TriremeServlet Node js import external websocket libraries

[kthyagaraj]

Apologies if this is not the right place to ask question, i wouldn't find any other option or forum online who can assist me on this.

I am using trireme servlet to run the node js script in my application. i have added all the maven dependencies and the deployment description looks as below

 <servlet>
    <servlet-name>TriremeServlet</servlet-name>
    <servlet-class>io.apigee.trireme.servlet.TriremeServlet</servlet-class>
    <init-param>
      <param-name>TriremeScript</param-name>
      <param-value>/WEB-INF/node/server.js</param-value>
    </init-param>
    <init-param>
      <param-name>TriremeResponseTimeout</param-name>
      <param-value>5</param-value>
    </init-param>
    <init-param>
      <param-name>TriremeStartupTimeout</param-name>
      <param-value>30</param-value>
    </init-param>
    <init-param>
      <param-name>TriremeSandbox</param-name>
      <param-value>false</param-value>
    </init-param>
  </servlet>
  <servlet-mapping>
    <servlet-name>TriremeServlet</servlet-name>
    <url-pattern>/servlet/*</url-pattern>
  </servlet-mapping>

And my server.js script is below the path /WEB-INF/node/server.js

var fs = require('fs');
var http = require('http');
var path = require('path');
var util = require('util');

....
var server = http.createServer(handleRequest);

server.listen(PORT, function() {
    console.log('Listening on %d', PORT);
});

The above code works fine , i would like to import external libraries to my server.js , added the websocket js files in the same dir /WEB-INF/node/, and tried to import as below. now the script is failing while i try to access the servlet, no errors on log..

var websocket = require('./websocket.js'); Is this the rightway to include the external libraries for the node script that is run by trireme servlet ... appreciate if any feedback

[gbrail]

This is a fine place to ask -- thanks!

It's been a while, but looking at TriremeServlet.java, I see that it calls:

ServletConfig.getServletContext().getRealPath("/")

to find the location of your script. Since "websocket.js" is in the same directory as server.js, then yes, your require statement should work without having trouble finding the module, as normal Node.js module resolution should apply and Trireme will use the Node.js "modules" module.

You could try two things:

First, does a very basic script load? I'm asking because "websocket.js," if it's the module I'm thinking of, won't work in Trireme anyway because it depends on a bunch of native stuff that Trireme doesn't support. It'd be great to test your script outside the servlet module first. The NPM module is a great place to start:

https://www.npmjs.com/package/trireme

Second, you can try putting the required code elsewhere, and setting NODE_PATH to find it, as you would for any other Node app:

https://nodejs.org/docs/latest-v0.10.x/api/modules.html

However in that case you'd use "require('websocket')" instead to load it.

[kthyagaraj]

thanks for your response, i was able to solve the problem, actually i was using the node module https://github.com/websockets/ws (this package was not working with trireme servlet). Have no idea wht's happening with the /ws modules, any guess why its not working ?

Later i switched to another package https://github.com/theturtle32/WebSocket-Node (this worked), i was able to do require(websocket) in my server.js

Now i am coming to second part of my implementation where i am stuck, just posting here if you can help me on this or suggest any

I have the server.js now running the websocket server on http. the code is below

var fs = require('fs');
var http = require('http');
var path = require('path');
var util = require('util');
var url = require('url');
var HashMap = require('hashmap');
var WebSocketServer = require('websocket').server;

var PORT = 33333;

var userConns = new HashMap();

var counter = 0;

function handleRequest(req, resp) {
    console.log('websocketservlet handleRequest: %s %s', req.method, req.url);

    if (/[^/]*\/websocketservlet\/newpatient.*$/.test(req.url)) {
        newPatient(req, resp);
    } else {
        resp.writeHead(404);
        resp.end();
    }
}

function newPatient(req, resp) {
    var q = url.parse(req.url, true).query;
    var userId = q.USER_ID;
    var patientName = q.PATIENT_NAME;
    var redirectUrl = q.REDIRECT_URL;
    console.log('websocketservlet newPatient: userID=' + userId + ' patientName=' + patientName + ' redirect=' + redirectUrl);

    // Websocket notification(s).
    if (userId) {
        var userConn = userConns.get(userId);
        if (userConn) {
            console.log('websocketservlet Sending data from Cached Connection object for userId : ' + userId);
            userConn.sendUTF(userId + "|" + patientName);
            console.log('websocketservlet Sent data from Cached Connection object for userId : ' + userId);
        } else {
            console.log('websocketservlet Cached Connection object not available for userId : ' + userId);
        }
    } else {
        console.log('websocketservlet userId not valid : ' + userId);
    }

    resp.writeHead(302, {
        Location: '/easycare' + redirectUrl
    });
    resp.end();
}

var server = http.createServer(handleRequest);
server.listen(PORT, function() {
    console.log('websocketservlet started.');
});

var wsServer = new WebSocketServer({
    httpServer: server
});

wsServer.on('request', function(request) {
    var connection = request.accept('user-notification', request.origin);
    console.log((new Date()) + ' Connection accepted. ' + connection);
    connection.on('message', function(message) {
        console.log('websocketservlet Received userId from client : ' + message.utf8Data);
        userConns.set(message.utf8Data, connection);
        console.log('websocketservlet connection cached for userId ' + message.utf8Data);
    });
    connection.on('close', function(reasonCode, description) {
        console.log('websocketservlet ' + (new Date()) + ' Peer ' + connection.remoteAddress + ' disconnected.');
    });
});

And my web.xml looks as mentioned previously and i am starting the servlet onstartup, when the server is up, so i have trireme servlet loading the server.js with websocket connection ready to use.

Now from my application client javascript i want to establish connection with the websocket and send and recieve messages for users. I am not able to establish connection with the websocket running on 33333 ` socket = new WebSocket('ws://localhost:33333/'); if i run the above websocket server and client as standalone node scripts , they all work fine, but i want that to be part of the application where i have necessity to use the trireme servlet.

i am running the servlet inside my application which is hosted on a Jboss server on port 8080, not sure what is the right approach i can do to establish a connection with websocket running inside a script which is called by trireme servlet , if any suggestions pl provide

[gbrail]

I'm not sure that you're going to be able to do what you want.

WebSockets work by upgrading the HTTP communication between the client and the server to a new protocol. So, your client would first make a regular HTTP request and then request an upgrade to WebSocket.

It might be the case that your program will work in "regular" Trireme, outside of JBoss. For instance, if you install Trireme using NPM and run "trireme server.js" then it may work because the WebSocket module is probably assuming that it can take control of the underlying HTTP socket and start the new protocol.

However, when you run a Trireme app as a servlet, it has to let the servlet engine take control over all the networking between the client and Trireme. That means that there's no way an app running inside a servlet on Trireme can upgrade the connection to WebSockets because it does not have control over the underlying socket.

So it may be the case that your program can work on Trireme, but I don't think it'll be possible to have it support web sockets from inside a servlet running on JBoss.

On Tue, Feb 13, 2018 at 5:27 PM, infloykiru notifications@github.com wrote:

thanks for your response, i was able to solve the problem, actually i was using the node module https://github.com/websockets/ws (this package was not working with trireme servlet). Have no idea wht's happening with the /ws modules, any guess why its not working ?

Later i switched to another package https://github.com/theturtle32/WebSocket-Node (this worked), i was able to do require(websocket) in my server.js

Now i am coming to second part of my implementation where i am stuck, just posting here if you can help me on this or suggest any

I have the server.js now running the websocket server on http. the code is below

var fs = require('fs'); var http = require('http'); var path = require('path'); var util = require('util'); var url = require('url'); var HashMap = require('hashmap'); var WebSocketServer = require('websocket').server;

var PORT = 33333;

var userConns = new HashMap();

var counter = 0;

function handleRequest(req, resp) { console.log('websocketservlet handleRequest: %s %s', req.method, req.url);

if (/[^/]*\/websocketservlet\/newpatient.*$/.test(req.url)) {
    newPatient(req, resp);
} else {
    resp.writeHead(404);
    resp.end();
}

}

function newPatient(req, resp) { var q = url.parse(req.url, true).query; var userId = q.USER_ID; var patientName = q.PATIENT_NAME; var redirectUrl = q.REDIRECT_URL; console.log('websocketservlet newPatient: userID=' + userId + ' patientName=' + patientName + ' redirect=' + redirectUrl);

// Websocket notification(s).
if (userId) {
    var userConn = userConns.get(userId);
    if (userConn) {
        console.log('websocketservlet Sending data from Cached Connection object for userId : ' + userId);
        userConn.sendUTF(userId + "|" + patientName);
        console.log('websocketservlet Sent data from Cached Connection object for userId : ' + userId);
    } else {
        console.log('websocketservlet Cached Connection object not available for userId : ' + userId);
    }
} else {
    console.log('websocketservlet userId not valid : ' + userId);
}

resp.writeHead(302, {
    Location: '/easycare' + redirectUrl
});
resp.end();

}

var server = http.createServer(handleRequest); server.listen(PORT, function() { console.log('websocketservlet started.'); });

var wsServer = new WebSocketServer({ httpServer: server });

wsServer.on('request', function(request) { var connection = request.accept('user-notification', request.origin); console.log((new Date()) + ' Connection accepted. ' + connection); connection.on('message', function(message) { console.log('websocketservlet Received userId from client : ' + message.utf8Data); userConns.set(message.utf8Data, connection); console.log('websocketservlet connection cached for userId ' + message.utf8Data); }); connection.on('close', function(reasonCode, description) { console.log('websocketservlet ' + (new Date()) + ' Peer ' + connection.remoteAddress + ' disconnected.'); }); });

And my web.xml looks as mentioned previously and i am starting the servlet onstartup, when the server is up, so i have trireme servlet loading the server.js with websocket connection ready to use.

Now from my application client javascript i want to establish connection with the websocket and send and recieve messages for users. I am not able to establish connection with the websocket running on 33333 ` socket = new WebSocket('ws://localhost:33333/'); i am running the servlet inside my application which is hosting on a Jboss server on port 8080, not sure what is the right approach i can do to establish a connection with websocket running inside a script which is called by trireme servlet , if any suggestions pl provide

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