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| </style></head><body bgcolor="#ffffff" text="#000000" link="#525D76" alink="#525D76" vlink="#525D76"><table border="0" width="100%" cellspacing="0"><!--PAGE HEADER--><tr><td><!--PROJECT LOGO--><a href="http://tomcat.apache.org/"><img src="../images/tomcat.gif" align="right" alt=" | |
| The Apache Tomcat Servlet/JSP Container | |
| " border="0"></a></td><td><h1><font face="arial,helvetica,sanserif">Apache Tomcat 7</font></h1><font face="arial,helvetica,sanserif">Version 7.0.77, Mar 28 2017</font></td><td><!--APACHE LOGO--><a href="http://www.apache.org/"><img src="../images/asf-logo.svg" align="right" alt="Apache Logo" border="0" style="width: 266px;height: 83px;"></a></td></tr></table><table border="0" width="100%" cellspacing="4"><!--HEADER SEPARATOR--><tr><td colspan="2"><hr noshade size="1"></td></tr><tr><!--LEFT SIDE NAVIGATION--><td width="20%" valign="top" nowrap class="noPrint"><p><strong>Links</strong></p><ul><li><a href="../index.html">Docs Home</a></li><li><a href="index.html">Config Ref. Home</a></li><li><a href="http://wiki.apache.org/tomcat/FAQ">FAQ</a></li><li><a href="#comments_section">User Comments</a></li></ul><p><strong>Top Level Elements</strong></p><ul><li><a href="server.html">Server</a></li><li><a href="service.html">Service</a></li></ul><p><strong>Executors</strong></p><ul><li><a href="executor.html">Executor</a></li></ul><p><strong>Connectors</strong></p><ul><li><a href="http.html">HTTP</a></li><li><a href="ajp.html">AJP</a></li></ul><p><strong>Containers</strong></p><ul><li><a href="context.html">Context</a></li><li><a href="engine.html">Engine</a></li><li><a href="host.html">Host</a></li><li><a href="cluster.html">Cluster</a></li></ul><p><strong>Nested Components</strong></p><ul><li><a href="globalresources.html">Global Resources</a></li><li><a href="jar-scanner.html">JarScanner</a></li><li><a href="listeners.html">Listeners</a></li><li><a href="loader.html">Loader</a></li><li><a href="manager.html">Manager</a></li><li><a href="realm.html">Realm</a></li><li><a href="resources.html">Resources</a></li><li><a href="sessionidgenerator.html">SessionIdGenerator</a></li><li><a href="valve.html">Valve</a></li></ul><p><strong>Cluster Elements</strong></p><ul><li><a href="cluster.html">Cluster</a></li><li><a href="cluster-manager.html">Manager</a></li><li><a href="cluster-channel.html">Channel</a></li><li><a href="cluster-membership.html">Channel/Membership</a></li><li><a href="cluster-sender.html">Channel/Sender</a></li><li><a href="cluster-receiver.html">Channel/Receiver</a></li><li><a href="cluster-interceptor.html">Channel/Interceptor</a></li><li><a href="cluster-valve.html">Valve</a></li><li><a href="cluster-deployer.html">Deployer</a></li><li><a href="cluster-listener.html">ClusterListener</a></li></ul><p><strong>web.xml</strong></p><ul><li><a href="filter.html">Filter</a></li></ul><p><strong>Other</strong></p><ul><li><a href="systemprops.html">System properties</a></li></ul></td><!--RIGHT SIDE MAIN BODY--><td width="80%" valign="top" align="left" id="mainBody"><h1>The Engine Container</h1><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Table of Contents"><!--()--></a><a name="Table_of_Contents"><strong>Table of Contents</strong></a></font></td></tr><tr><td><blockquote> | |
| <ul><li><a href="#Introduction">Introduction</a></li><li><a href="#Attributes">Attributes</a><ol><li><a href="#Common_Attributes">Common Attributes</a></li><li><a href="#Standard_Implementation">Standard Implementation</a></li></ol></li><li><a href="#Nested_Components">Nested Components</a></li><li><a href="#Special_Features">Special Features</a><ol><li><a href="#Logging">Logging</a></li><li><a href="#Access_Logs">Access Logs</a></li><li><a href="#Lifecycle_Listeners">Lifecycle Listeners</a></li><li><a href="#Request_Filters">Request Filters</a></li></ol></li></ul> | |
| </blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Introduction"><strong>Introduction</strong></a></font></td></tr><tr><td><blockquote> | |
| <p>The <strong>Engine</strong> element represents the entire request | |
| processing machinery associated with a particular Catalina | |
| <a href="service.html">Service</a>. It receives and processes | |
| <em>all</em> requests from one or more <strong>Connectors</strong>, | |
| and returns the completed response to the Connector for ultimate | |
| transmission back to the client.</p> | |
| <p>Exactly one <strong>Engine</strong> element MUST be nested inside | |
| a <a href="service.html">Service</a> element, following all of the | |
| corresponding Connector elements associated with this Service.</p> | |
| </blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Attributes"><strong>Attributes</strong></a></font></td></tr><tr><td><blockquote> | |
| <table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Common Attributes"><!--()--></a><a name="Common_Attributes"><strong>Common Attributes</strong></a></font></td></tr><tr><td><blockquote> | |
| <p>All implementations of <strong>Engine</strong> | |
| support the following attributes:</p> | |
| <table border="1" cellpadding="5"><tr><th width="15%" bgcolor="#023264"><font color="#ffffff">Attribute</font></th><th width="85%" bgcolor="#023264"><font color="#ffffff">Description</font></th></tr><tr><td align="left" valign="center"><code class="attributeName">backgroundProcessorDelay</code></td><td align="left" valign="center"> | |
| <p>This value represents the delay in seconds between the | |
| invocation of the backgroundProcess method on this engine and | |
| its child containers, including all hosts and contexts. | |
| Child containers will not be invoked if their delay value is not | |
| negative (which would mean they are using their own processing | |
| thread). Setting this to a positive value will cause | |
| a thread to be spawn. After waiting the specified amount of time, | |
| the thread will invoke the backgroundProcess method on this engine | |
| and all its child containers. If not specified, the default value for | |
| this attribute is 10, which represent a 10 seconds delay.</p> | |
| </td></tr><tr><td align="left" valign="center"><code class="attributeName">className</code></td><td align="left" valign="center"> | |
| <p>Java class name of the implementation to use. This class must | |
| implement the <code>org.apache.catalina.Engine</code> interface. | |
| If not specified, the standard value (defined below) will be used.</p> | |
| </td></tr><tr><td align="left" valign="center"><strong><code class="attributeName">defaultHost</code></strong></td><td align="left" valign="center"> | |
| <p>The default host name, which identifies the | |
| <a href="host.html">Host</a> that will process requests directed | |
| to host names on this server, but which are not configured in | |
| this configuration file. This name MUST match the <code>name</code> | |
| attributes of one of the <a href="host.html">Host</a> elements | |
| nested immediately inside.</p> | |
| </td></tr><tr><td align="left" valign="center"><code class="attributeName">jvmRoute</code></td><td align="left" valign="center"> | |
| <p>Identifier which must be used in load balancing scenarios to enable | |
| session affinity. The identifier, which must be unique across all | |
| Tomcat servers which participate in the cluster, will be appended to | |
| the generated session identifier, therefore allowing the front end | |
| proxy to always forward a particular session to the same Tomcat | |
| instance.</p> | |
| <p> | |
| Note that the <code>jvmRoute</code> can also be set using the | |
| <code>jvmRoute</code> system property. The <code>jvmRoute</code> | |
| set in an <code><Engine></code> attribute will override | |
| any <code>jvmRoute</code> system property. | |
| </p> | |
| </td></tr><tr><td align="left" valign="center"><strong><code class="attributeName">name</code></strong></td><td align="left" valign="center"> | |
| <p>Logical name of this Engine, used in log and error messages. <em>When | |
| using multiple <a href="service.html">Service</a> elements in the same | |
| <a href="server.html">Server</a>, each Engine MUST be assigned a unique | |
| name.</em></p> | |
| </td></tr><tr><td align="left" valign="center"><code class="attributeName">startStopThreads</code></td><td align="left" valign="center"> | |
| <p>The number of threads this <strong>Engine</strong> will use to start | |
| child <a href="host.html">Host</a> elements in parallel. The special | |
| value of 0 will result in the value of | |
| <code>Runtime.getRuntime().availableProcessors()</code> being used. | |
| Negative values will result in | |
| <code>Runtime.getRuntime().availableProcessors() + value</code> being | |
| used unless this is less than 1 in which case 1 thread will be used. If | |
| not specified, the default value of 1 will be used. </p> | |
| </td></tr></table> | |
| </blockquote></td></tr></table> | |
| <table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Standard Implementation"><!--()--></a><a name="Standard_Implementation"><strong>Standard Implementation</strong></a></font></td></tr><tr><td><blockquote> | |
| <p>The standard implementation of <strong>Engine</strong> is | |
| <strong>org.apache.catalina.core.StandardEngine</strong>. | |
| It supports the following additional attributes (in addition to the | |
| common attributes listed above):</p> | |
| <table border="1" cellpadding="5"><tr><th width="15%" bgcolor="#023264"><font color="#ffffff">Attribute</font></th><th width="85%" bgcolor="#023264"><font color="#ffffff">Description</font></th></tr></table> | |
| </blockquote></td></tr></table> | |
| </blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Nested Components"><!--()--></a><a name="Nested_Components"><strong>Nested Components</strong></a></font></td></tr><tr><td><blockquote> | |
| <p>You can nest one or more <a href="host.html">Host</a> elements inside | |
| this <strong>Engine</strong> element, each representing a different virtual | |
| host associated with this server. At least one <a href="host.html">Host</a> | |
| is required, and one of the nested <a href="host.html">Hosts</a> MUST | |
| have a name that matches the name specified for the | |
| <code>defaultHost</code> attribute, listed above.</p> | |
| <p>You can nest at most one instance of the following utility components | |
| by nesting a corresponding element inside your <strong>Engine</strong> | |
| element:</p> | |
| <ul> | |
| <li><a href="realm.html"><strong>Realm</strong></a> - | |
| Configure a realm that will allow its | |
| database of users, and their associated roles, to be shared across all | |
| <a href="host.html">Hosts</a> and <a href="context.html">Contexts</a> | |
| nested inside this Engine, unless overridden by a | |
| <a href="realm.html">Realm</a> configuration at a lower level.</li> | |
| </ul> | |
| </blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Special Features"><!--()--></a><a name="Special_Features"><strong>Special Features</strong></a></font></td></tr><tr><td><blockquote> | |
| <table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Logging"><strong>Logging</strong></a></font></td></tr><tr><td><blockquote> | |
| <p>An engine is associated with the | |
| <code>org.apache.catalina.core.ContainerBase.[enginename]</code> | |
| log category. Note that the brackets are actually part of the name, | |
| don't omit them.</p> | |
| </blockquote></td></tr></table> | |
| <table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Access Logs"><!--()--></a><a name="Access_Logs"><strong>Access Logs</strong></a></font></td></tr><tr><td><blockquote> | |
| <p>When you run a web server, one of the output files normally generated | |
| is an <em>access log</em>, which generates one line of information for | |
| each request processed by the server, in a standard format. Catalina | |
| includes an optional <a href="valve.html">Valve</a> implementation that | |
| can create access logs in the same standard format created by web servers, | |
| or in any number of custom formats.</p> | |
| <p>You can ask Catalina to create an access log for all requests | |
| processed by an <a href="engine.html">Engine</a>, | |
| <a href="host.html">Host</a>, or <a href="context.html">Context</a> | |
| by nesting a <a href="valve.html">Valve</a> element like this:</p> | |
| <div class="codeBox"><pre><code><Engine name="Standalone" ...> | |
| ... | |
| <Valve className="org.apache.catalina.valves.AccessLogValve" | |
| prefix="catalina_access_log." suffix=".txt" | |
| pattern="common"/> | |
| ... | |
| </Engine></code></pre></div> | |
| <p>See <a href="valve.html#Access_Logging">Access Logging Valves</a> | |
| for more information on the configuration attributes that are | |
| supported.</p> | |
| </blockquote></td></tr></table> | |
| <table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Lifecycle Listeners"><!--()--></a><a name="Lifecycle_Listeners"><strong>Lifecycle Listeners</strong></a></font></td></tr><tr><td><blockquote> | |
| <p>If you have implemented a Java object that needs to know when this | |
| <strong>Engine</strong> is started or stopped, you can declare it by | |
| nesting a <strong>Listener</strong> element inside this element. The | |
| class name you specify must implement the | |
| <code>org.apache.catalina.LifecycleListener</code> interface, and | |
| it will be notified about the occurrence of the corresponding | |
| lifecycle events. Configuration of such a listener looks like this:</p> | |
| <div class="codeBox"><pre><code><Engine name="Standalone" ...> | |
| ... | |
| <Listener className="com.mycompany.mypackage.MyListener" ... > | |
| ... | |
| </Engine></code></pre></div> | |
| <p>Note that a Listener can have any number of additional properties | |
| that may be configured from this element. Attribute names are matched | |
| to corresponding JavaBean property names using the standard property | |
| method naming patterns.</p> | |
| </blockquote></td></tr></table> | |
| <table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Request Filters"><!--()--></a><a name="Request_Filters"><strong>Request Filters</strong></a></font></td></tr><tr><td><blockquote> | |
| <p>You can ask Catalina to check the IP address, or host name, on every | |
| incoming request directed to the surrounding | |
| <a href="engine.html">Engine</a>, <a href="host.html">Host</a>, or | |
| <a href="context.html">Context</a> element. The remote address or name | |
| will be checked against configured "accept" and/or "deny" | |
| filters, which are defined using <code>java.util.regex</code> Regular | |
| Expression syntax. Requests that come from locations that are | |
| not accepted will be rejected with an HTTP "Forbidden" error. | |
| Example filter declarations:</p> | |
| <div class="codeBox"><pre><code><Engine name="Standalone" ...> | |
| ... | |
| <Valve className="org.apache.catalina.valves.RemoteHostValve" | |
| allow=".*\.mycompany\.com|www\.yourcompany\.com"/> | |
| <Valve className="org.apache.catalina.valves.RemoteAddrValve" | |
| deny="192\.168\.1\.\d+"/> | |
| ... | |
| </Engine></code></pre></div> | |
| <p>See <a href="valve.html#Remote_Address_Filter">Remote Address Filter</a> | |
| and <a href="valve.html#Remote_Host_Filter">Remote Host Filter</a> for | |
| more information about the configuration options that are supported.</p> | |
| </blockquote></td></tr></table> | |
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