Dan Johansson, CIO of the Swedish company Industrial and Financial Systems (IFS) talks about is over all architecture and experiences, including how they integrate multiple client types (including .NET) over a J2EE backend and Oracle DB.Dan in the interview explained that they have something we call Access Adapters which are basically like multi-channel protocol adaptors. Java-specific interfaces get .NET interfaces auto-generated which then talk over WSDL
It's essentially a gateway combined with a generated model interface to back-end services in the native technology of the client. They also do support SOAP interfaces but for performance reasons, when their own client talks to their own services they use our own binary protocol. Like their own version of WCF.
Dan explained that they wanted to build a richer experience for their clients so chose .NET on the client side but still wanted J2EE on the server side.