Holochain Programming References

Rust HDK

When you write a Holochain application, the part that lives in Holochain is called a DNA. It runs in a WebAssembly sandbox and talks to the host, or conductor, through the host API. The Rust HDK (Holochain Development Kit) makes it easy for you to write your DNAs in the Rust programming language.

Conductor APIs

The conductor exposes two RPC APIs over WebSocket interfaces:

For both of these APIs, you make an RPC call sending a MessagePack-serialized request to the conductor over WebSocket and listening for a response. On the interface that exposes the app API, you can also listen for signals broadcast by cells.

For ergonomic interaction with those two API’s there are two client implementations: One in JavaScript and one in Rust. If you intend to develop Holochain Apps with a web-based UI, it is likely that all you’ll ever need is the JavaScript client.

Conductor configuration

The conductor has a few settings that can (and should) be configured via a YAML config file. We’ve provided documentation of the internal structures that hold this config; if you can picture how to serialize this to YAML in your mind, you can write a config file! (We promise we’ll produce a more readable config file guide soon.)


There are three main binaries. You can run any of these on the command-line with the --help flag to get detailed documentation.

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