everest.store — sundbp/everest 0.4.0-alpha1

append-events! clj

(append-events! store stream-id expected-version events)

Appends the provided seq of events to the stream identified by the stream-id. Returns a map containing:

• everest.append/next-expected-version - the expected version which, when used, will successfully append events to the stream

Cannot append to the 'all' stream. Will fail if the current version of the stream doesn't match the expected-version.

delete-stream! clj

(delete-stream! store stream-id expected-version)

Deletes the specified stream and all of the events that were written into it.

Cannot delete the 'all' stream. Will fail if the current version of the stream doesn't match the expected-version.

read-event clj

(read-event store stream-id position)

Reads a single event from the stream-id at the specified position.

Supported parameters:

• stream-id - name of the stream or :all for the 'all' stream
• position - a positive number, nil/zero for the first event or :everest.event.position/last for the last event

read-stream-backward clj

(read-stream-backward store stream-id start cnt)

Reads a cnt of events from the position start of the specified stream stream-id backward.

Please see the documentation of read-stream-forward.

read-stream-forward clj

(read-stream-forward store stream-id start cnt)

Reads a cnt of events from the position start of the specified stream stream-id forward.

Parameters may have the following values:

• stream-id - a name of the stream or :all for the 'all' stream
• start - a positive number or nil/zero
• cnt - a positive number or nil/zero if all events should be read

Result is a stream slice, a map with the following structure:

• :everest.stream-slice/stream - the name of the stream being read from
• :everest.stream-slice/from - the position of the first event read or nil if no events were read
• :everest.stream-slice/next - the possible position of the next event (the next event in the stream will have a position >= the next position) or nil if no events were read
• :everest.stream-slice/direction - either
  • :everest.read-direction/forward or
  • :everest.read-direction/backward
• :everest.stream-slice/events - a seq of events that were read

An Event is a map of the following:

• :everest.event/stream - the name of the stream this event belongs to. This might be different from the stream id that was queried if the query stream-id is :all
• :everest.event/position - the position of this event
• :everest.event/timestamp - date when the event was written
• :everest.event/type - type of the event
• :everest.event/data, :everest.event/metadata - event data and metadata

subscribe clj

(subscribe subscription-source stream-id start opts)

Subscribe to the specified stream/events from the start position, exclusive (the reason for that being the usual use case for subscriptions when you want to catch up from the last position you have seen and processed successfully). This is a catch up subscription which will read all of the events from start to the current head and subscribe to the further updates.

Returns a (manifold) stream of events.

The start position might be:

• :all or 0 - stream will be read from the beginning
• number > 0 - the position of the last event that you processed succesfully (or any other position within a stream) - this is a catch up subscription
• :everest.subscription.events/new or nil - stream will receive only the newly appended events

You can pass in additional opts which include:

• :read-batch-size - batch size to be used when reading events for catch up
• :catch-up-executor - executor where the catch up work will happen