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Design Philosophy

Havklo is built on one core principle: separate computation from I/O. The orderbook engine (kraken-book) contains zero networking code and no async runtime dependencies. This enables:
  • Native performance with Tokio in backend systems
  • Browser execution when compiled to WebAssembly
  • Deterministic testing without network mocking
  • Runtime portability across different async executors

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Crate Hierarchy

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Crate Overview

CratePurposeWASMDeps
kraken-sdkUnified high-level APINo268
kraken-wsSpot WebSocket v2 + tradingNo~100
kraken-futures-wsFutures perpetuals streamingNo~100
kraken-authAPI authentication, token refreshNo~50
kraken-bookL2/L3 orderbook engineYes35
kraken-typesCore types, enums, errorsYes28
kraken-wasmJavaScript/TypeScript bindingsYes35
For browser/WASM usage, only kraken-book (35 deps) is needed. The full SDK includes the async runtime, networking, and observability.

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Data Flow

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Why This Matters

Same Logic Everywhere

CRC32 validation, decimal precision, and state management work identically native and in-browser.

Test Once, Run Anywhere

Unit tests run synchronously against kraken-book without mocking network calls.

Minimal Browser Bundle

Only 35 dependencies compile to WASM. No async runtime bloat.

Incremental Adoption

Use just kraken-types for definitions, or the full SDK for a complete solution.

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Dependency Strategy

kraken-types (28 deps)
└── serde, rust_decimal, thiserror
    └── Minimal, serialization-focused

kraken-book (35 deps)
└── kraken-types + BTreeMap, VecDeque
    └── Pure computation, no I/O

kraken-sdk (268 deps)
└── tokio, tungstenite, dashmap, tracing...
    └── Full async networking stack
When building a WASM app, JavaScript handles the WebSocket. The WASM module only runs orderbook logic - no networking compiled into the binary.