# Backend

The QuickDapp backend runs on Bun with ElysiaJS as the web framework. Everything flows through the ServerApp pattern, which provides clean access to the database, logger, WebSocket manager, worker system, and optional blockchain clients.

The backend uses Bun as its runtime and package manager. ElysiaJS handles HTTP and WebSocket connections, GraphQL Yoga provides the API layer, and DrizzleORM manages PostgreSQL access with full TypeScript integration.

When Web3 is enabled, the server also has Viem clients for reading from and writing to the blockchain, plus SIWE support for wallet-based authentication.

Every part of the backend receives a ServerApp object containing all the services it needs:

type ServerApp = {
  app: Elysia                                    // HTTP/WebSocket server
  db: Database                                   // DrizzleORM connection
  rootLogger: Logger                             // Root logger
  createLogger: (category: string) => Logger     // Logger factory
  startSpan: typeof startSpan                    // Sentry performance tracing
  workerManager: WorkerManager                   // Background job manager
  socketManager: ISocketManager                  // WebSocket manager
  createNotification: (userId, data) => Promise  // Send user notifications
  publicClient?: PublicClient                    // Blockchain read client (Web3)
  walletClient?: WalletClient                    // Blockchain write client (Web3)
}

GraphQL resolvers receive this through their context. Worker jobs get it as their first parameter. Any service you build can accept ServerApp to access shared resources.

src/server/
├── auth/           # Authentication (SIWE, email, OAuth)
├── bootstrap.ts    # ServerApp creation
├── db/             # Schema, queries, connection management
├── graphql/        # Resolvers and schema integration
├── lib/            # Logger, errors, crypto, chains
├── services/       # Business logic services
├── start-server.ts # Server startup
├── start-worker.ts # Worker process startup
├── types.ts        # ServerApp type definition
├── workers/        # Background job system
└── ws/             # WebSocket implementation

A GraphQL request arrives at ElysiaJS, which passes it to GraphQL Yoga. Yoga parses the query, checks for the @auth directive, and builds a context containing the ServerApp and authenticated user (if any). The resolver runs, queries the database through DrizzleORM, and returns the result.

WebSocket connections follow a similar pattern. Clients connect, optionally authenticate with a JWT, and receive real-time updates when notifications are created. The SocketManager routes messages to specific users or broadcasts to everyone.

Background jobs get submitted to the database queue. Worker processes poll for pending jobs, execute them with full ServerApp access, and mark them complete. Workers can send WebSocket messages back through IPC to the main server process.

• Bootstrap — How ServerApp gets created and configured
• Database — Schema design, queries, and transaction handling
• GraphQL — API schema, resolvers, and authentication
• Authentication — SIWE, email, and OAuth flows
• WebSockets — Real-time communication

See src/server/types.ts for the complete ServerApp type definition.