Lars Simon Winzer
32 lines
1.9 KiB
Markdown
32 lines
1.9 KiB
Markdown
# Commands
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Commands are the primary extension point of the server.
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Every client-facing operation e.g. checking a username, sending a chat message, joining a lobby is implemented as a command.
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Each command consists of four classes: a **Parser**, a **Request**, a **Handler**, and a **Response**.
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The infrastructure for routing and dispatching commands lives in the `network/` layer and is intentionally kept generic.
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The concrete implementations for each command live in `app/commands/` and are wired together at startup in `ServerApp`.
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<img src="../../../images/docs/networking/commands/overview.svg" alt="Overview of all components directly related to executing requests" />
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## Contents
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### Guides
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- [Implementing a Command](./guide-on-implementing-a-command.md) -
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Step-by-step walkthrough for adding a new command to the server, including registration and common pitfalls.
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### Reference
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- [Command Infrastructure](./commands-deep-dive.md) -
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Technical deep-dive into the `CommandParser`, `CommandParserDispatcher`, `CommandHandler`, `CommandRouter`, `Request`, and the response hierarchy.
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## Key Concepts
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**Each command is self-contained.**
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A command's Parser, Request, Handler, and Response all live in the same package under `app/commands/<name>/`.
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This keeps related code co-located and makes it easy to reason about a single command without navigating across multiple directories.
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**The `network/` layer knows nothing about specific commands.**
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`CommandParser` and `CommandHandler` are generic interfaces. The `CommandParserDispatcher` and `CommandRouter` operate on those interfaces.
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Adding a new command **never** requires modifying infrastructure code.
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**Registration happens at the composition root.**
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All commands are wired in `ServerApp` by calling `parserDispatcher.register(...)` and `commandRouter.register(...)`.
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This keeps the wiring explicit and compiler-checked.
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