HPPR Packet Links and Chunks

Tags: packet, content-convention

© R.A.Sol

This spec defines packet-level content conventions that are independent of any repository service.

+Link Header

Generic form:

+Link: <tag> <hash>

Common tags:

• request: this packet replies to that request
• supersedes: this packet replaces older version

Typed links are headers named [Type]+Link. Tools should scan header names containing +Link.

Hash links form a DAG. Cycles are impossible because packet hash includes all header bytes.

Chunked Content Convention

Large content can be split into chunk blobs with a manifest packet.

Manifest detection:

• has one or more Chunk+Link headers
• has Data-Length: 0

Syntax:

Chunk+Link: <start>..<end> <T>.<hash>.H3

• range is half-open: start inclusive, end exclusive
• T=B: raw blob chunk
• T=P: nested chunk manifest

Required header:

• Content-Total-Length: <n>

Optional headers:

• Content-Type
• Content-Hash-Full: B.<hash>.H3

Validation:

• chunk ranges contiguous
• no overlap
• total span exactly 0..<Content-Total-Length>

Nested manifests use 0-relative ranges in each sub-manifest. Depth limit is 8.

Default chunk size is 32 MiB. Smaller chunks improve random access and increase overhead.