Overview

Modular is the application framework for Fuchsia. It manages user experiences by composing UI, data, and users from a diverse set of components into logical and visual containers called Stories.

The framework defines classes of components to extend user experiences and provides software primitives for component composition, communication, task delegation, state management and data sharing.

Requirements to use Modular

Modular supports software written in any language (e.g. Flutter, C++) for any Fuchsia supported runtime, as long as it is a Fuchsia Component.

The Modular Framework communicates with components it launches via FIDL, the standard IPC mechanism for Fuchsia.

Extension Points

The framework defines several different classes of components which can be implemented by developers to extend the behavior of user experiences:

1. Modules are components which display UI and are visually composed in a Story.
2. Agents are components which run in the background to provide services and data to Modules and other Agents.
3. Shells manage system UI and mediate user interactions.
4. EntityProviders are components which provide access to data object (entities) which are shared between components running in modular.

basemgr and sessionmgr

After Fuchsia device startup, basemgr and sessionmgr are processes that provide session management, component lifecycle management and state management.

• basemgr is responsible for user authentication and authorization. It leverages the Base Shell to present UI.

• sessionmgr is responsible for the lifecycle of Stories, Modules and Agents, as well as service and state coordination between them. It leverages Session and Story Shells to manage the visual composition of these components.