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POTomcat throws AbstractMethodError for WebSocketServlet.createWebSocketInbound() when custom servlet runs
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  1. POTomcat throws AbstractMethodError for WebSocketServlet.createWebSocketInbound() when custom servlet runs
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    copied!<p>I work on a project in which I need to create a real time web application. I've developed a small program to test WebSockets with Apache Tomcat, but it doesn't work and instead throws an <code>AbstractMethodError</code> exception. The servlet compiles and the web application deploys fine.</p> <p>Here's the servlet's code.</p> <pre><code>public class TestWebSocket extends WebSocketServlet { private static final long serialVersionUID = 1L; @Override protected boolean verifyOrigin(String origin) { System.out.println("Origin: {}" + origin); return true; } @Override protected StreamInbound createWebSocketInbound(String subProtocol, HttpServletRequest request) { return new WebSocketConnection(); } private static class WebSocketConnection extends MessageInbound { @Override protected void onOpen(WsOutbound outbound) { System.out.println("Conexión abierta"); } @Override protected void onClose(int status) { System.out.println("Conexión cerrada"); } @Override protected void onBinaryMessage(ByteBuffer byteBuffer) throws IOException { System.out.println("No se soportan mensajes binarios"); throw new UnsupportedOperationException("No se soportan mensajes binarios"); } @Override protected void onTextMessage(CharBuffer charBuffer) throws IOException { final String user = charBuffer.toString(); System.out.println("Mensaje recibido: {}" + user); getWsOutbound().writeTextMessage(CharBuffer.wrap("Hola " + user + " desde WebSocket")); } } } </code></pre> <p>Here goes the deployment descriptor - <code>web.xml</code></p> <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt; &lt;web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"&gt; &lt;display-name&gt;TestWebSocket&lt;/display-name&gt; &lt;servlet&gt; &lt;servlet-name&gt;TestWebSocket&lt;/servlet-name&gt; &lt;servlet-class&gt;com.test.TestWebSocket&lt;/servlet-class&gt; &lt;/servlet&gt; &lt;servlet-mapping&gt; &lt;servlet-name&gt;TestWebSocket&lt;/servlet-name&gt; &lt;url-pattern&gt;/testWebSocket&lt;/url-pattern&gt; &lt;/servlet-mapping&gt; &lt;/web-app&gt; </code></pre> <p>And the client code - <code>testSocket.js</code>:</p> <pre><code>/* * For Testing websockets */ $(function(){ console.log("URL :" + 'ws://' + location.host + '/TestTomcatWebSocket/testWebSocket'); var ws = new WebSocket('ws://' + location.host + '/TestTomcatWebSocket/testWebSocket'); ws.onopen = function() { console.log("Websocket Ready!!"); sendMessage(); }; ws.onmessage= function(data) { console.log("message received : " + data); }; function sendMessage() { ws.send("Test"); }; }); </code></pre> <p>Upon execution the application finishes with the following <code>java.lang.AbstractMethodError</code> exception:</p> <pre><code>INFO: Server startup in 495 ms Origin: {}http://localhost:8080 Dec 17, 2012 1:58:51 AM org.apache.catalina.core.StandardWrapperValve invoke SEVERE: Servlet.service() for servlet [TestWebSocket] in context with path [/TestTomcatWebSocket] threw exception [Servlet execution threw an exception] with root cause java.lang.AbstractMethodError: org.apache.catalina.websocket.WebSocketServlet.createWebSocketInbound(Ljava/lang/String;)Lorg/apache/catalina/websocket/StreamInbound; at org.apache.catalina.websocket.WebSocketServlet.doGet(WebSocketServlet.java:125) at javax.servlet.http.HttpServlet.service(HttpServlet.java:621) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:307) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) </code></pre> <p>I use Apache Tomcat 7.0.33.</p>
 

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