Socket Programming

The classic daytime protocol (RFC 867) implemented as TCP client/server pairs in three languages: C, Python, and Java. A client opens a connection, the server replies with the current local date and time as a single line, and the connection is closed.

Files

File	Role	Language	Port
day_server.c / day_client.c	Daytime server / client	C (POSIX sockets)	entered interactively at run time
day_server.py / day_client.py	Daytime server / client	Python	8999
daytimeserver.java / daytimeclient.java	Daytime server / client	Java	1397

How to run

Run the server first, then the client (on the same machine).

C (POSIX)

gcc day_server.c -o day_server
gcc day_client.c -o day_client

./day_server        # prompt: Enter the server port:
./day_client        # prompt: Enter the port

Both programs ask for the port at run time — use the same number in each. The C server handles one client and then exits; the client connects, prints the time it receives, and exits.

Python

python day_server.py    # listens on port 8999, handles clients in a loop
python day_client.py    # connects to port 8999 and prints the reply

The Python server loops and serves one client at a time (closing each connection after the reply).

Java

javac daytimeserver.java daytimeclient.java
java daytimeserver             # listens on port 1397, loops
java daytimeclient [hostname]  # defaults to localhost

The Java client takes an optional hostname argument; it reads one line from the server and prints It is <time> at <host>.

Notes

• The C client connects to INADDR_ANY (0.0.0.0), so it is intended to be run on the same machine as the C server.
• The Python and Java servers run indefinitely; stop them with Ctrl+C.
• Response format is the platform's native date string (e.g. Sat Jun 24 18:30:00 2023), one line, terminated with \r\n where applicable.

License

MIT © 2023 Adithya N Raj