added listener mode

app.js

@@ -241,7 +241,117 @@ if (mode === "server"){
         }
     });
 
-} else {
+} else if (mode === 'listener'){
+    const localSend = new Client('127.0.0.1', localSendPort);
+    console.log('Configure your local pd patch(es) to listen on UDP Port ' + localSendPort)
+    // run the app in client mode
+    // ***** Websocket ******* //
+    // WebSocket that will automatically attempt to reconnect if the connection is closed, or if the remote server goes down
+    const ReconnectingWebSocket = require('reconnecting-websocket');
+    const serverIP = process.argv[3]
+    const serverPort = '8081';
+    const serverWSAddress = `ws://${serverIP}:${serverPort}`;
+    // options for the reconnecting websocket
+    const rwsOptions = {
+        // make rws use the webSocket module implementation
+        WebSocket: WebSocket, 
+        // ms to try reconnecting:
+        connectionTimeout: 1000,
+        //debug:true, 
+    }
+
+    // create a websocket
+    // console.log(`attempting to connect to server at ${serverWSAddress}`)
+    ws = new ReconnectingWebSocket(serverWSAddress, [], rwsOptions);
+
+    // if the server responds with an error
+    ws.addEventListener('error', () => {
+        console.log(`connection error: ${serverIP}`);
+    });
+    // on successful connection to server:
+    ws.addEventListener('open', () => {
+        console.log (`connected to server at ${serverWSAddress}`)
+    });
+    // on close:
+    ws.addEventListener('close', () => {
+        console.log("server connection closed");
+        localSend.close();
+        localReceive.close();
+    });
+    // handle messages
+    ws.addEventListener('message', (data) => {
+        let msg = JSON.parse(data.data);
+        console.log(msg)
+        switch (msg.cmd){
+            // in case you want to receive other data and route it elsewhere
+            case 'OSC':
+                // send formatted OSC message locally (i.e. a pd patch)
+
+                localSend.send(msg.addressPattern, msg.typeTagString, (err) => {
+                    if (err) console.error(err);
+                });  
+
+
+            break;
+
+            default:
+                // inform user that unknown message commang used
+                console.log('client sent message with unknown cmd: ' + msg)
+            break;
+        }
+    });
+
+
+    // Commented this out so that the 'listener' doesn't send data back into the network. we can revisit this another time, oc. 
+    //  // ***** Local UDP-Receiver ******* //
+    // // this is used by either mode!
+    // let localReceivePort;
+    // if(mode === 'server'){
+    //     localReceivePort = 7402
+    // } else if (mode === 'client'){
+    //     localReceivePort = 7404
+    // }
+    // const localReceive = new Server(localReceivePort, '0.0.0.0');
+    // // once running, inform user
+    // localReceive.on('listening', () => {    
+    //     console.log('Configure your local pd patch(es) to send on UDP Port ' + localReceivePort)
+    // })
+    // // handle message:  
+    // localReceive.on('message', (msg) => {
+    //     // validate correct OSC address pattern syntax
+    //     // console.log(msg)
+    //     if(msg[0].charAt(0) === '/'){
+    //         // get the address pattern
+    //         ap = msg[0]
+    //         // trim the address pattern
+    //         msg.shift()
+    //         // construct object to send over websocket
+    //         message = {
+    //             // cmd allows us to send other types of messages, ask Michael for more info if curious!
+    //             cmd: 'OSC',
+    //             date: new Date().toUTCString(),
+    //             addressPattern: ap,
+    //             // this is the data!
+    //             typeTagString: msg
+    //         }
+    //         // inform user
+    //         // console.log('sending to remote:\n', message)
+    //         // package data for the web, send it!
+    //         // if(ws){
+    //             ws.send(JSON.stringify(message))
+    //         // }
+
+    //     } else {
+    //         // if incoming OSC message does not have an address pattern, refuse to handle it
+    //         console.log('error, OSC Message must lead with an addressPattern\n\ni.e. /bioData')
+    //     }
+    // });
+
+}
+
+
+
+    else {
     // app needs to know what mode to run in
     console.log('error! first argument must be either \'client\' or \'server\'')
     // stop node process