Layering Strategy in SnelDB

This page gives a high-level view of how SnelDB is structured. It focuses on what each layer does and how requests flow through the system.

Layer 1: frontend — Transport and Connections

• Listens for client connections (e.g., Unix/TCP/HTTP).
• Reads requests and writes responses.
• Hands off parsing and execution to the command and engine layers.

Layer 2: command — Parse and Dispatch

• Parses user input (e.g., DEFINE, STORE, QUERY).
• Validates and turns text into typed commands.
• Dispatches to the appropriate operation in the engine.

Layer 3: engine — Core Logic

• Implements the main behaviors: define schemas, store events, run queries, replay, and flush.
• Chooses the right shard and updates on-disk data as needed.
• Stays independent from how clients connect or send requests.

Layer 4: shared — Common Utilities

• Configuration and response types used across layers.
• Logging setup and other small shared helpers.

Flow Summary (STORE example)

1. Frontend receives a request.
2. command parses and validates it.
3. The dispatcher routes to the correct engine operation.
4. engine executes and updates storage.
5. A response is returned to the client.

Why this layering?

• Clean separation: parsing, logic, and transport are independent.
• Easy to test: engine logic can be tested without real sockets.
• Scales well: clear boundaries support growth and optimization.