Is there someone can help me or give me a tutorial on how I can display the base64 string from Node.Js to JSP/HTML img tag?
Im passing base64 string to this Node.Js server from Java application.
var net = require('net');
var HOST = '127.0.0.1';
var PORT = 6969;
var cl = require('./client.js');
net.createServer(function(sock) {
console.log('CONNECTED: ' + sock.remoteAddress +':'+ sock.remotePort);
sock.on('data', function(data) {
sock.write(data);
var client = new cl.client(data);
});
sock.on('close', function(data) {
console.log('CLOSED: ' + sock.remoteAddress +' '+ sock.remotePort);
});
process.on('uncaughtException', function (err) {
console.error(err.stack);
console.log("Node NOT Exiting...");
});
}).listen(PORT, HOST);
console.log('Server listening on ' + HOST +':'+ PORT);
Does the Base64 string start with data:image/jpeg;base64(the type may be different).
If so, you can set the src attribute of img tag with it.
<img src="data:image/jpeg;base64XXXXXXXXX">
If the base64 string that you are passing already has data:image/[image type];base64 prefix then you can just set it in the image source you don't need to do anything special.
Or just have a method to check it and add the prefix if you don't have it.
function setBase64ToImage(baseString){
// data:image/[image type];base64
if(baseString.substring(0,4) != "data"){
baseString = "data:image/png;base64," + baseString;
}
return baseString;
}
and in your HTML img src tag
<img src=setBase64ToImage(data)>
If your question is how to pass data from node.js to the html file then you should use a template like ejs or something to make it easy.
https://github.com/tj/ejs or look at this question which anwers how to pass data from node to html.
Variables between Node.js Server and Client
Related
I'm having trouble while developing chat-like feature to my socket server.
First let me give you a little bit of my code:
document.conn = new ab.Session('ws://127.0.0.1:8090',
function () {
console.log('AB:Connected!');
conn.subscribe('room_1', function (topic, data) {
console.log('New message published to room "' + topic + '" : ' + data.content + ' by:' );
console.log(data);
});
},
function () {
console.warn('WebSocket connection closed');
},
{'skipSubprotocolCheck': true}
);
Currently it's attached to document just to try it out, the error I'm getting is as follows:
"Session not open"
I'm a bit confused about this error and it's origin, should I somehow define the connection?
do you start your socket server through cmd.exe ?
you need to use this command to start the server:
php c://wamp64/www/yourproject/bin/push-server.php
I wrote a piece of code that allows me search for all tweets hash tagged hello.
var stream = T.stream('statuses/filter', { track: 'hello', stall_warnings: true });
var counter = 0;
if (stream) {
console.log('connected!');
};
stream.on('tweet', function (tweet) {
console.log('tweet: '+ tweet.text);
console.log('by:' + ' #' + tweet.user.screen_name);
console.log('date:'+ ' ' + tweet.created_at + ' | ' + counter);
counter++;
});
How do I go about redirecting this so that I can create a web page that looks like a Twitter stream data, or something of the sort? Maybe using AngularJS.
You will have to create a web server first, try express.
then you can use something like sockets.io to communicate from the server to your client web page.
then on the webpage you must handle the messages to display them (angular, or maybe just jQuery) - basically on tweet you will send a message from your server to the client web page through socket.io, then your dront end javascript will get the message, parse it and decide how to display it.
Have a look at Sails.js, it's basically express with sockets integrated and a few more things
edit
say you export your server in server.js,
var http = require('./server.js');
var io = require('socket.io')(http);
stream.on('tweet', function (tweet) {
io.sockets.emit("new tweet", {
text: tweet.text,
by: tweet.user.screen_name,
date: tweet.created_at,
counter: counter++;
});
});
require('socket.io')(http) starts the "socket manager" on your server (and also publishes the js client side code for it), so clients can connect to your server through sockets.
io.sockets.emit will send a message to all connected clients.
on your web page you must have something like this
<div id="tweets"></div>
<script src="/your/js/jquery.js"></script>
<script src="/socket.io/socket.io.js"></script>
<script>
var socket = io();
socket.on("new tweet", function(tweet) {
$('#tweets').append('tweet: ' + tweet.text + '<br>');
$('#tweets').append('by:' + ' #' + tweet.by + '<br>');
$('#tweets').append('date:'+ ' ' + tweet.date + ' | ' + tweet.counter + '<br>');
});
</script>
the library /socket.io/socket.io.js was published by that require('socket.io')(http) from earlier, so we can use it on our clients.
the call io() basically connects to the server, and returns a handle to that connection (socket), we use that to receive all messages from the server, and on each message you can write the contents to the page anyway you want.
With socket.io you can broadcast events from the server to the client, in this case you could do something like this :
stream.on('tweet', function (tweet) {
io.sockets.emit("new tweet", tweet);
counter++;
});
And you could receive that event on the client-side like this :
var socket = io();
socket.on("new tweet", function(tweet){
//Do something with the tweet
});
This is a very basic and generic example, for more information you can look at the official documentation here.
Hy, I'm asking because I want to clear my mind about net sockets in Node.js:
I have an easy server that replicates the data received. It looks like this:
var net = require('net');
var HOST = '127.0.0.1';
var PORT = 1337;
net.createServer(function(sock) {
console.log('CONNECTED: ' + sock.remoteAddress +':'+ sock.remotePort);
sock.on('data', function(data) {
console.log('DATA ' + sock.remoteAddress + ': ' + data);
sock.write('You told me: ' + data);
});
sock.on('close', function(data) {
console.log('CLOSED: ' + sock.remoteAddress +' '+ sock.remotePort);
});
}).listen(PORT, HOST);
console.log('Server listening on ' + HOST +':'+ PORT);
So, if I want to make a really easy html page like this:
<input type="text" name="data" value="" />
<input type="button" value="Send data" onclick="send()" />
<div id="result"></div>
Now I will click on the button and the page sends data to the server, and write the answer into the "result" div. What i need to write or use in the function "send()" (just in order to send the data and receive the answer)? I searched for things like this a lot, but wasn't lucky...
I need to add an http server to the server file maybe?
I recommend you use SockJS module in server and client side. Look this example for client:
var sock = new SockJS('YOUR_SOCKJS_URL');
sock.onopen = function() {
console.log('open');
};
sock.onmessage = function(e) {
console.log('message', e.data);
};
sock.onclose = function() {
console.log('close');
};
function send(){ // this for onclick="send()"
sock.send();
}
For server use Sockjs module. example:
var http = require('http');
var sockjs = require('sockjs');
var echo = sockjs.createServer({ sockjs_url: 'http://cdn.jsdelivr.net/sockjs/0.3.4/sockjs.min.js' });
echo.on('connection', function(conn) {
conn.on('data', function(message) {
conn.write(message);
});
conn.on('close', function() {});
});
var server = http.createServer();
echo.installHandlers(server, {prefix:'/echo'});
server.listen(9999, '0.0.0.0');
Cannot get SSE events to file in browser.
This the server code (express):
app.all('/callme', function(req, res){
res.writeHead(200, {
'Connection': 'keep-alive',
'Content-Type': 'text/event-stream',
'Cache-Control': 'no-cache'
});
setInterval(function(){
console.log('writing');
res.write((new Date()).toString() + '\n');
}, 1000);
})
This the client code:
var source = new EventSource('/events');
source.onmessage = function(e) {
document.body.innerHTML += e.data + '<br>';
};
I use this same server code using XHR on the client and it works. The server appears to be sending the data correctly, but not getting fired in the browser..
I've already read JavaScript EventSource SSE not firing in browser Doesn't seem to apply here, as I'm not running anti-virus that would affect it.
It looks like the formatting on your event isn't correct
You want it formatted like this
res.write("id: " + Date.now() + "\ndata: " + message + "\n\n");
Also, check out this
node-easysse and easysse-client
I created a simple application as an attempt to integrate node, express, socket.io, and jade. The user enters some string ("tool ID") in a text field and clicks a submit button. That text is simply converted to all uppercase and the result is appended to the results section on the page. The results should be automatically updated for other clients viewing the page.
It mostly works. However the problem is that right after the user clicks the submit button on the page to submit the tool ID, the node console and browser javascript console both show the client disconnecting and then reconnecting.
To the user it looks like the results are updated correctly for a fraction of a second. Then the results go blank for another fraction of a second. Then the results are redisplayed. Since I am showing the user's session ID with the results, I can see that the session ID changes during the short time while the results go blank.
Note that if a different client is simply viewing the page, but not otherwise interacting, the results are updated smoothly (no brief time of results going blank) and that client doesn't seem to be disconnecting at all.
I don't want the client to disconnect and reconnect when they click the submit button on the form. Can someone tell me why this is happening and how I should be doing it properly?
My app.js (server)
var express = require('express');
var app = express();
var http = require('http');
var server = http.createServer(app);
io = require('socket.io').listen(server); // without the var, this becomes available to other files like routes.
var path = require('path');
var routes = require('./routes/routes');
var process = require('./routes/process');
var _ = require("underscore");
// all environments
app.set('port', 3097);
app.set('views', __dirname + '/views');
app.set('view engine', 'jade');
app.use(express.favicon());
//app.use(express.logger('dev'));
app.use(express.bodyParser()); //Tells server to support JSON, urlencoded, and multipart requests
app.use(express.methodOverride());
app.use(express.cookieParser('i7iir5b76ir857bveklfgf'));
app.use(express.session());
app.use(app.router);
app.use(express.static(path.join(__dirname, 'public')));
var toolIDs = [];
// development only
if ('development' == app.get('env')) {
app.use(express.errorHandler());
}
io.on("connection", function(socket) {
console.log("Client connected. Sending Update");
socket.on("toolsRequest", function() {
socket.emit('toolsReady', {toolIDs: toolIDs}); //This should go to the client that just connected.
});
socket.on("disconnect", function() {
console.log("Client Disconnected");
});
socket.on("toolsUpdate", function(data) {
processedToolID = process.process(data.toolID);
toolIDs.push({id: data.id, inputToolID: data.toolID, outputToolID: processedToolID});
io.sockets.emit("toolsUpdated", {toolIDs: toolIDs}); //This should go to all clients
console.log('Results Updated - notifying all clients');
});
});
// display main page
app.get('/', routes.home);
server.listen(app.get('port'), function(){
console.log('Express server listening on port ' + app.get('port'));
});
My routes.js
/*
* GET home page.
*/
exports.home = function(req, res){
res.render('home', { title: 'Tool'});
console.log("Just called route.home");
};
My home.jade
doctype 5
html
head
title= title
link(rel='stylesheet', href='/bootstrap/css/bootstrap.min.css')
link(rel='stylesheet', href='/bootstrap/css/bootstrap-responsive.min.css')
script(src='/socket.io/socket.io.js')
script(src="http://code.jquery.com/jquery.min.js")
script(src='/js/index.js')
block content
#wrapper
h1
a(href='/') TOOL
#display
div.row-fluid
div.inlineBlock
form#toolForm
label Tool ID
input(type="text", placeholder="e.g. abc123")#toolID
span.help-block You may enter a string.
button(class="btn")#submit
| Submit
br
div.inlineBlock.topAligned
h2 Results
br
div#results
br
My index.js (client)
function init() {
/*
On client init, try to connect to the socket.IO server.
*/
var socket = io.connect('http://example.com:3097/');
//We'll save our session ID in a variable for later
var sessionID = '';
//Helper function to update the results
function updateResults(toolIDs) {
$('#results').html('');
for (var i = 0; i < toolIDs.length; i++) {
$('#results').append('<span id="' + toolIDs[i].id + '">' + '<b>Creator ID:</b> ' + toolIDs[i].id + ' <b>Your ID:</b> ' + sessionID + ' <b>Input Tool:</b> ' + toolIDs[i].inputToolID + ' <b>Output Tool:</b> ' + toolIDs[i].outputToolID + (toolIDs[i].id === sessionID ? '<b>(You)</b>' : '') + '<br /></span>');
}
}
/*
When the client successfully connects to the server, an
event "connect" is emitted.
*/
socket.on('connect', function () {
sessionID = socket.socket.sessionid;
// Note this appears in the browser Javascript console, not node console
console.log('You are connected as: ' + sessionID);
socket.emit('toolsRequest'); //Request the tools data so we can update results
});
socket.on('toolsReady', function(data) {
updateResults(data.toolIDs);
console.log('Results have been updated from socket.on.toolsReady');
});
socket.on('toolsUpdated', function (data) {
updateResults(data.toolIDs);
console.log('Results updated from socket.on.toolsUpdated');
});
/*
Log an error if unable to connect to server
*/
socket.on('error', function (reason) {
console.log('Unable to connect to server', reason);
});
function getCitations() {
var toolID = $('#toolID').val()
socket.emit('toolsUpdate', {id: sessionID, toolID: toolID});
}
$('#submit').on('click', getCitations);
}
$(document).on('ready', init);
Here's what I see in the node console when a client clicks the submit button:
debug - websocket writing 5:::{"name":"toolsUpdated","args":[{"toolIDs":[{"id":"5a1dfX2dmxcogYT_11e8","inputToolID":"a123123","outputToolID":"A123123"},{"id":"OIuqao6TsTeddQm111e-","inputToolID":"1abcdefg","outputToolID":"1ABCDEFG"},{"id":"Qr_YQ2ZhQHbDpBlk11e_","inputToolID":"abcdefg","outputToolID":"ABCDEFG"}]}]}
Results Updated - notifying all clients
Just called route.home
info - transport end (socket end)
debug - set close timeout for client Qr_YQ2ZhQHbDpBlk11e_
debug - cleared close timeout for client Qr_YQ2ZhQHbDpBlk11e_
debug - cleared heartbeat interval for client Qr_YQ2ZhQHbDpBlk11e_
Client Disconnected
debug - discarding transport
debug - served static content /socket.io.js
debug - client authorized
info - handshake authorized 2bPKGgmLdD4fp-vz11fA
debug - setting request GET /socket.io/1/websocket/2bPKGgmLdD4fp-vz11fA
debug - set heartbeat interval for client 2bPKGgmLdD4fp-vz11fA
debug - client authorized for
debug - websocket writing 1::
Client connected. Sending Update
debug - websocket writing 5:::{"name":"toolsReady","args":[{"toolIDs":[{"id":"5a1dfX2dmxcogYT_11e8","inputToolID":"a123123","outputToolID":"A123123"},{"id":"OIuqao6TsTeddQm111e-","inputToolID":"1abcdefg","outputToolID":"1ABCDEFG"},{"id":"Qr_YQ2ZhQHbDpBlk11e_","inputToolID":"abcdefg","outputToolID":"ABCDEFG"}]}]}
Thanks, I appreciate the help.
Your submit button is actually reloading the page, which is why the socket is disconnecting, and why you see the socket response for such a short time. Just prevent the default action of the submit button. Change this:
$('#submit').on('click', getCitations);
To something similar:
$('#submit').click(function(event) {
event.preventDefault();
getCitations();
});