How to develop a backend service in C++

#1

Hi,
Is there any way to develop a c++ backend service?
We want to migrate our project to theia. Our project is written in C++. I have seen some extensions that can be developed by java like GLSP have a java version and a node version. But I have never seen an extension written by c++, only the logic code in c++ is OK. I know one way is to spawn a child c++ process and forward JSON-RPC messages between the frontend and the c++ process, but implementing this from zero is time-consuming for us, Could anyone give some idea or a simple demo is a big help?

#2

Hey @wss,

what is the current way you are interacting with your C++ service? Theia doesn’t necessarily require you to use JSON-RPC to communicate with your service. The usual approach would be to interact with the Theia backend via JSON-RPC (using the proxy method), and then let the backend do whatever it likes with the information that it receives.

Forwarding via JSON-RPC is one solution, but there are other ways to accomplish communication to another process as well. We have been recently doing something similar in the elk-libavoid router algorithm, where we just communicate using a custom stdio “protocol”.

#3

Note that it’s possible to make Node native extensions:

Node API: https://nodejs.org/docs/latest-v16.x/api/n-api.html#node-api
C++ wrappers: https://nodejs.org/docs/latest-v16.x/api/addons.html#c-addons

You’d need to expose the relevant functions from C++ to JS and then hook everything up using Inversify in the backend like any other component.

I don’t know if this method is the most efficient for what you have, but it’s an option. It also would only work on the Node/Electron backend, the components wouldn’t be able to be directly loaded in the frontend/browser.

#4

Hi msujew:
We have not used any way to interact with c++ currently. We found theia is a better cross-platform for us, but our backend program was written in c++ before, and we want to build our UI throw theia, We dot have any experience in combining c++ and theia , so want to get some help

#5

Hi paul-marechal:
Thank you very much for your reply, I read the link, and It is indeed useful, Is there any project used this way in GitHub? A demo project will save us a lot of time if possible.

#6

There is no Theia extension written in C++ that I know of, but since you can create JS functions and even objects you would just implement things in such a way that it follows Theia’s extension model and contributions and bind those using Inversify just as you would do with any other JS class.

I found the following examples for generic functionality written in C++:

Note that Theia implements a simple C addon to interface with Electron’s ffmpeg.dll:

#8

Hi paul-marechal
Hi,
I try your method, but get some errors when building. My steps as follow

  1. create a theia extension named “cppaddon” to theia blueprint template project
  2. Run “yarn build” and everything is ok
  3. add a binding.gyp file to appaddon extension,file content is
    image
  4. add a hello_world.cc file
    image
  5. build c++ addon by script in package.json
    image
  6. My project tree
    image
    image402Ă—610 16.6 KB
  7. Finally I run “yarn build” and get the error
    image
    image1278Ă—162 9.6 KB

    8.I do not know how to solve this,It seems that the project can not load addon.node file. Could you give me some help?
#9

@wss are you trying to load the node.js native module into the browser code of your application? Only the node (backend) part of your application is capable of loading *.node files. This is why webpack complains, as it tries to bundle the .node file into the browser build.

1 Like
#10

Hi,
Thank you for your reply. It works now when I load the c++ addon on the backend service.