<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html xmlns:fn="http://www.w3.org/2005/02/xpath-functions"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <link rel="stylesheet" href="../../../../doc/otp_doc.css" type="text/css"> <title>Erlang -- WebTool User Guide</title> </head> <body bgcolor="white" text="#000000" link="#0000ff" vlink="#ff00ff" alink="#ff0000"><div id="container"> <script id="js" type="text/javascript" language="JavaScript" src="../../../../doc/js/flipmenu/flipmenu.js"></script><script id="js2" type="text/javascript" src="../../../../doc/js/erlresolvelinks.js"></script><script language="JavaScript" type="text/javascript"> <!-- function getWinHeight() { var myHeight = 0; if( typeof( window.innerHeight ) == 'number' ) { //Non-IE myHeight = window.innerHeight; } else if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) { //IE 6+ in 'standards compliant mode' myHeight = document.documentElement.clientHeight; } else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) { //IE 4 compatible myHeight = document.body.clientHeight; } return myHeight; } function setscrollpos() { var objf=document.getElementById('loadscrollpos'); document.getElementById("leftnav").scrollTop = objf.offsetTop - getWinHeight()/2; } function addEvent(obj, evType, fn){ if (obj.addEventListener){ obj.addEventListener(evType, fn, true); return true; } else if (obj.attachEvent){ var r = obj.attachEvent("on"+evType, fn); return r; } else { return false; } } addEvent(window, 'load', setscrollpos); //--></script><div id="leftnav"><div class="innertube"> <img alt="Erlang logo" src="../../../../doc/erlang-logo.png"><br><small><a href="users_guide.html">User's Guide</a><br><a href="index.html">Reference Manual</a><br><a href="release_notes.html">Release Notes</a><br><a href="../pdf/webtool-0.8.9.pdf">PDF</a><br><a href="../../../../doc/index.html">Top</a></small><p><strong>WebTool</strong><br><strong>User's Guide</strong><br><small>Version 0.8.9</small></p> <br><a href="javascript:openAllFlips()">Expand All</a><br><a href="javascript:closeAllFlips()">Contract All</a><p><small><strong>Chapters</strong></small></p> <ul class="flipMenu" imagepath="../../../../doc/js/flipmenu"><li id="loadscrollpos" title="WebTool User Guide" expanded="true">WebTool User Guide<ul> <li><a href="webtool_chapter.html"> Top of chapter </a></li> <li title="Introduction "><a href="webtool_chapter.html#id230190">Introduction </a></li> <li title="Starting WebTool"><a href="webtool_chapter.html#id230209">Starting WebTool</a></li> <li title="Using WebTool"><a href="webtool_chapter.html#id230131">Using WebTool</a></li> <li title="Start a web based tool"><a href="webtool_chapter.html#id230873">Start a web based tool</a></li> <li title="Stop a web based tool"><a href="webtool_chapter.html#id230850">Stop a web based tool</a></li> <li title="Develop new web based tools"><a href="webtool_chapter.html#id230823">Develop new web based tools</a></li> </ul> </li></ul> </div></div> <div id="content"> <div class="innertube"> <h1>1 WebTool User Guide</h1> <h3><a name="id230190">1.1 Introduction </a></h3> <p>WebTool provides an easy and efficient way to implement web based tools with Erlang/OTP. WebTool configures and starts the webserver and the various web based tools.</p> <p>All tools that shall run under WebTool must have a *.tool file in the code path or in its priv directory. When WebTool starts it searches the code path for such files. For each <span class="code">ebin</span> directory in the path, the <span class="code">priv</span> directory is also searched. The *.tool files contain the configuration data for each web based tool.</p> <h3><a name="id230209">1.2 Starting WebTool</a></h3> <p>Start WebTool by calling the function <span class="code">webtool:start/0</span> or <span class="code">webtool:start/2</span>. If <span class="code">webtool:start/0</span> is used the start page of WebTool is available at <strong>http://localhost:8888/</strong> or <strong>http://127.0.0.1:8888/</strong>, and the directory containing the root directory for the webserver, is assumed to be <span class="code">webtool-<vsn>/priv</span>.</p> <p>Use <span class="code">webtool:start/2</span> if the default path for the root directory, port, ip-number or server name can not be used. See the Reference Manual for <span class="bold_code"><a href="webtool.html">webtool</a></span> for more information.</p> <p>WebTool, with the default configuration as in <span class="code">start/0</span>, can also be started with the <span class="code">start_webtool</span> script which is available in the <span class="code">priv</span> directory of the WebTool application. See the Reference Manual for <span class="bold_code"><a href="start_webtool.html">start_webtool</a></span> for further information about this script. For Windows users, the batch file <span class="code">start_webtool.bat</span> can be used for the same purpose.</p> <h3><a name="id230131">1.3 Using WebTool</a></h3> <p>Start WebTool and point the browser to the corresponding URL. At the top of the page there is a frame with a link named <strong>WebTool</strong>. Click that link and a page where it is possible to start the available tools will appear in the main frame.</p> <h3><a name="id230873">1.4 Start a web based tool</a></h3> <p>Click on the link labeled <strong>WebTool</strong> in the topmost frame, select the checkbox for each tool to start and click on the button labeled <strong>Start</strong>. A link to each tool that WebTool succeeded to start will appear in the topmost frame.</p> <h3><a name="id230850">1.5 Stop a web based tool</a></h3> <p>Click on the link labeled <strong>WebTool</strong> in the topmost frame. Select <strong>Stop Tools</strong> in the left frame. Select the checkbox for each tool to stop and click on the button labeled <strong>Stop</strong>.</p> <h3><a name="id230823">1.6 Develop new web based tools</a></h3> <p>WebTool can be used as a framework when developing new web based tools.</p> <p>A web based tool running under WebTool will typically consist of three parts.</p> <ul> <li>A *.tool file which defines how WebTool can find the tool's configuration data</li> <li>The Erlang code generating the web interface to the tool (HTML code)</li> <li>The tool itself.</li> </ul> <p>In most cases it is a good idea to separate the code for creation of the html-pages and the code for the logic. This increases the readability of the code and the logic might be possible to reuse.</p> <h4>The *.tool file</h4> <p>When WebTool starts it searches the current path for <span class="code">*.tool</span> files to find all available tools. The *.tool file contains a version identifier and a list of tuples which is the configuration data. The version identifier specifies the *.tool file version, i.e. not the version of webtool. Currently the only valid version is "1.2" and the only valid configuration tag is <span class="code">config_func</span>. <span class="code">config_func</span> specifies which function WebTool must call to get further configuration data for the tool. This means that a *.tool file generally must look like this:</p> <div class="example"><pre> {version,"1.2"}. [{config_func,{Module,Function,Arguments}}]. </pre></div> <p><span class="code">Module</span> is the name of the module where the callback function is defined. <span class="code">Function</span> is the name of the callback function, and <span class="code">Arguments</span> is the list of arguments to the callback function.</p> <h4>The configuration function</h4> <p>The *.tool file points out a configuration function. This function must return a list of configuration parameters (see the Reference Manual for <span class="bold_code"><a href="webtool.html">webtool</a></span>).</p> <p>The <span class="code">web_data</span> parameter is mandatory and it specifies the name of the tool and the link to the tool's start page. All other parameters are optional.</p> <p>If the tool requires any processes to run, the <span class="code">start</span> parameter specifies the function that WebTool must call in order to start the process(es).</p> <p>The <span class="code">alias</span> parameters are passed directly on to the webserver (INETS). The webserver has three ways to create dynamic web pages CGI, Eval Scheme and Erl Scheme. All tools running under WebTool must use Erl Scheme.</p> <p>Erl Scheme tries to resemble plain CGI. The big difference is that Erl Scheme can only execute Erlang code. The code will furthermore be executed on the same instance as the webserver.</p> <p>An URL which calls an Erlang function with Erl Scheme can have the following syntax:</p> <div class="example"><pre> http://Servername:Port/ErlScriptAlias/Mod/Func<?QueryString> </pre></div> <p>An <span class="code">alias</span> parameter in the configuration function can be an ErlScriptAlias as used in the above URL. The definition of an ErlScriptAlias shall be like this:</p> <p><span class="code">{alias,{erl_alias,Path,[Modules]}}</span>, e.g.</p> <p><span class="code">{alias,{erl_alias,"/testtool",[helloworld]}}</span></p> <p>The following URL will then cause a call to the function helloworld:helloworld/2 (if WebTool is started with default settings i.e. servername "localhost" and port 8888):</p> <p><span class="code">http://localhost:8888/testtool/helloworld/helloworld</span></p> <p>Note that the module <span class="code">helloworld</span> must be in the code path of the node running WebTool.</p> <p>Functions that are called via the Erl Scheme must take two arguments, <span class="code">Environment</span> and <span class="code">Input</span>. </p> <ul> <li> <span class="code">Environment</span> is a list of key/value tuples.</li> <li> <span class="code">Input</span> is the part of the URL after the "?", i.e. the part of the URL containing name-value pairs. If the page was called with the URL: <br> <span class="code">http://localhost:8888/testtool/helloworld/helloworld?input1=one&amp;input2=two</span> <br> <span class="code">Input</span> will be the string <span class="code">"input1=one&amp;input2=two"</span>. In the module <span class="code">httpd</span> in the INETS application there is a function <span class="code">parse_query</span> which will parse such a string and return a list of key-value tuples.</li> </ul> <p>An <span class="code">alias</span> parameter in the configuration function can also be a normal path alias. This can e.g. be used to point out a directory where HTML files are stored. The following definition states that the URL <span class="code">http://localhost:8888/mytool_home/</span> really points to the directory <span class="code">/usr/local/otp/lib/myapp-1.0/priv</span>:</p> <p><span class="code">{alias,{"/mytool_home","/usr/local/otp/lib/myapp-1.0/priv"}}</span></p> <p>See the INETS documentation, especially the module <span class="code">mod_esi</span>, for a more in depth coverage of the Erl Scheme.</p> <h4>A small example</h4> <p>A Hello World example that uses Erl Scheme would look like this. Note that this example does not have a process running and thus does not need a <span class="code">start</span> parameter in the configuration function. </p> <p><strong>helloworld.erl:</strong></p> <div class="example"><pre> -module(helloworld). -export([config_data/0]). -export([helloworld/2]). config_data()-> {testtool, [{web_data,{"TestTool","/testtool/helloworld/helloworld"}}, {alias,{erl_alias,"/testtool",[helloworld]}}]}. helloworld(_Env,_Input)-> [header(),html_header(),helloworld_body(),html_end()]. header() -> header("text/html"). header(MimeType) -> "Content-type: " ++ MimeType ++ "\r\n\r\n". html_header() -> "<HTML> <HEAD> <TITLE>Hello world Example </TITLE> </HEAD>\n". helloworld_body()-> "<BODY>Hello World</BODY>". html_end()-> "</HTML>". </pre></div> <p>To use this example with WebTool a *.tool file must be created and added to a directory in the current path, e.g. the same directory as the compiled <span class="code">helloworld.beam</span>.</p> <p><strong>testtool.tool:</strong></p> <div class="example"><pre> {version,"1.2"}. [{config_func, {helloworld,config_data,[]}}]. </pre></div> <p>When <span class="code">helloworld.erl</span> is compiled, start WebTool by calling the function <span class="code">webtool:start()</span> and point your browser to <strong>http://localhost:8888/</strong>. Select WebTool in the topmost frame and start TestTool from the web page. Click on the link labeled <strong>TestTool</strong> in the topmost frame.</p> </div> <div class="footer"> <hr> <p>Copyright © 2001-2011 Ericsson AB. All Rights Reserved.</p> </div> </div> </div></body> </html>