Crate holochain_cascade 

The Cascade is a multi-tiered accessor for Holochain DHT data.

It is named “the cascade” because it performs cascading lookups across multiple sources. In general, the flow is:

• Search in local storage, including the DhtStore and SyncScratch.
• If the data are not found locally, request the data from the network. Network responses are cached into the DhtStore

Not all lookups follow this pattern, namely links are treated differently. Where a lookup doesn’t follow this pattern, it is documented in the method documentation.

In order to support apps that want to be able to operate offline, a GetStrategy can be provided. Making a GetStrategy::Local request will avoid the network entirely. Making a GetStrategy::Network request will allow the cascade to go to the network, but not force it to. That means that if the requested data is available locally, the cascade won’t attempt to fetch it again.

Retrieve vs Get

There are two words used in cascade functions: “get”, and “retrieve”. They mean distinct things:

• “get” ignores invalid data, and sometimes takes into account CRUD metadata before returning the data, so for instance, Deletes are allowed to annihilate Creates so that neither is returned. This is a more “refined” form of fetching data.
• “retrieve” only fetches the data if it exists, without regard to validation status. This is a more “raw” form of fetching data.

Modules

authority

Functions for the various authorities to handle queries.

error

get_options_ext

Extension trait to convert GetOptions to NetworkRequestOptions.

Structs

CascadeImpl

The cascade is a multi-tiered accessor for Holochain DHT data.

CascadeOptions

Options for configuring cascade lookups.

Enums

CascadeSource

Marks whether data came from a local store or another node on the network

Traits

Cascade

A trait for accessing the cascade which can be mocked.