Transport Protocols

Asset Transport Protocols

The Asset System uses multiple transport strategies depending on asset size and connection type.

Small Assets

For assets smaller than a configurable threshold (typically < 1MB), the data is sent directly in the AssetFetchResponse or AssetUploadResponse message on the Reliable channel.

Large Assets (Chunked Upload)

For larger files, the system uses a chunked transfer protocol to avoid blocking the main thread or saturating memory.

1. Begin: Sender requests upload (AssetUploadBegin), receiver allocates resources and returns an UploadId.
2. Chunk: Sender transmits chunks sequentially (AssetUploadChunk).
3. Complete: Sender finalizes (AssetUploadComplete), receiver assembles and verifies the SHA-256 hash.

sequenceDiagram
    participant Sender
    participant Receiver

    Sender->>Receiver: AssetUploadBegin (Size, SHA)
    Receiver-->>Sender: UploadId (1234)
    
    loop Chunks
        Sender->>Receiver: AssetUploadChunk (ID=1234, Seq=0, Data...)
        Sender->>Receiver: AssetUploadChunk (ID=1234, Seq=1, Data...)
        Receiver-->>Sender: AssetUploadChunkResponse (BytesReceived)
    end

    Sender->>Receiver: AssetUploadComplete (ID=1234)
    Receiver-->>Sender: AssetUploadResponse (Success, AssetId)

WebRTC Data Channels

When using WebRTCConnection, assets can be transferred on a dedicated high-throughput data channel (separate from the reliable control channel) to prevent head-of-line blocking for latency-sensitive data.