Communication between desktop application and web frontend

My project can be divided into 3 components: Desktop application, Server backend, Server frontend. I am using websockets application-backend and backend-frontend communication. Frontend is single page application. Whole looks like this:

I need to implement communication between frontend and application (dotted arrow in the picture above). I am able to use backend server as a proxy, but it would be more useful to have direct communication between frontend and application so that backend resources aren't wasted.

Is there any way how I can establish direct connection between local app and web frontend?

PS: I am using Go for both backend and application, JavaScript for frontend and WebSockets for communication, but general architecture answers are welcomed.

Are you trying to connect to the JavaScript Frontend from your desktop application? If so, I can think of the following options

1. WebRTC. It's supported by Chrome (and Opera) and Firefox.
2. Chrome Native Messaging, this only works for chrome obviously, sends/receives info from stdin/out of your desktop application.

Overall I think WebRTC might be a better solution. Both of the solutions require you to run your web frontend in a modern browser though, Chrome/Firefox.

If you have to deal with IE, I can only think of having your desktop application to run a local web server, and have your web application poll/post to it. Even then, you have to work around cross domain issues, and you probably want to implement some level of security around it, so it gets fairly messy.

This might work, but may take quite a bit of extra thought to do securely:

Have your desktop program run a web(socket) server on some arbitrary port p, then try to talk to localhost:p from your frontend.

Or you could try to do WebRTC between the browser and desktop app. A quick search turned up https://github.com/coreos/go-webrtc-datachannel, which is just a planning document at this time.