If a regular internet user wishes to contact a TCP service on their computer but without having to go through the hassle of firewall translation I think I’m right in saying that the ‘best’ way to do this is by having a 3rd party in the middle that will accept connections from both the user’s home computer and their travelling computer and act as a proxy.
But how exactly is this achieved? Obviously the travelling computer just contacts the proxy server whenever it wants information, but how is this then relayed back to the home computer? Does the home computer keep a constant connection open with the proxy which allows bidirectional data flow?
If this is the case, how would I go about designing a Ruby/Sinatra server that would keep track of these permanent connections and then forward a travelling computer’s queries onwards? (Assume that the home computer’s service can make whatever calls would be necessary to establish the link)
Thanks guys!
EDIT
I think I over-generalised, I’m forwarding HTTP requests (or at least, the requests coming from the travelling computer will be HTTP based), so I figured it made sense to use sinatra to capture the requests from the traveller. My problem though is how to keep an open connection from the home computer to the proxy so I can forward the requests immediately.
I know persistent HTTP connections can be done, but that they’re a little convoluted, would I be better off having the home computer continually establish a lower level connection with the proxy and push the requests over that?
I think your general methodology will work – relay event messages from one computer to another by having the traveling computer send signals to the proxy and having the home computer request new information from the proxy.
If you want more continuous data flow, you may not want to use sinatra – specifically for receiving the data from the travelling computer. Check out Event Machine – https://github.com/eventmachine/eventmachine/wiki