Runtime Development

Developing runtime

Getting Started

First, make sure you have the CLI tool installed globally. To start the runtime development, first initialise a new Subsembly project:

subsembly init --to={projectPath}

Subsembly File Structure

Newly initialised Subsembly project has the following file structure:

subsembly-project
    assembly/
    │
    └───runtime    <--- Runtime API entries && defined types
    |
    └───frame      <--- Contains Executive and System modules used for orchestrating       
    runtime/
    │
    └───pallets    <--- Subsembly pallets included in the Runtime
yarn.lock              
package.json       <--- Subsembly dependencies

Runtime configuration

Top-level runtime folder consists of Runtime API entries that are exposed to the Host. Some functions of API are general to the blockchain, such as block production, execution, extrinsic submission and some others are specific to the module, such as Aura authorities. There is also, runtime.ts file, where types and constants for the frame modules and pallets are defined. We define general types that are used across the runtime and also pallet specific constants and types.

Some requirements for Runtime types, such as:

• Type should implement Codec interface from as-scale-codec. It makes sure that every type in the Runtime can be SCALE encoded and decoded.

• Make sure to avoid possible IntegerOverflow exceptions. For example, it does not make sense to use 8-bit unsigned integer as Timestamp Moment type, since the value of timestamp is way out of range of what 8-bit unsigned integer can hold.

Compiling

To compile the runtime:

subsembly compile

This should compile your runtime and place hex-encoded wasm binary to the build folder.