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Chat Client Server

Boby Thomas P

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18 May 2007CPOL1 min read

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An implementation of chat client and server with win32 sockets

Sample Image - chat_client_server.jpg - Click to enlarge image

Introduction

Recently I got myself introduced to socket programming. I read through many books and articles to get an insight into the subject. After learning a bit, I decided to share my knowledge with the world. For this purpose, I created a simple console based chat application. I hope this will be a good reference code for C++ socket programming. I am going to introduce the following concepts to you here.

Sockets
Multi threading

What is Chat Client Server?

The demo project given along with this article consists of two console-based applications.

Chat Server

Chat server is an application which does the following operations:

Listens for incoming calls from clients. Client running in any PC can connect to the server if IP address of the server is known.
Listens for messages from all the connected clients.
Broadcasts the message from clients to all the clients connected to the server.
You can also type-in messages in the server, which will be broadcasted to all the clients.

Chat Client

Chat client does the following things:

Sends messages to server as well as to all the connected clients.
Views the messages from all the clients and server.

Please download the PDF document to read the rest of the documentation. I have created a PDF because the article consists of 2-3 diagrams.

License

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

Written By

Boby Thomas P

Software Developer (Senior) DWS

Australia

Check my homepage for more details - Click Here

Comments and Discussions

Boby Thomas P10-Nov-06 0:37

10-Nov-06 0:37

Which one? chat client / server?

Regards,
Boby

behavior after cable break Win2k/ Winxp

Bennet Yee12-May-06 20:13

12-May-06 20:13

We tested the application under Windows 2000 and Windows XP.
We need to detect a cable break.
Under Windows 2000 - select() returns with readfds signaled after some seconds.
The following recv() returns 0, e.g. connection lost is recognised.
BUT: Under Windows XP nothing happens! No signal was send by select().

Why the application shows different behaviour in Win2k / winXP?
How to detect cable break under WinXP?

noise@ASU9-May-06 15:52

9-May-06 15:52

glad to view this article.i have a little idea.when a client sends message to the server, can u define a message format?for example,char[4096],the first 256bytes used for the nickname,when server send these back to all clients,them print the nickname before(-->),so the server donnot need to maintain a database for the nickname,and the clinet can change the nickname anytime he/she wants.

Re: i have an idea

Boby Thomas P9-May-06 21:22

9-May-06 21:22

thats a nice idea.

Regards,
Boby

integration of project

dimas757-May-06 9:54

7-May-06 9:54

hello, i´ve a problem with the project
the problem is that i don´t know how to integrate the project in my program in a "transparent" way, so i can use the functions provided.
i really need event driven messaging for my program, and this seems the only class out there that can do that (shame you can´t get the com events as easy as in the old times).
Could something give me more detailed instructions on how to use this classes in my program(really more detailed), or where to find an easier one? (spent countless hours in google, and found just this event driven class)

By the way, i´m using visual studio 6.0 and MFC classes

Thanks for the help

Dimas

Re: integration of project

mysterious_caveman10-Jun-07 10:43

mysterious_caveman

10-Jun-07 10:43

I don't know if i'm understanding you correctly... but if you want to make an application that is event driven just use the tools provided by win32 library. I'd suggest you learn about semaphores and signals then use the following:

HANDLE hMyEvent = CreateEvent(NULL, false, false, NULL); // non-signaled state with automatic reset

then whenever you want to wait for an event just do the following:

DWORD dwReturnValue = WaitForSingleEvent(hMyEvent, INFINITE); // or any time in ms

the above will sit and wait until hMyEvent is signaled. To signal it simply do the following:

SetEvent(hMyEvent);

Once the event is signaled a single thread will proceed and hMyEvent will be reset (to the unsignaled state).

I don't know if this is what you're asking, but hope it helps. Sorry it's so rushed. I'm on my way out but I thought I'd just quickly respond to this question off the top of my head because you sound like you're making your life difficult for no reason. Cheers.

raul_sfk7-May-06 0:48

7-May-06 0:48

I read your article Interprocess Communication using Sockets.
in codeproject.com. that's great!

one point i do not really understand. in code, server has created two separate sockets.
Why you need separate sockets?
would you please give me a hand or hint ?
thank you very much!! Laugh | :laugh:

Laugh | :laugh:

Boby Thomas P7-May-06 8:56

7-May-06 8:56

In server side, one socket listens to calls from outside and one each for each client to receive data.

In client side, one for sending and one for receiving data.

Regards,
Boby

SunithaC7-May-06 0:43

7-May-06 0:43

hi,
i have to develop one interprocess communication b/w two processes running in different PCs

Could please suggest me some nice site to start from very basic till good coding...

If possible give me one example of IPC program.
Smile | :)

Smile | :)

Regards,
Sunitha

Re: info required

Boby Thomas P7-May-06 8:56

7-May-06 8:56

Book Linux Programming Unleashed - SAMS covers basic details of Interprocess communications.
Eventhough the book is dealing with linux environment, the concepts are the same in windows also.

Regards,
Boby

Re: info required

roninttk9-May-06 22:13

9-May-06 22:13

To create communication between 2 networked computers, you will either need to setup a Client/Server model (like this demo program) or a Peer-to-Peer model. The Client/Server model establishes one program as the "Server" to which all other "Clients" connect to and receive directions from the server. The Peer-to-Peer model is a loosely connected group of network aware programs, none of which control the interation between each other.

Another important factor to consider is which protocol to implement: TCP/IP (used by this demo) or UDP/IP. TCP is a "connection oriented" socket communications, in which data is buffered, sent in sequential order, with guaranteed delivery. UDP is "connection-less" in that it packages up data and sends it off without caring if it is received by that addressee or not, nor in what order the packets are received. However, UDP strengths are reduced overhead (28 bytes to TCP's 40 bytes) and generally a higher throughput rate of message traffic.

TCP or UDP brings you up to Layer 4 on the OSI model. To establish your own communications between your 2 programs, you will essentially be creating your own messaging protocol which is contained within TCP segment or UDP datagram. So on one end you will create your message and send it within a WinSock call <send((char*)pmessage, msgsize)="">, if sent by TCP. The receiving program will get the message in memory buffer <recv((char*)pbuffer, &bytesreceived)="">, and then need to process the message contained in the buffer.

Therefore, many considerations are involved based on the type of communication requirements your program has:
1. Network I/O architecture (Client/Server vs. Peer-to-Peer)
2. Underlying protocols used (TCP vs. UDP - 2 most common)
I have a couple of books at the office I use for reference. One is "Network Programming for Microsoft Windows" by Microsoft Press. I also use MSDN's site pretty heavily for specific details about various function calls, but not the best read for learning.

Once you are past the preliminaries, then the real fun begins! You will get to learn about Blocking Mode vs. all the Non-Blocking Mode communications... but that is another story, for another time.

Best of luck,

Tobin Kaneshiro

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