How to realize communication between browser and backend?

I have a backend software that needs to be able to communicate with a gecko-based web browser (and vice-versa). What is the best way to realize this? Since HTTP is rather one-way (with the exception of e.g. reverse AJAX which I consider 开发者_如何学Pythonto be quite "hacky") I am wondering how to do this.

Would creating an NPAPI-based plugin be an option? Based on the data exchanged between the browser and backend, the browser needs to manipulate the DOM of a webpage. The manipulations need to be quite dynamic and communication speed is an important requirement.

I am glad for any help pointing me in the right direction or providing useful resources that might be worth reading!

Writing browser plugins isn't quite trivial, if you can use alternatives like WebSockets (or their emulations like web-socket-js, see here and here for more details).

Only if such alternatives don't give you enough control because of special requirements should you consider writing a browser plugin.
With it you would get the full benefits of native code (high control over whatever API you choose) but also the problems that come with it:

• you have to start to worry about privileges
• bugs can crash the whole browser
• you might have to handle behavioral differences between platforms and browsers
• you have to worry about distribution on multiple platforms
• ...

If you need the higher level of control for some reason you could

• implement the connection handling of your choice in the plugin
• let the JavaScript initiate connections and send data
• let the JavaScript register handlers for incoming data etc.
• on incoming data call those handlers and pass them the data

To get started with NPAPI plugins see here, to support IE too you'd have to write a content extension. Finally i would advise to take a look at FireBreath that already does much of the heavy lifting for you (hides the different APIs for IE and NPAPI, gives you a higher level API, fixes for browser bugs included, ...).