JvmRouteBinderValve (Apache Tomcat 8.5.20 API Documentation)

org.apache.catalina.ha.session

## Class JvmRouteBinderValve

- java.lang.Object
- - org.apache.catalina.util.LifecycleBase
  - - org.apache.catalina.util.LifecycleMBeanBase
    - - org.apache.catalina.valves.ValveBase
      - - org.apache.catalina.ha.session.JvmRouteBinderValve

- All Implemented Interfaces:
    MBeanRegistration, Contained, ClusterValve, JmxEnabled, Lifecycle, Valve

      public class JvmRouteBinderValve
      extends ValveBase
      implements ClusterValve

  Valve to handle Tomcat jvmRoute takeover using mod_jk module after node failure. After a node crashes, subsequent requests go to other cluster nodes. That incurs a drop in performance. When this Valve is enabled on a backup node and sees a request, which was intended for another (thus failed) node, it will rewrite the cookie jsessionid information to use the route to this backup cluster node, that answered the request. After the response is delivered to the client, all subsequent client requests will go directly to the backup node. The change of sessionid is also sent to all other cluster nodes. After all that, the session stickiness will work directly to the backup node and the traffic will not go back to the failed node after it is restarted!

  Add this Valve to your host definition at conf/server.xml . Since 5.5.10 as direct cluster valve:

        <Cluster>
        <Valve className="org.apache.catalina.ha.session.JvmRouteBinderValve" />
        </Cluster>

  Before 5.5.10 as Host element:

        <Host>
        <Valve className="org.apache.catalina.ha.session.JvmRouteBinderValve" />
        </Host>

  A Trick:
  You can enable this mod_jk turnover mode via JMX before you drop a node to all backup nodes! Set enable true on all JvmRouteBinderValve backups, disable worker at mod_jk and then drop node and restart it! Then enable mod_jk worker and disable JvmRouteBinderValves again. This use case means that only requested sessions are migrated.
  Author:
    Peter Rossbach

- - ### Nested Class Summary

    - ### Nested classes/interfaces inherited from interface org.apache.catalina.Lifecycle

      `Lifecycle.SingleUse`

  - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected CatalinaCluster` | `cluster` the cluster
    `protected boolean` | `enabled` enabled this component
    `static Log` | `log`
    `protected long` | `numberOfSessions` number of session that no at this tomcat instance hosted
    `protected String` | `sessionIdAttribute`
    `protected static StringManager` | `sm` The string manager for this package.

    - ### Fields inherited from class org.apache.catalina.valves.ValveBase

      `asyncSupported, container, containerLog, next`

    - ### Fields inherited from class org.apache.catalina.util.LifecycleMBeanBase

      `mserver`

    - ### Fields inherited from interface org.apache.catalina.Lifecycle

      `AFTER_DESTROY_EVENT, AFTER_INIT_EVENT, AFTER_START_EVENT, AFTER_STOP_EVENT, BEFORE_DESTROY_EVENT, BEFORE_INIT_EVENT, BEFORE_START_EVENT, BEFORE_STOP_EVENT, CONFIGURE_START_EVENT, CONFIGURE_STOP_EVENT, PERIODIC_EVENT, START_EVENT, STOP_EVENT`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `JvmRouteBinderValve()`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected void` | `changeRequestSessionID(Request request, String sessionId, String newSessionID)` Change Request Session id
    `protected void` | `changeSessionID(Request request, String sessionId, String newSessionID, Session catalinaSession)` change session id and send to all cluster nodes
    `CatalinaCluster` | `getCluster()` Returns the cluster the cluster deployer is associated with
    `boolean` | `getEnabled()`
    `protected String` | `getLocalJvmRoute(Request request)` get jvmroute from engine
    `protected Manager` | `getManager(Request request)` get ClusterManager
    `long` | `getNumberOfSessions()`
    `String` | `getSessionIdAttribute()` set session id attribute to failed node for request.
    `protected void` | `handleJvmRoute(Request request, String sessionId, String localJvmRoute)` Handle jvmRoute stickiness after tomcat instance failed.
    `protected void` | `handlePossibleTurnover(Request request)` handle possible session turn over.
    `void` | `invoke(Request request, Response response)` Detect possible the JVMRoute change at cluster backup node..
    `void` | `setCluster(CatalinaCluster cluster)` Associates the cluster deployer with a cluster
    `void` | `setEnabled(boolean enabled)`
    `void` | `setSessionIdAttribute(String sessionIdAttribute)` get name of failed request session attribute
    `protected void` | `startInternal()` Start this component and implement the requirements of `LifecycleBase.startInternal()`.
    `protected void` | `stopInternal()` Stop this component and implement the requirements of `LifecycleBase.stopInternal()`.

    - ### Methods inherited from class org.apache.catalina.valves.ValveBase

      `backgroundProcess, getContainer, getDomainInternal, getNext, getObjectNameKeyProperties, initInternal, isAsyncSupported, setAsyncSupported, setContainer, setNext, toString`

    - ### Methods inherited from class org.apache.catalina.util.LifecycleMBeanBase

      `destroyInternal, getDomain, getObjectName, postDeregister, postRegister, preDeregister, preRegister, register, setDomain, unregister`

    - ### Methods inherited from class org.apache.catalina.util.LifecycleBase

      `addLifecycleListener, destroy, findLifecycleListeners, fireLifecycleEvent, getState, getStateName, init, removeLifecycleListener, setState, setState, start, stop`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

    - ### Methods inherited from interface org.apache.catalina.Valve

      `backgroundProcess, getNext, isAsyncSupported, setNext`

- - ### Field Detail

    - #### log

          public static final Log log

    - #### cluster

          protected CatalinaCluster cluster

      the cluster

    - #### sm

          protected static final StringManager sm

      The string manager for this package.

    - #### enabled

          protected boolean enabled

      enabled this component

    - #### numberOfSessions

          protected long numberOfSessions

      number of session that no at this tomcat instance hosted

    - #### sessionIdAttribute

          protected String sessionIdAttribute

  - ### Constructor Detail

    - #### JvmRouteBinderValve

          public JvmRouteBinderValve()

  - ### Method Detail

    - #### getSessionIdAttribute

          public String getSessionIdAttribute()

      set session id attribute to failed node for request.
      Returns:
        Returns the sessionIdAttribute.

    - #### setSessionIdAttribute

          public void setSessionIdAttribute(String sessionIdAttribute)

      get name of failed request session attribute
      Parameters:
        `sessionIdAttribute` - The sessionIdAttribute to set.

    - #### getNumberOfSessions

          public long getNumberOfSessions()

      Returns:
        Returns the number of migrated sessions.

    - #### getEnabled

          public boolean getEnabled()

      Returns:
        Returns the enabled.

    - #### setEnabled

          public void setEnabled(boolean enabled)

      Parameters:
        `enabled` - The enabled to set.

    - #### invoke

          public void invoke(Request request,
                    Response response)
                      throws IOException,
                             ServletException

      Detect possible the JVMRoute change at cluster backup node..
      Specified by:
        `invoke` in interface `Valve`
      Parameters:
        `request` - tomcat request being processed
        `response` - tomcat response being processed
      Throws:
        `IOException` - if an input/output error has occurred
        `ServletException` - if a servlet error has occurred

    - #### handlePossibleTurnover

          protected void handlePossibleTurnover(Request request)

      handle possible session turn over.
      Parameters:
        `request` - current request
      See Also:
        `handleJvmRoute(Request, String, String)`

    - #### getLocalJvmRoute

          protected String getLocalJvmRoute(Request request)

      get jvmroute from engine
      Parameters:
        `request` - current request
      Returns:
        return jvmRoute from ManagerBase or null

    - #### getManager

          protected Manager getManager(Request request)

      get ClusterManager
      Parameters:
        `request` - current request
      Returns:
        manager or null

    - #### getCluster

          public CatalinaCluster getCluster()

      Description copied from interface: `ClusterValve`
      Returns the cluster the cluster deployer is associated with
      Specified by:
        `getCluster` in interface `ClusterValve`
      Returns:
        Returns the cluster.

    - #### setCluster

          public void setCluster(CatalinaCluster cluster)

      Description copied from interface: `ClusterValve`
      Associates the cluster deployer with a cluster
      Specified by:
        `setCluster` in interface `ClusterValve`
      Parameters:
        `cluster` - The cluster to set.

    - #### handleJvmRoute

          protected void handleJvmRoute(Request request,
                            String sessionId,
                            String localJvmRoute)

      Handle jvmRoute stickiness after tomcat instance failed. After this correction a new Cookie send to client with new jvmRoute and the SessionID change propagate to the other cluster nodes.
      Parameters:
        `request` - current request
        `sessionId` - request SessionID from Cookie
        `localJvmRoute` - local jvmRoute

    - #### changeSessionID

          protected void changeSessionID(Request request,
                             String sessionId,
                             String newSessionID,
                             Session catalinaSession)

      change session id and send to all cluster nodes
      Parameters:
        `request` - current request
        `sessionId` - original session id
        `newSessionID` - new session id for node migration
        `catalinaSession` - current session with original session id

    - #### changeRequestSessionID

          protected void changeRequestSessionID(Request request,
                                    String sessionId,
                                    String newSessionID)

      Change Request Session id
      Parameters:
        `request` - current request
        `sessionId` - original session id
        `newSessionID` - new session id for node migration

    - #### startInternal

          protected void startInternal()
                                throws LifecycleException

      Start this component and implement the requirements of `LifecycleBase.startInternal()`.
      Overrides:
        `startInternal` in class `ValveBase`
      Throws:
        `LifecycleException` - if this component detects a fatal error that prevents this component from being used

    - #### stopInternal

          protected void stopInternal()
                               throws LifecycleException

      Stop this component and implement the requirements of `LifecycleBase.stopInternal()`.
      Overrides:
        `stopInternal` in class `ValveBase`
      Throws:
        `LifecycleException` - if this component detects a fatal error that prevents this component from being used

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