A message flow within a message broker can be identified. The message flow can include nodes and connections. The nodes can include a reflective node, a pre-defined node and a user-defined node. The message broker can be an intermediary computer program code able to translate a message from a first formal messaging protocol to a second formal messaging protocol. The code can be stored within a computer readable medium. The reflective node within the message flow can be selected. The reflective node can be associated with an external resource which can be an executable code. The external resource can be executed which can result in the modifying of the structure of the message flow. The modification can occur during runtime. The modification can include node and/or connection adding, altering, and deleting.