Post on 29-Nov-2014
description
Dr. Roland Kuhn Akka Tech Lead @rolandkuhn
Akka and AngularJS
Reactive Applications in Practice
Reactive Applications
The Four Reactive Traits
2
http://reactivemanifesto.org/
Akka !
A fully Reactive toolkit on the JVM
The Actor Model
• fully message-driven: an Actor can react by • sending messages to other Actors • creating Actors • denominating behavior for the next message
• Actors are effectively single-threaded • failures are contained and escalated within the
supervisor hierarchy • scaling up & out through location transparency
4
Persistence Model: Event Sourcing
• based on storing change instead of updating state • persistent Actors generate events: • historic facts that do not change thereafter • storage is append-only log • current Actor state is updated by consuming events
• Actor can revisit the past by replaying events • events contain more business information than
current state snapshot
5
Command Query Responsibility Segregation
6
Client
write-!side
read-!side
Command Reply Query Reply
Events
Command Query Responsibility Segregation
• persistent Actors on write-side generate events • read-side independently consumes event streams • read model is fully decoupled from write model • queries are served from optimal storage: • SQL store • graph database • in-memory live view
• new read model can be generated on demand
7
Spray / Akka HTTP !
An Actor-Based Web Toolkit
Web-Server made Simple
• HTTP requests and responses are Actor messages • powerful routing DSL turns Actor into Web-Server • not a web framework: • just expose Actors as web endpoints • nicely suited for RESTful APIs
9
Important Disclaimer
• I know a lot about Akka, but … • I am not a web developer
10
Gabbler: The Write-Side
11
Gabbler Replayer
Journal
RouterLog
Input
POST
201
Gabbler: The Read-Side
12
Gabbler Replayer
Journal
RouterLog
Input
GET
Replay
200
Gabbler: The Whole Thing
13
Gabbler Replayer
Journal
RouterLog
Input
Further Information
• Code at https://github.com/hseeberger/gabbler • currently a pull request
• See also http://akka.io
14
©Typesafe 2014 – All Rights Reserved