All Known Subinterfaces:: CurrentEventsByPersistenceIdQuery, CurrentEventsBySliceQuery, CurrentEventsByTagQuery, CurrentLastSequenceNumberByPersistenceIdQuery, CurrentPersistenceIdsQuery, EventsByPersistenceIdQuery, EventsBySliceQuery, EventsByTagQuery, EventTimestampQuery, LoadEventQuery, PagedPersistenceIdsQuery, PersistenceIdsQuery

All Known Implementing Classes:: LeveldbReadJournal, PersistenceTestKitReadJournal

public interface ReadJournal

API for reading persistent events and information derived from stored persistent events.

The purpose of the API is not to enforce compatibility between different journal implementations, because the technical capabilities may be very different. The interface is very open so that different journals may implement specific queries.

There are a few pre-defined queries that a query implementation may implement, such as EventsByPersistenceIdQuery, PersistenceIdsQuery and EventsByTagQuery Implementation of these queries are optional and query (journal) plugins may define their own specialized queries by implementing other methods.

Usage:


 SomeCoolReadJournal journal =
   PersistenceQuery.get(system).getReadJournalFor(SomeCoolReadJournal.class, queryPluginConfigPath);
 Source<EventEnvolope, Unit> events = journal.eventsByTag("mytag", 0L);

For Scala API see ReadJournal.

Interface ReadJournal