Hi Ros people! My name is Santiago, i'm just beginning in robot-world, and
i'm making a client from Pharo smalltalk. My first goal is make work the
turtle simulator from XMLRPC.

So i have several questions, but right now i have two most important:

Considering a remote client (without direct access to server):

-  How can i get the message definition related to a topic? Can i ask to
the topic? Does the topic answer me in the error text something about the
type?

- Is any definition of a common TCPROS package to take as example of topic
usage?

  In this case, i'd spend a lot of time today trying to send messages to
the turtle throgh the velocity topic without any response (no movement, no
error, no feedback at all) and i tried with the logs, but without any
useful data.

 The process i'm following is:

  execute roscore
  execute turtle node

  then, from the client

  register as publisher in Velocity topic

  with the IP:PORT recived connect to the node with a TCP/ip connection
  sending a message with:

header
        type: master getTopicTypeRelated:/turtle1/command_velocity;  #here
i get the topicType from getTopicTypes
        topic: /turtle1/command_velocity;
        latching: false;
        callerId: anArbitraryId;
        messageDefinition: 'float32 linear
float32 angular';
        md5Sum:'9d5c2dcd348ac8f76ce2a4307bd63a13'.

in the body of the request i tried with float numbers (2.0 0.0) for
example.

All this data in binary.

I browse a lot of roscpp, rospy and rosjava trying to find how them create
and serialize the data, but i dont find meaningful differences. Maybe i'm
missing steps?


Thank you very much!


Santiago.