[Rock-dev] accessing ports in syskit compositions via services

[Felix Rehrmann]

Hi,

I have a composition (see below) that has an OrientationSrv, for which I 
found two ways of accessing the underlying port.
One is via the service, the other is via the orocos task. Latter has the 
problem that it depends on the port name of the orocos
task, which might not be named like the service port and in this case 
actually is not. The access via the service is a bit uncomfortable
as it requires the conversion into the data service first. - Is there 
another solution which allows to access the port via the service? Say
a bit more straight forward?

Felix

class RotateTo < Syskit::Composition

     add Base::Motion2DControlledSystemSrv, :as => 'system'
     add Base::OrientationSrv, :as => 'orientation'

     argument :target_angle, :default => 0.0
     argument :rate, :default => 0.1

     on :start do |ev|
         @cmd_writer = system_child.orocos_task.motion_command.writer
         # The orientation service knows the port under the name 
orientation_samples.
         @ori_reader = 
orientation_child.as(Base::OrientationSrv).orientation_samples_port.reader
         # The orocos task's port is actually called pose_samples.
         #@ori_reader = orientation_child.pose_samples_port.reader
     end

....

-- 

  Felix Rehrmann
  Researcher
  
  DFKI Bremen
  Robotics Innovation Center
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