kaizen

A dependency management and continuous delivery framework for the Unity platform.

Rationale

Breaking system functionality into smaller units that can be evolved and deployed independently of each other makes integration simpler because it can happen in small and localized steps. Divide and conquer.

In The Abstract

User visible functionality is grouped and delivered as coarse grained units called bundles.

Bundles are versioned groupings of components.

Components are versioned sets of files (such as a dotnet assembly and its xml documentation file for example) stored in repositories.

Repositories are directories of components, local or remote.

Components might declare dependencies on (versions of) other components.

The version number of a component is incremented every time a new version is published in accordance with semantic versioning rules.

Components can and should be published independently of each other.

In The Concrete

At the physical level there are only components distributed as zip files together with version and dependency metadata.

Two types of components are defined at this point:

1. A bundle is a component containing an informational text file (just so there's something to be zipped) and a set of dependencies on other components. A bundle's only purpose is to give a name to a set of component dependencies that together deliver a certain functionality (CodeEditor, for instance). Notice that bundles can also depend on other bundles allowing for arbitrary categorization of functionality.

2. An assembly is a component containing a dotnet dll together with its xml documentation file.

These two are enough for the purpose of distributing managed extensions to unity.

We're using [gradle] (http://www.gradle.org/) as the underlying infrastructure.

The Publisher POV

1. Declare dependencies.
2. ./gradlew update (downloads and unpacks dependencies)
3. Code something beautiful.
4. ./gradlew test
5. ./gradlew publish
6. Increment version numbers properly.

Handling UnityEngine.dll and UnityEditor.dll

Since those assemblies are strongly tied to the runtime they are shipped with they are not subject to continous delivery and instead have their versions pinned by the installation. They are still considered backwards compatible so bundles developed against older versions of them can still be installed.

The User POV

Users install bundles into their projects.

When a bundle is installed or updated all transitive dependencies are automatically resolved, downloaded and unpacked.

From the point of view of the user the current workflow goes like this:

1. user imports kaizen.unityPackage into the project
2. user selects which bundles are to be installed (at the current stage by editing kaizen/kaizen.d/bundles.gradle and uncommenting the relevant lines)
3. user asks kaizen to update the project with the selected bundles (atm by opening a shell in the kaizen directory and running './gradlew update' which causes all selected bundle dependencies to be resolved, downloaded and unpacked)

Repositories are like channels

Even though we're starting with a single remote repository for bundles and components the underlying infrastructure can handle any number of repositories which could be leveraged to implement things like private channels for paying customers, promotion workflows for components to migrate from unstable/experimental/beta channels into stable ones, etc.

New releases of unity might ship with a private repository containing snapshots of bundles promoted to 'builtin' status.

Contributors

See: https://github.com/Unity-Technologies/kaizen/graphs/contributors