Abstract: A system (1) has an analysis engine (2) for analysing transaction data (20) received in real time at an interface (3). A context generation engine—(25) directly receives transaction data (20) from the interface (3) and also macro data (26). Queue listeners (52) pull data from a shared memory queue (50(a), 50(b)) and feed it to transaction processors (53), which call a dynamic procedure (43) of the context generation engine (25) in real time. The transaction processors (53) therefore feeds transaction data and context parameters to a rule processor (61), effectively customizing the rule processor real time. Each rule processor (61) executes a decision tree to determine the rules to execute in real time.