State and event information
Publications can be categorized as follows:
- State publications
- State publications contain information about the current state of something, such as the price of stock or the current score in
a soccer match. When something happens (for example, the stock price changes
or the soccer score changes), the previous state information is no longer
required because it is superseded by the new information.
A subscriber
will want to receive the current version of the state information when it
starts up, and be sent new information whenever the state changes.
- Event publications
- Event publications contain information about individual events that occur, such as a trade in some stock or the scoring of a
particular goal. Each event is independent of other events.
A subscriber
will want to receive information about events as they happen.