Sending a packet class over TCP!

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Hello Codeproject!

Let's assume we have a class like so:

C#

public class MovedToPositionPacket : Packet
{
 public int nx { get; set;}
 public int ny { get; set;}

 public MovedToPositionPacket()
 {
 }
}

And we then convert this class to a byte array. The byte array then is copied to another byte array(Buffer) with the size of 4096, while the Packet Class is only 96 bytes big.

If we send that byte array(object) how can we convert it back to the same class without using the other 4000 empty bytes?

Posted 30-Jul-13 9:13am

Deviant Sapphire

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Ron Beyer 30-Jul-13 15:24pm

Is there something else in the parent "Packet" class that is needed? Seems like a waste to use 96 bytes to transfer 8 bytes worth of data... And even more of a waste using 4096 bytes to transfer 96 bytes. Can you post the code that converts the "Packet" into a byte array? You should not eat up an entire 3 packets of payload (which is only 1500 bytes per packet incidentally) to transfer such a small amount of data, something is wrong up stream.

Deviant Sapphire 30-Jul-13 15:28pm

The packets can differentiate from sizes, while a TCP buffer can only hold a specific amount of data.

Ron Beyer 30-Jul-13 15:45pm

The TCP buffer has a size, which is the MAXIMUM amount of data it can hold, that doesn't mean you have to transmit that much data with each go. Since TCP packets can only hold 1500 bytes each, your 4096 buffer needs 3 packets to send.

Deviant Sapphire 30-Jul-13 17:08pm

So, assuming I will send one array of 64 bytes. I will have to send another 63 packets of the same size in order to be able to read it? What is up with this protocol?

3 solutions

Solution 1

How is the receiver going to know what class this data belongs in?? Without some kind of metadata, it's impossible for it to know, so you're going to have to send something else beside 8 bytes.

Seriously, are you trying to come up with your own communication protocol??

Posted 30-Jul-13 11:15am

Dave Kreskowiak

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Deviant Sapphire 30-Jul-13 17:24pm

You just made me think about something interesting, thanks a lot, I think this just solved it.

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

SoMad · Accepted Answer · 2013-07-30T14:38:00

I am posting this after having seen the Solution you have posted (Solution 3).

I have been involved with specifying my share of binary wire protocols like this through the years. My advice is don't do this unless your requirements call for the smallest communication packets possible. If this is just a program you are creating to learn from, then by all means continue down this path as you will most likely learn a lot from it.

These days there are so many tools that make things like this easier and faster to develop and maintain in the future. I recommend you look into using JSON or XML serialization.
www.json.org[^]
http://www.w3resource.com/JSON/introduction.php[^]

Some CodeProject articles:
fastJSON[^]
fastBinaryJSON[^]

www.codeproject.com/KB/IP/#General[^]

Soren Madsen

Deviant Sapphire · Accepted Answer · 2013-07-30T11:30:00

The solution:

I will have to send a byte array in which the two first bytes of the array make up the type of the class(For instance a change of location of the player) and another byte that will tell the server how long the class's byte array is.

For instance

0 = ChangeLocationPacket

Visually, it would look lik this:

( [0] [5 bytes long] [2] [3] [4] [5] [6] )

^ this will be the new byte array, every byte in the array splitted with a [ and a ].

You would then read it out by firstly checking out what type of class it is using either and if or a switch statement:

C#

if(array[0] == 0)
 type = ChangeLocationPacket.GetType();

Then, you would check out how many bytes in length it is:

C#

int Length = (int)array[1];

You could even use two or three bytes to add them up together, or use some magical formula lieing around here in codeproject.

Next, you would read it out, and in this case, there is only one byte which tells how long it is so the code to read it out would be:

C#

Array.Copy(array, 2, newarray, 0, Length);

And afterwards you could return the object and the type in order to convert it back to the class.

Sending a packet class over TCP!

3 solutions

Solution 4

Solution 1

Solution 3

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Sending a packet class over TCP!

3 solutions

Solution 4

Solution 1

Solution 3

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