Implement the integration of a telemetry server on YarpJS framework

[nunoguedelha]

(This PR was moved from https://github.com/robotology/yarp.js/pull/21)

This PR implements the integration of a telemetry server on YarpJS for serving Open MCT telemetry visualizer.

We connect the robot interface Yarp ports to the Open MCT via the yarp.js Yarp-to-websocket server are listed below as follows:

• [x] Retrieve Yarp data: the yarp.js server reads the Yarp output ports, like for instance /icubSim/inertial. => DONE (server created and working on http or https.)
• [x] History and Realtime servers (listen to OpenMCT): for extending the server with these services, yarp.js has two additional sockets http://localhost:<port>/history and http://localhost:<port>/realtime where it listens to requests coming from OpenMCT, asking for new telemetry data. => DONE
• [x] History and Realtime servers (reply to OpenMCT):yarp.js replies sending the buffered data within a range depending on the requested time boundaries. => DONE
  • [x] Realtime data request by Open MCT was failing. => This was due to wrong request address from the Realtime Telemetry plugin (in Open MCT) => now set to ws://localhost:/realtime (https://github.com/dic-iit/element_software-engineering/issues/50#issuecomment-863877317 and https://github.com/dic-iit/element_software-engineering/issues/50#issuecomment-864163884)
  • [x] "Cross-Origin Request Blocked" issue. => Open MCT server configuration has the "Same Origin resource" constraint when fetching data from resources. => solved by properly setting the CORS settings in the response header from the Yarp.js server (https://github.com/dic-iit/element_software-engineering/issues/50#issuecomment-864163884 and https://github.com/dic-iit/element_software-engineering/issues/50#issuecomment-864724209)
• [x] Bufferize data: the data read from the YARP port should then be pushed to the History server buffer. Scalar and vector data should be supported. => DONE (https://github.com/dic-iit/element_software-engineering/issues/50#issuecomment-865529850)
• [x] Limit History server buffer depth. => DONE

[nunoguedelha]

Did a quick test and verified same functionality as in the old repo. Now YarpJS is a dependency.

[nunoguedelha]

@traversaro , the PR is ready for review.

[nunoguedelha]

The code seems nice, but it may be difficult to use especially for someone without a lot of node experience. Do you plan to have a README (also something simple) to explain how to run the code?

Yes absolutely, I have another PR coming with the implementation of all the remaining ports with iCub data, After or with that one I can add a README. The commands for running the telemetry servers and the Client are really simple. I will add a short how-to for adding a port to read.

[nunoguedelha]

Merging ...