mirror of
https://github.com/logos-messaging/nim-chat-sdk.git
synced 2026-01-02 14:13:07 +00:00
32 lines
1.3 KiB
Markdown
32 lines
1.3 KiB
Markdown
# Message Segmentation
|
||
|
||
Split large payloads into Waku-sized segments with optional Reed–Solomon parity for robust reconstruction. Inbound segmented messages are reassembled and persisted until complete.
|
||
|
||
## Features
|
||
|
||
- **Segmentation**: Outbound payloads over the configured size are split into segments; smaller payloads pass through unchanged.
|
||
- **Reconstruction**: Inbound segments can be processed out of order and reassembled into the original message.
|
||
- **Erasure coding**: Adds parity segments at 12.5% of data segments (≤ SegmentsReedsolomonMaxCount), enabling recovery with ~87.5% of segments.
|
||
- **Persistence**: Segments and completion state are stored (SQLite) and survive restarts.
|
||
- **API simplicity**: Main parameter is the maximum segment size; inject your persistence object.
|
||
|
||
## Essential API
|
||
|
||
- **Types**: `SegmentationHander`, `Chunk`, `Message`
|
||
- **Outbound**: `segmentMessage(handler, chunk: Chunk): Result[seq[Chunk], string]`
|
||
- **Inbound**: `handleSegmentationLayer(handler, message: var Message): Result[void, string]`
|
||
- **Helpers**: `isParityMessage(segment: SegmentMessage): bool`
|
||
|
||
Notes
|
||
- Parity rate is 12.5% (`SegmentsParityRate = 0.125`).
|
||
|
||
## Wire format
|
||
|
||
Segments are protobuf-encoded (`segment_message.proto`):
|
||
|
||
## Tests
|
||
|
||
See `tests/test_segmentation.nim` for examples covering in-order/out-of-order and parity recovery paths.
|
||
|
||
|