Hello game devs,

I'm doing a project on finding a theoretical model suitable for comparing mmo server architectures primarily from a scalability point of view. I am still in the starting phase of this project. My main problem is the lack of literature on mmo servers, other than short articles and guides on how to get started, with specific APIs. This is not interesting, as I am not going to implement anything for the scope of this project.

Any books related to this subject will be a great help! It does not need to be game related. I am currently looking into simulations related to petri nets.

My focus is mainly on mmorpg games, as their general tendencies are one entity per client, large persistent worlds, worlds are easy to split up in regions, and both real time (the flow of the game) and non real time (inventory management and skill tree) actions.

Best regards

Jannek

Most of those are "company proprietary" and if you'll find a write-up, it will be only some section that's presented at a conference like the Game Developer's Conference.

The best MMO-type systems you'll find documented are military simulations based on DIS and HLA. However, those typically don't use the same set of trade-offs as MMO games, because what it means to scale is different (they have battles of 1000s of people -- each using an expensive milsim installation) and the technologies are different (per-property subscriptions like HLA are not efficient for known-target protocols like games.)

I'm not sure exactly what you would write about.

There is very little duplication in the real world.

There are some individual components. They use SQL databases for some stuff. They uses non-SQL databases for some stuff. They use lots and lots and lots of custom developed server code.

There are a few industry-known wrappers that are so-so for functionality. For example, EA has "DirtySock" a wrapper around socket libraries that offers both reliable and unreliable data channels over UDP, along with offering a few other useful tidbits for manipulating a data connectivity mesh. But that is just one tiny speck in the giant ecosystem of technology needed inside an MMO.

I remember a DICE presentation from a few years ago, I think it was from a Star Wars MMO, where they revealed their server executable (just the code) was about 50MB compiled. Then they went over their enormous source code tree structure, tens of thousands of files and huge piles of vendor specific libraries. That was the main server, they also had similar programs to re-direct between machines and load balance and serve as intermediate data caches and do other things.

I cannot imagine a very agnostic way to compare server scalability of their platform against the server scalability of WoW or the server scalability of EVE Online. Other than "Databases are connected this way" and "large in-memory nosql data stores are kept here and here and here", there is probably very little similarity.