I started brushing up on my DDD skills by re-reading Evans.(2004).
The main inspiration was to determine how to document a domain model.

Various searches led me to this article: https://medium.com/nexa-digital/my-journey-into-cqrs-and-event-sourcing-4bd7d0c1c670

It’s the start of a series of articles on Event Sourcing/CQRS in Elixir. The sample application is about consent for medical records, but looks to be ideal for consent for GDPR!

This is a great introduction to CQRS with a functional approach.

The underlying git repository is here: https://github.com/rodrigobotti/cqrs_es_consent

Typically you would want to advertise exciting features when advertising a book. This time I want to prome boring releases.

This book includes a chapter on how we managed to take the drama out of releasing software. The software we released was exciting, but the actual releases were calm and measured. In one case we had a project manager prepare 30 scenarios, 27 bad and 3 good. In the end it went so well that none of the good scenarios applied. This was the digital release of the Cursed Child Script book.

Here is the book including a chapter on how we made the magic:

https://leanpub.com/development2019

Here is the guidance from the ICO

https://ico.org.uk/for-organisations/guide-to-data-protection/guide-to-the-general-data-protection-regulation-gdpr/accountability-and-governance/data-protection-by-design-and-default/#:~:text=The%20UK%20GDPR%20requires%20you,by%20design%20and%20by%20default’.

The idea is that any system that is being worked on requires data protection by design and default.

This includes:

Asking permission from the user to use their personal information. If they need to opt in this needs to be explicit rather than assumed. (There are some circustances where permission is not required, but you need to make the owner of the data aware).

You should also record the version of the privacy notice that they accepted. If the terms change to include additional usage then permission needs to be requested again before the data is used. Permission may also be withdrawn.

The use, storage and processes must be clear. Breaches of these need to be reported to the authorities and affected users.

Fully doing this is not simple. There are benefits. This will typically require personal data to be held in a single place which can simplify processes (less duplication and inconsistency). The need to understand your internal processes will also help. It forces good communication practices.

This looks interesting (https://eventmodeling.org/posts/what-is-event-modeling/)

If you want to report a bug to a (typically an open source) project. Follow these steps:

Check if the bug is already in the tracker. If so see if you could add a new test case to demonstrste the issue.

If it is not in the tracker create a simple test case that demonstrates the problem. Being able to recreate the issue makes it far easier to work on, making it far more likely to be picked to work on.

If you know how to fix the problem check that they accept Pull Requests and supply one. Allow the maintainer to edit it. Its likely that you are going to have missed some internal rules of the project.

Contributions to documentation are really appreciated by maintainers.

I have been following Codurance Fireside Chats (This is Episode 38).

Public Interest Note: I currently work for Codurance.

In this episode Sandro mentions that there is very little impact that you can have in 20% of the time.
I disagree, you can achieve a big impact with small changes over an extended period.

A good example came when I was supporting a production client system (in addition to other new development work). At the start of each day I would check the most frequent error listed in the logs for the past 24 hours. I would either try and resolve that error or improve the logging so that it can be resolved in the future. This would take less than 15 minutes per day.

There is an interesting statistical effect that happens in any distribution of events. It is extremely unlikely that everything happens at the same frequency. Certain items will dominate the sample.. Items that have identical frequencies are likely to be coupled (such as a system reporting the same error in two places). This is known as the Power Law

By using the Power Law I was able to significantly reduce the volume of error messages. The top 5 formed 50% of the overall messages so in a week the error volume had halved. This made the error logs easier to read. This process repeated for a few months and eventually there were only a handful of errors left that were so infrequent as to not be worth fixing. The next target was the warnings.

This makes a great principle: try and fix or improve one small thing each day. Even if the rest of the day is fairly monotonous at least you have that one small win. By the end of a year you will have hundreds of small wins which should be significant (even if some of them had to be rolled back).

Today I have found my diary has 10 meetings.

This is a reminder never to let this happen again.

This looks to be very interesting: https://github.com/burrito-elixir/burrito

I am going to see if I can make this work with home_server

This now has a yaml config file that allows you to specify the configuration.

https://github.com/chriseyre2000/home_server

So far I have been using it for a week. There have been a few false positives, but knowing when the VPN is down really helps.

apoc is a set of useful addons for Neo4j

I have been using brew to install neo4j on my machine.

brew install neo4j

This can be combined with

brew services.start neo4j
and

brew services stop neo4j

This typically installs a db on http://localhost:7474/browser

On mac via homebrew you need to look in /usr/local/Cellar/neo4j/4.4.5/libexec
To enable apoc copy apoc-4.4.0.3-core.jar from labs to plugins

You also need to change config/neo4j.conf

I have set the following value:

dbms.security.procedures.unrestricted=apoc.*

Restarting neo4j get this working.