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Asked: 2025-04-09T18:15:51+05:30

How can I prevent code duplication in a client authoritative multiplayer game while ensuring consistent logic across client and server?

I’m diving into building a real-time multiplayer web game, and I’m running into a bit of a dilemma that I think others might have faced too. So, here’s the situation: I’m using a client authoritative server architecture with tools like Phaser, Node, AWS, and all that good stuff. The game mechanics involve players walking around and picking up items—nothing too wild, right?

However, I’m finding myself faced with the issue of code duplication. Let’s say, for example, a player walks to the right and picks up food. On the server side, I need to implement logic to determine the new player location and update the list of items. But then the client side also needs that same logic to know what to display—like moving the player on the screen and playing a specific animation for picking up the food.

It just seems like I’m writing lots of the same code in two different places. Ideally, I want the game to feel seamless and responsive on the client side while still keeping everything consistent with the server. But, is it correct to have this approach of duplicating code between the client and server? It feels a bit off to me, and I’m concerned about maintenance down the line.

Have others dealt with this kind of situation? How do you manage to keep the logic consistent across both the client and server without writing the same thing twice? I’ve heard about some options like implementing shared libraries or even exploring RPC (Remote Procedure Calls) to sync things up, but I’m not fully convinced. Any insights, solutions, or best practices from those who’ve tread this path before would be super helpful! How do you ensure there’s no code bloat while maintaining that important connection between the client and server logic? It seems tricky, but I’m all ears for any advice!

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    2 Answers

    1. The problem you’re encountering is common in client-server development, particularly with multiplayer games: having logic duplicated between client and server creates significant maintenance overhead and risks inconsistencies. One practical solution is to define your core game mechanics (such as player movement and interactions) within a shared JavaScript library that can be imported both client-side and server-side. Doing this ensures that logic remains consistent and avoids the pitfalls of maintaining separate implementations, simplifying debugging and future enhancements. Technologies such as Webpack or Node modules can help encapsulate and share this logic effectively, streamlining your development process and reducing code bloat.

      An alternative or complementary approach involves utilizing Remote Procedure Calls (RPC) or event-driven systems provided by tools like Socket.io or WebSockets to communicate clearly defined events between client and server. In this structure, the server primarily acts as an authoritative validator rather than duplicating entire client functionalities, while clients are responsible for rendering and user interactions. The combination of shared business logic libraries for common elements, together with well-defined protocols and RPC calls for synchronization, typically forms the best-practice approach. This balances responsiveness, maintains authoritative control, and significantly reduces duplicated efforts, leading to highly manageable and maintainable game codebases in the long term.

    2. Dealing with Code Duplication in Multiplayer Games

      It sounds like you’re grappling with a common issue in game development! Finding yourself duplicating code for similar functionality on both the client and server sides can be frustrating.

      A few methodologies might help you streamline your code:

      • Shared Libraries: Consider creating a shared library that both your client and server can reference. This way, you can centralize your game logic in one place. Think of rules for player movement, item pickups, etc., as reusable functions or classes. Whenever you update something, it’s reflected both places!
      • Remote Procedure Calls (RPC): This could be a good direction to explore! RPC allows you to call functions on the server from the client as if they were local. You can keep your logic on the server while just sending/receiving data. The downside is you might need to manage some more complexity, but it could keep things DRY (Don’t Repeat Yourself).
      • Data-driven approach: Instead of duplicating the logic, you might find it useful to send events (like “move right” or “pick up item”) from the client to the server. The server can then handle the logic and send back the necessary state updates to the client. This might help reduce the need to duplicate code.
      • Visual Representation: For animations and visuals, you could maintain event listeners in your client to respond to server updates. If the server updates the player’s position, the client can use that to render the graphics without needing to duplicate the movement logic.

      In the end, the goal is to keep your code clean and maintainable while ensuring a smooth experience for players. It’s definitely a balancing act, but with shared libraries or a smart use of event-driven design, you can minimize duplication while still keeping things responsive!

      Keep experimenting with different approaches, and don’t hesitate to reach out to the community; many are facing (or have faced) similar challenges!