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<!DOCTYPE document [
  <!ENTITY project SYSTEM "project.xml">
]>
<document url="valve.html">

  &project;

  <properties>
    <author email="craigmcc@apache.org">Craig R. McClanahan</author>
    <title>The Valve Component</title>
  </properties>

<body>


<section name="Introduction">

  <p>A <strong>Valve</strong> element represents a component that will be
  inserted into the request processing pipeline for the associated
  Catalina container (<a href="engine.html">Engine</a>,
  <a href="host.html">Host</a>, or <a href="context.html">Context</a>).
  Individual Valves have distinct processing capabilities, and are
  described individually below.</p>

    <blockquote><em>
    <p>The description below uses the variable name $CATALINA_HOME
    to refer to the directory into which you have installed Tomcat 6,
    and is the base directory against which most relative paths are
    resolved.  However, if you have configured Tomcat 6 for multiple
    instances by setting a CATALINA_BASE directory, you should use
    $CATALINA_BASE instead of $CATALINA_HOME for each of these
    references.</p>
    </em></blockquote>

</section>


<section name="Access Log Valve">

  <subsection name="Introduction">

    <p>The <strong>Access Log Valve</strong> creates log files in the same
    format as those created by standard web servers.  These logs can later
    be analyzed by standard log analysis tools to track page hit counts,
    user session activity, and so on.  The files produces by this <code>Valve</code>
    are rolled over nightly at midnight.  This <code>Valve</code>
    may be associated with any Catalina container (<code>Context</code>,
    <code>Host</code>, or <code>Engine</code>), and
    will record ALL requests processed by that container.</p>

  </subsection>

  <subsection name="Attributes">

    <p>The <strong>Access Log Valve</strong> supports the following
    configuration attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.valves.AccessLogValve</strong> to use the
        default access log valve.</p>
      </attribute>

      <attribute name="directory" required="false">
        <p>Absolute or relative pathname of a directory in which log files
        created by this valve will be placed.  If a relative path is
        specified, it is interpreted as relative to $CATALINA_HOME.  If
        no directory attribute is specified, the default value is "logs"
        (relative to $CATALINA_HOME).</p>
      </attribute>

      <attribute name="pattern" required="false">
        <p>A formatting layout identifying the various information fields
        from the request and response to be logged, or the word
        <code>common</code> or <code>combined</code> to select a
        standard format.  See below for more information on configuring
        this attribute. Note that the optimized access does only support
        <code>common</code> and <code>combined</code> as the value for this
        attribute.</p>
      </attribute>

      <attribute name="prefix" required="false">
        <p>The prefix added to the start of each log file's name.  If not
        specified, the default value is "access_log.".  To specify no prefix,
        use a zero-length string.</p>
      </attribute>

      <attribute name="resolveHosts" required="false">
        <p>Set to <code>true</code> to convert the IP address of the remote
        host into the corresponding host name via a DNS lookup.  Set to
        <code>false</code> to skip this lookup, and report the remote IP
        address instead.</p>
      </attribute>

      <attribute name="suffix" required="false">
        <p>The suffix added to the end of each log file's name.  If not
        specified, the default value is "".  To specify no suffix,
        use a zero-length string.</p>
      </attribute>

      <attribute name="rotatable" required="false">
        <p>Deafult true. Flag to determine if log rotation should occur.
           If set to false, then this file is never rotated and
           <tt>fileDateFormat</tt> is ignored. Use with caution!
        </p>
      </attribute>

      <attribute name="condition" required="false">
        <p>Turns on conditional logging. If set, requests will be
           logged only if <tt>ServletRequest.getAttribute()</tt> is
           null. For example, if this value is set to
           <tt>junk</tt>, then a particular request will only be logged
           if <tt>ServletRequest.getAttribute("junk") == null</tt>.
           The use of Filters is an easy way to set/unset the attribute
           in the ServletRequest on many different requests.
        </p>
      </attribute>

      <attribute name="fileDateFormat" required="false">
        <p>Allows a customized date format in the access log file name.
           The date format also decides how often the file is rotated.
           If you wish to rotate every hour, then set this value
           to: <tt>yyyy-MM-dd.HH</tt>
        </p>
      </attribute>

      <attribute name="buffered" required="false">
        <p>Deafult true. Flag to determine if logging will be buffered.
           If set to false, then access logging will be written after each 
           request.
        </p>
      </attribute>

    </attributes>

    <p>Values for the <code>pattern</code> attribute are made up of literal
    text strings, combined with pattern identifiers prefixed by the "%"
    character to cause replacement by the corresponding variable value from
    the current request and response.  The following pattern codes are
    supported:</p>
    <ul>
    <li><b>%a</b> - Remote IP address</li>
    <li><b>%A</b> - Local IP address</li>
    <li><b>%b</b> - Bytes sent, excluding HTTP headers, or '-' if zero</li>
    <li><b>%B</b> - Bytes sent, excluding HTTP headers</li>
    <li><b>%h</b> - Remote host name (or IP address if
        <code>resolveHosts</code> is false)</li>
    <li><b>%H</b> - Request protocol</li>
    <li><b>%l</b> - Remote logical username from identd (always returns
        '-')</li>
    <li><b>%m</b> - Request method (GET, POST, etc.)</li>
    <li><b>%p</b> - Local port on which this request was received</li>
    <li><b>%q</b> - Query string (prepended with a '?' if it exists)</li>
    <li><b>%r</b> - First line of the request (method and request URI)</li>
    <li><b>%s</b> - HTTP status code of the response</li>
    <li><b>%S</b> - User session ID</li>
    <li><b>%t</b> - Date and time, in Common Log Format</li>
    <li><b>%u</b> - Remote user that was authenticated (if any), else '-'</li>
    <li><b>%U</b> - Requested URL path</li>
    <li><b>%v</b> - Local server name</li>
    <li><b>%D</b> - Time taken to process the request, in millis</li>
    <li><b>%T</b> - Time taken to process the request, in seconds</li>
    </ul>

    <p>
    There is also support to write information from the cookie, incoming
    header, the Session or something else in the ServletRequest.
    It is modeled after the apache syntax:
    <ul>
    <li><b><code>%{xxx}i</code></b> for incoming headers</li>
    <li><b><code>%{xxx}c</code></b> for a specific cookie</li>
    <li><b><code>%{xxx}r</code></b> xxx is an attribute in the ServletRequest</li>
    <li><b><code>%{xxx}s</code></b> xxx is an attribute in the HttpSession</li>
    </ul>
    </p>


    <p>The shorthand pattern name <code>common</code> (which is also the
    default) corresponds to <strong>%h %l %u %t "%r" %s %b"</strong>.</p>

    <p>The shorthand pattern name <code>combined</code> appends the
    values of the <code>Referer</code> and <code>User-Agent</code> headers,
    each in double quotes, to the <code>common</code> pattern
    described in the previous paragraph.</p>

  </subsection>

</section>


<section name="Remote Address Filter">

  <subsection name="Introduction">

    <p>The <strong>Remote Address Filter</strong> allows you to compare the
    IP address of the client that submitted this request against one or more
    <em>regular expressions</em>, and either allow the request to continue
    or refuse to process the request from this client.  A Remote Address
    Filter can be associated with any Catalina container
    (<a href="engine.html">Engine</a>, <a href="host.html">Host</a>, or
    <a href="context.html">Context</a>), and must accept any request
    presented to this container for processing before it will be passed on.</p>

    <p>The syntax for <em>regular expressions</em> is different than that for
    'standard' wildcard matching. Tomcat uses the
    <a href="http://jakarta.apache.org/regexp/">Jakarta Regexp</a> library.
    Please consult the Regexp documentation for details of the expressions
    supported.</p>

  </subsection>

  <subsection name="Attributes">

    <p>The <strong>Remote Address Filter</strong> supports the following
    configuration attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.valves.RemoteAddrValve</strong>.</p>
      </attribute>

      <attribute name="allow" required="false">
        <p>A comma-separated list of <em>regular expression</em> patterns
        that the remote client's IP address is compared to.  If this attribute
        is specified, the remote address MUST match for this request to be
        accepted.  If this attribute is not specified, all requests will be
        accepted UNLESS the remote address matches a <code>deny</code>
        pattern.</p>
      </attribute>

      <attribute name="deny" required="false">
        <p>A comma-separated list of <em>regular expression</em> patterns
        that the remote client's IP address is compared to.  If this attribute
        is specified, the remote address MUST NOT match for this request to be
        accepted.  If this attribute is not specified, request acceptance is
        governed solely by the <code>accept</code> attribute.</p>
      </attribute>

    </attributes>

  </subsection>

</section>


<section name="Remote Host Filter">

  <subsection name="Introduction">

    <p>The <strong>Remote Host Filter</strong> allows you to compare the
    hostname of the client that submitted this request against one or more
    <em>regular expressions</em>, and either allow the request to continue
    or refuse to process the request from this client.  A Remote Host
    Filter can be associated with any Catalina container
    (<a href="engine.html">Engine</a>, <a href="host.html">Host</a>, or
    <a href="context.html">Context</a>), and must accept any request
    presented to this container for processing before it will be passed on.</p>

    <p>The syntax for <em>regular expressions</em> is different than that for
    'standard' wildcard matching. Tomcat uses the
    <a href="http://jakarta.apache.org/regexp/">Jakarta Regexp</a> library.
    Please consult the Regexp documentation for details of the expressions
    supported.</p>

  </subsection>

  <subsection name="Attributes">

    <p>The <strong>Remote Host Filter</strong> supports the following
    configuration attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.valves.RemoteHostValve</strong>.</p>
      </attribute>

      <attribute name="allow" required="false">
        <p>A comma-separated list of <em>regular expression</em> patterns
        that the remote client's hostname is compared to.  If this attribute
        is specified, the remote hostname MUST match for this request to be
        accepted.  If this attribute is not specified, all requests will be
        accepted UNLESS the remote hostname matches a <code>deny</code>
        pattern.</p>
      </attribute>

      <attribute name="deny" required="false">
        <p>A comma-separated list of <em>regular expression</em> patterns
        that the remote client's hostname is compared to.  If this attribute
        is specified, the remote hostname MUST NOT match for this request to be
        accepted.  If this attribute is not specified, request acceptance is
        governed solely by the <code>accept</code> attribute.</p>
      </attribute>

    </attributes>

  </subsection>

</section>


<section name="Request Dumper Valve">


  <subsection name="Introduction">

    <p>The <em>Request Dumper Valve</em> is a useful tool in debugging
    interactions with a client application (or browser) that is sending
    HTTP requests to your Tomcat-based server.  When configured, it causes
    details about each request processed by its associated <code>Engine</code>, 
    <code>Host</code>, or <code>Context</code> to be logged according to 
    the logging configuration for that container.</p>

    <p><strong>WARNING: Using this valve has side-effects.</strong>  The
    output from this valve includes any parameters included with the request.
    The parameters will be decoded using the default platform encoding. Any
    subsequent calls to <code>request.setCharacterEncoding()</code> within
    the web application will have no effect.</p>

  </subsection>


  <subsection name="Attributes">

    <p>The <strong>Request Dumper Valve</strong> supports the following
    configuration attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.valves.RequestDumperValve</strong>.</p>
      </attribute>

    </attributes>

  </subsection>


</section>


<section name="Single Sign On Valve">

  <subsection name="Introduction">

    <p>The <em>Single Sign On Vale</em> is utilized when you wish to give users
    the ability to sign on to any one of the web applications associated with
    your virtual host, and then have their identity recognized by all other
    web applications on the same virtual host.</p>

    <p>See the <a href="host.html#Single Sign On">Single Sign On</a> special
    feature on the <strong>Host</strong> element for more information.</p>

  </subsection>


  <subsection name="Attributes">

    <p>The <strong>Single Sign On</strong> Valve supports the following
    configuration attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.authenticator.SingleSignOn</strong>.</p>
      </attribute>

      <attribute name="requireReauthentication" required="false">
        <p>Default false. Flag to determine whether each request needs to be 
        reauthenticated to the security <strong>Realm</strong>. If "true", this
        Valve uses cached security credentials (username and password) to
        reauthenticate to the <strong>Realm</strong> each request associated 
        with an SSO session.  If "false", the Valve can itself authenticate 
        requests based on the presence of a valid SSO cookie, without 
        rechecking with the <strong>Realm</strong>.</p>
      </attribute>
 

    </attributes>

  </subsection>


</section>


<section name="Form Authenticator Valve">

  <subsection name="Introduction">

    <p>The <strong>Form Authenticator Valve</strong> is automatically added to
    any <a href="context.html">Context</a> that is configured to use FORM
    authentication.</p>

    <p>If any non-default settings are required, the valve may be configured
    within <a href="context.html">Context</a> element with the required
    values.</p>

  </subsection>

  <subsection name="Attributes">

    <p>The <strong>Form Authenticator Valve</strong> supports the following
    configuration attributes:</p>

    <attributes>

      <attribute name="className" required="true">
        <p>Java class name of the implementation to use.  This MUST be set to
        <strong>org.apache.catalina.authenticator.FormAuthenticator</strong>.</p>
      </attribute>

      <attribute name="characterEncoding" required="false">
        <p>Character encoding to use to read the username and password parameters
        from the request. If not set, the encoding of the request body will be
        used.</p>
      </attribute>

    </attributes>

  </subsection>

</section>


</body>


</document>
