This is my blog where I like to focus on things of a software development nature.
This blog introduces a stream-based command/event programming model that can be applied to many programming languages. Having an event-driven approach to programming like this helps achieve resiliency and responsiveness. Resiliency should speak for itself, and responsiveness often leads to an improved user experience. Since writing up on Event-drive Finite State Machines a couple of years back,…
I often use Event-driven Finite State Machines to capture stateful behaviour. Doing so in combination with a compiler with a strong type system helps me to think about all possible combinations of the effects of commands on a given state, and what the events produced (if any) are. In particular, I find many programs required for embedded applications can often be safely expressed by using…
A while back, I wrote about converging observations in IoT and described how we de-duplicate sensor data. This post is a follow-on in that it describes the same domain in terms of how we distribute the data itself. My inspiration for this particular post is from Colin Breck's excellent post on "Shared-Nothing Architectures for Server Replication and Synchronization". In particular, Colin describes…
The problem is this. You have a sensor on a farm that transmits its observations. The observations can be received by one or more towers. Each tower forwards the observations it receives to a server that then stores them. You now have a situation where a single observation has been recorded twice. What to do? You might choose to de-duplicate at the server. You know that there can only be one…
When running Spring's PetClinic Spring Boot reference application, my experimental Landlord project appears to save 5 times the memory for the second instance of it. My terse observations show that PetClinic requires about 250MiB of resident memory when running as a standalone Java 8 application. When running two instances of it hosted by Landlord, approximately 342.2 MiB of resident memory is…
I've been thinking for some time about when closed source should become open, particularly in the context of when your core business is about producing software. If your core business is to provide a service such as movies, as in the case of Netflix, then the dynamics are different. Because the core business is to produce movies then simply go OSS and reap the benefits from having done so (as…
Let’s face it, microservices sound great, but they’re sure hard to set up and get going. There are service gateways to consider, setting up service discovery, consolidated logging, rolling updates, resiliency concerns… the list is almost endless. Distributed systems benefit the business, not so much the developer. Until now. Whatever you think of sbt , the primary build tool of Lagom , it is a…
Disclaimer: I'm the technical lead for Lightbend ConductR - a tool that focuses on managing distributed systems with a key goal of resiliency. I've been doing a reasonable amount of travelling over the past few years. Overall I enjoy it; I don't think that I'm away that much that it has become painful - may be 3-6 international flights per year. One of the things you hear about when travelling is…
One question I have had to answer a few times as the tech lead of ConductR , and I think it is a healthy question, is on why did Lightbend create ConductR? This post is my personal attempt to describe the rationale for it two years ago, and why I think it is more relevant than ever. Back then we wanted a tool that was focused on making the deployment and management of applications and services…
I thought that it'd be useful to share my personal perspective on the meaning of our company name change. Here are the contents of an email that I sent out to everyone within Lightbend, and which was warmly received. --- Hi fellow lightbenders, I’m very excited about the Lightbend name, and want to provide my view on what it means to me. About two years ago, I presented at YOW. YOW is a great…
A strong feature of Scala is the embracing of both Functional Programming (FP) and Object Orientation (OO). This was a very deliberate and early design decision of Scala in recognition of the strengths of both approaches over the decades. I hope to show you that utilising both approaches to developing software can work together. Over the past two years of using Scala on a daily basis I’ve found…
About a year ago I made some predictions on Java, JavaScript and Maven for 2013 . There has been some movement, so time to report back: Java Java 8 didn't quite make it as a GM release, but mid-March 2014 now appears to be the date. Java 8 has been available for playing with for some time during 2013 though. I must confess to having been excited at the prospect of Java 8's lambda support a year…
One of my responsibilities on the Play team is to enhance the JavaScript development experience. We will shortly be releasing a strategy document on what is coming for Play 2.3 in this regard. As a preview though, one of the things the strategy will be advocating for is the use of WebJars . WebJars are JavaScript web libraries deployed to well known repositories including Maven Central. There are…
I'm thrilled to be able to announce that I am starting as a Senior Engineer with Typesafe this coming Monday. I'll be working on the Play framework. I'm excited to become involved in the Typesafe mission. In many ways Typesafe feels like an early SpringSource given its culture, focused people and established open-source projects. I'll be based just south of Sydney (where I live) and work alongside…
A couple of predictions for this year: Java will become cool again JavaScript running on the JVM will be interesting Maven will become cool Java Java 8 will bring lambda functions into the fold and enhance its collections to support them. Functions as first-class objects are one of my favourite features of other languages such as JavaScript. What I like about them is the mainly the flow of writing…
Gosh, what a long time since I last blogged. Truth is I've moved over to R&D within VMware and I've been working on really interesting cloud stuff that has taken up all of my cycles. I'll be writing more about that soon. There's a big debate here in Australia on the benefits of the National Broadband Network (NBN). The opposition in government are asking for justification in terms of business case…
On occasion I'm a little disappointed when I see developers create frameworks and toolkits. I understand that it is enjoyable to do so, but we, as application developers, should be majorly focused on the business needs of developing applications. Quite often we think that xyz widget doesn't do exactly what is "required" and therefore pursue a path of days (weeks) writing frameworks and toolkits.…
The @Resource documentation states that the "name" attribute refers to "The JNDI name of the resource". Spring has overloaded this to mean that you can refer to bean identifiers… but as far as the Java spec goes, there's no contractual obligation for a resource name to refer to a bean id. @Resource referring to Spring bean ids is therefore quite Spring-specific. @Autowired is Spring specific.…
I've seen some comment out there regarding how to version RESTful services and so thought it about time to add in my own position on this. I don't subscribe to crafting your own MIME type as these should refer to well-known entities. I also don't subscribe to passing a version number as an Accept param. Despite there being client/server compatibilities in this regard (Ruby), the developer is not…
I've now read Martin Fowler's review of the LMAX architecture and I feel good. This is very similar to what I've been doing for a long time with messaging (Spring Integration, Camel, AMQ, RMQ etc.). LMAX is an event driven architecture. The Input Disruptor can be your favourite messaging broker. The Business Logic Processors are your message queue consumers. AMQP can certainly attain the goals…
I'm working in a distributed team at the moment where I don't have access to infrastructure available within the company's firewall. The application I'm working on has a nice RESTful API with JSON payloads for its logic layer. As I'm mostly developing the presentation layer I needed a quick method of generating something that would simulate the logic layer. One thing that I felt was important is…
"DAO coding paradigms can require some skill" is a sentence that presently appears at Wikipedia in the description of Data Access Objects. I find DAOs very useful and honing the skill is worth it. The article goes on to state a benefit being, "Improved efficiency and performance of the data layer since it is standard reusable software". The majority of DAO implementations that I see tend to…
My Zoneinfo TZ library is now available up at the Codehaus . V1.0.0 should make it to the central Maven repo shortly. The project has mailing lists, continuous integration, issue tracking and all of those things you'd come to expect. Interestingly, the site that hosts the zoneinfo files themselves has disappeared tonight. Fingers crossed that it'll come back soon! I hope that this project proves…
Recently I've been doing a lot of development in GWT . I have to say that, despite being a big fan of pure JavaScript RIA , I'm liking GWT a lot. It has been a couple of years since I touched GWT and it has come a long way. I particularly like the Activities and Places API, although there's a bit of a learning curve there. One thing I don't particularly like though is Sencha's EXT-GWT , or GXT as…
I now have a job with VMware starting January 24th and I'm excited! My role is as a vFabric consulting software engineer within the professional services division . Over the past 12 years I've been an independent contracting developer/architecture/designer and launched quite a few of my own products. I suppose one of the initial drivers to go contracting for me back then was that it was lucrative…