State of the World (SOW) Topics

One of the core features of AMPS is the ability to persist the most recent update for each distinct message published to a given topic. The State of the World (SOW) can be thought of as a database where messages published to AMPS are filtered into topics, and where the topics store the latest update to each distinct message. The SOW gives subscribers the ability to quickly resolve any differences between their data and updated data in the SOW by querying the current state of a topic or any set of messages inside a topic. Topics recorded in the SOW are also used for caching data, providing "point in time" snapshots of active data flows, providing key/value stores over data flows, and so on. Topics recorded in the SOW are the underlying sources for AMPS aggregation and analytics capabilities, and the ability to store the previous state of a message is the foundation of advanced messaging features such as delta messaging and out of focus notifications.

AMPS also provides the ability to keep historical snapshots of the contents of the SOW, which allows subscribers to query the contents of the SOW at a particular point in time and replay changes from that point in time.

AMPS can maintain the SOW for a topic in a persistent file, which will be available across restarts of the AMPS server. The SOW can also be transient, in which case the state of the SOW does not persist across server restarts.

Topics do not keep the current values in the SOW by default. To provide this capability for a topic, you must configure AMPS to maintain the topic in the SOW by adding a definition for the Topic to the SOW section of the AMPS configuration file.