Hi,

did you have a look at the technical overview page?

http://www.ros.org/wiki/ROS/Technical%20Overview

It gives you a sort of more detailed overview on how the middle ware
works. Documentation on the XMLRPC APIs can be found here:

http://www.ros.org/wiki/ROS/Master_Slave_APIs

Lorenz

> Hi!
> 
> I am trying to understand how ROS communication works and possibly write
> C library to access master node etc. I dislike python and c++ somewhat.
> 
> I have found wiki page http://www.ros.org/wiki/ROS/TCPROS and not much
> more about exact details how ROS communicates. I do not complain, ROS is
> not end user product and documentation never will be complete there. So
> I launched roscore and 
> 
> sudo tcpdump -i lo port 11311 -w -  > tmp
> 
> to get fast view on it. But what is weird, in dump I see only HTTP
> headers and first line of XML in plaintext. Can someone point me to some
> wiki page or source file explaining method or compression or other
> reason for this? What I see now:
> 
> tonu@hp:~$ rosservice list 
> /rosout/get_loggers
> /rosout/set_logger_level
> tonu@hp:~$ 
> tonu@hp:~/ros$ strings tmp
> a,/+
> a,/+
> a,/+
> POST /RPC2 HTTP/1.0
> Hosn
> a,/+
> <?xml version='1.0'?>
> HTTP/1.0 200 OK
> a,/+
> Server: BaseHTTP/0.3 Pytn
> a,/+
> Date: Sat, 02 Apr 2011 0n
> a,/+
> Content-type: text/xml
> a,/+
> Content-length: 1112
> a,/+
> a,/+
> <?xml version='1.0'?>
> a,/+
> a,/+
> yiPOST / HTTP/1.1
> User-Ag
> ,/@|
> fJ@|
> ,/@|
> ,/@|
> 7POST / HTTP/1.1
> User-Ag
> fK@|
> fK@|
> 7HTTP/1.0 200 OK
> ,/@|
> f\@|
> 7Server: BaseHTTP/0.3 Pyt
> ,/@|
> 7Date: Sat, 02 Apr 2011 0
> ,/@|
> 7Content-type: text/xml
> ,/@|
> 7Content-length: 278
> ,/@|
> ,/@|
> 7<?xml version='1.0'?>
> ,/@|
> ,/@|
> 7POST / HTTP/1.1
> User-Ag
> <|K@
> ,/@|
> 4|L@
> ,/@|
> ,/@|
> 8POST / HTTP/1.1
> User-Ag
> 8HTTP/1.0 200 OK
> 4|N@
> ,/@|
> 8Server: BaseHTTP/0.3 Pyt
> 4|O@
> ,/@|
> 8Date: Sat, 02 Apr 2011 0
> 4|P@
> ,/@|
> 8Content-type: text/xml
> 4|Q@
> ,/@|
> 8Content-length: 274
> 4|R@
> ,/@|
> 4|S@
> ,/@|
> 8<?xml version='1.0'?>
> 4|T@
> ,/@|
> ,/@|
> 8POST / HTTP/1.1
> User-Ag
> ;POST / HTTP/1.1
> User-Ag
> ;HTTP/1.0 200 OK
> <Server: BaseHTTP/0.3 Pyt
> <Date: Sat, 02 Apr 2011 0
> <Content-type: text/xml
> <Content-length: 286
> <<?xml version='1.0'?>
> <POST / HTTP/1.1
> User-Ag
> <POST / HTTP/1.1
> User-Ag
> <HTTP/1.0 200 OK
> <Server: BaseHTTP/0.3 Pyt
> <Date: Sat, 02 Apr 2011 0
> <Content-type: text/xml
> <Content-length: 291
> <<?xml version='1.0'?>
> tonu@hp:~/ros$ 
> 
> 
>   TƵnu
> 
> _______________________________________________
> ros-users mailing list
> ros-users@code.ros.org
> https://code.ros.org/mailman/listinfo/ros-users

-- 
Lorenz Mösenlechner            | moesenle@in.tum.de
Technische Universität München | Boltzmannstr. 3
85748 Garching bei München     | Germany
http://ias.cs.tum.edu/         | Tel: +49 (89) 289-26910