SomeoneElse,

The IP (connection-oriented) protocol doesn''t really allow for packets, per se. Logically, it transfers a stream of bytes from one point to another. Technically, yes, at the very bottom of the communications it is all packet-driven, but neither application side see''s this happening; it''s transparent. What you can do is create "objects" that you send back and forth-- packets of information. Basically build your own protocol on top of the IP connection. It''s much like reading & writing to a file. Whatever you dump to the file has to be readable and parseable by a client.

I wrote one such protocol (over IP) for a game. I called it "COP" which stands for "Common Object Protocol". At the very top level of abstraction, communications between two machines is a series of "objects" being transmitted.

Both the client and server send "object packets" back and forth to talk to each-other. I would then define each object type, size and information (the size can be dynamic.)

So all communication would look like this:
[DWORD-OBJECT-SIZE] [DWORD-OBJECT-ID] [... object ...]

Where:
[DWORD-OBJECT-SIZE] is a DWORD (4-byte) size. It specifies the number of bytes that follow, which is a single object.
[DWORD-OBJECT-ID] is a COP object ID. It''s what gives meaning to the data. If the client recognizes the object ID then it can parse/decode the information; if not, it can safely "skip" or ignore the object entirely.
[... object ...] is a series of bytes with length [DWORD-OBJECT-SIZE].

In this sense, you can think of each object as a ''packet'' of information. You could build something similar using UDP, but UDP packets are limited in size. Typically only about 1.5k in size before they are broken up or simply dropped by routers. There is a Winsock 2 function call, somewhere in the ioctlsocket() function that will tell you what the max packet size is.

UDP is certainly the faster method of the two, when as-close-to-real-time transmission is required/needed. In this case you would simply have a small buffer that you sendto() and recvfrom(). Then, like the IP method above, you would have some sort of ID number as the first 1, 2 or 4 bytes that tells the reciever what information is inside the packet.


Hope this helps,
// CHRIS

struct GamePacket
{
unsigned long COMMAND;
char RECEIVED_FROM_PLAYER[32];
int XPOS;
int YPOS;
...so on
}

then cast it to (char*) when you send it over

-BacksideSnap-