This figure demonstrates the relationship of Databus, Data Tokens and Reactions. The figure shows a Reaction that gets activated due to availability of it's Data Tokens. When all the Data Tokens are available and match the Reaction Conditions (example, constraint on the values of a Data Token) then the Reaction fires. The firing of a Reaction executes the Active-EJB method and may generate one or more Data Tokens. These Data Tokens may be for the return values to the callee or for more requests for one or more Active EJBs. These Data Tokens are 'pushed' to the AC4J Databus which then routes them to the proper Process Context. The registered Reactions may get matched and fired depending on their conditions.