Methods and systems for enabling arbitrary components to control communications, such as data transfers, without having or requiring prior knowledge of each other. The system includes a component that creates controller objects for a communication, such as a data transfer involving several components. Further, the component associates the controller objects with a communication session object of the data transfer, such as a data transfer session object. One or more of the components involved in the data transfer obtain the controller objects through the data transfer session object and execute source-specific instructions included in the obtained controller objects to generate user interfaces. The user interfaces enable the components to control aspects of the communication, such as the data transfer.