Hello,
I had to explain to someone about how my networked game is structured and I came up with a simple diagram (I made in a few minutes) showing different parts of the projects and technologies that are used. Not perfect though!
Putting it here anyway hoping someone might find it helpful! 
Diagram is made in https://app.diagrams.net
Why microservices?
Well, it is not like the real-world microservices we see in an enterprise, there is no discovery server, and no load balancing,…
They are simply two stand-alone spring boot apps communicating via REST API. If I ever want to make multiple networked games, then there will be a master server for each game but I am going to have only one account server.
Looks great, thanks for sharing, keep us updated with this!
So, as far as I understood, those microservice APIs are meant to manage the Game databases through account servers via REST APIs, Right?
Hi, looks ok. Its always a lot of work with microservices. But worth for bigger projects. At least with structure like this you can add more microservices that will help. For example split match making/etc.
Thanks, guys for joining the discussion, I appreciate your feedback.
The account server has its own database (MongoDB Atlas) to only keep user login info and account balance (I am still not 100% certain if I want to add a wallet or not).
The master server also has its own database (again using MongoDB Atlas). This server will keep a dynamic list of online game servers and their IP address, when a client wants to connect to a game server hosted by a friend it will ask for the connection info from the master server. It also contains features like a social profile (for friends list,…), and store boards,… It will also contain a virtual shop for buying special items. Unlike physical village shops that use in-game coins, virtual shop will use real currency.
So for example when a player buys an item from the virtual shop (master server), the master server will make a REST request to the account server to check the player balance and process item purchasing.
I may also consider saving player inventory data and stats on the master server as well so when he connects with a different device his inventory items and stats will be synced.
Finally, the game server is a JME server and runs game systems simulation (Physics, AI,…) with ECS (I am using Simsilica libraries like Zay-ES, SiO2, SimEthereal,… ). Entities data (npcs, enemies,…) is persisted in an embedded and fast (hybrid) SQL database (HSQLDB) that is handled behind the scene by Zay-ES.
When a game server is started it must register itself on the master server so it will be visible to other players for connecting.
