A program includes expressions written in a process-based language. A process kernel executes sets of operational semantics rules governing the meanings of the expressions in the program. A first expression is parsed. The first expression describes that a process is a choice of two processes. The first process of the two processes expresses that a first query is submitted to a queue, after which the first process continues with a first set of actions. The second process of the two processes expresses that a second query is submitted to the queue, after which the second process continues with a second set of actions. The first expression reduces to a second expression. The second expression describes that a third query is submitted to the queue after which the first process runs in parallel with the second process if the third query is in canonical form.