Scalable applications

Scalability is a crucial aspect of modern application development. Depending on your platform, scalability can take different forms. On devices and personal systems, applications need to scale up to use multiple cores efficiently in order to deliver a quality user experience. On servers, applications also need to scale out to distribute work across systems.

The Scala programming language is designed around scalability. It gives you the tools you need to spread work across multiple cores with minimal impact on your application design. When combined with the open source Akka toolkit it also allows you to easily spread your application across multiple systems.

Scala additionally offers the advantage of building on the Java™ programming language and platform. Not only can you use all the familiar Java libraries directly in your Scala code, you can also intermingle Scala with existing or new Java code. Akka also works with both Scala and Java code, and although it's been easier to use Akka with Scala in the past the new Java 8 lambdas feature is bringing the two languages to a more equal footing.

The site name emphasizes the Scala language since that's central to my view of developing scalable applications, but the site is actually devoted to helping developers learn about building scalable applications with Java, Scala, and Akka, with other toolkits and extensions to come in the future.

Looking for help with scalability or performance issues, in Java or Scala? Email me to find out about my consulting, training, or mentoring services.

Recent Articles

The first four articles in my IBM developerWorks® JVM Concurrency series have been published (along with a companion article to the second one):

• JVM concurrency: Java and Scala concurrency basics
• Java 8 language changes
• JVM concurrency: Java 8 concurrency basics
• JVM concurrency: To block, or not to block?
• JVM concurrency: Asynchronous event handling in Scala

The Scalable Scala blog on this site includes background and added information on the articles.

Recent Presentations

Acting Concurrent: The Akka actor model for Java and Scala is my presentation to the Seattle Java Users Group meeting on 19 August 2014. This starts with a look at Java 8 and Scala concurrency features, then moves on to using Akka actors in both Scala and Java, including discussion of retrofitting existing Java applications to Akka. You can view the full video on Vimeo. Click the image below to view the slide set (use mouse clicks or arrow keys to move through the slides, or scroll with your mouse wheel).

Building on Akka I/O: Using Akka Asynchronous Actor Networking is my presentation to the Scala at the Sea meetup group on 12 August 2014. This starts with an introduction to the akka.io UDP and TCP support, then shows how the TCP support can be used to build an SMTP client, including an implementation based on Akka's Finite State Machine (FSM) support. It also discusses the evolving state of the Reactive Streams Akka implementation, which is intended to provide support for higher-level protocols in the future. Click the image below to view the slide set (use mouse clicks or arrow keys to move through the slides, or scroll with your mouse wheel).

About me

I've been developing software for more than 30 years, using everything from assembler language to Lisp — and more recently, Scala. Most of my earlier work was in data communications, often interfacing with custom hardware for real-time processing of events via interrupts. From that I moved into working with XML in Java, and then into web services. I'm still involved in web services today, as a committer on Apache CXF and by providing Java web services training and consulting services for clients worldwide, but also increasingly involved in developing other types of scalable, reactive, server applications.

Much of my background has been focused on performance and scalability. The approach of developing code without regard to performance, based on the assumption that you can "tune" it afterward, has led many organizations into massive time and cost overruns. Performance requirments need be clearly spelled out as part of any substantial development work, and developers need to have a feeling for how their design choices effect the potential performance of the application. Scalability is one very important factor in performance — to the extent that your application is scalable you can add more resources as needed to meet performance demands, which takes pressure off other aspects of your design. But scalability doesn't just happen, it needs to be part of how your developers structure the application.

Fortunately, tools like Scala and Akka, and even Java 8, are making it easy to build more-scalable applications. On this site, and in my IBM developerWorks series of articles, I'll be covering some of the ways you can do this.