We’ve built a set of .NET libraries (in C#) which are used to interact with an outside resource. The outside resource provide bindings in Java and .NET, so it was necessary to build our libraries in one of those languages and we’re officially a Windows shop.
We also use PHP/Javascript for a lot of our front-end web applications. Is it possible for these PHP/Javascript web applications to interact with our .NET libraries? We have both IIS and Apache web servers if that makes a difference. Communication would need to go in both directions.
The most obvious approach is exposing your .NET libraries as web services on a web server (either IIS or Apache/Mono). This allows both JS and PHP to consume the same service endpoints (JS via AJAX, PHP vs web service calls).
If extreme performance is a concern – for example, your PHP apps need to make heavy calls into the .NET libraries as if they are native, then web services are probably not the best approach. For that, you might want to look into making COM Callable Wrappers for your .NET libraries and consuming them from PHP.