com.vaadin.server.communication.JSR356WebsocketInitializer Maven / Gradle / Ivy
/*
* Copyright (C) 2000-2024 Vaadin Ltd
*
* This program is available under Vaadin Commercial License and Service Terms.
*
* See for the full
* license.
*/
package com.vaadin.server.communication;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.ServletRegistration;
import javax.servlet.annotation.WebListener;
import org.atmosphere.cpr.AtmosphereFramework;
import com.vaadin.server.VaadinServlet;
/**
* 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 {@link WebListener} is Servlet 3.0 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.
*
* @since 7.5.0
* @author Vaadin Ltd
*/
@WebListener
public class JSR356WebsocketInitializer implements ServletContextListener {
private static boolean atmosphereAvailable = false;
static {
try {
org.atmosphere.util.Version.getRawVersion();
atmosphereAvailable = true;
} catch (NoClassDefFoundError e) {
}
}
/**
* "ServletConfig" which only provides information from a
* {@link ServletRegistration} and its {@link ServletContext}.
*/
public static class FakeServletConfig implements ServletConfig {
private final ServletRegistration servletRegistration;
private final ServletContext servletContext;
public FakeServletConfig(ServletRegistration servletRegistration,
ServletContext servletContext) {
this.servletContext = servletContext;
this.servletRegistration = servletRegistration;
}
@Override
public String getServletName() {
return servletRegistration.getName();
}
@Override
public ServletContext getServletContext() {
return servletContext;
}
@Override
public String getInitParameter(String name) {
return servletRegistration.getInitParameter(name);
}
@Override
public Enumeration getInitParameterNames() {
return Collections.enumeration(
servletRegistration.getInitParameters().keySet());
}
}
@Override
public void contextInitialized(ServletContextEvent sce) {
ServletContext servletContext = sce.getServletContext();
if (servletContext.getMajorVersion() < 3) {
return;
}
init(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.
*
* @param servletContext
* The servlet context
*/
public void init(ServletContext servletContext) {
if (!atmosphereAvailable) {
return;
}
Map regs = servletContext
.getServletRegistrations();
for (String servletName : regs.keySet()) {
ServletRegistration servletRegistration = regs.get(servletName);
if (isVaadinServlet(servletRegistration, servletContext)) {
try {
initAtmosphereForVaadinServlet(servletRegistration,
servletContext);
} catch (Exception e) {
getLogger().log(Level.WARNING,
"Failed to initialize Atmosphere for "
+ servletName,
e);
}
}
}
}
/**
* 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.
*
* @param servletRegistration
* The servlet registration info for the servlet
* @param servletContext
*/
public static void initAtmosphereForVaadinServlet(
ServletRegistration servletRegistration,
ServletContext servletContext) {
String servletName = servletRegistration.getName();
String attributeName = getAttributeName(servletName);
if (servletContext.getAttribute(attributeName) != null) {
// Already initialized
getLogger().warning("Atmosphere already initialized");
return;
}
getLogger().finer("Creating AtmosphereFramework for " + servletName);
AtmosphereFramework framework = PushRequestHandler.initAtmosphere(
new FakeServletConfig(servletRegistration, servletContext));
servletContext.setAttribute(attributeName, framework);
getLogger().finer("Created AtmosphereFramework for " + servletName);
}
/**
* Returns the name of the attribute in the servlet context where the
* pre-initialized Atmosphere object is stored.
*
* @param servletName
* The name of the servlet
* @return The attribute name which contains the initialized Atmosphere
* object
*/
public static String getAttributeName(String servletName) {
return JSR356WebsocketInitializer.class.getName() + "." + servletName;
}
/**
* Checks if the given attribute name matches the convention used for
* storing AtmosphereFramework references.
*
* @param attributeName
* the attribute name to check
* @return true if the attribute name matches the convention,
* false otherwise
*/
private static boolean isAtmosphereFrameworkAttribute(
String attributeName) {
return attributeName
.startsWith(JSR356WebsocketInitializer.class.getName() + ".");
}
/**
* Tries to determine if the given servlet registration refers to a Vaadin
* servlet.
*
* @param servletRegistration
* The servlet registration info for the servlet
* @return false if the servlet is definitely not a Vaadin servlet, true
* otherwise
*/
protected boolean isVaadinServlet(ServletRegistration servletRegistration,
ServletContext servletContext) {
try {
String servletClassName = servletRegistration.getClassName();
if (servletClassName.equals("com.ibm.ws.wsoc.WsocServlet")) {
// Websphere servlet which implements websocket endpoints,
// dynamically added
return false;
}
// Must use servletContext class loader to load servlet class to
// work correctly in an OSGi environment (#20024)
Class servletClass = servletContext.getClassLoader()
.loadClass(servletClassName);
return VaadinServlet.class.isAssignableFrom(servletClass);
} catch (Exception e) {
// This will fail in OSGi environments, assume everything is a
// VaadinServlet
return true;
}
}
private static final Logger getLogger() {
return Logger.getLogger(JSR356WebsocketInitializer.class.getName());
}
@Override
public void contextDestroyed(ServletContextEvent sce) {
// Destroy any AtmosphereFramework instance we have initialized.
// This must be done here to ensure that we cleanup Atmosphere instances
// related to servlets which are never initialized
ServletContext servletContext = sce.getServletContext();
Enumeration attributeNames = servletContext.getAttributeNames();
while (attributeNames.hasMoreElements()) {
String attributeName = attributeNames.nextElement();
if (isAtmosphereFrameworkAttribute(attributeName)) {
Object value = servletContext.getAttribute(attributeName);
if (value instanceof AtmosphereFramework) {
// This might result in calling destroy() twice, once from
// here and once from PushRequestHandler but
// AtmosphereFramework.destroy() deals with that
((AtmosphereFramework) value).destroy();
}
}
}
}
/**
* Checks if Atmosphere is available on the classpath.
*
* @return true if Atmosphere is available, false
* otherwise
*/
public static boolean isAtmosphereAvailable() {
return atmosphereAvailable;
}
}