Packets in LUBE

[Sekaru]

I've recently managed to get LUBE to work and I've noticed a pretty big issue. Is there any way to send specific packets when you need to from both client and server and handle them in the order they were sent in?

For example:

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-- client
function sendPlayerLoc
   udp:send(player.x)
   udp:send(player.y)
end

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--server
function handlePlayerLoc
   player.x = udp.readdata() -- obviously aren't the actual functions
   player.y = udp.readdata()
end

Thanks in advance.

[bartbes]

Yeah, using tcp.

[Sekaru]

Yeah, using tcp.

So just using the tcpServer:receive and tcpServer:send?

Like,

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-- client
function sendSomething
   tcpServer:send(player.x)
end

But how would the client know which function to call to receive the data?

[bartbes]

Using a tcpClient, of course. TCP is a protocol meant to deliver reliably and in order. UDP is lossy, packets can be lost, arrive in different order, etc, the advantage is that this allows you to not care about old packets, so it's generally more suitable for realtime games.

[Sekaru]

Using a tcpClient, of course. TCP is a protocol meant to deliver reliably and in order. UDP is lossy, packets can be lost, arrive in different order, etc, the advantage is that this allows you to not care about old packets, so it's generally more suitable for realtime games.

Well what I mean is if I need to send different things like sendPlayerMove or sendPlayerDeath, how will the client know the index of the sending procedure?

So like in VB (let the hate begin) I would do something like this in the server:

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tcp.write(sPlayerMove)
tcp.write(player.x)

And in the client I'd have:

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If Index = sPlayerMove then HandlePlayerMove()

And in the Handle function you'd have the reading. Is there anything like that?

[bartbes]

Oh, well, you don't. Instead, with everything you send what it is, and read that on the other end.

[Przemator]

When you read from a TCP socket, you're guaranteed to read the data in order it was sent. If ALL of your data has to be delivered, then you have to use TCP. UDP is good for data that expires after a short time (if it's old, it's useless) or that is replaced by new data.

If you send player state via UDP, you might include a timestamp, and only process the data if the timestamp is larger than the maximum of already received data from the client.

[Sekaru]

Oh, well, you don't. Instead, with everything you send what it is, and read that on the other end.

So if I wanted to send different things in different orders I couldn't? Would that mean that I would just have to send everything every time I want to send something?

When you read from a TCP socket, you're guaranteed to read the data in order it was sent. If ALL of your data has to be delivered, then you have to use TCP. UDP is good for data that expires after a short time (if it's old, it's useless) or that is replaced by new data.

If you send player state via UDP, you might include a timestamp, and only process the data if the timestamp is larger than the maximum of already received data from the client.

Yeah I understand that. I just can't understand how there isn't a central function that checks the index of the message which then passes it onto a function that determines which function to use to handle the data.

[Przemator]

So if I wanted to send different things in different orders I couldn't? Would that mean that I would just have to send everything every time I want to send something?

What are you saying here? I don't understand. You receive a packet, then you read what it is, then you do something with it. With TCP, you are sure that ALL things will come through, and that they will come in order of being sent.

I can imagine a scenario:

player A sends data:

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"action|hit|B"
"chat|gotcha B!"
"action|hit|C"
"chat|now i killed C!"

TCP server gets all that in the right order, while UDP server might get sth like this:

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"action|hit|C"
"action|hit|B"
"chat|now i killed C!"

So, the order isn't correct and one message is missing.

[Sekaru]

Okay. What I'm doing is trying to send different things at different times so the packets will usually not be sent in the same order each time.

Let's take a simple game for example where you have skills, combat and moving.

Assuming we have 3 players online, let's assume they all send these things:
P1 Sends: Moving, Combat, Skills
P2 Sends: Combat, Skills, Moving
P3 Sends: Skills, Moving, Combat

As you can see they all send data in a different order. How does the server know to execute the function that handles Moving if that is sent first and so on for the rest of them?