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@chitan
Created July 7, 2012 01:44
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How to use WebSocket of Tomcat
<!DOCTYPE html>
<html>
<head>
<meta charset=UTF-8>
<title>Tomcat WebSocket Chat</title>
<script>
var ws = new WebSocket("ws://localhost:8080/TomcatWebSocket/wschat/WsChatServlet");
ws.onopen = function(){
};
ws.onmessage = function(message){
document.getElementById("chatlog").textContent += message.data + "\n";
};
function postToServer(){
ws.send(document.getElementById("msg").value);
document.getElementById("msg").value = "";
}
function closeConnect(){
ws.close();
}
</script>
</head>
<body>
<textarea id="chatlog" readonly></textarea><br/>
<input id="msg" type="text" />
<button type="submit" id="sendButton" onClick="postToServer()">Send!</button>
<button type="submit" id="sendButton" onClick="closeConnect()">End</button>
</body>
</html>
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<servlet>
<servlet-name>WsChatServlet</servlet-name>
<servlet-class>wsapp.WsChatServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>WsChatServlet</servlet-name>
<url-pattern>/wschat/WsChatServlet</url-pattern>
</servlet-mapping>
</web-app>
//This sample is how to use websocket of Tomcat.
package wsapp;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.util.ArrayList;
import org.apache.catalina.websocket.MessageInbound;
import org.apache.catalina.websocket.StreamInbound;
import org.apache.catalina.websocket.WebSocketServlet;
import org.apache.catalina.websocket.WsOutbound;
public class WsChatServlet extends WebSocketServlet{
private static final long serialVersionUID = 1L;
private static ArrayList<MyMessageInbound> mmiList = new ArrayList<MyMessageInbound>();
public StreamInbound createWebSocketInbound(String protocol){
return new MyMessageInbound();
}
private class MyMessageInbound extends MessageInbound{
WsOutbound myoutbound;
@Override
public void onOpen(WsOutbound outbound){
try {
System.out.println("Open Client.");
this.myoutbound = outbound;
mmiList.add(this);
outbound.writeTextMessage(CharBuffer.wrap("Hello!"));
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
public void onClose(int status){
System.out.println("Close Client.");
mmiList.remove(this);
}
@Override
public void onTextMessage(CharBuffer cb) throws IOException{
System.out.println("Accept Message : "+ cb);
for(MyMessageInbound mmib: mmiList){
CharBuffer buffer = CharBuffer.wrap(cb);
mmib.myoutbound.writeTextMessage(buffer);
mmib.myoutbound.flush();
}
}
@Override
public void onBinaryMessage(ByteBuffer bb) throws IOException{
}
}
}
@mahantheshp
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I am getting exception below exception,while staring the server.(D:\novworkspace.metadata.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\lexus-drivers-webapp\WEB-INF\lib\tomcat-servlet-api-7.0.27.jar) - jar not loaded. See Servlet Spec 3.0, section 10.7.2. Offending class: javax/servlet/Servlet.class

@jaygajera
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can i get all the material of wesocket?

@achyut
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achyut commented Mar 28, 2016

Thank a lot!

@pavelantushevich
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Where did you get the package "org.apache.catalina.websocket" from?
Somehow my catalina.jar (from Tomcat 9) don't has it.
And I can't find it somewhere.
Please, give me link of needed lib or official resourse url.

@CFM880
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CFM880 commented Mar 17, 2017

@pavelantushevich
WebSocketServlet Deprecated.
Replaced by the JSR356 WebSocket 1.1 implementation and will be removed in Tomcat 8.0.x.
WebSocketServlet @doc

@mnsuccess
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Thank a lot! good

@bhargavbhegde7
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Thanks!

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ghost commented Jan 23, 2018

This is a great code thank you. Going to run it on my site.

@DCubix
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DCubix commented Aug 26, 2019

Doesn't work with Tomcat 9

@VashishthSingh
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Can want java code for client side not the javascript code can anyone provide me plz.TQ

@Sivanesan1996m
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how to solve this error
error: package org.apache.catalina.websocket does not exist
import org.apache.catalina.websocket.MessageInbound;

Note : already import org.apache.catalina.websocket.* jar file

@natsiosti
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I am trying Dr. Danny Coward's code on pp6 of his Websocket book but has been returning an 'undefined' error for years. Could someone look at Dr. Coward's code and tell where I am getting wrong.

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