The invention discloses a method, computer system and computer program of interacting with a user of a messaging client. In the method a transactive engine engages via an agent, a natural language interaction with a user of a messaging client in order to initiate a transaction and determines, based on an adaptive script of the agent, the semantics of natural language input from the user. The existing form of the script is adapted to take into account historical interaction between the agent and the user and historical interaction between other users and the agent. The transactive engine constructs at least one command necessary to execute the transaction and transmitting the at least one command to at least one information system in order to execute the transaction. Furthermore, the transactive engine receives information about the executed transaction from the at least one information system, processes the received information relating to the executed transaction to form a natural language response to the user of the messaging client, and sends the natural language response to the messaging client.