Good way of communicating between web and desktop app

Question

I want my web app (running in a browser) to, at some point, communicate (bidirectionally) with a desktop app (in Windows), the client has installed in its computer.

What's an elegant and modular and simple way of doing this (with Java and C#)?

Not much information will be passed between the web app and the desktop app. Just something like "I was here", "Pick this from this point", etc.

Answer 1

I solved that problem by using a database on the network. All communications where made trough the database.

Website -> DB -> User logged in <- DB <- Desktop

However, if no trusted information needs to be shared, you could consider just posting and reading some http headers to a common website, or a simple log file.

Greetings

Answer 2

I suggest you to use the backend part of your webapp, assuming that your app is based on some backend services.

You have two options:

1. Your desktop apps use the same services of your web app. You must use a class that mimic a web-browser to give the data (curl, ie). If your web app is based on AJAX push ( APE Server i.e ) use library that is able to run some javascript
2. Use a REST protocol, with a JSON format in your backend services. It's easy to manage and is supported by many client-side languages (java/c#/python....)
3. Use a specialized endpoint only for your desktop app,for C#, you can use WCF, that allow you, in one of his forms bidirectional communications. For JAVA, there are WSDL, DWR

My preferred solution is to decouple the web app in a front-end side and a backend side, that expose the services as REST that are used by the web app via AJAX.

If I need true bidirectional communication with other desktop app, I'll create a separate service / endpoint for it. (APE , WCF, ..)