Package org.apache.catalina

Interface Valve

All Known Subinterfaces:
ClusterValve
All Known Implementing Classes:
AbstractAccessLogValve, AccessLogValve, AuthenticatorBase, BasicAuthenticator, ClusterSingleSignOn, CrawlerSessionManagerValve, DigestAuthenticator, ErrorReportValve, ExtendedAccessLogValve, FormAuthenticator, HealthCheckValve, JDBCAccessLogValve, JsonAccessLogValve, JsonErrorReportValve, JvmRouteBinderValve, LoadBalancerDrainingValve, NonLoginAuthenticator, PersistentValve, ProxyErrorReportValve, RemoteAddrValve, RemoteCIDRValve, RemoteHostValve, RemoteIpValve, ReplicationValve, RequestFilterValve, RewriteValve, SemaphoreValve, SingleSignOn, SpnegoAuthenticator, SSLAuthenticator, SSLValve, StuckThreadDetectionValve, ValveBase
public interface Valve

A Valve is a request processing component associated with a particular Container. A series of Valves are generally associated with each other into a Pipeline. The detailed contract for a Valve is included in the description of the invoke() method below.

HISTORICAL NOTE: The "Valve" name was assigned to this concept because a valve is what you use in a real world pipeline to control and/or modify flows through it.
Author:
Craig R. McClanahan, Gunnar Rjnning, Peter Donald

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    backgroundProcess()
    Execute a periodic task, such as reloading, etc.
    Valve
    getNext()
    Returns the next Valve in this pipeline, or null if this is the last Valve in the pipeline.
    void
    invoke(Request request, Response response)
    Perform request processing as required by this Valve.
    boolean
    isAsyncSupported()
     
    void
    setNext(Valve valve)
    Set the next Valve in the pipeline containing this Valve.

  • Method Details

    • getNext

      Valve getNext()
      Returns the next Valve in this pipeline, or null if this is the last Valve in the pipeline.
      Returns:
      the next Valve in the pipeline containing this Valve, or null if this is the last Valve in the pipeline.

    • setNext

      void setNext(Valve valve)
      Set the next Valve in the pipeline containing this Valve.
      Parameters:
      valve - The new next valve, or null if none

    • backgroundProcess

      void backgroundProcess()
      Execute a periodic task, such as reloading, etc. This method will be invoked inside the classloading context of this container. Unexpected throwables will be caught and logged.

    • invoke

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

      Perform request processing as required by this Valve.

      An individual Valve MAY perform the following actions, in the specified order:

      • Examine and/or modify the properties of the specified Request and Response.
      • Examine the properties of the specified Request, completely generate the corresponding Response, and return control to the caller.
      • Examine the properties of the specified Request and Response, wrap either or both of these objects to supplement their functionality, and pass them on.
      • If the corresponding Response was not generated (and control was not returned, call the next Valve in the pipeline (if there is one) by executing getNext().invoke().
      • Examine, but not modify, the properties of the resulting Response (which was created by a subsequently invoked Valve or Container).

      A Valve MUST NOT do any of the following things:

      • Change request properties that have already been used to direct the flow of processing control for this request (for instance, trying to change the virtual host to which a Request should be sent from a pipeline attached to a Host or Context in the standard implementation).
      • Create a completed Response AND pass this Request and Response on to the next Valve in the pipeline.
      • Consume bytes from the input stream associated with the Request, unless it is completely generating the response, or wrapping the request before passing it on.
      • Modify the HTTP headers included with the Response after the getNext().invoke() method has returned.
      • Perform any actions on the output stream associated with the specified Response after the getNext().invoke() method has returned.
      Parameters:
      request - The servlet request to be processed
      response - The servlet response to be created
      Throws:
      IOException - if an input/output error occurs, or is thrown by a subsequently invoked Valve, Filter, or Servlet
      ServletException - if a servlet error occurs, or is thrown by a subsequently invoked Valve, Filter, or Servlet

    • isAsyncSupported

      boolean isAsyncSupported()