A distributed event processing system that can organize (e.g., order) input streams regardless of actual time of receipt is provided. This order may simply be arrival order or given explicitly on a specific event attribute, such as a timestamp or sequence number. Traditional standing event queries, such as a temporal correlation of events across multiple streams, often block if an input stream is slow or may produce an incorrect answer if events fail to arrive within the fixed time interval. In response to this situation, the subject innovation employs punctuation and heartbeats in connection with a robust and scalable event processing system. The innovation discloses mechanisms by which heartbeats and timestamps can be regularly generated by low-level nodes (e.g., sources) and propagated through the network, to unblock standing event pattern queries and align events from multiple distributed streams.