Maybe I was not searching for the right terms but I had a bit of hard time to find how to this on the internet. Most of the solutions are about writing either in the line above or below the target line. I wanted to write text on the middle of a JSON object. Bear in mind I ain’t no AWK or SED wizard, I just started using AWK and there is probably far more efficient ways of doing this, I just couldn’t find them.
The Agile Manifesto has been written 13 years ago with the intention of changing the way software development projects were executed at the time. It prescribed the following:
Individuals and interactions over processes and tools
Working software over comprehensive documentation
Customer collaboration over contract negotiation
Responding to change over following a plan
Shortly after a few software development methodologies were fleshed out based on the agile manifesto mantras, probably the most notable are XP and SCRUM. While these two are massively adopted by almost all the software companies in the world (I swear I don’t remember seeing a IT job advertisement without mentioning SCRUM), some new trends that I consider interesting are starting to emerge like #NoEstimates, Programmer Anarchy and Mob Programming.
I first heard of The Passionate Programmer about 1 year ago through Rasmus (@rasmuschristens), my team lead at that time, he recommended the book after hearing Chad Fowler in a conference and described it as highly inspiring. After all this time, I finally found some time to read it, and I must say I was also inspired.
I decided to start working on a simple example, a bank application, that shows how aggregates can be modeled using Diyes.
The aggregate I decided to model is a bank account, it will exemplify some basic concepts of aggregate modeling. First of, we create a class that inherits from AbstractAggregate
public class Account : AbstractAggregate
How we normally go about modeling aggregates is we expose methods which are the commands that can be performed on our aggregates. So in this case I decided to have an Open, a Deposit and a Withdraw method. First thing we do in these methods is checking the preconditions for their execution, if the preconditions are met, we apply an event describing what happened. Continue reading diyes: practical modeling of aggregates
After we have seen how the event store works by saving and loading events related with an identity, in this post I am going up in the abstraction layer and talk about aggregates. A very good introduction to aggregate design can be found in Vaughn Vernons’ articles – Effective Aggregate Design.
So the other day I was thinking to myself I wanted to know a bit more about event sourcing (ES) and the Command Query Responsibility Segregation pattern (CQRS). I have used ES before in a project before but I used library which was’t made by me. This gave me knowledge on how to model a domain using events but it didn’t give me the “down to the iron” experience of it. So I thought, what better way to learn about ES than by implementing a ES library myself.