In this tip you can see how to use the Angular Websocket module for connecting client applications to servers. For this case, we have a Java endpoint, as below:
package com.mycompany.angularws;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import java.util.logging.Logger;
import javax.websocket.OnClose;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.server.ServerEndpoint;
@ServerEndpoint("/atpendpoint")
public class ATPWSEndpoint {
private static final Logger LOG = Logger.getLogger(ATPWSEndpoint.class.getName());
private static Set<Session> peers = Collections.synchronizedSet(new HashSet<Session>());
@OnMessage
public String onMessage(String message) {
if (message != null) {
if (message.equals("HELLO SERVER")) {
return "{\"hello\": \"Hello, if you need the ATP list just press the button ...\"}";
} else if (message.equals("ATP SERVER")) {
return "[{\"name\": \"Nadal, Rafael (ESP)\", \"email\": \"nadalrafael@gmail.com\", \"rank\": \"1\"},"
+ "{\"name\": \"Djokovic, Novak (SRB)\", \"email\": \"djokovicnovak@gmail.com\", \"rank\": \"2\"},"
+ "{\"name\": \"Federer, Roger (SUI)\", \"email\": \"federerroger@gmail.com\", \"rank\": \"3\"},"
+ "{\"name\": \"Wawrinka, Stan (SUI)\", \"email\": \"wawrinkastan@gmail.com\", \"rank\": \"4\"},"
+ "{\"name\": \"Ferrer, David (ESP)\", \"email\": \"ferrerdavid@gmail.com\", \"rank\": \"5\"}]";
}
}
return "";
}
@OnOpen
public void onOpen(Session peer) {
LOG.info("Connection opened ...");
peers.add(peer);
}
@OnClose
public void onClose(Session peer) {
LOG.info("Connection closed ...");
peers.remove(peer);
}
}And, we access this endpoint like this:
- the client sends a hello message (HELLO SERVER), and the server answers with a simple text (Hello, if you need the ATP list just press the button ...).
- the client send another message, (ATP SERVER), and the server answers with a JSON object containing a list of tennis players
- the client will display this list in a table
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" type="text/css"
href="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.8/angular-csp.css">
<title>Angular JS Web-Socket</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body ng-app="ATP_PLAYERS" class="ng-cloak">
<script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.3.8/angular.min.js"></script>
<script src="resources/js/angular-websocket.js"></script>
<div ng-controller="atpController">
<div id="helloId"></div>
<form ng-submit="submit()">
<button id="btnAtpId" type="submit" disabled>Send Message</button>
</form>
<table>
<thead>
<tr>
<th>Rank</th>
<th>Name</th>
<th>E-mail</th>
</tr>
</thead>
<tbody>
<tr ng-repeat="item in ATP.atp">
<td>{{item.rank}}</td>
<td>{{item.name}}</td>
<td>{{item.email}}</td>
</tr>
</tbody>
</table>
</div>
<script language="javascript" type="text/javascript">
angular.module('ATP_PLAYERS', ['ngWebSocket'])
.factory('ATP', function ($websocket) {
// Open a WebSocket connection
var ws = $websocket("ws://" + document.location.host +
document.location.pathname + "atpendpoint");
var atp = [];
ws.onMessage(function (event) {
console.log('message: ', event.data);
var response;
try {
response = angular.fromJson(event.data);
} catch (e) {
document.getElementById("helloId").innerHTML =
"Sorry, connection failed ...";
document.getElementById("btnAtpId").disabled = false;
console.log('error: ', e);
response = {'error': e};
}
if (response.hello) {
document.getElementById("helloId").innerHTML = response.hello;
document.getElementById("btnAtpId").disabled = false;
} else {
for (var i = 0; i < response.length; i++) {
atp.push({
rank: response[i].rank,
name: response[i].name,
email: response[i].email
});
}
}
});
ws.onError(function (event) {
console.log('connection Error', event);
});
ws.onClose(function (event) {
console.log('connection closed', event);
});
ws.onOpen(function () {
console.log('connection open');
ws.send('HELLO SERVER');
});
return {
atp: atp,
status: function () {
return ws.readyState;
},
send: function (message) {
if (angular.isString(message)) {
ws.send(message);
}
else if (angular.isObject(message)) {
ws.send(JSON.stringify(message));
}
}
};
})
.controller('atpController', function ($scope, ATP) {
$scope.ATP = ATP;
$scope.submit = function () {
ATP.send("ATP SERVER");
};
});
</script>
</body>
</html>
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