node.js - communicate with TCP server (data == JSON) - json

Question

I'm new to node.js, dived into it during the last weekend and had fun with various examples and small tutorials.
Now I'd like to start a little project for my local area network and have a few questions to get myself into the right direction.
Setup:
I've got a server service running on my lan. It's possible to communicate with that service via TCP and/or HTTP (it's possible to enable or disable TCP or HTTP or both of them) on a specific port and sends and receives data via JSON on a request.
What I basically want to do is to create a webinterface based on node.js for that service, to receive and send JSON data with a webbrowser from and to that service.
Problem:
I already do know how to setup an http server based on node.js. But right now I'm stuck in finding an idea how to create a client based on node.js which stands between the service and the webbrowser client to pass through data from client to server and vise versa. Something like a router or proxy.
Here is a basic scheme based on the client's (webbrowser) point of view:
Send: Webbrowser requests -> node.js routes -> service receives
Receive: Webbrowser receives <- node.js routes <- service responds
Questions:
- Go for TCP or HTTP? (maybe disabling the HTTP Server would spare some ressources) - maybe already answered by this post
- Are there any node.js packages that would fit my needs?
- Go for a framework (expressions?) or would plain node.js be just enough?
- Any hints appreciated :)
edit:
- Is it possible to bind a network device like eth0 inside node.js instead of defining the ip address?
Thanks for your help && best regards
cefra

Answer 1

There's no reason why you can't have a REST HTTP service.
Use something like express to handle routing.
If I understand your problem correctly then you have a webservice written in "foobar" on a TCP port somewhere you can connect to with node.
So if your using express you would write something like
app.get("/resources/", function(req, res) {
var socket = new net.Socket();
socket.connect(port, host, function() {
socket.on("data", function(json) {
res.contentType("json");
res.send(json);
socket.end();
});
socket.write(...);
});
});
So basically you've written a http middleman that contacts your service over TCP then writes the data down the response of your HTTP request.