A plurality of application servers hosts a plurality of business applications. A plurality of Application Program Interface (API) servers host a plurality of APIs to provide programmatic access to the plurality of business applications, each of the APIs configured to receive request messages compiled by a remote client application. An example method includes receiving a plurality of request messages generated by the remote client application, each request message requesting an activity to be performed by the targeted API, with respect to an associated application, and comprising at least one data component, and a request component including a reusable identified schema definition specific to the targeted API.