Hi Carlos,
Yes it is possible. NetSimple is using a "protocolless" connection - similar to something telnet or similar may use. Because the connection has no "high level" protocol you would need to develop your own protocol and then implement this on both the server side, and client side. If the information being transferred is not completely trivial then it might be better to use an existing protocol.
For example, the most common high-level protocol which programs use when communicating with each other is HTTP or HTTPS.
This can be trivially small, to really complicated, so it allows the connection to "grow" as needs grow.
Building a server like this with NetTalk is really easy, using the NetWebServiceMethod templates. You can create trivial methods, or complicated ones.
If you've not done it before this will probably take you 2 to 3 days to set up - there are some webinars worth watching and so on. If you've done it before it'll likely take no more than an hour or so to get a server up and running.
cheers
Bruce