1. A computer readable medium including program code for providing a message-based interface for exchanging information about financial instrument impairment calculations, the medium comprising: program code for receiving via a message-based interface exposing at least one service as defined in a service registry and from a heterogeneous application executing in an environment of computer systems providing message-based services, a first message for a query for calculations of an impairment amount and an unwinding amount for a financial instrument, including calculations for analyzing effects by different calculation parameters on risk provisions and accounting balances, the first message including a message package hierarchically organized as: a financial instrument impairment calculation financial services calculate query message entity; and a parameters package including a parameters entity, wherein the parameters entity includes a set of books identifier, a date, a currency code, a financial instrument impairment exposure amount, an effective interest percent, a financial instrument write down amount, and an unwinding amount calculation requested indicator; and program code for sending a second message to the heterogeneous application responsive to the first message.