Writing the ros pub command inside the launch file

edit

This is a command line command:

rostopic pub /rec_pose_as/goal path_exam/RecordOdomActionGoal "header:
  seq: 0
  stamp:
    secs: 0
    nsecs: 0
  frame_id: ''
goal_id:
  stamp:
    secs: 0
    nsecs: 0
  id: ''
goal: {}"

I want to use a launch file to run this command, so I do the following:

<node pkg='rostopic' type='rostopic' name='some_arbitary_name' args='pub /rec_pose_as/goal path_exam/RecordOdomActionGoal 
"header:
  seq: 0
  stamp:
    secs: 0
    nsecs: 0
  frame_id: ""
goal_id:
  stamp:
    secs: 0
    nsecs: 0
  id: ""
goal: {}"' />

But I get the error

rostopic: error: Argument error: mapping values are not allowed here
  in "<string>", line 1, column 14:
    header:   seq: 0   stamp:     secs: 0     nse ...

The error appears to come at seq: (the arrow points at colon)

What should be done? Would be grateful to any help