Streams¶
Streams are individual instances of state on the Ceramic network. Every stream is mutable and can only be modified when it receives a transaction signed by the account that owns it.
How streams work¶
Stream identifiers¶
Every stream is identified by its streamID, which is its unique address on the Ceramic network. When applications load a stream from the network using its streamID, its current state is returned. Alternative, applications can load a previous version of a stream's state by using the commitID of the specific version wanted.
Streamcode¶
Every stream that is created on Ceramic must reference a streamcode in its metadata, which is a script that contains the processing logic used to transform a stream's current state into the next state upon receipt of a new transaction. In general, you can think of streamcode as reusable state processing logic and streams as the individual states it generates.
Today Ceramic supports two types of streams: tile documents which store mutable JSON documents with schema validation, and CAIP-10 links which store a link between a Web3 wallet account and a Ceramic account.
Metadata¶
Every stream can specify a few metadata properties:
| Metadata property | Required? | Description |
|---|---|---|
streamtype |
Yes | The streamcode used by the stream |
controller |
Yes | The Ceramic account (DID) that can modify the stream |
schema |
No | The schema for the stream |
family |
No | Used to associate collections of streams |
tags |
No | Used to create subgroupings of streams |
Content¶
The type of content that a stream can store is determined by its streamcode.
Building with streams¶
Store JSON content →¶
Tile Document (CIP-8) is streamcode that stores a mutable JSON document with schema validation, providing similar functionality as a NoSQL document.
Store blockchain account links →¶
CAIP-10 Link (CIP-7) is streamcode that stores a link between a Web3 wallet account and a Ceramic account.
New streamcode¶
Ceramic does not yet suport the arbitrary creation of new streamcode. If you'd like to create new streamcode to support additional use cases for streams, reach out on the Ceramic Discord.