Any good tutorials or resources for learning how to design a scalable and "component" based game 'framework'?

Question

In short I'm creating a 2D mmorpg and unlike my last "mmo" I started developing I want to make sure that this one will scale well and work well when I want to add new in-game features or modify existing ones.

With my last attempt with an avatar chat within the first few thousand lines of code and just getting basic features added into the game I seen my code quality lowering and my ability to add new features or modify old ones was getting lower too as I added more features in. It turned into one big mess that some how ran, lol.

This time I really need to buckle down and find a design that will allow me to create a game framework that will be easy to add and remove features (aka things like playing mini-games within my world or a mail system or buddy list or a new public area with interactive items).

I'm thinking that maybe a component based approach MIGHT be what I'm looking for but I'm really not sure. I have read documents on mmorpg design and 2d game engine architecture but nothing really explained a way of designing a game framework that will basically let me "plug-in" new features into the main game.

Hope someone understands what I mean, any help is appreciated.

Answer 1

Yes, I got what you want...

Basically, you will have to use classic OOP design, the same one that business software coders use...

You will first have to lay out the basic engine, that engine should have a "module loader" or a common OOP-style interface, then you either code modules to be loaded (like, as .dlls) or you code directly within your source code, using that mentioned OOP-style interface, and NEVER, EVER allow a module to depend on each other...

The communication, even inside your code, should be ALWAYS using a interface, never put "public" vars in your modules and use it somewhere else, otherwise you will end with a awfull and messy code.

But if you do it properly, you can do some really cool stuff (I for example, changed the entire game library (API that access video, mouse, keyboard, audio...) of my game, in the middle of development... I just needed to recode one file, that was the one that made the interface between logic, and game library...)

Answer 2

If you search for component-based systems within games, you will find something quite different to what you are actually asking for. And how best to do this is far from agreed upon just yet, anyway. So I wouldn't recommend doing that. What you're really talking about is not really anything specific to games, never mind MMOs. It's just the ability to write maintainable code which allows for extension and improvements, which was a problem for business software long before games-as-a-service became so popular and important.

I'd say that addressing this problem comes primarily from two things. Firstly, you need a good specification and a resulting design that makes an attempt to understand future requirements, so that the systems you write now are more easily extended when you come to that. No plug-in architecture can work well without a good idea of what exactly you hope to be plugging in. I'm not saying you need to draw up a 100-page design doc, but at the very least you should be brainstorming your ideas and plans and looking for common ground there, so that when you're coding feature A, you are writing it with Future feature B in mind.

Secondly, you need good software engineering principles which mean that your code is easy to work with and use. eg. Read up on the SOLID principles, and take some time to understand why these 5 ideas are useful. Code that follows those rules is a lot easier to twist to whatever future needs you have.

There is a third way to improve your code, but which isn't going to help you just yet: experience. Your code gets better the more you write and the more you learn about coding. It's possible (well, likely) that with an MMO you are biting off a lot more than you can chew. Even teams of qualified professionals end up with unmaintainable messes of code when attempting projects of that magnitude, so it's no surprise that you would, too. But they have messes of code that they managed to see to completion, and often that's what it's about, not about stopping and redesigning whenever the going gets tough.

Answer 3

What you're thinking about is exactly what this article describes. It's a lovely way to build games as I have blogged about, and the article is an excellent resource to get your started.