add rpc server to the oculus module to control finite state machine of the module

[kouroshD]

Problem: Especially by using the VIVE, it is often tricky to distinguish the left from the right hand. It would be better and safer to start the teleoperation pipeline from a terminal command Solution: An RPC command is added to the oculus module.

[kouroshD]

@S-Dafarra @GiulioRomualdi if you can test this feature for the demo, it would be great. I could build it without any problem, but I could not test it.

[S-Dafarra]

I quickly checked it. Here a couple of comments:

1. the RPC answer is asynchronous, hence you need to use some mutex around.
2. I would suggest using separate methods dealing with each command.
3. Instead of using the respond method, you can specify a thrift with all the commands you need (http://www.yarp.it/git-master/thrift_tutorial_simple.html). This has the following advantages:
   • for each command it automatically generates a virtual method that you can implement, thus automatically addressing point 2 above;
   • it handles automatically the help command;
   • it handles automatically more complex inputs, like vectors
   • if you write some documentation, this is automatically reported when typing help myCommand
   • it is more scalable; it is easier to add/change/remove commands

You can find some example of usage of the thrifts in the walking-controller:

• the thrift file is https://github.com/robotology/walking-controllers/blob/75429cbbf444c92496beb863667cac0c50eb542e/src/WalkingModule/thrifts/WalkingCommands.thrift
• this is the command to launch in the CMakeLists https://github.com/robotology/walking-controllers/blob/75429cbbf444c92496beb863667cac0c50eb542e/src/WalkingModule/CMakeLists.txt#L37-L38 this will automatically create some files that you need to add to the executable https://github.com/robotology/walking-controllers/blob/75429cbbf444c92496beb863667cac0c50eb542e/src/WalkingModule/CMakeLists.txt#L42.
• In the module then, you include the autogenerated header https://github.com/robotology/walking-controllers/blob/75429cbbf444c92496beb863667cac0c50eb542e/src/WalkingModule/include/WalkingControllers/WalkingModule/Module.h#L53. This has the same name of the thrift file.
• you inherit from the autogenerated class (that has the same name of the thrift file): https://github.com/robotology/walking-controllers/blob/75429cbbf444c92496beb863667cac0c50eb542e/src/WalkingModule/include/WalkingControllers/WalkingModule/Module.h#L61
• You implement the methods related to the commands: https://github.com/robotology/walking-controllers/blob/75429cbbf444c92496beb863667cac0c50eb542e/src/WalkingModule/include/WalkingControllers/WalkingModule/Module.h#L258-L288
• You still have the RPC port https://github.com/robotology/walking-controllers/blob/75429cbbf444c92496beb863667cac0c50eb542e/src/WalkingModule/include/WalkingControllers/WalkingModule/Module.h#L120
• You use this commands to "attach" the methods you implemented to the RPC port https://github.com/robotology/walking-controllers/blob/75429cbbf444c92496beb863667cac0c50eb542e/src/WalkingModule/src/Module.cpp#L170-L176
• You close the port normally: https://github.com/robotology/walking-controllers/blob/75429cbbf444c92496beb863667cac0c50eb542e/src/WalkingModule/src/Module.cpp#L356

[kouroshD]

@S-Dafarra I have updated the PR with the requested changes. Please have a look on it. Thanks.

[kouroshD]

@S-Dafarra Thank you for the comments, I have updated the PR with your comments.

[kouroshD]

@S-Dafarra I have updated the PR with your suggestions. Moreover, I have rebased the code. Let me know if you have other comments as well. Thanks.

[kouroshD]

We have tested PR added to this branch : https://github.com/robotology/walking-teleoperation/tree/modify_dcmWalkingRetargeting_rpc_Oculus It was working as expected. @S-Dafarra If you can approve the PR, I will proceed with the merge.

[S-Dafarra]

Just one comment for future reference. When using the gloves now, we could avoid connecting to the JoypadControlClient. In any case we can proceed.