In this article it has been looked how to program using sockets by implementing an echo server along with a client that is used to send and receive string messages. It will start off by giving a quick introduction to TCP/IP fundamentals and then explain how sockets fit into the diagram. Most network application can be divided into two pieces: a client and a server. A client is the side that initiates the communication process, where as the server responds to incoming client requests. There would be contains three types of service from this software, that is Message Transfer service, Voice Transfer service and File Transfer service. All this sorts are the design issue of this software.

2.  Overview
 Chapter Briefs
 Socket
 Socket Programming
 Socket Type
 Implementation issues
 Control Flow
 Design
 Implementation
 Discussion
 Future Development

3.  In this article it has been looked how to program using sockets by
implementing an echo server along with a client that is used to
send and receive string messages. It will start off by giving a
quick introduction to TCP/IP fundamentals and then explain how
sockets fit into the diagram.

4. • Most network application can be divided into two pieces: a client
and a server. A client is the side that initiates the communication
process, where as the server responds to incoming client requests.
• There are numerous network protocols, such as Netbios, RPC
(Remote Procedure Call), DCOM, Pipe, IPC (Inter-process
Communication) that can be used for the Comm Link. Here is
only look at TCP/IP.

5. Although TCP can be implemented to work over any transport protocol,
it's usually synonymous with IP. TCP is a connection-oriented stream
protocol (like a telephone call). This is shown below with a factious
network topology layout, where the data packet takes (n) number of
hops to get from the source to the Destination.

6. A socket is made up of 3 identifying properties:
Protocol Family, IP Address and Port Number.
For TCP/IP Sockets:
The protocol family is AF_INET (Address Family Internet)
The IP Address identifies a host/service machine on the network.
Port defines the Service on the machine that communicating to/from
The port numbers from 0 to 255 are well-known ports, and the use of these
port numbers in your application is highly discouraged. Many well-known
services which are use have assigned port numbers in this range.
Service Name Port Number
ftp 21
telnet 23
http 80

7. An interface between an application processes and transport layer.
The application process can send/receive messages to/from another
application process (local or remote) via a socket.

8. socket ( )
bind( )
+---->listen ( )
| accept( )
| (block until connection from client )
| read( )
| write( )
+----- close( )
close( )
• The steps to get a server up and running are shown below
(read from top to bottom). This is how our sample code is
written, so it's a good idea to get familiar with the process.

9. The steps the client needs to take in order to communicate with the
server.
• socket( )
• connect( )
• write( )
• read( )
• close( )
1. Create a socket with the server IP address
2. Connect to the server, this step also names the socket
3. Send data to the server
4. Read data returned (echoed) back from the server
5. Close the socket

10. Winsock control comes with VB6 and is used to create
applications that access the low-level functions of the
Transmission Control Protocol/Internet Protocol (TCP/IP).
Client and server will interact with each other to exchange data.
So, the programming discipline using socket is known as socket
programming.
Winsock Operating Modes:
1. sckTCPProtocol
2. sckUDPProtocol

11. There are several Internet socket types:
Datagram sockets, also known as connectionless sockets, which use
User Datagram Protocol (UDP)
Stream sockets, also known as connection-oriented sockets, which
use Transmission Control Protocol (TCP) or Stream Control
Transmission Protocol (SCTP).
Raw sockets (or Raw IP sockets), typically available in routers and
other network equipment. Here the transport layer is bypassed, and
the packet headers are not stripped off, but are accessible to the
application.

12. Sockets are usually implemented by an API library such as Berkeley
sockets, first introduced in 1983. Most implementations are based
on Berkeley sockets, for example Winsock introduced in 1991.
Other socket API implementations exist, such as the STREAMS-
based Transport Layer Interface (TLI).
Development of application programs that utilize this API is called
socket programming or network programming.

13. User
Name
User
Password
Encode
password then
Save to Data
1 User Entry
D Data Save
Figure : DFD for register new user:

14. Receiver’s
User
Name If Receiver online then
“Send”
2 Check Online
D Data Log Save
Figure : Control Flow to Send Message

15. Sender’s
User
Name Option (Yes/No)
2 Chat Requested
If Yes, Then
Message Received
If No, Then
Message
Ignored
Figure 3 : Control Flow to Receive Message

16. Receiver’s
User Name If Receiver online then
“Send” File Receive
Request
2 Check Online
If Receiver – Yes
Then Send File
Check
If Receiver – No
Then Send process Break
Figure 4 : Control Flow to Send File

17. File Receive
Request
A File Receive requested
By <Sender>
2 Message Display
If – Yes
Then display
message Where to
save the file
Check
If – No Then
receive process break.
Figure 5 : Control Flow to Receive File

18. Requested
User Name
“Accept voice chat”
Option (Yes/No)
6 Message Show
If Press – Yes
Check For Supported
Sound Hardware
Check
If Receiver – No
Then voice chat process
Break
If (Supported) = True
Then Chat Start
If (supported) = False
Then Show Error Msg.
Figure 6 : Control Flow Voice Chat

19. Figure 7 : User administrator add panel

20. Figure 8 : Server Log pan store every status change it
made change by user and the server administrator.
These logs are stored in flat data mode.

21. Figure 9: The session info contains the online user information.
User entire time. His/Her encoded password.

22. Figure 10 : The user login form.

23. Figure 11: This is the most valuable client side main form.

24. Figure 12 : Data Receive From.
Figure 13: Voice Chat Client.

25. Figure 14 : Client Side Option Dialog

26. The installation phase arrives only after the implementation phase
has been successfully competed. The final system now stands
ready to be delivered to the users. The principal objectives of the
installation phase are to replace the existing system by the newly
created system is smooth, trouble -free manner. In order to
accomplish the objectives, three activities must be performed.

27. Finally this software is completed successfully in implemented in
real field successfully. But man has a concern about something
new. In this way the development process will be continuing. At
present it covers to text based chat, voice chat and file transfer. All
this shorts as it was in requirement successfully done. But
committed with market it is need farther more development.
Otherwise it would be out of business. In this manner some plan
made for future work and research.

28. Future development is on plan. which are video chat or
video conference. Existing software will be more interactive
look. Some games will be added to it. Animation will be
applied. Sound effect and Sound theme will be make
resonance to cha user. Funny Aviary keeps support when
no one is online of according to user demand.