2019.2 flatsim questions after updated

Autonomous Machines Robotics - Isaac Isaac SDK
1

Some data prototype has been change , but the wiki has no corresponding update.

In 2019.1 flatsim, simulation speed publish data type is “DifferentialBaseStateProto”,published in “flatsim.app.json”

{
        "source": "base_simulation/isaac.flatsim.DifferentialBaseSimulator/diff_base_state",
        "target": "segway_odometry/isaac.navigation.DifferentialBaseOdometry/state"
},

Corresponding data prototype is “isaac2019.1/messages/differential_base.capnp”,but in 2019.2 this prototype has been removed.

I find the data prototype “DifferentialState” in “isaac2019.2/messages/navigation.capnp”,node’s graph source is:

{
        "source": "simulation.subgraph/interface/diff_base_state",
},

I searched “simulation.subgraph/interface/diff_base_state” in your component_api page at
https://docs.nvidia.com/isaac/isaac/doc/component_api.html

Here is the msg only related:

isaac.flatsim.DifferentialBaseSimulator
Description

Simulates a differential base by translating base commands into acutator commands, and by publishing base state computed based on rigid body state from the simulator
Type: Codelet - This component ticks either periodically or when it receives messages.

Incoming messages

diff_base_command [StateProto]: Input command message with desired body speed
physics_bodies [RigidBody3GroupProto]: Input state of the base rigid body as computed by physics
Outgoing messages

physics_actuation [ActuatorGroupProto]: Output actuator message with desired accelerations for each wheel
diff_base_state [DifferentialBaseStateProto]: Output state of differential base

Unlike 2019.1,the data prototype “DifferentialBaseStateProto” cannot be found in anywhere in 2019.2.

After searching all the files in 2019.2.I found the most likely data type “DifferentialState”.I decide to look up inside it.

Here is my code:

ISAAC_PROTO_RX(DifferentialState, diff);
....
tickOnMessage(rx_diff());
....
 if (rx_diff().available()) {
        auto diff = rx_diff().getProto();
        printf("%lf\t%lf\t%lf\t%lf\t%lf\t%lf\t%lf\t\n",
               diff.getPositionX(),
               diff.getPositionY(),
               diff.getHeading(),
               diff.getSpeedX(),
               diff.getSpeedY(),
               diff.getAngularSpeed(),
               diff.getTimestamp()
        );
    }

Printed values:

0.000000	0.000000	0.000000	0.000000	0.000000	0.000000	0.000000	
0.000000	0.000000	0.000000	0.000000	0.000000	0.000000	0.000000	
0.000000	0.000000	0.000000	0.000000	0.000000	0.000000	0.000000	
0.000000	0.000000	0.000000	0.000000	0.000000	0.000000	0.000000	
0.000000	0.000000	0.000000	0.000000	0.000000	0.000000	0.000000

Is there any thing wrong?

Which graph should I use to get the speed data published by the simulation?

And another question:
Which graph should I publish my odom like liear_speed & angular_speed back to?

Thanks.