I am making a web page using angular 6.0.8 with the cli too. I was able to successfully start the server using nodejs Child Process like this
var child=children.exec("ng serve",{},function(error,stdin,stdout){
console.log('server terminated: '+error);
});
Then when I try to close the server like this
child.kill("SIGKILL");
It cuts off the connection between the server and my nodejs program but the server doesnt actually close until the host nodejs program does even thought the child process now registers as killed. I also tried to close it by connecting to the readline of the child process but that seemed to just cause more errors. this is what I tried
var childrl=readline.createInterface({stdin:child.stdin,stdout:child.stdout});
childrl.write(null,{ctrl:true,name:"c"});
the error it gave me is that input.on is not a function.
Try using Node.JS's child_process to spawn a new process something like below:-
var angular = require('child_process').spawn('ng', ['serve']);
When you need to close the angular server, you may use something like below:-
angular.kill('SIGINT');
Hope it helps.
Related
I have a fairly simple Node.js service that basically just fields a few HTTP requests. This runs fine via the GraalVM node command. However, when I use node --jvm --polyglot service.js My Node service dies shortly after starting. Nothing else in the code has changed.
What is interesting is that the following code seems to kill my Node.js service
const { MongoClient } = require("mongodb")
console.log("got MongoClient")
And when I run Graal Node without --jvm --polyglot everything works fine.
If I comment out the Mongo stuff, running with --jvm --polyglot, everything works fine.
What could possibly be going on where trying to run the MongoDB Node.js driver under GraalVM could be causing problems?
It may not be that it dies, but after starting my HTTP service
const server = app.listen(port, () => console.log(`Server running... test at http://${hostname}:${port}/ping`))
it no longer accepts HTTP requests. ???
The best approach would be to raise an issue on GraalVM's repos, probably on the Graal.js one: https://github.com/oracle/graaljs. It could be a bug.
You can also debug the process and maybe that will reveal additional details of what's happening: https://www.graalvm.org/tools/chrome-debugger/
I am beginning with server side programming by following a online course. As per my understanding, we use mongoose.connect(url) to connect to mongodb where url can be localhost url on which mongodb server is running.
But recently I forgot to run the local mongodb server using mongod. When I ran my node app with following code, it worked just fine :
var mongoose = require('mongoose');
mongoose.Promise = global.Promise;
mongoose.connect(process.env.MONGO_URL || 'mongodb://localhost:27017/TodoApp');
const {Todo} = require('./../server/models/todos');
const {ObjectID} = require('mongodb');
Todo.remove({}).then((result)=>{
console.log(result);
});
It worked fine with no error even though mongodb server was not running. When I checked the local database using Robo-3T tool, the documents were removed. I have verified this again.
I am unable to understand why my node app was able to connect to mongodb://localhost:27017/TodoApp even though mongodb server was not running on localhost:27017. Also, why Robo-3T tool was able to connect to this localhost: 27017 if server was not running.
Thanks.
The mongodb server was already running. Looks like the server does not shuts down on closing the terminal. It still runs in background. We have to close it using Ctrl+C.
More info: mongodb doesn't stop when I close terminal
Thanks #Sergio Tulentsev.
The reason is simple, the process is running in the background. If you search for 'services' - (in windows), scroll down to check for MongoDb, you will see that the process is running (Started). If set to Automatic, it starts up even after every restart.
Another reason is MongoDB server runs as a service in the background. Even if you restart your computer, it may be running.
I recognized at my win 10, MongoDB server is automatically started. So, you don't need to run mongod on your local.
At win 10 you can check it by:
type services in the search box;
open Services window;
Find MongoDB Server in the list;
Check Startup Type.
Probably your startup type is Automatic, you can change MongoDB Server startup type here.
It occurs when you don't stop the server explicitly and close your terminal.The server is running in background.You can see that in your task manager as well. Press Ctrl+C to quit and it will stop your server.
I inherited a project which utilizes node.js and socket.io, both of which I am not too familiar with.
I installed node.js and npm via homebrew and socket.io via npm.
The current setup has two different "sites": The frontend, that the user interacts with, and the backend that handles all the communications with a DB. The application uses several different displays, and the previous developer deemed it best to use the current setup.
I can successfully start the node server by invoking node node-server.js. In the head of the node-server.js, socket.io is being called like:
var sys = require('sys')
var exec = require('child_process').exec;
var io = require('socket.io').listen(8090);
[...]
In my front end, I call socket.io like this:
<script src="http://192.168.1.111:8090/socket.io/socket.io.js"></script>
<script>
var socket = io.connect('http://192.168.1.111:8090');
[...]
However, when I debug the page, I get the following error messages:
SyntaxError: Unexpected identifier 'to' (anonymous function) socket.io.js:1
ReferenceError: Can't find variable: io sample.html
In the terminal window, where I started the node server, I get the output:
debug - served static content /socket.io.js
I should add that the two sites reside in separate folders - I access the frontend through a local Apache server, the piece that interacts with the DB sits someplace else on the same machine.
How would I correctly call the socket.io in my client?
Is there a way to enable better debugging?
Update
So the to in the error message, is because whenever the browser tries to load the socket.js file, it gets the reply of Welcome to socket.io
this is my first node.js and socket.io application , i didn't use express ,I want to deploy the application on heroku do i need to use it ? i mean i just did npm install socket.io on localhost and in my server file i.e game.js i have io = require("socket.io") and socket = io.listen(Number(process.env.PORT)) only and in one of the files where from where i am sending the message i have socket = io.connect();
so please tell me if i need to use express and how show i modify my existing application ?
I have given the link to the source of application
( https://github.com/bitgeeky/herokutest )
Although the Application works fine on localhost by changing the port no , to some port no like (8000) but Heroku error log on doing "heroku open" is http://pastebin.com/MtB0z5vQ
I noticed that you haven't created a http server. I am assuming that you are creating a web application, since you are deploying to heroku. For that, you need to create a http server in nodejs.
Go through socket.io https://github.com/LearnBoost/socket.io
Also http://socket.io/#how-to-use
This should get you started
Note: You do not need express. But it will make your work easier in many ways. Depends on the type of application that you want to create.
i have just started learning node and i am using node-v0.4.11 on Fedora 12. It installed without any errors and i am able to run some basic programs but there are some things i cant figure out
If i create a server at a port and then if i stop node using Ctrl+C
i cannot use that port again for starting a server without restarting
the system.
my code looks like this
var port=8080;
var count=0;
var http=require('http');
var server = http.createServer(function(req, res) {
count++;
console.log('request no '+count+' received');
res.writeHead(200);
res.end('you are at port '+port);
});
server.listen(port);
console.log('server started at port '+port);
Now when i save the file and execute it the server starts. But when i stop the server from the shell , i cannot start the server again at the port i started before(in this case port 8080).This is bad because every time i have to make changes in that file i have to change the port number too.Can i stop this behavior?
EDIT:
This is the error that i get when i try to start the server at the same port again
Server started at 8080
node.js:203
throw e; // process.nextTick error, or 'error' event on first tick
^
Error: listen EADDRINUSE
at errnoException (net_uv.js:557:11)
at Array.<anonymous> (net_uv.js:632:28)
at EventEmitter._tickCallback (node.js:195:26)
i saw the process list after i terminated node using Ctrl+C and i found node was still running. So i killed it and checked the process list again to make sure it was dead and it was(i could not see it in the process list). Now i again tried to start the server at the same port but i got the same error as above.And once i stop the server and make request from the browser the request hangs up for ever(it keeps on waiting).
My next problem is that in the above when the server starts and i make
the first request count is incremented 3 times and i can see 3
messages at the console. This is just for the first request,if i make
more requests count is just incremented once. Whats wrong?
this problem is solved
My next problem is that if i change res.writeHead(200); to
res.writeHead(404); or any other valid status code like 300 node
gives error at the command line but these are valid status codes and
the server should start and respond to each request according the
status code like Not found for 404. What am i doing wrong?
this problem is solved
I am not able to use Firebug's 'Net' tab to monitor requests when i
send requests to the server created by Node. Is there a way to do so?
Thanks for bearing.
i cannot start the server again at the port i started before
You should not be seeing this behavior, and I cannot reproduce it. Do you get an error message when you try to start the server again? What is it? Once you've stopped the server, do you see any node processes in your process list? If so, can you start your server after you kill them?
count is incremented 3 times and i can see 3 messages at the console
Your browser is sending multiple requests. For example, in Chrome, you might get (1) a pre-fetch request (where Chrome downloads the page it thinks you want), (2) the actual page request, and (3) a request for favicon.ico; your Node app is listening for all requests, not just requests to the / URL. After the initial request, the browser caches the favicon, etc. and doesn't need to request them again.
Try adding console.log(req.url); to your callback and see what URLs the browser is asking for.
any other valid status code like 300 node gives error at the command line
I can't reproduce this problem. What error are you receiving?
I am not able to use Firebug's 'Net' tab to monitor requests when i send requests to the server created by Node
I'm also not able to reproduce this. Firebug and other client-side debugging tools don't know or care what technology is running on the server; it just speaks HTTP.