1. A method of data service execution, comprising: receiving at application runtime an indication that a first data service has returned a result indicating the first data service has been invoked successfully; evaluating an expression, based at least in part on the result; in the event the result does not exceed a threshold, re-invoking the first data service; and in the event the result exceeds the threshold, publishing an event associated with successful invocation of the first data service and invoking a second data service determined dynamically at application runtime based at least in part on an outcome of the evaluation of the expression, wherein the second data service is invoked by an element configured to subscribe to the event.