Socket programming beginners questions - c++

Question

I'm really new to this whole socket and server development, I'm not yet familiar with how it all works.
I made a simple flash application that needs to communicate with a socket,
With that, I used a socket that supports AS3 and works on "Red Tamarin",
Well I'll get to the point:
I currently have a loop that always runs socket.receive()
It responds and even displays text that I send from my flash application.
My goal is to get a simple online flash game,
Probably use SQL / SQLite to save information and export it to players,
What I don't understand is how I can take it there..
What I thought I'll need to do is something like so:
On the server side:
Have a loop that runs as long as the server is alive, that loop should always check every connection it has with clients and wait for commands coming from them, such as log in, update player position, disconnect, request list of objects in given positions
Client side:
Send information to the server according to the action, like when a player moves, send the new position to the server in a similar way to this : "MovePlayer[name][x][y]"
Is my plan really how things should be?
And about the actual information being sent, I'm curious, will it be efficient to constantly send the server string data? (that's what I'm used to work with, not some weird bytes and stuff)
Thanks in advance!

Answer 1

You're on the right track. But I encourage you to first define a communication protocol. You can start by defining what a command looks like. For example:
COMMAND <space> PARAM1 <space> PARAM2 <line-break>
A few considerations on the protocol definition:
What if PARAM1 is a string and contains spaces? How can you tell the start and end of each parameter?
Your parameters could also contain a line-break.
If your client application is installed by your clients, they'll need to update it once in a while. To complicate even further, they may run an older version and expect it to work, even if you have changed your protocol. This imposes a need for protocol versioning. Keep that in mind if you require user interaction for updating the client part of your application.
These are the most fundamental considerations I can think for your scenario. There may be other important considerations, but most of them depend on how your game works. Feel free to amend my list if you think I forgot something OP should consider.
After defining what a command looks like, document all commands you believe your applications needs. Don't segregate definition of a command unless it becomes too complex or excessively long for some of your operations. Try to keep things simple.
Now back to your questions:
Is my plan really how things should be?
Yes. That's exactly how it should be.
And about the actual information being sent, I'm curious, will it be efficient to constantly send the server string data? (that's what I'm used to work with, not some weird bytes and stuff)
That depends on a number of factors:
Which protocol you're using (TCP, UDP, etc);
Number of concurrent clients;
Average time to process a command;
Do you broadcast updates to other players?
How you did implement your server application;
Physical contraints:
Hardware: CPU, memory, etc;
Network: bandwidth, latency, etc;
(source: it20.info)

Answer 2

look at this
https://code.google.com/p/spitfire-and-firedrop/
there you will see the basic of building a socket server with redtamarin
see in particular
https://code.google.com/p/spitfire-and-firedrop/source/browse/trunk/spitfire/src/spitfire/Server.as
the details is as follow, redtamarin basically use blocking sockets with select()
with a max hard coded FD_SETSIZE of 4096
see:
https://code.google.com/p/redtamarin/wiki/Socket#maxConcurrentConnection
so here what happen in your server loop
you basically have an array of sockets object
you loop every x milliseconds and for each socket
you ask if you can read it
if you can read on the socket, you then compare if this socket obj is the server
if it is the server that means you have a new connection
if not that means a client try to send you data and so you read this data
and then pass it to an "interpreter"
later in the same loop you check if the socket obj is still valid
and if you can write to it
if you can write and the socket object is not the server
then you can send data to the client
here the equivalent code in C for reference
http://martinbroadhurst.com/source/select-server.c.html
http://www.lowtek.com/sockets/select.html
for a very basic example look at socketpolicyd
https://code.google.com/p/spitfire-and-firedrop/wiki/socketpolicyd
https://code.google.com/p/spitfire-and-firedrop/source/browse/trunk/socketpolicyd/src/spitfire/SocketPolicyServer.as
and compare the implementation with Perl and PHP
http://www.adobe.com/devnet/flashplayer/articles/socket_policy_files.html