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Posted 9 Aug 2001

Peer-to-Peer Communicator and File Transfer

, 14 Aug 2001
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Get youself a peer-to-peer communicator and exchange files across a network.

Sample Image - SimpleChat.jpg


On this web site you would probably find every functionality that was put into this application. I realize that. Hence I'm not going to post the source code just yet. However, I've put it up here to see how much interest this application would attract, specifically if there is any interest in the techniques that I've used to implement it. I'm going to enumerate some of the techniques in this short article. Let me know if there is anything of interest to you and I will probably write up a separate article for whatever is requested.


This is a peer-to-peer communicator that allows you to chat with a single person at a time and exchange files simultaneously.

Sockets, ..., sockets, ... Zzzzzap! (::) (Connection established)

A socket library built upon Berkley sockets was designed and implemented. I've taken a well known approach of having an object package itself into a stream on the sender's side and do the opposite on the receiver side. Using the library above, a hierarchy of classes is introduced to accommodate the file transfer.


A set of classes encapsulate the threading/synchronization Windows API. Each thread is responsible for handling logically separated functional areas of the software. That is, I've introduced:

  • A UI thread.

    This thread is the MFC's main thread that handles all UI components. This thread is a subscriber for event notifications from the rest of the threads.

  • A couple of Listener threads.

    One of which is to listen for incoming requests for the first connection with the remote party to be established. Once the connection is up, another Listener is brought alive to await for any possible requests to send a file.

  • A Sender thread.

    This thread handles the file sending functionality.

  • A Receiver thread.

    This thread handles the file receiving functionality.

Event Model

The Sender and Receiver threads notify the UI thread about the progress of the work by adding notification events into the shared memory queue. The UI thread polls the queue for the notifications every few milliseconds. This approach is good enough for such a simple application, but if I was to have a lot of worker (Hello Microsoft! :)) threads, I should have probably created a dedicated worker thread which all it would do is to sit locked on the queue's mutex, until an event is added and then do UI_Thread::PostThreadMessage(), so that UI would have much faster response to the application events.


I hope by now you're not yelling at the monitor, hoping that I might hear it "Where is the Source Code?!". Well, honestly I don't believe that one can learn a lot from a load of not very well documented source code. So if there are people who want to know, let me know what part of this software would be of most interest to you and I'll come up with an article.


Well, after getting several emails with the source request, I figured I should probably give it to the community :) Unfortunately I don't have time to explain all of the concepts of the NetLib that is included here, but basically this library allows you in a limited form to marshal an arbitrary C++ object(s) across a network. Some threading and synch classes are included and provider/consumer design pattern is applied for communicating with the UI thread. As soon as I get a brake from work, I'll come up with a better article. Actually let me know if there is a need for it.

Well happy coding to you, I hope this will be of some help.


This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

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Comments and Discussions

QuestionExtent of multi threaded file transfer Pin
Kumar9010-Jun-17 0:26
memberKumar9010-Jun-17 0:26 
QuestionHow to execute the code provided by you Pin
Member 129495351-Feb-17 4:39
memberMember 129495351-Feb-17 4:39 
GeneralMy vote of 1 Pin
amit9051015-Nov-14 23:02
memberamit9051015-Nov-14 23:02 
QuestionPeer-to-Peer Communicator and File Transfer Pin
Member 1003840117-May-13 10:38
memberMember 1003840117-May-13 10:38 
GeneralMy vote of 5 Pin
Member 43208447-May-12 10:42
memberMember 43208447-May-12 10:42 
Questionhow to run the program...??? Pin
Member 861304130-Mar-12 1:36
memberMember 861304130-Mar-12 1:36 
Questionhow to run the program Pin
max_lord21-Oct-10 22:31
membermax_lord21-Oct-10 22:31 
Generalproblem Pin
donon25-Jan-10 21:51
memberdonon25-Jan-10 21:51 
Generallooking for the more clear article Pin
Member 417159017-Nov-09 5:52
memberMember 417159017-Nov-09 5:52 
General[Message Deleted] Pin
it.ragester2-Apr-09 22:53
memberit.ragester2-Apr-09 22:53 
GeneralThank you Pin
Li Shu30-Oct-08 3:46
memberLi Shu30-Oct-08 3:46 
GeneralVS 2005 Pin
ewasta12-May-08 11:15
memberewasta12-May-08 11:15 
AnswerRe: VS 2005 Pin
Itai Basel24-Jun-08 10:09
memberItai Basel24-Jun-08 10:09 
GeneralRe: VS 2005 Pin
Kristof Nacsa20-Jun-14 9:31
memberKristof Nacsa20-Jun-14 9:31 
Generalquestion Pin
sajjad alizadeh9-May-08 7:47
membersajjad alizadeh9-May-08 7:47 
Questionfile transfer with peer to peer network ? Pin
benard4-Mar-08 5:11
memberbenard4-Mar-08 5:11 
QuestionNat Traversal? Pin
bluewater02092-Mar-08 22:36
memberbluewater02092-Mar-08 22:36 
Generalfatal error C1083 Pin
leenkinpark30531-Oct-07 20:12
memberleenkinpark30531-Oct-07 20:12 

i've downloaded the source code. when i tried to compiled, it says that "fatal error C1083: Cannot open include file: 'SimpleChatDlg.h': No such file or directory". so, where can i get the file??


Questiontransfer file Pin
hwzmail9-Oct-07 0:27
memberhwzmail9-Oct-07 0:27 
Generalthe progrem use too mach memory! Pin
twblue25-Jun-07 0:13
membertwblue25-Jun-07 0:13 
GeneralRe: the progrem use too mach memory! Pin
jan bont31-Jul-08 4:10
memberjan bont31-Jul-08 4:10 
AnswerRe: the progrem use too mach memory! Pin
Dr. B.M. Linden11-Sep-09 10:03
memberDr. B.M. Linden11-Sep-09 10:03 
Questiondoes it resolve domain names? Pin
breakpoint27-Mar-06 21:32
memberbreakpoint27-Mar-06 21:32 
GeneralRe: peer to peer file transfer Pin
FabianSauer21-May-06 22:06
memberFabianSauer21-May-06 22:06 
Questionhow to compile and create an exe file Pin
how jack21-Feb-06 16:48
memberhow jack21-Feb-06 16:48 

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