What is required to create an application that will constantly work on some server (for example, FTP)?

Question

C++ / C#

Hello, I want to create an application that will not work on my computer, but let's say on a rented hosting, tell me what you need to use for this. Specifically: which PLs are best suited, if C # is a priority, which libraries are better to use, except for the standard ones, maybe someone knows open source projects with such a task. Essentially I want to write a server to create a server-client communication, but I have never worked on such a task before.
Thank you all in advance for your replies and advice.

Answer 1

The conditions "work on the Internet" (not a local network) and "24/7" set special requirements that can be neglected when developing some kind of "nonsense" and often they do it, but this will not work for you.
For example, for reliable communication (Wi-Fi disappears, contact in the cable ...) you need to study the TCP protocol, understand when "breaks" occur, how to detect them in general. I researched using the Wireshark network sniffer, actually removing the cable and turning off the Wi-Fi router (I wanted to do something special on Arduino, etc., but there was no money, and I could do without it) and, of course, , read the theory - forums, articles, only understood in practice.
As for the "Internet", in addition to reliable communication, there is another nuance here - bots, there are much more of them than I thought, but their logic is incomprehensible, the server has just been registered, the port is naturally not 80, etc., but nevertheless, not even a day passes , as after sorting through all the ports, a bot appears and sends it is not clear what, and the server "crashes" with a parsing error, so you need to take it into account right away, otherwise they will interfere already at the testing stage.
Algorithmic thinking is also important here, I had a very bad time with it, so at first it was hard to work with code in which each line is "wrapped" in try-catch, and in catch there are five more lines (logging, etc.) and it's still not clear what it is better to do in each catch, whether to disconnect the client, or something. :) But, water and stones sharpens - I'm used to it.
And now about libraries... All this four-paragraph tirade to the fact that I never found libraries that would do everything listed for me, they are all too abstract, but I searched very well and I can do it much better than writing, but the result is just wasted time, so do it yourself!
Languages ​​- I also tried different ones - no matter what is more familiar and suitable for other requirements of the task, write in that one.

Answer 2

The application cannot run on the FTP server. An FTP server is needed to transfer files because it's just a File Transfer Protocol.
And you need to understand a little deeper how programs work and what a network is, because at the moment your question is formulated extremely incorrectly and it is difficult to give you useful advice.

Answer 3

If you want a web interface then asp. If the client is a northern connection, then dig towards sockets

Answer 4

Take C#, take those libraries that you need and write. You need a web take asp you need a server take sockets.

Answer 5

To run an arbitrary program, you need a VPS - a full-fledged virtual server, for example, on Ubuntu. There will be root access and you can put whatever you want.