Steps

1. Declare role symbols

   Role identifiers are symbol values. Put them in a small, dependency-free module so every contributor can import them without pulling implementations.

   // src/roles.ts
   export const NOTIFIER_ROLE = Symbol("Notifier");
   export const CHANNEL_ROLE = Symbol("Channel");
   export const FORMATTER_ROLE = Symbol("Formatter");

2. Define interfaces

   // src/types.ts
   export interface Formatter {
     format(message: string): string;
   }
   
   export interface Channel {
     send(message: string): Promise<void>;
   }
   
   export interface Notifier {
     notify(message: string): Promise<void>;
   }

3. Implement components

   // src/plain-formatter.ts
   import { injectable } from "@xwiki/platform-component-annotation-default";
   import type { Formatter } from "./types";
   
   @injectable()
   export class PlainFormatter implements Formatter {
     format(message: string): string {
       return message;
     }
   }

   // src/loud-formatter.ts
   import { injectable } from "@xwiki/platform-component-annotation-default";
   import type { Formatter } from "./types";
   
   @injectable()
   export class LoudFormatter implements Formatter {
     format(message: string): string {
       return message.toUpperCase() + "!";
     }
   }

   // src/console-channel.ts
   import { injectable } from "@xwiki/platform-component-annotation-default";
   import type { Channel } from "./types";
   
   @injectable()
   export class ConsoleChannel implements Channel {
     async send(message: string): Promise<void> {
       console.log(`[console] ${message}`);
     }
   }

   // src/memory-channel.ts
   import { injectable } from "@xwiki/platform-component-annotation-default";
   import type { Channel } from "./types";
   
   @injectable()
   export class MemoryChannel implements Channel {
     public readonly sent: string[] = [];
     
     async send(message: string): Promise<void> {
       this.sent.push(message);
     }
   }

4. Implement a component that injects others

   // src/default-notifier.ts
   import { inject, injectAll, injectable, named } from "@xwiki/platform-component-annotation-default";
   import { CHANNEL_ROLE, FORMATTER_ROLE } from "./roles";
   import type { Channel, Formatter, Notifier } from "./types";
   
   @injectable()
   export class DefaultNotifier implements Notifier {
     constructor(@inject(FORMATTER_ROLE) @named("loud") private readonly formatter: Formatter,
       @injectAll(CHANNEL_ROLE) private readonly channels: Channel[], ) {}
       
     async notify(message: string): Promise<void> {
       const formatted = this.formatter.format(message);
       await Promise.all(this.channels.map((c) => c.send(formatted)));
     }
   }

5. Register all components

   // src/register.ts
   import { manager } from "@xwiki/platform-component-manager-default";
   import { CHANNEL_ROLE, FORMATTER_ROLE, NOTIFIER_ROLE } from "./roles";
   
   manager
     .registerComponent(
       FORMATTER_ROLE,
       () => import("./plain-formatter").then((m) => m.PlainFormatter),
       { name: "plain" }
     )
     .registerComponent(
       FORMATTER_ROLE,
       () => import("./loud-formatter").then((m) => m.LoudFormatter),
       { name: "loud" }
     )
     .registerComponent(
       CHANNEL_ROLE,
       () => import("./console-channel").then((m) => m.ConsoleChannel),
       { name: "console" }
     )
     .registerComponent(
       CHANNEL_ROLE,
       () => import("./memory-channel").then((m) => m.MemoryChannel),
       { name: "memory" }
     )
     .registerComponent(
       NOTIFIER_ROLE,
       () => import("./default-notifier").then((m) => m.DefaultNotifier)
     );

6. Initialize and resolve

   // src/bootstrap.ts
   import "./register"; 
   // side-effect import: triggers registrations 
   import { _init, resolverPromise } from "@xwiki/platform-component-manager-default";
   import { NOTIFIER_ROLE } from "./roles";
   import type { Notifier } from "./types";
   async function main() {
       await _init();
       const resolver = await resolverPromise;
       const notifier = await resolver.getAsync<Notifier>(NOTIFIER_ROLE);
       await notifier.notify("hello world");
       // → ConsoleChannel logs: "[console] HELLO WORLD!"
       // → MemoryChannel appends "HELLO WORLD!" to its `sent` array. 
   }
   
   main();