NodeJs - how to use socket.io to send tcp packet to another computer in local area network

Question

I have NodeJs web service in based web socket. One of my file by the server side tries send xml to printer in local area network on ip address 192.168.1.5 but this ip is in my physical network not in area network by server side. When I open the web service on localhost it's work but when I open my service via network it's not work. How can I use web socket that nodejs app will send xml via TCP to another localhost in local area network using socket client just like me?

for example (my local area network):

localhost - 192.168.1.100

printer - 192.168.1.5

localhost (my physical computer) -> opening web service (NodeJS) on browser -> running script (service) -> sending xml via TCP to printer (192.168.1.5)

is this scenario possible?

Answer 1

You can't directly use webSocket or socket.io to send a plain TCP packet. webocket is its own protocol and socket.io runs on top of webSocket. It initiates a connection with an http request, uses it's own data format framing and its own security scheme. As such a webSocket client can only connect to a webSocket server or a socket.io client to a socket.io server, not to a plain TCP device.

You can use the Net module in node.js to make plain TCP connections. So, you can contact the printer directly from node.js if that would work.

But, you can't make plain TCP connections directly form a browser web page without using some sort of browser plug-in that has access to native code or without sending some sort of http or webSocket or socket.io request to a server and having the server contact the printer on your behalf (which would require server and printer to be on the same local network).