1. A method for enabling a developer to concurrently debug parallel activities, comprising: receiving a request to debug an at least one business process through a graphical user interface (GUI), wherein the at least one business process includes a parallel activity; presenting a graphical representation of the at least one business process; receiving input which indicates where one or more breakpoints are to be added to the at least one business process; inserting the one or more breakpoints to the at least one business process and recording the one or more breakpoints in a data structure which links each breakpoint to its associated activity; instantiating an instance of the at least one business process and executing the instance; entering debug mode automatically and pausing execution of the instance when a breakpoint is reached; receiving an instruction to perform a parallel-step operation on the parallel activity; executing a plurality of current activities in the parallel activity concurrently, wherein said current activities in compiled format containing machine level instructions; and pausing execution before executing a next activity, which is determined by a token-based flow control block, wherein availability of a token in a token pool indicates a corresponding activity is ready to be executed next; and wherein after the production server executes a plurality of current activities in the parallel activity concurrently, the production server inserts an implicit breakpoint at the next activity.