| Apache Tomcat Configuration ReferenceThe Context Container| Introduction |  | 
  The Context element represents a web
  application, which is run within a particular virtual host.
  Each web application is based on a Web Application Archive
  (WAR) file, or a corresponding directory containing the corresponding
  unpacked contents, as described in the Servlet Specification (version
  2.2 or later).  For more information about web application archives,
  you can download the
  Servlet
  Specification, and review the Tomcat
  Application Developer's Guide. The web application used to process each HTTP request is selected
  by Catalina based on matching the longest possible prefix of the
  Request URI against the context path of each defined Context.
  Once selected, that Context will select an appropriate servlet to
  process the incoming request, according to the servlet mappings defined
  in the web application deployment descriptor file (which MUST
  be located at /WEB-INF/web.xmlwithin the web app's
  directory hierarchy). You may define as many Context elements as you
  wish.  Each such Context MUST have a unique context path. In
  addition, a Context must be present with a context path equal to
  a zero-length string.  This Context becomes the default
  web application for this virtual host, and is used to process all
  requests that do not match any other Context's context path. For Tomcat 5, unlike Tomcat 4.x, it is NOT recommended to place
  <Context> elements directly in the server.xml file. This
  is because it makes modifying the Context configuration
  more invasive since the main conf/server.xmlfile cannot be
  reloaded without restarting Tomcat. Context elements may be explicitly defined:
   
  In the $CATALINA_HOME/conf/context.xmlfile: 
  the Context element information will be loaded by all webapps.In the 
  $CATALINA_HOME/conf/[enginename]/[hostname]/context.xml.defaultfile: the Context element information will be loaded by all webapps of that
  host.In individual files (with a ".xml" extension) in the 
  $CATALINA_HOME/conf/[enginename]/[hostname]/directory.
  The name of the file (less the .xml) extension will be used as the
  context path. Multi-level context paths may be defined using #, e.g.foo#bar.xmlfor a context path of/foo/bar. The
  default web application may be defined by using a file calledROOT.xml.Only if a context file does not exist for the application in the 
  $CATALINA_HOME/conf/[enginename]/[hostname]/; in an individual
  file at/META-INF/context.xmlinside the application files. If
  the web application is packaged as a WAR then/META-INF/context.xmlwill be copied to$CATALINA_HOME/conf/[enginename]/[hostname]/and renamed to
  match the application's context path. Once this file exists, it will not be
  replaced if a new WAR with a newer/META-INF/context.xmlis
  placed in the host's appBase.inside a Host element in the main
  conf/server.xml With the exception of server.xml, files that define Context
   elements may only define a single Context element.
   In addition to explicitly specified Context elements, there are
  several techniques by which Context elements can be created automatically
  for you.  See 
  Automatic Application Deployment and
  User Web Applications
  for more information. 
    The description below uses the variable name $CATALINA_HOME
    to refer to the directory into which you have installed Tomcat 5,
    and is the base directory against which most relative paths are
    resolved.  However, if you have configured Tomcat 5 for multiple
    instances by setting a CATALINA_BASE directory, you should use
    $CATALINA_BASE instead of $CATALINA_HOME for each of these
    references. | 
 | Attributes |  | 
  | Common Attributes |  | 
    All implementations of Context
    support the following attributes: | Attribute | Description | 
|---|
 | backgroundProcessorDelay | This value represents the delay in seconds between the 
        invocation of the backgroundProcess method on this context and 
        its child containers, including all wrappers. 
        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 host 
        and all its child containers. A context will use background 
        processing to perform session expiration and class monitoring for
        reloading. If not specified, the default value for this attribute is 
        -1, which means the context will rely on the background processing 
        thread of its parent host. |  | className | Java class name of the implementation to use.  This class must
        implement the org.apache.catalina.Contextinterface.
        If not specified, the standard value (defined below) will be used. |  | cookies | Set to trueif you want cookies to be used for
        session identifier communication if supported by the client (this
        is the default).  Set tofalseif you want to disable
        the use of cookies for session identifier communication, and rely
        only on URL rewriting by the application. |  | crossContext | Set to trueif you want calls within this application
        toServletContext.getContext()to successfully return a
        request dispatcher for other web applications running on this virtual
        host.  Set tofalse(the default) in security
        conscious environments, to makegetContext()always
        returnnull. |  | docBase | The Document Base (also known as the Context
        Root) directory for this web application, or the pathname
        to the web application archive file (if this web application is
        being executed directly from the WAR file).    You may specify
        an absolute pathname for this directory or WAR file, or a pathname
        that is relative to the appBasedirectory of the
        owning Host. If a symbolic link is used for docBase then changes to the
        symbolic link will only be effective after a Tomcat restart or
        by undeploying and redeploying the context. A context reload is not
        sufficient. Do not choose a docBase that starts with your Host's appBase string.
        The default appBase is "webapps" so do not choose a docBase like
        "webapps-foo."  Doing so will lead to deployment errors: see 
        Bugzilla for details. The value of this field must not be set when the Context is
        configured using a META-INF/context.xmlfile as it will be
        inferred by the automatic deployment process. |  | override | Set to trueto have explicit settings in this
        Context element override any corresponding settings in the
        default settings associated with the owning
        Host.  The default isfalse. |  | privileged | Set to trueto allow this context to use container
        servlets, like the manager servlet. Use of theprivilegedattribute will change the context's parent class loader to be the
        Catalina class loader rather than the Shared class
        loader. |  | path | The context path of this web application, which is
        matched against the beginning of each request URI to select the
        appropriate web application for processing.  All of the context paths
        within a particular Host must be unique.
        If you specify a context path of an empty string (""), you are
        defining the default web application for this Host, which
        will process all requests not assigned to other Contexts. The value of this field must not be set except when statically
        defining a Context in server.xml, as it will be inferred from the
        filenames used for either the .xml context file or the docBase. |  | reloadable | Set to trueif you want Catalina to monitor classes in/WEB-INF/classes/and/WEB-INF/libfor
        changes, and automatically reload the web application if a change
        is detected.  This feature is very useful during application
        development, but it requires significant runtime overhead and is
        not recommended for use on deployed production applications.  That's
        why the default setting for this attribute is false.  You
        can use the Manager web
        application, however, to trigger reloads of deployed applications
        on demand. |  | wrapperClass | Java class name of the org.apache.catalina.Wrapperimplementation class that will be used for servlets managed by this
        Context.  If not specified, a standard default value will be used. |  | useHttpOnly | Should the HttpOnly flag be set on session cookies to prevent client
          side script from accessing the session ID? Defaults to
          false. | 
 | 
 | Standard Implementation |  | 
    The standard implementation of Context is
    org.apache.catalina.core.StandardContext.
    It supports the following additional attributes (in addition to the
    common attributes listed above): | Attribute | Description | 
|---|
 | allowLinking | If the value of this flag is true, symlinks will be
        allowed inside the web application, pointing to resources outside the
        web application base path. If not specified, the default value
        of the flag isfalse. NOTE: This flag MUST NOT be set to true on the Windows platform
        (or any other OS which does not have a case sensitive filesystem),
        as it will disable case sensitivity checks, allowing JSP source code
        disclosure, among other security problems. |  | antiJARLocking | If true, the Tomcat classloader will take extra measures to avoid
        JAR file locking when resources are accessed inside JARs through URLs.
        This will impact startup time of applications, but could prove to be
        useful on platforms or configurations where file locking can occur.
        If not specified, the default value is false. antiJARLockingis a subset ofantiResourceLockingand therefore, to prevent duplicate
        work and possible issues, only one of these attributes should be set
        totrueat any one time.
 |  | antiResourceLocking | If true, Tomcat will prevent any file locking.
        This will significantly impact startup time of applications, 
        but allows full webapp hot deploy and undeploy on platforms 
        or configurations where file locking can occur.
        If not specified, the default value is false. antiJARLockingis a subset ofantiResourceLockingand therefore, to prevent duplicate
        work and possible issues, only one of these attributes should be set
        totrueat any one time.
 Please note that setting this to truehas some side
        effects, including the disabling of JSP reloading in a running server:
        see 
        Bugzilla 37668. Please note that setting this flag to true in applications that are
        outside the appBase for the Host (the webappsdirectory
        by default) will cause the application to be deleted on
        Tomcat shutdown.  You probably don't want to do this, so think twice
        before setting antiResourceLocking=true on a webapp that's outside the
        appBase for its Host. |  | cacheMaxSize | Maximum size of the static resource cache in kilobytes. 
        If not specified, the default value is 10240(10 megabytes). |  | cacheTTL | Amount of time in milliseconds between cache entries revalidation.
        If not specified, the default value is 5000(5 seconds). |  | cachingAllowed | If the value of this flag is true, the cache for static
        resources will be used. If not specified, the default value
        of the flag istrue. |  | caseSensitive | If the value of this flag is false, all case sensitivity
        checks will be disabled. If not 
        specified, the default value of the flag istrue. NOTE: This flag MUST NOT be set to false on the Windows platform
        (or any other OS which does not have a case sensitive filesystem),
        as it will disable case sensitivity checks, allowing JSP source code
        disclosure, among other security problems. |  | processTlds | Whether the context should process TLDs on startup.  The default
        is true.  The false setting is intended for special cases
        that know in advance TLDs are not part of the webapp. |  | swallowOutput | If the value of this flag is true, the bytes output to
        System.out and System.err by the web application will be redirected to
        the web application logger. If not specified, the default value
        of the flag isfalse. |  | tldNamespaceAware | If the value of this flag is true, the TLD files
        XML validation will be namespace-aware.  If you turn this flag on,
        you should probably also turntldValidationon.  The
        default value for this flag isfalse, and setting it
        to true will incur a performance penalty. |  | tldValidation | If the value of this flag is true, the TLD files
        will be XML validated on context startup.  The default value for
        this flag isfalse, and setting it to true will incur
        a performance penalty. |  | unloadDelay | Amount of ms that the container will wait for servlets to unload.
        If not specified, the default value of the flag is 2000ms. |  | unpackWAR | If true, Tomcat will unpack all compressed web applications before
        running them.
        If not specified, the default value is true. |  | useNaming | Set to true(the default) to have Catalina enable a
        JNDIInitialContextfor this web application that is
        compatible with Java2 Enterprise Edition (J2EE) platform
        conventions. |  | workDir | Pathname to a scratch directory to be provided by this Context
        for temporary read-write use by servlets within the associated web
        application.  This directory will be made visible to servlets in the
        web application by a servlet context attribute (of type
        java.io.File) namedjavax.servlet.context.tempdiras described in the
        Servlet Specification.  If not specified, a suitable directory
        underneath$CATALINA_HOME/workwill be provided. | 
 | 
 | 
 | Nested Components |  | 
  You can nest at most one instance of the following utility components
  by nesting a corresponding element inside your Context
  element: 
  Loader -
      Configure the web application class loader that will be used to load
      servlet and bean classes for this web application.  Normally, the
      default configuration of the class loader will be sufficient.Manager -
      Configure the session manager that will be used to create, destroy,
      and persist HTTP sessions for this web application.  Normally, the
      default configuration of the session manager will be sufficient.Realm -
      Configure a realm that will allow its
      database of users, and their associated roles, to be utilized solely
      for this particular web application.  If not specified, this web
      application will utilize the Realm associated with the owning
      Host or Engine.Resources -
      Configure the resource manager that will be used to access the static
      resources associated with this web application.  Normally, the
      default configuration of the resource manager will be sufficient.WatchedResource - The auto deployer will monitor the 
      specified static resource of the web application for updates, and will
      reload the web application if is is updated. The content of this element
      must be a string. | 
 | Special Features |  | 
  | Logging |  | 
    A context is associated with the 
       org.apache.catalina.core.ContainerBase.[enginename].[hostname].[path]log category.  Note that the brackets are actually part of the name, don't omit them. | 
 | Automatic Context Configuration |  | 
    If you use the standard Context implementation,
    the following configuration steps occur automtically when Catalina
    is started, or whenever this web application is reloaded.  No special
    configuration is required to enable this feature. 
    If you have not declared your own Loader
       element, a standard web application class loader will be configured.
       If you have not declared your own Manager
        element, a standard session manager will be configured.If you have not declared your own Resources
        element, a standard resources manager will be configured.The web application properties listed in conf/web.xmlwill be processed as defaults for this web application.  This is used
        to establish default mappings (such as mapping the*.jspextension to the corresponding JSP servlet), and other standard
        features that apply to all web applications.The web application properties listed in the
        /WEB-INF/web.xmlresource for this web application
        will be processed (if this resource exists).If your web application has specified security constraints that might
        require user authentication, an appropriate Authenticator that
        implements the login method you have selected will be configured. | 
 | Environment Entries |  | 
    You can configure named values that will be made visible to the
    web application as environment entry resources, by nesting
    <Environment>entries inside this element.  For
    example, you can create an environment entry like this: |  |  |  |  |  | 
<Context ...>
  ...
  <Environment name="maxExemptions" value="10"
         type="java.lang.Integer" override="false"/>
  ...
</Context>
 |  |  |  |  |  | 
This is equivalent to the inclusion of the following element in the
    web application deployment descriptor (/WEB-INF/web.xml): |  |  |  |  |  | 
<env-entry>
  <env-entry-name>maxExemptions</env-entry-name>
  <env-entry-value>10</env-entry-value>
  <env-entry-type>java.lang.Integer</env-entry-type>
</env-entry>
 |  |  |  |  |  | 
but does not require modification of the deployment descriptor
    to customize this value. The valid attributes for an <Environment>element
    are as follows: | Attribute | Description | 
|---|
 | description | Optional, human-readable description of this environment entry. |  | name | The name of the environment entry to be created, relative to the
        java:comp/envcontext. |  | override | Set this to falseif you do not want
        an<env-entry>for the same environment entry name,
        found in the web application deployment descriptor, to override the
        value specified here.  By default, overrides are allowed. |  | type | The fully qualified Java class name expected by the web application
        for this environment entry.  Must be one of the legal values for
        <env-entry-type>in the web application deployment
        descriptor:java.lang.Boolean,java.lang.Byte,java.lang.Character,java.lang.Double,java.lang.Float,java.lang.Integer,java.lang.Long,java.lang.Short, orjava.lang.String. |  | value | The parameter value that will be presented to the application
        when requested from the JNDI context.  This value must be convertable
        to the Java type defined by the typeattribute. | 
 | 
 | Resource Links |  | 
     This element is used to create a link to a global JNDI resource. Doing
     a JNDI lookup on the link name will then return the linked global 
     resource. For example, you can create a resource link like this: |  |  |  |  |  | 
<Context ...>
  ...
  <ResourceLink name="linkToGlobalResource"
            global="simpleValue"
            type="java.lang.Integer"
  ...
</Context>
 |  |  |  |  |  | 
The valid attributes for a <ResourceLink>element
    are as follows: | Attribute | Description | 
|---|
 | global | The name of the linked global resource in the 
        global JNDI context. |  | name | The name of the resource link to be created, relative to the
        java:comp/envcontext. |  | type | The fully qualified Java class name expected by the web
        application when it performs a lookup for this resource link. | 
 | 
 | Transaction |  | 
    You can declare the characteristics of the UserTransaction
    to be returned for JNDI lookup for java:comp/UserTransaction. 
    You MUST define an object factory class to instantiate
    this object as well as the needed resource parameters as attributes of theTransactionelement, and the properties used to configure that object factory. The valid attributes for the <Transaction>element
    are as follows: | Attribute | Description | 
|---|
 | factory | The class name for the JNDI object factory. | 
 | 
 | 
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