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Datei: engine.xml Sprache: XML

Original von: Apache^©

<?xml version="1.0" encoding="UTF-8"?>

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

 &project;

 <properties>
 <author email="[email protected]">Craig R. McClanahan</author>
 <title>The Engine Container</title>
 </properties>

<body>

<section name="Table of Contents">
<toc/>
</section>

<section name="Introduction">

 The Engine element represents the entire request
 processing machinery associated with a particular Catalina
 <a href="service.html">Service</a>. It receives and processes
 all requests from one or more Connectors,
 and returns the completed response to the Connector for ultimate
 transmission back to the client.

 Exactly one Engine element MUST be nested inside
 a <a href="service.html">Service</a> element, following all of the
 corresponding Connector elements associated with this Service.

</section>

<section name="Attributes">

 <subsection name="Common Attributes">

 All implementations of Engine
 support the following attributes:

 <attributes>

 <attribute name="backgroundProcessorDelay" required="false">
 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.
 </attribute>

 <attribute name="className" required="false">
 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.
 </attribute>

 <attribute name="defaultHost" required="true">
 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.
 </attribute>

 <attribute name="jvmRoute" required="false">
 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.
 </attribute>

 <attribute name="name" required="true">
 Logical name of this Engine, used in log and error messages. 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.
 </attribute>

 <attribute name="startStopThreads" required="false">
 The number of threads this Engine 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. If 1 thread is
 used then, rather than using an <code>ExecutorService</code>, the
 current thread will be used.
 </attribute>

 </attributes>

 </subsection>

 <subsection name="Standard Implementation">

 The standard implementation of Engine is
 org.apache.catalina.core.StandardEngine.
 It supports the following additional attributes (in addition to the
 common attributes listed above):

 <attributes>

 </attributes>

 </subsection>

</section>

<section name="Nested Components">

 You can nest one or more <a href="host.html">Host</a> elements inside
 this Engine 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.

 You can nest at most one instance of the following utility components
 by nesting a corresponding element inside your Engine
 element:
 <ul>
 <li><a href="realm.html">Realm</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>

</section>

<section name="Special Features">

 <subsection name="Logging">

 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.

</subsection>

 <subsection name="Access Logs">

 When you run a web server, one of the output files normally generated
 is an access log, 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.

 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:

<source><![CDATA[<Engine name="Standalone" ...>
 ...
 <Valve className="org.apache.catalina.valves.AccessLogValve"
 prefix="catalina_access_log" suffix=".txt"
 pattern="common"/>
 ...
</Engine>]]></source>

 See <a href="valve.html#Access_Logging">Access Logging Valves</a>
 for more information on the configuration attributes that are
 supported.

 </subsection>

 <subsection name="Lifecycle Listeners">

 If you have implemented a Java object that needs to know when this
 Engine is started or stopped, you can declare it by
 nesting a Listener 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:

<source><![CDATA[<Engine name="Standalone" ...>
 ...
 <Listener className="com.mycompany.mypackage.MyListener" ... >
 ...
</Engine>]]></source>

 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.

 </subsection>

 <subsection name="Request Filters">

 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:

<source><![CDATA[<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>]]></source>

 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.

 </subsection>

</section>

</body>

</document>

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