Libraries

Library types

Libraries are packaged modules. Their purpose is to be built (or packaged) and embedded into the code of a deployed service.

They are divided into two main types of libraries that only differ in their usage.

Contracts provide explicit type-safe interfaces between deployed services, that can be statically checked at compile time and and validated at runtime using JSONSchema. For more details on contracts, see the contracts documentation.

Packages reduce code duplication between services by providing shared logic and configuration. These packages must not become too big in order for them to remain usable and must be well documented.

Library structure

A typical Swarmion library has the following structure:

├── my-library/
|   ├── src/
|   |   ├── index.ts             # all exported code from the library MUST be referenced in this file
|   |   ├── myFirstFolder/
|   |   |   ├── index.ts         # all exported code from the folder MUST be referenced in this file
|   |   |   └── ...              # other files and folders
|   |   ├── mySecondFolder/
|   |   |   ├── index.ts         # all exported code from the folder MUST be referenced in this file
|   |   |   └── ...              # other files and folders
|   |   └── ...                  # other files and folders
|   ├── package.json             # library dependencies
|   └── tsconfig.json            # Typescript configuration

The golden rule of libraries

In order to safely use code from a library outside of it, all exported code must be explicitly declared at the root level.

Generate a library

You can generate a new library respecting these guidelines using the @swarmion/nx-plugin