[ros-users] smach_viewer in electric

[Ken Conley]

On Fri, Oct 28, 2011 at 10:55 AM, Jonathan Bohren
<jonathan.bohren at gmail.com> wrote:
> It appears that in Electric, rospy enforces that strings in ROS messages be
> ASCII strings, so the output of the python pickle module can't be encoded.
>  to fix this we should be able to just change SmachContainerStatus
> (https://kforge.ros.org/smach/executive_smach/file/d79964e4c22f/smach_msgs/msg/SmachContainerStatus.msg)
> from:
> 12 # A pickled user data structure
> 13 string local_data
> to:
> 12 # A pickled user data structure
> 13 byte[] local_data
> I don't currently have the time to test this, but I'm pretty sure this is
> the problem.
> -j

I answered this on Answers as well, but for completeness here, I think
this is a regression caused by attempting to have Py3k compatibility.
I have backed this change out on the ROS 1.6 branch (r15301) for now
while we can attempt to figure out a different approach to this
compatibility.  Py3k separates the notion of strings and bytes; this
distinction has ripple effects when attempting to serialize 'strings'
and the like in Python 2, which treats such data identically.   The
priority is to maintain Python 2 compatibility; I'm guessing a more
significant rewrite of the serializer is necessary to be compatible
with the Py3k distinctions.

 - Ken

>
> On Fri, Oct 28, 2011 at 1:40 PM, Tully Foote <tfoote at willowgarage.com>
> wrote:
>>
>> Hi Manuel,
>>
>> There's already an open thread on this at
>>
>> http://answers.ros.org/question/2032/smach-introspection-server-fails-in-electric
>>
>> Tully
>>
>> 2011/10/28 Manuel Rodríguez <mrodriguez at robotnik.es>:
>> > Hi all,
>> >
>> > I'm using smach with the introspection server and the smach_viewer.py
>> > but does not work fine (it just shows the machine but does not update in
>> > which state the machine is), moreover the script running the
>> > introspection
>> > server periodically shows the following exception:
>> >>
>> >> Traceback (most recent call last):
>> >>   File "/usr/lib/python2.6/threading.py", line 532, in
>> >> __bootstrap_inner
>> >>     self.run()
>> >>   File "/usr/lib/python2.6/threading.py", line 484, in run
>> >>     self.__target(*self.__args, **self.__kwargs)
>> >>   File
>> >>
>> >> "/opt/ros/electric/stacks/executive_smach/smach_ros/src/smach_ros/introspection.py",
>> >> line 160, in _status_pub_loop
>> >>     self._publish_status('HEARTBEAT')
>> >>   File
>> >>
>> >> "/opt/ros/electric/stacks/executive_smach/smach_ros/src/smach_ros/introspection.py",
>> >> line 225, in _publish_status
>> >>     self._status_pub.publish(state_msg)
>> >>   File
>> >> "/opt/ros/electric/stacks/ros_comm/clients/rospy/src/rospy/topics.py",
>> >> line
>> >> 695, in publish
>> >>     self.impl.publish(data)
>> >>   File
>> >> "/opt/ros/electric/stacks/ros_comm/clients/rospy/src/rospy/topics.py",
>> >> line
>> >> 872, in publish
>> >>     serialize_message(b, self.seq, message)
>> >>   File
>> >> "/opt/ros/electric/stacks/ros_comm/clients/rospy/src/rospy/msg.py",
>> >> line 151, in serialize_message
>> >>     msg.serialize(b)
>> >>   File
>> >>
>> >> "/opt/ros/electric/stacks/executive_smach/smach_msgs/src/smach_msgs/msg/_SmachContainerStatus.py",
>> >> line 120, in serialize
>> >>     buff.write(struct.pack('<I%ss'%length, length, _x.encode()))
>> >> UnicodeDecodeError: 'ascii' codec can't decode byte 0x80 in position 0:
>> >> ordinal not in range(128)
>> >
>> > Has anyone knows how to solve this trouble?
>> > Best regards,
>> > Manuel
>> >
>> > _______________________________________________
>> > ros-users mailing list
>> > ros-users at code.ros.org
>> > https://code.ros.org/mailman/listinfo/ros-users
>> >
>> >
>>
>>
>>
>> --
>> Tully Foote
>> Systems Engineer
>> Willow Garage, Inc.
>> tfoote at willowgarage.com
>> (650) 475-2827
>> _______________________________________________
>> ros-users mailing list
>> ros-users at code.ros.org
>> https://code.ros.org/mailman/listinfo/ros-users
>
>