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Architecture Overview

This framework is a web mapping platform designed to let teams add interactive maps to public-facing services in a consistent, extensible, and framework-agnostic way.

At its core, it provides:

  • A stable map UI with consistent behaviour
  • A plugin system for extending functionality
  • An abstraction layer over multiple mapping engines

The system is designed so that the core controls rendering and layout, while plugins declaratively contribute behaviour and UI. ---

High-level Structure

The framework consists of five main parts:

  1. Public API (Vanilla JS wrapper)
  2. Core React component
  3. Map provider abstraction
  4. Plugin system
  5. Rendering and slot system

1. Public API (Vanilla JS wrapper)

The framework is consumed via a vanilla JavaScript API, making it easy to integrate into a wide range of environments (including legacy stacks and non-React applications).

This wrapper:

  • Instantiates the core component
  • Passes configuration, plugins, and providers
  • Exposes events and methods to the host application

Note: Internally, the UI is implemented in React, but this is an implementation detail and not required knowledge for consumers.


2. Core Component

The core component is the orchestrator of the application. It:

  • Owns application state
  • Controls rendering and layout
  • Provides consistent map interactions (search, identify, draw, pan, etc.)
  • Manages plugins, providers, and UI composition

Stability Guarantee: Plugins never control the render lifecycle. The core always mounts and renders independently of plugin success or failure.


3. Map Provider Abstraction

The framework is not tied to a specific mapping library. It uses a mapProvider interface defining semantic operations such as:

  • Fitting the map to bounds
  • Setting the view zoom and centre
  • Querying features

This allows providers to be swapped without rewriting plugins or UI code.

Our reference provider, offering the most complete and tested experience:

Out of the boxWorks immediately with no additional
Modern and lightweightBetter performance with smaller bundle sizes
Vector tile supportMost comprehensive support for vector tiles
Enhanced accessibilityThe most accessbile offering

Esri (Experimental)

An alternative provider with specific advantages:

British National GridNative support for BNG coordinate systems

4. Plugin System

Declarative by Design

Plugins describe what they add using a manifest (buttons, panels, shortcuts). They are contributors, not "render owners."

Registration vs Rendering

  • Registration: Reads manifests and populates central registries at load time.
  • Rendering: Controlled entirely by the core, which decides where and how items appear based on current state.

Isolation

Each plugin receives a ring-fenced slice of state. They have read access to appState, mapState, appConfig, and services (eventBus, geocoding, etc.).


5. Rendering and Slot System

The UI uses a slot-based system. Slots represent logical areas (e.g., actions, side panels, modals).

Plugins declare UI elements with layout hints (which slot to use, modal vs non-modal, mobile vs desktop behavior). The core evaluates these rules to guarantee:

  • Consistent layout and accessibility
  • Centralized responsive design
  • UI stability (plugins cannot "block" the interface)

Event Bus

Provides two-way, decoupled communication between the core, plugins, and the vanilla JS layer. This allows external applications to react to internal state changes without tight coupling.

Mental Model for Developers

CoreThe Platform
PluginsDeclarative Feature Descriptions
ProvidersAdapters for Map Engines
SlotsLayout Positions
StateShared Context

Tech stack

ReactUI component framework
MapLibrePrimary mapping engine
WebpackModule bundling (UMD, ESM builds)
JestTesting framework
SCSSStyling
BabelJavaScript compilation