The APR Format

APR (Aprender Portable Runtime) is a binary format optimized for ML model deployment.

Design Goals

  1. Zero-copy loading - No parsing, direct memory access
  2. Compile-time embedding - Works with include_bytes!()
  3. Cross-platform - Native, WASM, embedded
  4. Security - Optional encryption and signing

File Structure

┌────────────────────────────────────────┐
│  Magic (4 bytes): "APRN"               │
├────────────────────────────────────────┤
│  Version (2 bytes): major.minor       │
├────────────────────────────────────────┤
│  Flags (2 bytes): compression, etc.   │
├────────────────────────────────────────┤
│  Header length (4 bytes)              │
├────────────────────────────────────────┤
│  Payload length (8 bytes)             │
├────────────────────────────────────────┤
│  Metadata (variable)                  │
│  - Name (null-terminated string)      │
│  - Description (optional)             │
│  - Custom fields                      │
├────────────────────────────────────────┤
│  Payload (variable)                   │
│  - Tensor data                        │
│  - Model weights                      │
│  - Optionally compressed (zstd)       │
└────────────────────────────────────────┘

Flags

BitNameDescription
0CompressedPayload is zstd compressed
1EncryptedPayload is AES-256-GCM encrypted
2SignedEd25519 signature present
3-15ReservedFuture use

Version History

VersionFeatures
1.0Initial release, basic bundling
1.1Compression support (zstd)
1.2Encryption (AES-256-GCM)

Comparison with Other Formats

FeatureAPRSafeTensorsGGUFONNX
Zero-copy✅✅❌❌
Rust-native✅❌❌❌
WASM support✅✅❌❌
Encryption✅❌❌❌
Quantization✅❌✅✅