To show my students a simple HTTP request and response that they could capture using Wireshark, I whipped up a simple Node.js HTTP server:
var fs = require('fs');
var http = require('http');
var port = 80;
var file = process.argv[2]; //This file contains a 42 byte HTML page
http.createServer(function (req, res) {
res.writeHead(200, { 'content-type' : 'text/html' }); // Sends first packet
fs.createReadStream(file).pipe(res); // Sends second packet
}).listen(port);
Unfortunately, the two lines transmitting the HTTP header and the HTML are sent as two separate TCP packets (even though they are both quite small). It would be simpler for my students if the HTTP header and HTML were just one packet. How could I change my code to do this?
var http = require('http');
var fs = require('fs');
var file = process.argv[2];
http.createServer(function(request, response) {
response.writeHeader(200, {"Content-Type": "text/html;"});
fs.readFile(file, function (err, html) {
if (err) {
throw err;
}
response.write(html);
response.end();
});
}).listen(8000);
the reason it won't work is that Node.js runs everything asynchronously. When you are loading your html file, the server creation starts the same time. By the time you are about to write your html to your tcp socket, the file most likely won't be ready.
I see what you were trying to do before... I misread your code because of the indentation. Let me know if this snippet works.
try using something like-
var file = process.argv[2];
fs.readFile(file, function (err, html) {
if (err) {
throw err;
}
http.createServer(function(request, response) {
response.writeHeader(200, {"Content-Type": "text/html"});
response.write(html);
response.end();
}).listen(8000);
});
Related
Im self-educating Node.js. I have created two simple HTML files (summer.html and winter.html) and noded the JS on node.js. I went on localhost:5354/summer.html (and winter.html). Nothing is showing up and I got an error message
This site can’t be reached
The connection was reset.
Try:
Checking the connection
Checking the proxy and the firewall
Running Windows Network Diagnostics
ERR_CONNECTION_RESET
I have tested other lessons and was able to display results on localhost:5354/ but this one doesnt work. What did I do wrong?
JS
var http = require('http');
var url = require('url');
var fs = require('fs');
http.createServer(function (req, res) {
var q = url.parse(req.url, true);
var filename = "." + q.pathname;
fs.readFile(filename, function(err, data) {
if (err) {
res.writeHead(404, {'Content-Type': 'text/html'});
return res.end("404 Not Found");
}
res.writeHead(200, {'Content-Type': 'text/html'});
res.write(data);
return res.end();
});
}).listen(5343);
Hit this URL
localhost:5343/summer.html
Because, You listen in 5343 PORT. But you hit 5354 Port
UPDATE
Thanks to #robertklep and #vallo for pointing out that I was not parsing the multipart request properly.
Here's the updated server code with some re-worked sample code from Busboy:
'use strict';
// Require
var http = require('http');
var Busboy = require('busboy');
var fs = require('fs');
// Server
var server = http.createServer(function(request, response) {
if (request.method === 'POST') {
var busboy = new Busboy({ headers: request.headers });
busboy.on('file', function(fieldname, file, filename, encoding, mimetype) {
file.pipe(fs.createWriteStream(`../db/images/${filename}`));
});
busboy.on('finish', function() {
response.writeHead(200, { 'Connection': 'close' });
response.end("That's all folks!");
});
return request.pipe(busboy);
}
response.writeHead(404);
response.end();
});
server.listen(8000, '192.168.7.25', () => {});
I am trying to post a jpg to an endpoint but the resulting image cannot be opened :
The file “image_copy.jpg” could not be opened. It may be damaged or
use a file format that Preview doesn’t recognize.
Some background:
Everything (servers, storage) are being hosted locally
Have made a decision to only use native Node modules like http and fs due to storage constraints on a microcontroller board
Am using form-data as it eases the pain of multi-part forms and uploads as well as sets the correct request headers
Here is some sample code broken into two scripts:
Server
'use strict';
// Require
var http = require('http');
// Server
var server = http.createServer((request, response) => {
var body = [];
request.on('data', function(chunk) {
body.push(chunk);
});
request.on('end', function() {
saveImage(Buffer.concat(body),null);
response.statusCode = 200;
response.end('thanks')
});
});
server.listen(8000, '192.168.7.25', () => {});
// Process
function saveImage(data,callback) {
var fs = require('fs');
fs.writeFile('../db/images/image_copy.jpg', data, function(err) {});
}
Client
'use strict';
// Require
var FormData = require('form-data');
var fs = require('fs');
var http = require('http');
// Vars
var form = new FormData();
// Process
form.append('my_file', fs.createReadStream('/temp/1.jpg'));
var request = http.request({
hostname: '192.168.7.25',
port: 8000,
path: '/api/premises/v1/image',
method: 'POST',
headers: form.getHeaders()
});
form.pipe(request);
request.on('response', function(res) {
console.log(res.statusCode);
});
After executing, the jpg is uploaded and saved to the correct file location (and also has the same file size as the source jpg) but the new image can't be opened.
Even if I encode the incoming chunk as binary and set the encoding on fs.writeFile to binary, I get a similar result.
What am I doing wrong? Thank you!
The client is uploading in multipart/form-data format, which is a format that can contain, amongst others, file data.
However, this means that the server should parse this format to extract the file data. Right now, the server is just taking the request body verbatim and writing it to a file.
The multiparty module can help you, and one of its usage examples shows you how to hook it up with http.Server: https://github.com/pillarjs/multiparty#usage
var multiparty = require('multiparty');
var http = require('http');
var util = require('util');
http.createServer(function(req, res) {
// parse a file upload
var form = new multiparty.Form();
form.parse(req, function(err, fields, files) {
res.writeHead(200, {'content-type': 'text/plain'});
res.write('received upload:\n\n');
res.end(util.inspect({fields: fields, files: files}));
});
}).listen(8000);
Using that, you can extract the file data from (I think) files.my_file and write it to the file.
I just get started learning some JavaScript and I encountered a strange problem when I use JSON.stringify to convert a string into json format. It got very slow and evantually produced a wrong result(not <"what ever in the string">). At the point where it happens, the source of the string is actually a TCP connection(to a java program). Here is the code I used.
var http = require("http");
http.createServer(function (request, response) {
response.writeHead(200, {'Content-Type': 'application/json'});
var net = require('net');
var client = new net.Socket();
client.connect(3344,'192.168.1.4',function(){
......
}
client.on('data', function(result){
......
response.write(JSON.stringify(result));
......
response.end();
});
client.on('error', function(ex) {
var error = "error code: "+ex.code;
response.write(JSON.stringify(error));
response.end();
}
});
(Result is a plain text that has nothing to do with JSON)
when it executed to "response.write(JSON.stringify(result));", it almost stopped there for a minute and gave me a wrong result. However, the "response.write(JSON.stringify(error));" down below works complete fine. So I change the code a little bit to:
var http = require("http");
http.createServer(function (request, response) {
response.writeHead(200, {'Content-Type': 'application/json'});
var net = require('net');
var client = new net.Socket();
client.connect(3344,'192.168.1.4',function(){
......
}
client.on('data', function(result){
......
var result2 = result+' ';
response.write(JSON.stringify(result2));
......
response.end();
});
client.on('error', function(ex) {
var error = "error code: "+ex.code;
response.write(JSON.stringify(error));
response.end();
}
});
Then there is no problem at all.
I suppose there are some problem with the character encoding? Does anyone know why it behaves like this?
var http = require("http");
http.createServer(function (request, response) {
response.writeHead(200, {'Content-Type': 'application/json'});
var net = require('net');
var client = new net.Socket();
client.connect(3344,'192.168.1.4',function(){
......
}
client.on('data', function(result){
......
response.write(result);
//response.write({"data":result});
......
response.end();
});
client.on('error', function(ex) {
var error = "error code: "+ex.code;
response.write(error);
//response.write({"error code":ex.code});
response.end();
}
});
On nodejs.org socket.setTimeout, it says
When an idle timeout is triggered the socket will receive a 'timeout' event but the connection will not be severed.
But when I test code like this:
var http = require('http');
server = http.createServer(function (request, response) {
request.socket.setTimeout(500);
request.socket.on('timeout', function () {
response.writeHead(200, {'content-type': 'text/html'});
response.end('hello world');
console.log('timeout');
});
});
server.listen(8080);
The socket is closed immediately after timeout, and no data is replied to the browser. Which is quite different from the document. Is this a bug or is there any tricks dealing socket under http module?
The documentation is indeed correct, however it looks like the http module adds a 'timeout' listener which calls socket.destroy(). So what you need to do is get rid of that listener by calling request.socket.removeAllListeners('timeout').
So your code should look like:
var http = require('http');
server = http.createServer(function (request, response) {
request.socket.setTimeout(500);
request.socket.removeAllListeners('timeout');
request.socket.on('timeout', function () {
response.writeHead(200, {'content-type': 'text/html'});
response.end('hello world');
console.log('timeout');
});
});
server.listen(8080);
var http = require("http");
var sys = require('sys')
var filename = process.ARGV[2];
var exec = require('child_process').exec;
var com = exec('uptime');
http.createServer(function(req,res){
res.writeHead(200,{"Content-Type": "text/plain"});
com.on("output", function (data) {
res.write(data, encoding='utf8');
});
}).listen(8000);
sys.puts('Node server running')
How do I get the data streamed to the browser ?
If you're just generally asking whats going wrong, there are two main things:
You're using child_process.exec() incorrectly
You never called res.end()
What you're looking for is something more like this:
var http = require("http");
var exec = require('child_process').exec;
http.createServer(function(req, res) {
exec('uptime', function(err, stdout, stderr) {
if (err) {
res.writeHead(500, {"Content-Type": "text/plain"});
res.end(stderr);
}
else {
res.writeHead(200,{"Content-Type": "text/plain"});
res.end(stdout);
}
});
}).listen(8000);
console.log('Node server running');
Note that this doesn't actually require 'streaming' in the sense that the word is generally used. If you had a long running process, such that you didn't want to buffer stdout in memory until it completed (or if you were sending a file to the browser, etc), then you would want to 'stream' the output. You would use child_process.spawn to start the process, immediately write the HTTP headers, then whenever a 'data' event fired on stdout you would immediately write the data to HTTP stream. On an 'exit' event you would call end on the stream to terminate it.