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+<?xml version="1.0" encoding="latin1" ?>
+<!DOCTYPE chapter SYSTEM "chapter.dtd">
+
+<chapter>
+  <header>
+    <copyright>
+      <year>2001</year><year>2009</year>
+      <holder>Ericsson AB. All Rights Reserved.</holder>
+    </copyright>
+    <legalnotice>
+      The contents of this file are subject to the Erlang Public License,
+      Version 1.1, (the "License"); you may not use this file except in
+      compliance with the License. You should have received a copy of the
+      Erlang Public License along with this software. If not, it can be
+      retrieved online at http://www.erlang.org/.
+    
+      Software distributed under the License is distributed on an "AS IS"
+      basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+      the License for the specific language governing rights and limitations
+      under the License.
+    
+    </legalnotice>
+
+    <title>WebTool User Guide</title>
+    <prepared></prepared>
+    <docno></docno>
+    <date></date>
+    <rev></rev>
+    <file>webtool_chapter.xml</file>
+  </header>
+
+  <section>
+    <title>Introduction </title>
+    <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
+      <c>ebin</c> directory in the path, the <c>priv</c> directory is
+      also searched. The *.tool files contain the configuration data
+      for each web based tool.</p>
+  </section>
+
+  <section>
+    <title>Starting WebTool</title>
+    <p>Start WebTool by calling the function <c>webtool:start/0</c> or
+      <c>webtool:start/2</c>.  If <c>webtool:start/0</c> is used the
+      start page of WebTool is available at
+      <em>http://localhost:8888/</em> or
+      <em>http://127.0.0.1:8888/</em>, and the directory containing
+      the root directory for the webserver, is assumed to be
+      <c><![CDATA[webtool-<vsn>/priv]]></c>.</p>
+    <p>Use <c>webtool:start/2</c> if the default path for the root
+      directory, port, ip-number or server name can not be used. See
+      the Reference Manual for <seealso marker="webtool">webtool</seealso> for more information.</p>
+    <p>WebTool, with the default configuration as in <c>start/0</c>,
+      can also be started with the <c>start_webtool</c> script which
+      is available in the <c>priv</c> directory of the WebTool
+      application. See the Reference Manual for <seealso marker="start_webtool">start_webtool</seealso> for further
+      information about this script. For Windows users, the batch file
+      <c>start_webtool.bat</c> can be used for the same purpose.</p>
+  </section>
+
+  <section>
+    <title>Using WebTool</title>
+    <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 
+      <em>WebTool</em>. Click that link and a page where it is
+      possible to start the available tools will appear in the main
+      frame.</p>
+  </section>
+
+  <section>
+    <title>Start a web based tool</title>
+    <p>Click on the link labeled <em>WebTool</em> in the topmost  frame,
+      select the checkbox for each tool to start and
+      click on the button labeled <em>Start</em>. A link to each tool
+      that WebTool succeeded to start will appear in the topmost frame.</p>
+  </section>
+
+  <section>
+    <title>Stop a web based tool</title>
+    <p>Click on the link labeled <em>WebTool</em> in the topmost
+      frame. Select <em>Stop Tools</em> in the left frame. Select the
+      checkbox for each tool to stop and click on the button labeled
+      <em>Stop</em>.</p>
+  </section>
+
+  <section>
+    <title>Develop new web based tools</title>
+    <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>
+    <list type="bulleted">
+      <item>A *.tool file which defines how WebTool can find the tool's
+       configuration data</item>
+      <item>The Erlang code generating the web interface to the tool (HTML
+       code)</item>
+      <item>The tool itself.</item>
+    </list>
+    <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>
+
+    <section>
+      <title>The *.tool file</title>
+      <p>When WebTool starts it searches the current path for
+        <c>*.tool</c> 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
+        <c>config_func</c>. <c>config_func</c> 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>
+      <code type="none">
+   {version,"1.2"}.
+   [{config_func,{Module,Function,Arguments}}].      </code>
+      <p><c>Module</c> is the name of the module where the callback
+        function is defined. <c>Function</c> is the name of the
+        callback function, and <c>Arguments</c> is the list of
+        arguments to the callback function.</p>
+    </section>
+
+    <section>
+      <title>The configuration function</title>
+      <p>The *.tool file points out a configuration function. This
+        function must return a list of configuration parameters (see
+        the Reference Manual for <seealso marker="webtool">webtool</seealso>).</p>
+      <p>The <c>web_data</c> 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 <c>start</c>
+        parameter specifies the function that WebTool must call in
+        order to start the process(es).</p>
+      <p>The <c>alias</c> 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>
+      <code type="none"><![CDATA[
+http://Servername:Port/ErlScriptAlias/Mod/Func<?QueryString>      ]]></code>
+      <p>An <c>alias</c> parameter in the configuration function can be
+        an ErlScriptAlias as used in the above URL. The definition of
+        an ErlScripAlias shall be like this:</p>
+      <p><c>{alias,{erl_alias,Path,[Modules]}}</c>, e.g.</p>
+      <p><c>{alias,{erl_alias,"/testtool",[helloworld]}}</c></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><c>http://localhost:8888/testtool/helloworld/helloworld</c></p>
+      <p>Note that the module <c>helloworld</c> 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, <c>Environment</c> and <c>Input</c>. 
+        </p>
+      <list type="bulleted">
+        <item><c>Environment</c> is a list of key/value tuples.</item>
+        <item><c>Input</c> 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></br>
+<c><![CDATA[http://localhost:8888/testtool/helloworld/helloworld?input1=one&amp;input2=two]]></c>        <br></br>
+<c>Input</c> will be the string
+        <c><![CDATA["input1=one&amp;input2=two"]]></c>.  In the module
+        <c>httpd</c> in the INETS application there is a function
+        <c>parse_query</c> which will parse such a string and return
+         a list of key-value tuples.</item>
+      </list>
+      <p>An <c>alias</c> 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
+        <c>http://localhost:8888/mytool_home/</c> really points to the
+        directory <c>/usr/local/otp/lib/myapp-1.0/priv</c>:</p>
+      <p><c>{alias,{"/mytool_home","/usr/local/otp/lib/myapp-1.0/priv"}}</c></p>
+      <p>See the INETS documentation, especially the module
+        <c>mod_esi</c>, for a more in depht coverage of Erl Scheme.</p>
+    </section>
+
+    <section>
+      <title>A small example</title>
+      <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 <c>start</c> parameter in the
+        configuration function.
+        </p>
+      <p><em>helloworld.erl:</em></p>
+      <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)-&gt;
+            [header(),html_header(),helloworld_body(),html_end()].
+
+        header() -&gt;
+            header("text/html").
+
+        header(MimeType) -&gt;
+            "Content-type: " ++ MimeType ++ "\\r\
+\\r\
+".
+
+        html_header() -&gt;    
+            "&lt;HTML&gt;
+               &lt;HEAD&gt;
+                  &lt;TITLE&gt;Hello world Example &lt;/TITLE&gt;
+               &lt;/HEAD&gt;\
+".
+
+        helloworld_body()-&gt;
+            "&lt;BODY&gt;Hello World&lt;/BODY&gt;".
+
+        html_end()-&gt;
+            "&lt;/HTML&gt;".
+      </pre>
+      <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 <c>helloworld.beam</c>.</p>
+      <p><em>testtool.tool:</em></p>
+      <code type="none">
+        {version,"1.2"}.
+        [{config_func, {helloworld,config_data,[]}}].
+      </code>
+      <p>When <c>helloworld.erl</c> is compiled, start WebTool by
+        calling the function <c>webtool:start()</c> and point your
+        browser to <em>http://localhost:8888/</em>. Select WebTool in
+        the topmost frame and start TestTool from the web page.  Click
+        on the link labeled <em>TestTool</em> in the topmost frame.</p>
+    </section>
+  </section>
+</chapter>
+