fdb-java-eventstore

An event store layer build on top of FoundationDB

Layout

Data is stored in two separate subspaces

Global Subspace

Globally ordered based time
Global / [versionstamp] /

Global subspace tuple value is a pointer to an event in the stream subspace stored in the format of <event number>@<stream id>. When reading from the global subspace via the readAll* methods we resolve the pointer and return the message from the stream subspace

QUESION: Could we pack in the <event number>@<stream id> or equivalent into the key so we didnt need to retrieve the value? What type of performance boost would that give?

Stream Subspace

Stream / id (stream hash) / version /

• message Id
• stream id
• message type,
• message data
• message metadata
• event number
• created Date (UTC from epoch)
• Versionstamp (Global position)

Using

EventStoreLayer requires you pass in a FoundationDB Database as well as a DirectorySubspace. The DirectorySubspace is where we'll store all our events.

Create a DirectoryLayer

new DirectoryLayer(true).createOrOpen(tr, Collections.singletonList("es")).get();

Create EventStoreLayer

EventStoreLayer es = new EventStoreLayer(db, eventStoreSubspace);

Create EventStoreLayer with default "es" DirectorySubspace

EventStoreLayer es = EventStoreLayer.getDefault(db);

Append

EventStoreLayer es = new EventStoreLayer(db, eventStoreSubspace);
String stream = "test-stream";
es.appendToStream(stream, ExpectedVersion.ANY, createNewStreamMessage());

Read

Read from a stream

ReadStreamSlice read = es.readStreamForwards("test-stream", 0, EventStoreLayer.MAX_READ_SIZE);

Read backwards from a stream

ReadStreamSlice read = es.readStreamBackwards(stream, StreamPosition.END, 10);

Read from the all subspace

ReadAllSlice read = es.readAllForwards(Position.START, 10);

Read backwards from the all subspace

ReadAllSlice read = es.readAllBackwards(Position.END, 10);

Build / CI / Plugins

• Travis CI [https://travis-ci.org/seancarroll/fdb-java-es]
• SonarCloud [https://sonarcloud.io/dashboard?id=seancarroll_fdb-java-es]
• CodeCov [https://codecov.io/gh/seancarroll/fdb-java-es]
• Coveralls [https://coveralls.io/github/seancarroll/fdb-java-es]
• Code Climate [https://codeclimate.com/repos/5bf0b88184303f02850000c0/settings/test_reporter]
• Snyk [https://app.snyk.io/org/seancarroll/projects]

running locally

Downloads

https://www.foundationdb.org/download/

https://www.foundationdb.org/downloads/6.2.22/macOS/installers/FoundationDB-6.2.22.pkg

https://www.foundationdb.org/downloads/1.6.3/macOS/installers/FoundationDB-Document-Layer-1.6.3.pkg

configuration /usr/local/etc/foundationdb

cd /usr/local/foundationdb has an install script data and logs

On macOS, FoundationDB is started and stopped using launchctl as follows:

host:~ user$ sudo launchctl load /Library/LaunchDaemons/com.foundationdb.fdbmonitor.plist host:~ user$ sudo launchctl unload /Library/LaunchDaemons/com.foundationdb.fdbmonitor.plist It can be stopped and prevented from starting at boot as follows:

host:~ user$ sudo launchctl unload -w /Library/LaunchDaemons/com.foundationdb.fdbmonitor.plist

fdbcli