Multiformats
A collection of protocols which aim to future-proof systems, today. They do this mainly by enhancing format values with self-description. This allows interoperability, protocol agility, and helps us avoid lock in.
The self-describing aspects of the protocols have a few stipulations:
- They MUST be in-band (with the value); not out-of-band (in context).
- They MUST avoid lock-in and promote extensibility.
- They MUST be compact and have a binary-packed representation.
- They MUST have a human-readable representation.
Unsigned-varint
VARiable INTeger format used in all the multiformats. The encoding is:
- Unsigned integers are serialized 7 bits at a time, starting with the least significant bits.
- The most significant bit (msb) in each output byte indicates if there is a continuation byte (msb = 1).
- There are no signed integers.
- Integers are minimally encoded.
Refer unsigned-varint spec for details.
Multibase
Base encoding is converting binary-data to plain-text. There are several base-encoding definitions that can convert binary-data to a small subset of, typically, ASCII code. Purpose,
- Printable character set.
- A bridge to backward-compatibility.
- When a channel cannot, do-not, allow binary data.
Refer multibase for details.
Multicodec
Multicodec is an agreed-upon codec table. It is designed for use in binary representations, such as keys or identifiers (i.e CID). Find the canonical table of multicodecs at [table.csv].
Refer multicodec spec for details.
IPLD Foundational Principles
- Block, A block is a chunk of an IPLD DAG, encoded in a format. Blocks have CIDs.
- Node, A node is a point in an IPLD DAG (map, list, number, etc.). Many nodes can exist encoded inside one Block.
- Link, A link is a kind of IPLD Node that points to another IPLD Node. Links are what make IPLD data a DAG rather than only a tree. Links are content-addressable (CID).
- Path Segment, A path segment is a piece of information that describes a move from one Node to a directly connected child Node. (In other words, a Path-Segment is either a map key or a list index.)
- Path, A path is composed of Path Segments, thereby describing a traversal from one Node to another Node somewhere deeper in the DAG.
- Transforming content of a Block into Nodes conforming to the IPLD Data Model should never require interpretation in the context of anything not contained in the Block plus CID.
- Similarly, traversing an IPLD Node according to a Path should not require interpretation in the context of anything not already contained in that Node plus Path.
- Format, is the standardized representation of IPLD Links and Paths. It describes how to translate between structured data and binary. MUST remain consistent across all codec implementations.
- Content addressability refers to the ability to refer to content by a trustless identifier.
- IPLD links must not be cyclic, even if we add support for relative links.
- IPLD path resolution means the same thing, everywhere, every time.
Reference:
List of active multiformat specification(s).
- Micro-site, http://multiformats.io
- Unsigned varint, https://github.com/multiformats/unsigned-varint
- Multicodec, https://github.com/multiformats/multicodec
There are other implementations that can suite your need better:
