asciireflector 1.2

asciireflector is a simple, unix based reflector program that allows sharing of data between clients through a TCP stream-socket
asciireflector is a simple, unix based reflector program that allows sharing of data between clients through a TCP stream-socket connection. The reflector reads ASCII lines from each connected client, buffers them in a shared pool (ringbuffer) and sends all lines back to each client.

Usage and protocol:

Client reception is initiated by sending a textline to the reflector. This will usually be the data that is to be shared between clients. This line gets stored in the reflectors buffer unless it is the text "POLL". All lines send to the reflector have to end with a newline character. If the line is preceded by the keyword "PUSH", the line gets distributed by the reflector with the PUSH removed, but no lines get send back to the client. Otherwise immediately after the reception from the client, all textlines that have
been received since the last sending of text will be written back to the client. This sequence is finished when the text "OVER" is send from the reflector. This means no new textlines are in the ringbuffer. To close the socket connection with the reflector, send the word "LOGOUT".

Note that the reflector sends the last textline that was received from the client back to the client during the next iteration. This can be used to test if the speed of the network connection is sufficient to maintain complete reception of the ringbuffer. If the first line
received is not equal to the last line send, the ringbuffer has been overwritten by another client in the mean time, indicating that reception is too slow. Reflector use should be stopped in such a case.

Thus the client should run the following sequence repeatedly:

1. Connect to reflector
2.) Send data

2.1.) Send data as "textline", store as "last_textline"

OR

2.2) Send "POLL"

OR

2.3) Send "PUSH__and__some_text" to send text without having to receive anything (i.e. proceed to 4.)

3.) Read data
3.1.) Read "textline" unless PUSH was send
3.1.2) If first "textline" is not "last_textline" abort with an error
3.2.) Repeat from 3.1 until "textline" is the "OVER"
4.) ... do other stuff ...
5.) Goto 2. or send "LOGOUT"

The use of ASCII and stream-sockets was used for its easy of use and transparency - its not very efficient though for realtime applications that have to transport a lot of data.

Compilation and test:

To compile the source type
make

Then run
asciireflector

To test, connect to the reflector in (a few) different terminal(s) with telnet localhost 1522 and type a few lines.

The program was developed on a RedHat Linux system but should work with any unix system that provides a pthread implementation.

Limits and settings:

The current (compiled-in defaults) are:

Port number 1522
Connections 20
Line Length 128 chars (including newline)
Size of Ringbuffer 1024 lines

Change the defines in the .h files to adjust to your application.

What's New in This Release:

Fixed connection count
Added a few messages
Fixed PUSH behaviour

last updated on:
June 5th, 2006, 19:21 GMT
price:
FREE!
developed by:
A. Schiffler
homepage:
www.ferzkopp.net
license type:
GPL (GNU General Public License) 
category:
ROOT \ System \ Networking

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