Package com.vaadin.flow.server.communication

Class JSR356WebsocketInitializer

java.lang.Object
com.vaadin.flow.server.communication.JSR356WebsocketInitializer
All Implemented Interfaces:
jakarta.servlet.ServletContextListener, EventListener
public class JSR356WebsocketInitializer extends Object implements jakarta.servlet.ServletContextListener
Initializer class for JSR 356 websockets.

Websocket specification says that initialization of websocket end points should be done in the servlet context initialization phase. Some servers implement this strictly so that end points cannot be registered after the context initialization phase.

Note that WebListener is Servlet 5.0 API so this will not be run for older servers (unless added to web.xml), but these servers do not support JSR 356 websockets either.

For internal use only. May be renamed or removed in a future release.

Since:
1.0
Author:
Vaadin Ltd

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    static class 
    JSR356WebsocketInitializer.FakeServletConfig
    "ServletConfig" which only provides information from a ServletRegistration and its ServletContext.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final String
    SKIP_INITIALIZATION_ATTRIBUTE
    The name of the servlet context attribute which, when set to Boolean.TRUE, makes this listener leave Atmosphere uninitialized when the servlet context is initialized.

  • Constructor Summary

    Constructors
    Constructor
    Description
    JSR356WebsocketInitializer()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    contextDestroyed(jakarta.servlet.ServletContextEvent sce)
     
    void
    contextInitialized(jakarta.servlet.ServletContextEvent sce)
     
    static String
    getAttributeName(String servletName)
    Returns the name of the attribute in the servlet context where the pre-initialized Atmosphere object is stored.
    void
    init(jakarta.servlet.ServletContext servletContext)
    Initializes Atmosphere for use with Vaadin servlets found in the given context.
    static void
    initAtmosphereForVaadinServlet(jakarta.servlet.ServletRegistration servletRegistration, jakarta.servlet.ServletContext servletContext)
    Initializes Atmosphere for use with the given Vaadin servlet
    static boolean
    isAtmosphereAvailable()
    Checks if Atmosphere is available on the classpath.
    protected boolean
    isVaadinServlet(jakarta.servlet.ServletRegistration servletRegistration, jakarta.servlet.ServletContext servletContext)
    Tries to determine if the given servlet registration refers to a Vaadin servlet.

    Methods inherited from class java.lang.Object

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

  • Field Details

    • SKIP_INITIALIZATION_ATTRIBUTE

      public static final String SKIP_INITIALIZATION_ATTRIBUTE
      The name of the servlet context attribute which, when set to Boolean.TRUE, makes this listener leave Atmosphere uninitialized when the servlet context is initialized.

      An integration sets it when it registers the push WebSocket endpoints itself and initializes Atmosphere later, with initAtmosphereForVaadinServlet(ServletRegistration, ServletContext).

      For internal use only. May be renamed or removed in a future release.

      See Also:

  • Constructor Details

    • JSR356WebsocketInitializer

      public JSR356WebsocketInitializer()

  • Method Details

    • contextInitialized

      public void contextInitialized(jakarta.servlet.ServletContextEvent sce)
      Specified by:
      contextInitialized in interface jakarta.servlet.ServletContextListener

    • init

      public void init(jakarta.servlet.ServletContext servletContext)
      Initializes Atmosphere for use with Vaadin servlets found in the given context.

      For JSR 356 websockets to work properly, the initialization must be done in the servlet context initialization phase, unless the SKIP_INITIALIZATION_ATTRIBUTE attribute of the context says that an integration takes care of the push WebSocket endpoints.

      Parameters:
      servletContext - The servlet context

    • initAtmosphereForVaadinServlet

      public static void initAtmosphereForVaadinServlet(jakarta.servlet.ServletRegistration servletRegistration, jakarta.servlet.ServletContext servletContext)
      Initializes Atmosphere for use with the given Vaadin servlet

      For JSR 356 websockets to work properly, the initialization must be done in the servlet context initialization phase, unless an integration that set the SKIP_INITIALIZATION_ATTRIBUTE attribute registers the push WebSocket endpoints itself. Such an integration calls this method later, before the Vaadin servlet is initialized, so that the servlet uses the Atmosphere instance created here.

      Parameters:
      servletRegistration - The servlet registration info for the servlet
      servletContext - The servlet context

    • getAttributeName

      public static String getAttributeName(String servletName)
      Returns the name of the attribute in the servlet context where the pre-initialized Atmosphere object is stored.
      Parameters:
      servletName - The name of the servlet
      Returns:
      The attribute name which contains the initialized Atmosphere object

    • isVaadinServlet

      protected boolean isVaadinServlet(jakarta.servlet.ServletRegistration servletRegistration, jakarta.servlet.ServletContext servletContext)
      Tries to determine if the given servlet registration refers to a Vaadin servlet.
      Parameters:
      servletRegistration - The servlet registration info for the servlet
      servletContext - the context of the servlet
      Returns:
      true if the servlet class is a Vaadin servlet, false otherwise (including when the servlet class cannot be loaded)

    • contextDestroyed

      public void contextDestroyed(jakarta.servlet.ServletContextEvent sce)
      Specified by:
      contextDestroyed in interface jakarta.servlet.ServletContextListener

    • isAtmosphereAvailable

      public static boolean isAtmosphereAvailable()
      Checks if Atmosphere is available on the classpath.
      Returns:
      true if Atmosphere is available, false otherwise