I made a little improvement in my in-memory-storage database using D-Bus instead of pipes. I wrote the simple D-Bus client to control the database like with the echo command and systemd user service.
Read more about in-memory-storage in first post.
For my little project i3-change.py I need lightweight in-memory database. My first idea was to use Redis (I have some experience with it) but it requires some library to control it. I need something more lightweight. I think using linux named pipes is elegant way how communicate with a database. Here is the full source of my lightweight in-memory database: https://github.com/petrposvic/in-memory-storage.