How to publish TF for slam_gmapping

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Hi,

I completed the tutorial on [slam_gmapping using Logged data]. When I play the basic_localisation_stage.bag and run "rostopic echo tf", I realised that there are 3 messages published every 100ms:

1. odom-->base_footprint
2. base_footprint-->base_link
3. base_link-->base_laser

So, if i want to run gmapping with TF, do I need to publish all those three types messages in every cycle? (2) and (3) have fixed values, and may be unneccessarily to be published again. So, they can be published only at the beginning of the process.

I am not sure how the slam_gmapping works with the TF, as in does it subscribe all the three messages in every cycle? I need to minimise data transfer since I am using Labview to transfer the odometry data to ROS.

Any help would be much appreciated. Thanks