This invention is about engineering approach to development of transactional workflow applications and about ability of this way produced applications to concurrently process large number of workflow requests of identical type with high speed. It provides methods and articles of manufacture: for graphical development of fully executable workflow application; for producing configuration of class objects and threads with capacity for concurrent processing of multitude of requests of identical type for transactional workflow and for concurrent execution and synchronization of parallel workflow-activity sequences within processing of a workflow request; for application self-scaling up and self-scaling down of its processing capacity; and for real-time visualization of application's thread structures, thread quantity, thread usage, and scaling-enacted changes in threads structure and quantity.