Domain Driven Development

Badoo Londroid

Last night I went to a meeting of that alternative Java (i.e. Android) development group Londroid, sponsored by Badoo, a social networking tool, and hosted at Skill Matter/CodeNode. William Gibson once refered to Britain as Mirror World, like America but oddly different, and the same is true of Android to Java. It’s where the Java desktop world went when the internet turned up and everything went all server-side, so the meeting had a certain surreal quality for me.

Building a framework with Clean Architecture with Rich King
First up was Rich from the sponsor Badoo. Rich discussed how the Clean Architecure principals, as described in “Uncle” Bob Martin’s blog post, impacted on the development of the Badoo Android application. Here’s a description of Clean from the man himself:

What Rich described in his presentation is separating the parts of the system into domains (shades of DDD here), usually done in the Java world when designing for a Microservice architecture. Because of the limited nature of the Android platform, all this is in what might be described as a micro-monolith (think there’s a niche for nano-services on Android?). All-in-all a nice presentation, only spoilt by ghost transmissions from the presentation upstairs.

Presentation Patterns Using Rx with Yoel Gluschnaider and Flavio Zanda
Although there are few Spring-like frameworks in Android, again due to the limitations of platform, RxJava has taken off, mostly as a more sophisticated option or supplement to data-binding.

However, there’s still a need for what frameworks usually implement, in this case the Model-View-Controller (MVC) design pattern for managing the interactions between the screen and what goes on the the back. Alternatives to this pattern are the Model-View-Presentor (MVP) and the Model-View-ViewModel (MVVM) patterns. The former, and the one they recommended, is a variation on MVC pattern and, like this, the view makes a request to the controller and the controller consults the model about how to respond. MVC assumes the controller is pretty dumb, just acting as a junction box separating the View from the Model. MVP moves most of the decision making to the controller, to the point that View does almost nothing (a Passive View pattern, as it’s been called). MVVM is more complicated, by the sounds of it, and I haven’t had time to do any research on it at the moment, but that also looks interesting.

Yoel and Flavio’s talk was very engaging and interesting, despite it’s short length.

The Three Real Problems in Software Development

This was a presentation I attended at Skills Matter/CodeNode, just off Broadgate, by Pete Smith.

The three problems, as Pete sees it, are:

  • grouping and separating the work into domains, both in terms of software and people;
  • using the tools and technology wisely;
  • communication.

He highlighted different aspects of these problems and indicated some solutions, but, unfortunately, didn’t provide any unique insights from a Domain Driven Design perspective, which, I felt, was the whole point. Nevertheless, his presentation was well delivered. It was taped, so you can watch it here.