This is a collection of articles I wrote over the years, presently with a strong focus on building reactive systems with Akka.
Published on 19 April 2018
Update 20.04.2018: added Polyglot Maven Scala has a rich ecosystem and active community producing a lot of useful libraries. So much so that, sometimes it is not easy as a newcomer to decide which library to pick for a given task (this is the case for example when it comes to database access and JSON – Read More
Published on 23 March 2018
In the previous parts of this article series, we have looked at various functionality of Akka Cluster: distributed data, persistence, message delivery semantics and cluster sharding. We are far from done with exploring Akka Cluster features, but today it is time to look at one feature that is extremely useful when it comes to building – Read More
Published on 20 March 2018
Akka’s ActorSelection makes it possible to look up actors by logical path in the hierarchy:
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val selection: ActorSelection = context.actorSelection("../processor/storage") |
This selection can then be used like ActorRef in order to send messages to it using the tell or ask patterns:
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selection ! Storage.Store("important words") val allWords: Future[Seq[String]] = selection ? Storage.RetrieveAll |
ActorSelection is therefore quite useful and allows more flexibility when designing an actor system given that trees – Read More
Published on 26 February 2018
In Tour of Akka Cluster – Eventual consistency, persistent actors and message delivery semantics we started to look into making the reactive payment processor resilient to node crashes by exploring Akka Persistence, a mechansim that provides durability guarantees for actor state. We also briefly mentioned Akka Cluster Sharding which offers a way to automatically distribute – Read More
Published on 31 January 2018
In Tour of Akka Cluster – Akka Distributed Data we looked into building a reactive payment processing system using Akka Distributed Data as a means to provide master-master replication to the order storage component. We did not, however, ensure in any way of form that the system as a whole could withstand individual node crashes. – Read More
Published on 3 January 2018
Building distributed systems is hard. Pesky things like the laws of physics get in the way of maintaining state accross geographically (and chronologically) disparate systems, and, if that weren’t already outrageous enough in itself, those systems may be subject to network failures, forcing us to think about annoying tradeoffs regarding consistency, availability and the meaning – Read More
Published on 16 November 2017
A bit over two years ago, I wrote about my initial thoughts on fatherhood a bit after our daughter was born. Our son Théo is now 4 months old and I find it fitting to write a follow-up. Life with one kid Life with one kid is easy (in a couple). You’re two adults (well, – Read More
Published on 26 August 2017
So you’ve just learned Akka and are tremendously excited. It’s got dispatchers, routers, supervisors – so many shiny things to play with, and in style (I mean, come on, a dispatcher sounds a lot nicer than, say, an AbstractSingletonProxyFactoryBean). And so it happens that, perhaps even unknowingly to you (you’re busy configuring a pool router), – Read More
Published on 26 July 2017
Akka uses the The Φ Accrual Failure Detector for failure detection, which is to say for answering the question of whether a node is alive or not. That’s one of the harder problems of distributed systems since it is virtually impossible (from the point of view of one node) to tell the difference of a – Read More
Published on 20 June 2017
One anti-pattern I’ve observed in networked Akka applications is a tendency to forget that it is, well, networked and to treat the network as a friendly place. How does that look like? Well, consider the following piece of code:
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actorOnDifferentNode.tell(veryImportantMessage, sender()); |
Akka’s default message sending mechanism is the fire-and-forget tell method. And that works great – – Read More
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© Copyright 2018. manuel bernhardt. All rights reserved.