Adventures in IT

Image: Pixabay Breaking your application down into components can be a useful approach to a "divide and conquer" methodology.  Assigning specific behaviour to a component and then defining interfaces for other components to access it allows you to develop a service driven architecture.  I'm in the process of decomposing a monolithic application into services that will eventually become standalone micro-services.  Part of the task ahead lies in determining the service boundaries, which are analogous to software components for my micro-service application.  I want components to be modular to allow them to be developed and deployed as independently as possible.  I'm using the approach suggested by Eric Evans in his  book on domain driven design  where he describes the concept of "bounded contexts".  I like to think of a bounded context as being for domain models as a namespace is for classes.  These contexts are spaces where a domain model defined in t

Image: Pixabay SOLID is a mnemonic acronym for five object-oriented design principals that are intended to make software designs more understandable (see Wikipedia ). They were promoted by a chap called Robert C Martin who has been programming since before I was born and is an authority on writing clean code.  Laravel is a PHP framework that implements the model-view-controller (MVC) pattern. A lot of people think that their responsibility for OOP design ends with adopting a framework, but actually Laravel is relatively un-opinionated on your OOP design and you still need to think about writing code that is testable and maintainable.  The reason that SOLID principals matter becomes apparent when you work on a single project for a long time. If you're writing throwaway applications for clients that you never expect to work on again (presumably because the client won't hire you again) then the quality of your code doesn't matter. But if you're the guy stuck

I'm busy writing an Ansible script and want to test it locally before trying to deploy it anywhere.  The easiest way to try and make my local environment as close to my deployment environment was to set up a network of Virtualbox VMs. The problem was that I've always configured my VM's to use NAT networking.  I ssh onto them by setting port forwarding and have never really needed them to have their own address. The solution to this problem is pretty simple.  Just stop the machines and add a new network adapter of type "Host Only".  This adapter will handle communication between the guest and host machines. The trick is that you need to configure the guest OS network interface too. To do this SSH onto your VM and run "ip add" to list your network adapters.  If you're like me and started with NAT before adding "Host Only" as your second adapter the output should look something like this: You need to identify the adapter that is y

Image: Pixabay Calling PHP a double-claw hammer is a bit of an in-joke in the PHP community .  A lot of people bemoan PHP as a language – it's fashionable to do so and it seems to be a way to look clever.   The joke came about from a blog post where somebody pointed out all of the problems with PHP (here's a rebuttal -  https://blog.codinghorror.com/the-php-singularity/   ) Anyway, PHP is a warty language that sucks in academic circles but it doesn't matter because it's really good at web stuff, there are lots of people who know it (so it's cheap to hire), there are lots of libraries and frameworks (so it's cheap and fast to develop in).  The commercial world is willing to overlook the academic warts. I'm busy helping to improve the performance of an API server.  As part of my effort I'm profiling calls to the endpoints.  I'm using Blackfire to generate call graphs and also logging the sql queries that the ORM is producing so that I can check