOCTYPE HTML&gt;
jbe@510 303 &lt;html&gt;
jbe@510 304 &lt;head&gt;
jbe@510 305 &lt;title&gt;&lt!-- WEBMCP SLOTNODIV title --&gt;&lt;/title&gt;
jbe@510 306 &lt;link rel="stylesheet" type="text/css" media="screen" href="__BASEURL__/static/style.css"/&gt;
jbe@510 307 &lt;/head&gt;
jbe@510 308 &lt;body&gt;
jbe@510 309 &lt;!-- WEBMCP SLOT content --&gt;
jbe@510 310 &lt;/body&gt;
jbe@510 311 &lt;/html&gt;</pre>
jbe@510 312 <p>
jbe@510 313 The following elements in a layout file get replaced automatically:
jbe@510 314 </p>
jbe@510 315 <ul>
jbe@510 316 <li><tt>__BASEURL__</tt> gets replaced with the application's base web address.</li>
jbe@510 317 <li><tt>&lt;!-- WEBMCP SLOT </tt><i>slot_name</i><tt> --&gt;</tt> gets, if the slot is not empty, replaced with a <tt>&lt;div&gt;</tt> element (with the <tt>id</tt> attribute set to "<tt>slot_</tt><i>slotname</i>") that contains the slot's content.</li>
jbe@510 318 <li><tt>&lt;!-- WEBMCP SLOTNODIV </tt><i>slot_name</i><tt> --&gt;</tt> gets replaced with the slot's content (without wrapping it in an additional <tt>&lt;div&gt;</tt> element).</li>
jbe@510 319 </ul>
jbe@511 320 <h2>Internationalization/Localization</h2>
jbe@511 321 <p>
jbe@511 322 To translate certain strings in your application, simply use the <a href="#_">underscore function</a>. A language can be selected with <tt><a href="#locale.set">locale.set</a>{lang = "code"}</tt> where <tt>code</tt> is a language code. The translations for strings are expected to be contained in files "<tt>locale/translations.</tt><i>language_code</i><tt>.lua</tt>". These files should return a table that maps strings to their corresponding translation:
jbe@511 323 </p>
jbe@511 324 <pre>
jbe@511 325 return{
jbe@511 326 ["Are you sure?"] = "Bist Du sicher?";
jbe@511 327 ["User '#{name}' created"] = "Benutzer '#{name}' created";
jbe@511 328 }</pre>
jbe@511 329 <p>
jbe@511 330 Such translation files can be automatically created with the <tt>langtool.lua</tt> program, found in the framework's <tt>bin/</tt> directory.
jbe@511 331 </p>
jbe@518 332 <h2>Global variables and the environment</h2>
jbe@518 333 <p>
jbe@518 334 To avoid accidental programming errors, WebMCP forbids setting of global variables by default. This is overridden by using the prefix "<tt>_G.</tt>" (<a href="#_G">see reference</a>) when setting the variable, e.g. <tt>_G.myvar = 7</tt>, or by setting the variable in a file with the same name of the global varaible (but suffixed with "<tt>.lua</tt>") in the <tt>env/</tt> directory of the framework or application. Note, however, that the lifetime of global variables is not predictable as it depends on process recycling of the Moonbridge webserver (one fork will handle more than one request) and because there may be multiple forks of the Lua machine which all have their own global variable space (there is usually more than one fork).
jbe@518 335 </p>
jbe@518 336 <p>
jbe@519 337 If an application needs to store request related data, the global table <a href="#app"><tt>app</tt></a> should be used (e.g. <tt>app.myvar = true</tt> instead of <tt>_G.myvar = true</tt>). The <tt>app</tt> table gets automatically initialized (i.e. emptied) for each request.
jbe@519 338 </p>
jbe@519 339 <p>
jbe@518 340 Global variables are still useful when providing access to libraries, for example. WebMCP automatically loads certain libraries and functions though an autoloader mechanism. On read-accessing any unknown variable, WebMCP will search the framework's and application's <tt>env/</tt> directories for an appropriate file (e.g. "<tt>my_func.lua</tt> if you invoke "<tt>my_func()</tt>") or a matching directory (e.g. "<tt>my_module/</tt> if you access "<tt>my_module.my_func()</tt>). In case of an existing directory in <tt>env/</tt>, an empty table with autoloading capabilities is automatically created as global variable with the name of the directory. The autoloading mechanism allows directories to contain further files which can be used to initialize variables within that table when accessed. Directories can also contain a special file called "<tt>__init.lua</tt>" that always gets executed when the table is accessed for the first time. The <tt>env/</tt> root directory can also contain a file ("<tt>env/__init__.lua</tt>") which gets executed before any configuration is loaded.
jbe@518 341 </p>
jbe@518 342 <p>
jbe@519 343 A good place to store utility functions is a global table called <tt>util</tt>. This table will be automatically accessible if you create a <tt>env/util/</tt> directory in your WebMCP application. To provide a function <tt>util.myfunc(...)</tt> simply create a file <tt>env/util/myfunc.lua</tt>, with the following function definition:
jbe@518 344 </p>
jbe@519 345 <pre>
jbe@519 346 -- filename: env/util/myfunc.lua
jbe@519 347 function util.myfunc()
jbe@519 348 slot.put_into("hello", "Hello World!")
jbe@519 349 end</pre>
jbe/bsw@0 350 <h2>Directory structure of a WebMCP application</h2>
jbe@513 351 <p>
jbe@513 352 Summarizing information from the previous section, we get the following directory structure for a WebMCP application:
jbe@513 353 </p>
jbe/bsw@0 354 <ul>
jbe/bsw@0 355 <li>
jbe/bsw@0 356 Base Directory
jbe/bsw@0 357 <ul>
jbe/bsw@0 358 <li>
jbe/bsw@0 359 <tt>app/</tt>
jbe/bsw@0 360 <ul>
jbe@510 361 <li><tt>_prefork/</tt></li>
jbe@510 362 <li><tt>_postfork/</tt></li>
jbe/bsw@0 363 <li>
jbe@510 364 <tt>main/</tt> (typically "main" is the only application)
jbe@278 365 <ul>
jbe@510 366 <li><tt>_prefork/</tt></li>
jbe@510 367 <li><tt>_postfork/</tt></li>
jbe@510 368 <li><tt>_filter/</tt></li>
jbe@510 369 <li><tt>_filter_action/</tt></li>
jbe@510 370 <li><tt>_filter_view/</tt></li>
jbe@510 371 <li><tt>_layout/</tt></li>
jbe@278 372 <li>
jbe@510 373 <tt>index/</tt> (module "index" is the default module)
jbe/bsw@0 374 <ul>
jbe/bsw@0 375 <li>
jbe/bsw@0 376 <tt>_action/</tt>
jbe/bsw@0 377 <ul>
jbe@510 378 <li><i>action_name</i><tt>.lua</tt></li>
jbe@510 379 <li><i>another_action_name</i><tt>.lua</tt></li>
jbe/bsw@0 380 <li>&hellip;</li>
jbe/bsw@0 381 </ul>
jbe/bsw@0 382 </li>
jbe@510 383 <li><tt>index.lua</tt> (view "index" of module "index" is the default view)</li>
jbe@510 384 <li><i>other_view_name</i><tt>.lua</tt></li>
jbe/bsw@0 385 <li>&hellip;</li>
jbe/bsw@0 386 </ul>
jbe/bsw@0 387 </li>
jbe/bsw@0 388 <li>
jbe/bsw@0 389 <i>other_module_name</i><tt>/</tt>
jbe@510 390 <ul><li>&hellip;</li></ul>
jbe/bsw@0 391 </li>
jbe/bsw@0 392 </ul>
jbe/bsw@0 393 </li>
jbe/bsw@0 394 <li>
jbe/bsw@0 395 <i>other_application_name</i><tt>/</tt>
jbe/bsw@0 396 <ul>
jbe/bsw@0 397 <li>&hellip;</li>
jbe/bsw@0 398 </ul>
jbe/bsw@0 399 </li>
jbe/bsw@0 400 </ul>
jbe/bsw@0 401 </li>
jbe/bsw@0 402 <li>
jbe/bsw@0 403 <tt>config/</tt>
jbe/bsw@0 404 <ul>
jbe@510 405 <li><tt>development.lua</tt> (e.g. to be used for development purposes)</li>
jbe@510 406 <li><tt>production.lua</tt> (e.g. to be used for production)</li>
jbe@510 407 <li><i>other_config_name</i><tt>.lua</tt></li>
jbe/bsw@0 408 <li>&hellip;</li>
jbe/bsw@0 409 </ul>
jbe/bsw@0 410 </li>
jbe/bsw@0 411 <li>
jbe/bsw@0 412 <tt>db/</tt>
jbe/bsw@0 413 <ul>
jbe@510 414 <li><tt>schema.sql</tt> (not used by WebMCP, but may be used to initialize a database)</li>
jbe/bsw@0 415 </ul>
jbe/bsw@0 416 </li>
jbe/bsw@0 417 <li>
jbe@518 418 <tt>env/</tt>
jbe@518 419 <ul>
jbe@518 420 <li><tt>__init.lua</tt></li>
jbe@519 421 <li><i>some_global_variable_name</i><tt>.lua</tt></li>
jbe@518 422 <li>
jbe@519 423 <i>another_global_variable_name</i><tt>/</tt>
jbe@518 424 <ul>
jbe@518 425 <li><tt>__init.lua</tt></li>
jbe@518 426 <li><i>attribute_name</i><tt>.lua</tt></li>
jbe@518 427 <li>
jbe@518 428 <i>another_attibute_name</i><tt>/</tt>
jbe@518 429 <ul><li>&hellip;</li></ul>
jbe@518 430 </li>
jbe@518 431 </ul>
jbe@518 432 </li>
jbe@518 433 </ul>
jbe@518 434 <li>
jbe@510 435 <tt>locale/</tt> (translation files used by the <a href="#_">underscore function</a>")
jbe/bsw@0 436 <ul>
jbe/bsw@0 437 <li>
jbe/bsw@0 438 <tt>translations.de.lua</tt>
jbe/bsw@0 439 </li>
jbe/bsw@0 440 <li>
jbe/bsw@0 441 <tt>translations.en.lua</tt>
jbe/bsw@0 442 </li>
jbe/bsw@0 443 <li>
jbe/bsw@0 444 <tt>translations.</tt><i>languagecode</i><tt>.lua</tt>
jbe/bsw@0 445 </li>
jbe/bsw@0 446 <li>&hellip;</li>
jbe/bsw@0 447 </ul>
jbe/bsw@0 448 </li>
jbe/bsw@0 449 <li>
jbe/bsw@0 450 <tt>model/</tt>
jbe/bsw@0 451 <ul>
jbe/bsw@0 452 <li>
jbe@510 453 <i>model_name</i><tt>.lua</tt> (code must create a model class in camel case, e.g. "<tt>ModelName</tt>" if the file name is "<tt>model_name.lua</tt>")
jbe/bsw@0 454 </li>
jbe/bsw@0 455 <li>
jbe/bsw@0 456 <i>another_model_name</i><tt>.lua</tt>
jbe/bsw@0 457 </li>
jbe/bsw@0 458 <li>&hellip;</li>
jbe/bsw@0 459 </ul>
jbe/bsw@0 460 </li>
jbe/bsw@0 461 <li>
jbe/bsw@0 462 <tt>static/</tt>
jbe/bsw@0 463 <ul>
jbe/bsw@0 464 <li>&hellip; (images, javascript, ...)</li>
jbe/bsw@0 465 </ul>
jbe/bsw@0 466 </li>
jbe/bsw@0 467 <li>
jbe@510 468 <tt>tmp/</tt> (needs to be writable by the user executing WebMCP)
jbe/bsw@0 469 </li>
jbe/bsw@0 470 </ul>
jbe/bsw@0 471 </li>
jbe/bsw@0 472 </ul>
jbe@278 473 <h2>Starting your application</h2>
jbe@278 474 <p>
jbe@527 475 If the <tt>moonbridge</tt> executable is within your system's search path for binaries (i.e. if optional step&nbsp;2 of the installation instructions has been carried out), you can directly call the <tt>mcp.lua</tt> script (found in <tt>framework/bin/mcp.lua</tt>). Pass the following arguments to <tt>mcp.lua</tt>:
jbe@513 476 </p>
jbe@513 477 <ol>
jbe@513 478 <li>Path of the WebMCP framework directory, e.g. <tt>./framework</tt></li>
jbe@513 479 <li>Path of your application's directory, e.g. <tt>./demo-app</tt></li>
jbe@522 480 <li>Name of your application (usually <tt>main</tt>)</li>
jbe@513 481 <li>Name of configuration (e.g. <tt>devel</tt> to use config/devel.lua)</li>
jbe@513 482 </ol>
jbe@513 483 <p>
jbe@527 484 Alternatively, the <tt>moonbridge</tt> binary may be called manually (e.g. by invoking <tt>../moonbridge/moonbridge</tt>). In this case, the following five arguments are required:
jbe@278 485 </p>
jbe@278 486 <ol>
jbe@513 487 <li>Path to <tt>mcp.lua</tt>, e.g. <tt>./framework/bin/mcp.lua</tt></li>
jbe@513 488 <li>Path of the WebMCP framework directory, e.g. <tt>./framework</tt></li>
jbe@513 489 <li>Path of your application's directory, e.g. <tt>./demo-app</tt></li>
jbe@522 490 <li>Name of your application (usually <tt>main</tt>)</li>
jbe@513 491 <li>Name of configuration (e.g. <tt>devel</tt> to use config/devel.lua)</li>
jbe@278 492 </ol>
jbe@513 493 <p>
jbe@513 494 Note that the demo application will require a database to be set up prior to starting. Execute the following shell commands first:
jbe@513 495 </p>
jbe@513 496 <pre>
jbe@513 497 createdb webmcp_demo
jbe@513 498 psql -v ON_ERROR_STOP=1 -f demo-app/db/schema.sql webmcp_demo</pre>
jbe/bsw@0 499 <h2>Automatically generated reference for the WebMCP environment</h2>
jbe/bsw@0 500 <ul>

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