Network Stream Class

• Download demo project - 24 Kb

Introduction

The Stream class is very useful to network programming because if you want to send some data over network you first need to pack some diffrent structs to one packet, then send it over network and afterwoods you have to reconstruct the old data structure:

datastructure -> stream -> send ->...network...-> receive -> stream -> datastructure

Output of Example program:

Test 1: seemless stream by using the end() method:

 putting 11 bytes to stream...->"1________x"
 putting 21 bytes to stream...->"2________xa________x"
 putting 31 bytes to stream...->"3________x_________xb________x"
 stream complete. Ready to send it over any device (eg. network)
 deleting test data to make sure all data safely are in stream...
 stream looks like:
 -------------------------------------------------------------------
  31 5F 5F 5F 5F 5F 5F 5F 5F 78 00 32 5F 5F 5F 5F 5F 5F 5F 5F 78 61 
  5F 5F 5F 5F 5F 5F 5F 5F 78 00 33 5F 5F 5F 5F 5F 5F 5F 5F 78 5F 5F 
  5F 5F 5F 5F 5F 5F 5F 78 62 5F 5F 5F 5F 5F 5F 5F 5F 78 00 
 -------------------------------------------------------------------
 <63 Data Bytes, 63 Total>

Test 2: stream with header and block information by using the 
endWidthBlockList() method:

 putting 11 bytes to stream...->"1________x"
 putting 21 bytes to stream...->"2________xa________x"
 putting 31 bytes to stream...->"3________x_________xb________x"
 stream complete. Ready to send it over any device (eg. network)
 deleting test data to make sure all data safely are in stream...
 stream looks like:
 -------------------------------------------------------------------
  03 00 00 00 0B 00 00 00 31 5F 5F 5F 5F 5F 5F 5F 5F 78 00 15 00 00 
  00 32 5F 5F 5F 5F 5F 5F 5F 5F 78 61 5F 5F 5F 5F 5F 5F 5F 5F 78 00 
  1F 00 00 00 33 5F 5F 5F 5F 5F 5F 5F 5F 78 5F 5F 5F 5F 5F 5F 5F 5F 
  5F 78 62 5F 5F 5F 5F 5F 5F 5F 5F 78 00 
 -------------------------------------------------------------------
 <63 Data Bytes, 79 Total>
 reconstruct old structure :
 Number of blocks: 3
 Stream Block Nr.  = 1
 Stream Block size = 11 bytes
 Stream Block data = "1________x"
 Stream Block Nr.  = 2
 Stream Block size = 21 bytes
 Stream Block data = "2________xa________x"
 Stream Block Nr.  = 3
 Stream Block size = 31 bytes
 Stream Block data = "3________x_________xb________x"
done. 

Using the code

The way you use this class is easy. You just have to make an instance of stream and then add data to it. When finished you have to call end or endWithBlockList to get the stream. The diffrence between end and endWithBlockList:

• end() will give you the complete Data in one Block without any header or block information. You will not be able to reconstruct the datastructure from this, but anyway you may need it if you don't need header and blockinformations (eg. voice over ip)
• endWithBlockList() will give you a complete stream with header and a list of blocks. With this you can reconstruct your data structure.

Here an example on how to use it if you want to send data over network:

Code on the first PC

Stream myStream;
myStream.begin();
    
// fill in some data to stream:
myStream.add("Hello",6); // 5 + '\0'
myStream.add("World",6); // 5 + '\0' 
myStream.add("!",2); // 1 + '\0'
char * myData = (char *) myStream.endWithBlockList();

now you have to send the myData over network and receive it on a second pc(i will not show you how to do that at this time ;-P)

now the code for the second Pc:

// data was received over TCP/IP and stored in char * myData

// get header information
tStreamheader * pStreamheader = (tStreamheader *)myData;
unsigned long * pBlocksize; // this will hold our block lenght
char * pBlockdata = NULL; // this will hold our block data

// offset pointer beginning after header...
unsigned long myoffset = sizeof(tStreamheader); 

for (i = 0; i< (int) pStreamheader->numblocks; i++) // all blocks to be processed
{
  // get our blocksize of next block
  pBlocksize = (unsigned long *) (myData + myoffset); 
  myoffset+=sizeof(unsigned long); // go to it
  pBlockdata = new char[*pBlocksize]; // make room for block data
  memmove(pBlockdata, myData + myoffset,*pBlocksize); // copy the block data
  myoffset+=*pBlocksize; // step to next block (blocksize+blockdata)

  printf("%s ",pBlockdata); // print out blockdata 
  // hint: if its not a zeroterminated string we will get rubbish, 
  // so don't forget the '\0'

  delete [] pBlockdata; // we don't need the data anymore...
  pBlockdata = NULL; // to make shure no one will make unwanted quickreboots
}

program on second PC will print out:

Hello World !

tStreamheader is a struct for the header information of our stream. It contains only one variable at this time(unsigned long numblocks) but it is easy to enhance it if you need more detailed information in the header like source, destination, time, totalsize,...

History

Version 1.0 released at 24.04.2003