Event (MS) §

Structure §

• key: uid
• value: Data, following a Data contract (MS)

→ Apache Avro and Google’s Protobuf

Design §

• include the whole truth
• keep events atomic

Types §

• unkeyed: no key, value
• keyed: unique key, value
• entity: unique key, value, unique value

Stream §

multiple events → Event stream (ms)

Materializing state §

→ saving all entity events in order into a table

• delete: tombstone → keyed event with value = null

Compacting §

avoid infinite event history → compact the list

• only pick latest event for each event type
• if event = tombstone, skip it