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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>
+