Tracing Flow of Data in a Distributed Computing Application

A method is provided for tracing dataflow in a distributed computing application. For example, the method includes incrementally advancing a dataflow in a dataflow path of one or more dataflow paths according to two or more directives encoded in two or more data messages. The method further includes performing the two or more directives. The dataflow path includes one or more operators including at least one merge operator operative to merge the two or more data messages and merge the two or more directives. One or more of the incrementally advancing of the dataflow and the performing of the two or more directives are implemented as instruction code performed on a processor device.