I just started learning Node.js, and I'm wondering when developer should/need to use http.createServer()
My process of thinking is: "When I want to catch data from server I use: http.request and http.get methodes.
When I want to POST on server I will use http.request with POST method options parameter.
I just can’t figure out, when I should use http.createServer() method?
If I work on remote server (server is already exists).
I red documentation: This class is used to create a TCP or IPC server.
w3School says: The http.createServer() method turns your computer into an HTTP server.
If you can, give me comprehensive explanation with real world example.
Thanks
When you use something like http.request(), you're connecting to another HTTP server and requesting data from it. If you wanted to be that server yourself, you would need to use http.createServer() to do that.
For example, a common use case of Node.js is to create an API server that receives HTTP requests from web pages and fetches or manipulates data in a database. It takes the resulting data and sends it as an HTTP response.
The Node.js documentation you read seems to be for net.createServer(). While http.createServer() does create an underlying TCP server, it also accepts a callback for listening for HTTP requests.
See also: https://nodejs.org/api/http.html#http_http_createserver_options_requestlistener
Related
How I can use app.use in socket.io? E.g.
io.on('connection', function(data){
app.use('uri here', function(req, res){
// emitting here
});
});
It's really?
I have:
ss1.example.com (head-server for caching online users with users servers).
ss2.example.com (first app server)
ss3.example.com (second app server)
You're misunderstanding something here. The sequence of events when a web page is loaded is as follows:
User initiates page load (by clicking on something or by typing something in the URL bar or by selecting a bookmark).
Browser parses the server, gets the host and port out of the URL and sends an http GET request for the path to the IP address for that host and port.
Web server receives the GET request and sends back to the browser an HTML page.
The web server may or may not use middleware when that request is received (depending upon what it wants to do).
Browser parses the HTML page and then runs scripts in the page.
Javascript in the web page runs and initiates socket.io connection to some host (often to the same host that the web page came from).
Web server receives socket.io request and socket.io handle recognizes the web request as a socket.io connection request.
Server-side socket.io code responds to client request for socket.io connection and a socket.io connection is initiated between browser and server.
Client or server can then send data over the socket.io connection.
Now, to your question about where to insert app.use(). That is for http middleware. You would insert that in the regular web server request chain, typically right before you app.get() and app.post() request handlers. You would not typically use http middleware for a socket.io connection.
If you wish to run some code before any socket.io connection connects, then you would use io.use() and use a socket.io middleware handler. That will give you access to the http request information on every socket.io connection request.
If you wish to run some code on every socket.io message that is received (regardless of the message name), that is not a supported feature of socket.io. There are some add-ons that hack into socket.io to allow you to essentially do a socket.on('*', ...) type event handler for all incoming socket.io messages, but that is not something that socket.io supports as a built-in feature.
If one of these options still doesn't sound like what you want, then please explain to use what actual problem you're trying to solve and we can better make a suggestion for that particular problem.
Note your question is a bit like an XY problem where you asked how to do what you think is the solution (using app.use() for socket.io) rather than describing the actual problem you want to solve. The problem with that type of question is that if you're wrong about the solution direction, then all we can really tell you is that you're wrong with that solution because you didn't describe the actual problem so we can direct you to the right type of solution. In the future, you will probably get better answers if you make sure to describe the problem you're trying to solve, not just the solution you're trying.
The HTTP client built into Node.js doesn't seem to support pipelining requests. However, it occurred to me that it may be possible to create an Agent that sets up pipelining in the background. There may be issues getting the response data back the way it should be, but perhaps the Agent could fake out some socket objects to make the HTTP client work like normal?
Has this been done? Alternatively, is there an alternative HTTP client that is a drop-in replacement for the main that supports pipelining? (Ultimately, I'd like to use it with the AWS SDK, so it needs to be compatible.)
I have a nodejs app, and every client has an open socket connection, the reason i am using sockets because I need to update the data on the client whenever the data in the database changes by an external process.
However every other operation in my app doesn't require a socket connection and mostly initiated by the client (CRUD operations), But i am confused about one thing since I always have an open socket connection, wouldn't it be better to use that socket connection for every operation and make the app with pure socket logic?
When using websockets maybe it's fine. But if socket.io switches to XHR (AJAX) transport it might be irrational.
Take a look at the differencies of these two approaches:
In case of simple AJAX (without socket.io) when you want to get some info from server, or change something on a server, you send GET or POST request,
and server responses. Everything's fine.
But in case of socket.io (XHR transport) there is one request to send data, and another to get the response.
(You can make your own experiment - write io.set('transports', ['xhr-polling']); and try to send data to the server and make server respond -
you will see 2 AJAX requests in the Network tab)
So instead of one AJAX request socket.io makes two requests.
This is not because socket.io is bad. This is a feature of sockets approach. This approach is good if you want one side (client or server) to send messages independenly from the other. This is what socket.io does very good.
But if you want to do "request-response" stuff it's the best to use simple AJAX because of traffic economy (note that I compare simple AJAX to socket.io AJAX. Websockets - is another story).
But since this question is about approaches and can't have 100% "yes" or "no" answer, there are might be different opinions.
Sorry for English. I tried to write as clearly as I could :)
I'm working on an application that relies on data that the browser sends within the HTTP headers (and there's no way around this). This also happens to be my first time working with something node.js based, so it's very likely I'm completely missing something simple!
Basically what I want to be able to do is call a method on the server from the client, and in that method read the HTTP headers that the client sent.
Meteor doesn't yet provide a supported API for serving HTTP from your app. This is intentional: in the not-too-distant future, your app server is likely to not be just a single process directly serving end users, but an arbitrarily parallelizable service behind a proxy tier. So we'll need to provide a supported API for responded to HTTP requests (REST, eg) that continues to work in such a setting.
Are you sure it needs to be HTTP and that you can't just use a Meteor method?
If you really need to accept direct HTTP requests now, take a peek at how packages/accounts-oauth-helper/oauth_server.js uses __meteor_bootstrap__.app to hook into the Connect middleware framework. This will work for now, but we don't promise that Meteor will always be powered by Connect :)
How do I receive events from the browser in my node.js code? (e.g: I imagine Mixpanel, kissmetrics, etc do something like this?
thanks
The same way any other web server receives events from the browser: the browser makes an HTTP request to the URL of your server and the server receives that request. Listening for HTTP requests is the "Hello World" example for node.js.
What you're looking for is http://hummingbirdstats.com/ realtime stats 20 times a second.
You should also checkout socket.io if you haven't. Websockets events are faster than HTTP requests.
You have to send them to your server, via AJAX or some similar method.
Remember, node code runs on the server; the browser runs on the client. The way to get information back and forth from a server to a client running a web browser is an HTTP request.
I recommend dnode. Search for dnode on the browser in the README. It's a quick and complete example of making a RPC. In this case the remote function would be an event handler.
It uses socket.io, which supports websockets, flash sockets, and xhr.