core

This project is a light-weight publisher-subscriber/service(Server-Client) communicate protocol based on gRPC. For cases having difficulty on installing ROS, or needy to combine control system to web page.

preliminary

Install gRPC.

compile

$ cd ${worker space}/core 
$ mkdir build 
$ cd build 
$ cmake .. -DCMAKE_PREFIX_PATH=${grpc-install-prefix} -DCMAKE_INSTALL_PREFIX=${grpc-install-prefix} 
$ make -j8 
$ make install 

local environment setting

$ export PATH="${worker space}/bin:$PATH" 
$ echo export CORE_LOCAL_IP="127.0.0.1" >> ~/.bashrc 
$ echo export CORE_MASTER_ADDR="127.0.0.1:10010" >> ~/.bashrc 
$ echo export PROTO_PATH=/${HOME}/.local/include >> ~/.bashrc

You can also choose your setting bash file. "CORE_LOCAL_IP" should be your local device IP, and "CORE_MASTER_ADDR" should be set to same as your local/remote NodeCore launched device.

For example, if you have device A (192.168.0.106) and device B (192.168.0.172). And you run your core master node on device A on port 10010, then on each device A and B, the "CORE_MASTER_ADDR" should be "192.168.0.106:10010", and "CORE_LOCAL_IP" on device A is "192.168.0.106", "CORE_LOCAL_IP" on device B is "192.168.0.172".

example compile

$ cd ${worker space}/core/example/c++
$ mkdir build 
$ cd build 
$ cmake .. -DCMAKE_PREFIX_PATH=${grpc-install-prefix} 

For me ${grpc-install-prefix} is /${HOME}/.local

run

$ source ~/.bashrc 
$ NodeCore 
$ ./NodeTestPub // terminal 1
$ ./NodeTestSub // terminal 2

This is the basic Publisher/Subscriber protocol, it support multiple subscribers subscribe to one topic, and also multiple publishers publish to a topic is legal but not recommended.

$ NodeCore 
$ ./NodeTestServiceServer // terminal 1
$ ./NodeTestServiceClient // terminal 2

This is the basic ServiceServer/Client protocol, if you launch multiple Server on one service, only the last one works functionally.

JavaScript preliminary

First you should install node and npm.

$ cd ${worker space}/core/example/js
$ npm init
$ npm install @grpc/grpc-js
$ npm install protobufjs
$ npm install ws

JavaScript example

$ NodeCore
$ cd ${worker space}/core/example/js/helloworld 
$ node TestPublisher // terminal 1 or you can also use c++ helloworld example publisher with js subscriber
$ node TestSubscriber // terminal 2 or you can also use c++ helloworld example subscriber with js publisher
$ node TestServiceServer // terminal 3 ...
$ node TestServiceClient // terminal 4 ...

All these node should be able to cooperate with c++ program. if you got some error, it might mostly because the message definition. The js message with _{alphabet} would become upper case in nested structure. For exmaple if you use hello.hello: string_field in js declaration should be : {stringField: "hello"} instead of : {string_field: "hello"}

Further example

Combine c program and js to obtain a user interface and dashboard. In data-collect-sim, we write a virtual IMU with bias in c, and shows data and get calibration command from web UI.

My.Movie.4.mp4