[Winsock]Spliting sticked data

[BlackCatSLO]

Hy. I have problem im working on some app with winsock, but some times data came glued together. I did make function for spliting and data format does look like this
L0004T0001dataHF

[ L0004 <--- lenght of data(value L0000 to L9999) T0001 <--- data type(values T1 to T9999) ] - header[ 10 Byts]
[ data ] - data[ lenght 0B - 9999B ]
[ HF <-- checksum not very good ] - footer [ 2 Byts ]

and 12Bytes is alot for data for spliting...do anyone knows how to split data withow single chars witch can messup data information
(example)
1. packet data[454353453vddffs324]
spliter [v]
2. packet data[dgfh45egh54645645]

recived data [454353453vddffs324vdgfh45egh54645645]
result 1:[454353453]
result 2:[ddffs324]
result 3:[dgfh45egh54645645]


But i will get three packets from two becouse the function did think there are two spliters.
Can anybody tell me what to use that method im using right now(L0004T0001dataHF ) or....?

[opus]

-1- For using a splitter you need to use a character that is not used inside your messages! It seems you are using straight numbers and characters in your messages, so use something like "|", "{" ......
-2- in your message headers you have the infromation about the length of a single message, you could parse the header and read only the needed length of the message recieved, delete the read part of the message recieved and restart the parsing. This way you don't even need a splitter!

[BlackCatSLO]

I only tried to show you what problems do i have with spliters i do have all chars in the data from 0...255 with wide.

[Al42]

I only tried to show you what problems do i have with spliters i do have all chars in the data from 0...255 with wide.

Assuming you have no control over the data format:

If all characters are valid data (including possibly escaped characters), and the elements aren't fixed length, the data wasn't designed to be parsed. So evidently you're missing something in your analysis of the data. If you're correct, the data is useless.

[alkatran]

It looks like you're trying to do what I used to do: put the length of each packet at the start. This isn't the best way to do it for two reasons: it's complicated and easy to screw up.

What you want to do is separate packets using a delimiter (any character will do). The only thing you need to worry about then is making sure the delimiter doesn't end up in the data!

'In a module
public function makePacket(byval data as string) as string
  data = replace(data, "/", "/a") '/ is our escape character
  data = replace(data, "|", "/b") '| is our packet delimiter
  makepacket = data & "|"
end function
public function breakPacket(byref refReceivedData as string, byref refPacketData as string) as boolean
  refPacketData = left(refReceivedData, instr(refReceivedData, "|")) 'grab the first packet
  if refPacketData <> "" then '(it will be "" if there were no complete packets)
    refReceivedData = mid(refReceivedData , len(refReceivedData)) 'cut packet off received data
    refPacketData  = replace(refPacketData, "/b", "|") 'get '|'s in data back
    refPacketData  = replace(refPacketData, "/a", "/") 'get '\'s in data back
    breakPacket = true
  end if
end function

'In your received event
static data as string
dim s as string
winsock.getdata s,,bytestotal
data = data & s 'build up data over time, in case packets are split in half
while breakPacket(data, s) 'take packets out of data
  process(s)
wend

[the182guy]

The only way to do it is to use delimeters and sub delimaters like..

key
PACKET_DEL = "|"
SUB_DEL = "$"

PACKET_DEL header SUB_DEL data SUB_DEL footer PACKET_DEL header SUB_DEL data SUB_DEL footer PACKET_DEL

In the above example each packet is delimted, but then the sections of a single packet are delimited by a seperate char

[TokersBall_CDXX]

[VB6]

You can split using a delim of more than one characters (a string)

Dim sStringParse As String
Dim sArray() As String
Dim iString As Variant
 
sStringParse = "This is a test *** test is * a test *** test 123"
sArray = Split(sStringParse, "***")
For Each iString In sArray
    MsgBox iString
Next

[BlackCatSLO]

Hmm i did come to another problem. If is more than 4k data sticket together then i it will be dataarrived triggered multiple times so if is this 4kB of data then ***Data*Data*Dat
and then i will recive next part a*Data***Da and next
ta*Data***Data* How do i know when is the end of the packet, and then trigger data spliting. I think this problem can be solved with data lenght in the header.
Every time i start thinking more and more logical problems came to my mind.

[alkatran]

The code I provided keeps them together, as long as you always send data that's been run through 'makePacket'

[CVMichael]

If you send the length of the "packet" then the receiving application will know how much to read.
When using this method, you don't need to send a packet delimiter like makepacket (or something like that).

See the code here as an example:
http://www.vbforums.com/showpost.php...17&postcount=8

[alkatran]

Problems with preceding the packet with their length:
- just one incorrect packet will take out a lot of other packets
- limited size packets (going over the size limit creates an incorrect packet)
- more complicated to write and read