event sourcing

• An event is something that has happened in the past.
• Saving & loading objects
• There is no Delete
• Business Value of the Event Log

event store

• Open-source, functional database with Complex Event Processing in JavaScript
• Build with mixture C#, C++ and JavaScript, can run either on Mono or .NET
• Binaries are available from http://geteventstore.com
• Source available at https://github.com/EventStore/EventStore
• .NET & HTTP API (AtomPub over HTTP)
• More at https://github.com/EventStore/EventStore/wiki

setup dev evnironment

Post BuildStuff work by Paul Stack (@stack72): https://github.com/stack72/vagrant-geteventstore.

Setup instructions in my blog post Setup EventStore with Vagrant

why ?

A single model cannot be appropriate for reporting, searching,
and transactional behaviors…

@gregyoung at BuildStuff 2013

projections

Left Fold: function(state, event) → state

  when([SomePatternMatch],
    function(state, event) { return new state; });

  

projections

• use JavaScript to configure a left fold
• can query historical data and then continue running into the future
• everything is a stream
• to be released out of beta Jan 2014

here should be dragons...

... but I f**ked up my EventStore installation 2h ago

Available at

https://talks.praglowski.com/get-event-store/