In a message grouping application, the broker/ESB architecture allows the messages mid-flow to pause and collecting them into groups according to a correlation string that is calculated from the content of the messages. Furthermore, minimum/maximum quantity and timeout constraints are applied to the group. Once a collection, as a group of related messages, is deemed complete, they are combined into one message and routed or transformed as directed in their combined content. This scheme allows message processing to be batched according to the combined business meaning of multiple inputs.