The IPLD Data Model

IPLD defines a Data Model that details the forms that data can take in memory, and through which a codec transforms that memory to and from encoded bytes.

Like the JSON data model, the IPLD Data Model includes data Kinds which include Booleans, Strings, Ints, Floats, Null, Lists and Maps, but also adds Bytes and Links (CIDs).

The Data Model is how we reason about data moving through the various states—in-memory, programmatic access and manipulation, and serialization to and from bytes for storage or transfers.

The data model defines a common representation of basic types that are easily representable by common programming languages and found in the most common and successful serialization formats.

const data = {
 string: "☺️  we can do strings!",
 ints: 1337,
 floats: 13.37,
 booleans: true,
 lists: [1, 2, 3],
 bytes: new Uint8Array([0x01, 0x03, 0x03, 0x07]),
 links: CID(bafyreidykglsfhoixmivffc5uwhcgshx4j465xwqntbmu43nb2dzqwfvae)
}

Read more about the Data Model at ipld.io/docs/data-model

Blocks and Nodes

IPLD data is quantified in terms of nodes and blocks. A node is a point in a graph, while a block is a collective unit of data that is serialized and hashed to generate a content address (CIDs). Blocks typically include many nodes.

If we define an example block of data using JSON:

{"a": ["b", "c"]}

We can see 5 nodes:

1. The enclosing map

2. The key (the string "a")

3. The list

4. The first list value (the string "b")

5. The second list value (the string "c")

Read more about Nodes and their relationship to other IPLD concepts at ipld.io/docs/data-model/node

Kinds

We refer to the different kinds of representable data in the Data Model as "kinds": Booleans, Strings, Ints, Floats, Null, Bytes, Lists, Maps and Links.

We use the term "kinds" here to disambiguate this from "types", which is a term we use at the Schemas level.

The 'recursive kinds' are Maps and Lists (since they can contain other kinds).

Read more about IPLD Kinds and specifics of what we expect regarding their bounds and representation at ipld.io/docs/data-model/kinds