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Setting relative URL for javascript (websocket connecting to Spring MVC)

I'm following this tutorial : https://www.baeldung.com/websockets-spring
I tested the app and it works perfectly when running on the embedded-tomcat server. However, when I try to deploy and run the same app on an external tomcat server it breaks, because instead of the URL being
localhost:8080/chat
it becomes
myhostIP:port/spring-boot-web-jsp/chat
So I modified the javascript file adding /spring-boot-web-jsp in front of the existing URLs. When I run the webapp the sockets connect successfully and send data. However now my Spring MVC Controller doesn't work.
My javascript :
var stompClient = null;
function setConnected(connected) {
document.getElementById('connect').disabled = connected;
document.getElementById('disconnect').disabled = !connected;
document.getElementById('conversationDiv').style.visibility
= connected ? 'visible' : 'hidden';
document.getElementById('response').innerHTML = '';
}
function connect() {
var socket = new SockJS('/spring-boot-web-jsp-1.0/chat');
stompClient = Stomp.over(socket);
stompClient.connect({}, function(frame) {
setConnected(true);
console.log('Connected: ' + frame);
stompClient.subscribe('/spring-boot-web-jsp-1.0/topic/messages', function(messageOutput) {
showMessageOutput(JSON.parse(messageOutput.body));
});
});
}
function disconnect() {
if(stompClient != null) {
stompClient.disconnect();
}
setConnected(false);
console.log("Disconnected");
}
function sendMessage() {
var from = document.getElementById('from').value;
var text = document.getElementById('text').value;
stompClient.send("/spring-boot-web-jsp-1.0/app/chat", {},
JSON.stringify({'from':from, 'text':text}));
}
function showMessageOutput(messageOutput) {
var response = document.getElementById('response');
var p = document.createElement('p');
p.style.wordWrap = 'break-word';
p.appendChild(document.createTextNode(messageOutput.from + ": "
+ messageOutput.text + " (" + messageOutput.time + ")"));
response.appendChild(p);
}
My Controller :
#MessageMapping("/chat")
#SendTo("/topic/messages")
public OutputMessage send(Message message) throws Exception {
String time = new SimpleDateFormat("HH:mm").format(new Date());
return new OutputMessage(message.getFrom(), message.getText(), time);
}
My message broker :
#Configuration
#EnableWebSocketMessageBroker
public class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {
#Override
public void configureMessageBroker(MessageBrokerRegistry config) {
config.enableSimpleBroker("/topic");
config.setApplicationDestinationPrefixes("/app");
}
#Override
public void registerStompEndpoints(StompEndpointRegistry registry) {
registry.addEndpoint("/chat");
registry.addEndpoint("/chat").withSockJS();
}
}
I've tried modifying the Controller to :
#MessageMapping("app/chat")
#SendTo("/topic/messages")
public OutputMessage send(Message message) throws Exception {
String time = new SimpleDateFormat("HH:mm").format(new Date());
return new OutputMessage(message.getFrom(), message.getText(), time);
}
#MessageMapping("spring-boot-web-jsp-1.0/app/chat")
#SendTo("spring-boot-web-jsp-1.0/topic/messages")
public OutputMessage send(Message message) throws Exception {
String time = new SimpleDateFormat("HH:mm").format(new Date());
return new OutputMessage(message.getFrom(), message.getText(), time);
}
and a bunch of other variations but none of them work.
How can I modify the Controller and javascript file to work when testing through external Apache Tomcat as well as embedded (setting a relative URL of some sort)? And how can I get this to work properly on the external Tomcat?

Remove your tomcat/webapps/ROOT directory
Rename your final jar/war/ear file to ROOT.jar/war/ear
Deploy it on tomcat
Tomcat will deploy your app under root directory localhost:8080/chat

Read data from a website using Nashorn

I want to retrieve data from a website using Nashorn script engine
I have the java code where I can retrieve data from a sample website template.
Now I want to call that java file from java script file.
following is the code:
JAVA CODE(Nsample.java):
package sample;
import java.net.*;
import java.io.*;
public class Nsample
{
public static void main(String[] args)
{
String output = getUrlContents("https://freewebsitetemplates.com/");
System.out.println(output);
}
public static String getUrlContents(String theUrl)
{
StringBuilder content = new StringBuilder();
try
{
URL url = new URL(theUrl);
URLConnection urlConnection = url.openConnection();
BufferedReader bufferedReader = new BufferedReader(new
InputStreamReader(urlConnection.getInputStream()));
String line;
while ((line = bufferedReader.readLine()) != null)
{
content.append(line + "\n");
}
bufferedReader.close();
}
catch(Exception e)
{
e.printStackTrace();
}
return content.toString();
}
}
JAVASCRIPT code:(sample.js)
var n = Java.type('C.JavaFolder.sample.Nsample');
var result = n.getUrlContents("https://freewebsitetemplates.com/");
print(result);
I'm trying to compile javascript code using command prompt but it is showing CLASSNOTFOUNDEXCEPTION.
The command was jjs sample.js.Im assuming I did some mistake in Java.type() function.
Can anyone solve this?

This line is the problematic line:
var n = Java.type('C.JavaFolder.sample.Nsample');
Java.type accepts fully qualified java type name. Based on your Java code, your package seems to be "sample" and class name is "Nsample". So the fully qualified class name would be "sample.Nsample".
You should compile your Java classes and specify the directory in -classpath option (of jjs tool or your java application if you use javax.script API with nashorn).

Instead of calling Java from JavaScript , I tried to call JavaScript from java and worked well.
I created some functions in JavaScript and invoked those functions from Java code.
Following is the code.Hope this helps.
Test.java:
import javax.script.*;
import java.io.*;
import java.util.*;
public class Test{
public static void main(String[] args) throws Exception{
ScriptEngine engine = new ScriptEngineManager().getEngineByName("Nashorn");
engine.eval(new FileReader("test.js"));
Invocable invoke = (Invocable)engine;
Object res = invoke.invokeFunction("httpGet","https://www.javaworld.com");
System.out.println(res);
}
}
test.js:
var httpGet = function(theUrl){
var con = new java.net.URL(theUrl).openConnection();
con.requestMethod = "GET";
return asResponse(con);
}
function asResponse(con){
var d = read(con.inputStream);
return d;
}
function read(inputStream){
var inReader = new java.io.BufferedReader(new
java.io.InputStreamReader(inputStream));
var inputLine;
var response = new java.lang.StringBuffer();
while ((inputLine = inReader.readLine()) != null) {
response.append(inputLine);
}
inReader.close();
return response.toString();
}

How to display javascript console.log in eclipse console?

Title says it all. I am wondering if i can display javascript console.log in eclipse console rather than web browser's dev console?

Just found an article regarding this.
This is How it works(For Window 7).
Install Node.js javascript engine at Node.js
Open your Eclipse, in the menu
Run->External Tools->External Tools Configuration
Create new launch configuration under program category.
Set
Location : C:\WINDOWS\system32\cmd.exe
Working Directory : C:\WINDOWS\system32
Argument : /c "node ${resource_loc}"
Now create new environment variable 'node' refers to node.exe file(wherever you installed)
All done.

Redirect javascript console.logs, in Java console
Here is my solution to get javascript console messages in Java (with SWT browser)
create shell SWT and SWT browser see: Shell + Browser
create custom function SWT see: call Java from JavaScript
Add listener on error events in javascript see: mdn event error
Override console object in javascript and call custom java function (2.)
Here is my example snippet:
import org.eclipse.swt.SWT;
import org.eclipse.swt.SWTError;
import org.eclipse.swt.browser.Browser;
import org.eclipse.swt.browser.BrowserFunction;
import org.eclipse.swt.browser.LocationAdapter;
import org.eclipse.swt.browser.LocationEvent;
import org.eclipse.swt.browser.ProgressListener;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
public class Snippet307d3 {
public static final Shell createShell() {
final var display = new Display();
final var shell = new Shell(display);
shell.setText("Snippet DEBUG");
shell.setLayout(new FillLayout());
shell.setBounds(10, 10, 300, 200);
return shell;
}
public static final Browser createBrowser(Shell shell) {
try {
return new Browser(shell, SWT.NONE);
} catch (final SWTError e) {
System.out.println("Could not instantiate Browser: " + e.getMessage());
shell.getDisplay().dispose();
System.exit(-1);
return null;
}
}
public static final void runShell(Shell shell) {
shell.open();
final var display = shell.getDisplay();
while (!shell.isDisposed())
if (!display.readAndDispatch())
display.sleep();
display.dispose();
}
public static void main(String[] args) {
// -> Create shell
final var shell = createShell();
// -> Create browser
final var browser = createBrowser(shell);
browser.setJavascriptEnabled(true);
// -> set HTML or use setUrl
browser.setText(createHTML());
// browser.setUrl(URL_DOCUMENT_HTML_TEST);
// -> Create custom function
final BrowserFunction function = new CustomFunction(browser, "theJavaFunctionDebugInEclipse");
// -> Register function for cleanup
browser.addProgressListener(ProgressListener.completedAdapter(event -> {
browser.addLocationListener(new LocationAdapter() {
#Override
public void changed(LocationEvent event) {
browser.removeLocationListener(this);
System.out.println("left java function-aware page, so disposed CustomFunction");
function.dispose();
}
});
}));
// -> 6) Start shell
runShell(shell);
}
private static class CustomFunction extends BrowserFunction {
public CustomFunction(Browser browser, String name) {
super(browser, name);
}
#Override
public Object function(Object[] arguments) {
for (final Object v : arguments)
if (v != null)
System.out.println(v.toString());
return new Object();
}
}
private static String createHTML() {
return """
<!DOCTYPE>
<html lang='en'>
<head>
<title>DEBUG SWT</title>
<script>
const console = {
log : function(args) {
try {
theJavaFunctionDebugInEclipse('redirect > ' + args);
} catch (_e) {
return;
}
},
error : function(args) {
this.log(args);
},
exception : function(args) {
this.log(args);
},
debug : function(args) {
this.log(args);
},
trace : function(args) {
this.log(args);
},
info : function(args) {
this.log(args);
}
};
window.addEventListener('error', function(e) {
console.log(e.type + ' : ' + e.message);
console.log(e);
});
</script>
</head>
<body>
<input id=button type='button' value='Push to Invoke Java'
onclick='function1();'>
<p>
<a href='http://www.eclipse.org'>go to eclipse.org</a>
</p>
<script>
// bad char sequence .. send error
eeeee
function function1() {
let result;
try {
// Call bad function java .. send log
result = badFunctionJava(12, false, null, [ 3.6,
[ 'swt', true ] ], 'eclipse');
} catch (e) {
console.log('a error occurred: ' + e.message);
return;
}
}
</script>
</body>
</html>
""";
}
}

Further to #ringord's answer here, these would be the commands for your External Tools Configuration on Linux:
Location : /home/<user>/.nvm/versions/node/<version>/bin/node (or wherever you installed node)
Working Directory : /home/<user>
Arguments : ${container_loc}/${resource_name}

Can I use JS in silverlight app?

I have Silverlight app. For example I want add some JS script which can interact with SL app. For example I want add google map use JS api. Can I do this, But I must send some data from SL to JS to add pins on map, draw figures on map ect.

If you are using Windows Phone and you dont mind that part of the xaml to be a webview yo can.
First add a webview to the xaml
<phone:WebBrowser Name="webView" BorderThickness="0" BorderBrush="Transparent" IsScriptEnabled="True"
ScriptNotify="WebBrowser_ScriptNotify" />
Then you have to bind the webview with the load event and then saveg files to storage and load your html and js files
webView.Loaded += WebBrowser_OnLoaded;
private void WebBrowser_OnLoaded(object sender, RoutedEventArgs e)
{
SaveFilesToIsoStore();
chatView.Navigate(new Uri("Assets/HtmlContent/index.html", UriKind.Relative));
}
private void SaveFilesToIsoStore()
{
//These files must match what is included in the application package,
//or BinaryStream.Dispose below will throw an exception.
string[] files = {
"Assets/HtmlContent/index.html",
"Assets/HtmlContent/js/libs/jquery-1.11.0.min.js", "Assets/HtmlContent/js/pagejs.js", "Assets/HtmlContent/css/style.css"
};
IsolatedStorageFile isoStore = IsolatedStorageFile.GetUserStoreForApplication();
if (false == isoStore.FileExists(files[0]))
{
foreach (string f in files)
{
StreamResourceInfo sr = Application.GetResourceStream(new Uri(f, UriKind.Relative));
using (BinaryReader br = new BinaryReader(sr.Stream))
{
byte[] data = br.ReadBytes((int)sr.Stream.Length);
SaveToIsoStore(f, data);
}
}
}
}
private void SaveToIsoStore(string fileName, byte[] data)
{
string strBaseDir = string.Empty;
string delimStr = "/";
char[] delimiter = delimStr.ToCharArray();
string[] dirsPath = fileName.Split(delimiter);
//Get the IsoStore.
IsolatedStorageFile isoStore = IsolatedStorageFile.GetUserStoreForApplication();
//Re-create the directory structure.
for (int i = 0; i < dirsPath.Length - 1; i++)
{
strBaseDir = System.IO.Path.Combine(strBaseDir, dirsPath[i]);
isoStore.CreateDirectory(strBaseDir);
}
//Remove the existing file.
if (isoStore.FileExists(fileName))
{
isoStore.DeleteFile(fileName);
}
//Write the file.
using (BinaryWriter bw = new BinaryWriter(isoStore.CreateFile(fileName)))
{
bw.Write(data);
bw.Close();
So on the js you have to talk to the c# like this
function sendMessageToCodeBehind(someData) {
window.external.notify(JSON.stringify({ method: 'AddMessage', data: someData }));
}
On the code behind you would recibe the messages from the webview like this:
private void WebBrowser_ScriptNotify(object sender, NotifyEventArgs e)
{
var example = new { method = string.Empty, data = new object() };
var obj = JsonConvert.DeserializeAnonymousType(e.Value, example);
switch (obj.method) {
case "methodName":
}
}
And you would send back messages to the js like this
webView.InvokeScript("jsMethodName", JsonConvert.SerializeObject(new { Message = "some json message" }));

How to define Spring WebSocket subscriber path

I want to know how to define the subscriber path.
For instance, declaration of subscribing path
stompClient.subscribe("/topic/simplemessagesresponse", function(servermessage) {
Why there are two parts 'topic' and 'simplemessageresponse' .. what they refere. How many such domain parts can be there and why ? My question is on not only for the client side, but also server side . SimpMessagingTemplate.convertAndSend("/topic/simplemessagesresponse", "Message to client");
There are tutorials showing the websocket server and client samples. But no enough details of rules to declare the subscriber path and how the subscriber path could be found.
What are the dependencies to change the path when it is declared in server and client side. I think another similar question is raised because of the a location change of a page where the websocket client is written.

Quoting the STOMP spec documentation:
Note that STOMP treats this destination as an opaque string and no
delivery semantics are assumed by the name of a destination. You
should consult your STOMP server's documentation to find out how to
construct a destination name which gives you the delivery semantics
that your application needs.
That means that destination semantics is broker specific:
For RabbitMQ: check out the Destinations section under the STOMP
plugin documentation- http://www.rabbitmq.com/stomp.html For
For ActiveMQ: check out the Working with Destinations with Stomp -
https://activemq.apache.org/stomp.html

I have implemented the websocket stomp by following this blog.
I replaced #SendTo by SimpMessagingTemplate.
Here is my sample ChatController
#Autowired
private SimpMessagingTemplate simpMessagingTemplate;
#MessageMapping("/dualchart")
#ResponseBody
public void dualchat(MessageDTO message) {
// forward message to destination
String destination = "/topic/dualchat/" + message.getToUser();
simpMessagingTemplate.convertAndSend(destination, message);
}
MessageDTO
#JsonIgnoreProperties
public class MessageDTO extends BaseModel {
private String fromUser;
private String toUser;
private String message;
public String getFromUser() {
return fromUser;
}
public void setFromUser(String fromUser) {
this.fromUser = fromUser;
}
public String getToUser() {
return toUser;
}
public void setToUser(String toUser) {
this.toUser = toUser;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
Web Socket Config
<websocket:message-broker application-destination-prefix="/app">
<websocket:stomp-endpoint path="/dualchat">
<websocket:sockjs />
</websocket:stomp-endpoint>
<websocket:simple-broker prefix="/topic" />
</websocket:message-broker>
Javascript
var socket = new SockJS("/starter.web.admin/dualchat");
var stompClient = Stomp.over(page.socket);
stompClient.connect({}, socketJsConnectedCallback, socketJsErrorCallback);
function socketJsConnectedCallback() {
var myId = "111"; // replace this Id
stompClient.subscribe('/topic/dualchat/' + myId, function(message) {
console.log("you reveived a message::::::::::" + JSON.stringify(message));
// you have message, and you can do anything with it
});
}
function socketJsErrorCallback(error){console.log(error);}
function sendMessage(message) {
var data = {
toUser : "1",
message : message
}
stompClient.send("/app/dualchat", {}, JSON.stringify(data );
}
Hope this will help next search...