Project Architecture

Relevant source files

This document describes the multi-module Maven structure of PatternFly Java, including the parent POM hierarchy, module organization, dependency relationships, and the layered architecture that separates foundation components from UI components and integration modules. For information about the build system and development workflows, see Build System and Development. For details about GWT and J2CL integration approaches, see GWT vs J2CL.

Module Overview

PatternFly Java consists of 15 Maven modules organized in a hierarchical structure. The following table lists all modules with their Maven coordinates and purposes:

Module	Artifact ID	Packaging	Purpose
Parent POMs
Root	`patternfly-java-parent`	`pom`	Root parent POM with project metadata and plugin configuration
Code Parent	`patternfly-java-code-parent`	`pom`	Parent for code modules with dependency management
BOM	`patternfly-java-bom`	`pom`	Bill of materials for dependency version management
Build Config	`patternfly-java-build-config`	`jar`	Shared configuration for checkstyle, license, and code quality tools
Foundation Layer
Core	`patternfly-java-core`	`gwt-lib`	Base classes, utilities, component foundation, Popper.js integration
Tokens	`patternfly-java-tokens`	`gwt-lib`	Design token enum generated from PatternFly JSON
Icons	`patternfly-java-icons`	`gwt-lib`	Icon factory methods generated from SVG sources (~1000+ icons)
UI Layer
Components	`patternfly-java-components`	`gwt-lib`	62 UI components (buttons, forms, navigation, etc.)
Layouts	`patternfly-java-layouts`	`gwt-lib`	Page layouts (grid, flex, stack, etc.)
Charts	`patternfly-java-charts`	`gwt-lib`	Chart components with web component wrappers
Extensions
Code Editor	`patternfly-java-codeeditor`	`gwt-lib`	Code editor extension component
Finder	`patternfly-java-finder`	`gwt-lib`	Hierarchical navigation finder extension
Integration
GWT	`patternfly-java-gwt`	`gwt-lib`	GWT module aggregation and resource injection
J2CL	`patternfly-java-j2cl`	`jar`	J2CL dependency aggregation with JavaScript externs
Documentation
API Doc	`patternfly-java-apidoc`	`jar`	Aggregated Javadoc generation from all modules
Showcase	`patternfly-java-showcase`	`jar`	Demo application built with J2CL

Sources: pom.xml113-126 README.md106-122

Parent POM Hierarchy

The project uses a multi-level parent POM hierarchy to organize build configuration, plugin management, and dependency management:

Parent POM Responsibilities:

`patternfly-java-parent` (Root)

The root parent defines project-wide metadata, properties, and plugin configurations that apply to all modules:

Project Metadata: License, organization, developers, SCM, issue management
Version Properties: Dependency versions (Elemento, GWT, J2CL, PatternFly, etc.)
Plugin Management: Configures plugins used across modules without activating them
Global Plugins: Code quality tools (checkstyle, license, editorconfig, impsort)
Profiles: apidoc, showcase, quick-build, release

Key properties defined: pom.xml78-111

`patternfly-java-code-parent`

Extends the root parent and provides dependency management for all code modules:

Dependency Management: Imports PatternFly Java BOM, Elemento BOM, JUnit BOM
License Configuration: References patternfly-java-build-config for license headers
Checkstyle Configuration: References patternfly-java-build-config for checkstyle rules

Dependency management: code-parent/pom.xml35-64

`patternfly-java-bom`

Provides centralized version management for all PatternFly Java artifacts. This module has an independent parent (org.jboss:jboss-parent) to avoid circular dependencies. Consumers import this BOM to ensure consistent versions across all PatternFly Java dependencies.

Dependency declarations: bom/pom.xml83-200

Sources: pom.xml23-27 code-parent/pom.xml23-33 bom/pom.xml23-28

Layered Architecture

PatternFly Java follows a strict layered architecture where higher layers depend on lower layers but never the reverse:

Foundation Layer

The foundation layer provides primitive building blocks used throughout the project:

patternfly-java-core

Base Classes: BaseComponent, BaseComponentSVG all UI components extend one of these
Common Interfaces: HasItems, HasIdentifier, ComponentContext, Expandable, Closeable
CSS Class Builder: Classes static methods generating PatternFly CSS class strings (component(), layout(), modifier(), util())
ARIA Constants: Aria string constants for all ARIA attributes (aria-label, aria-expanded, aria-hidden, etc.)
Popper Integration: Embedded Popper.js for positioned overlays (tooltips, popovers, dropdowns)
Generated Code: Version.java contains PATTERN_FLY_MAJOR_VERSION, used by Classes to prefix all CSS class names

Key files: core/src/main/java/org/patternfly/style/Classes.java23-413 core/src/main/java/org/patternfly/core/Aria.java18-47

Core module POM: core/pom.xml30-63

patternfly-java-tokens

Single Enum Class: org.patternfly.token.Token
Generated Source: Created from @patternfly/tokens NPM package JSON
Token Properties: name (CSS variable), value (default), var (wrapped in var())

Token enum usage: README.md257-280

patternfly-java-icons

Factory Classes: IconSets.java, IconSpecs.java
Generated Sources: Created from SVG files in @patternfly/patternfly and @fortawesome/* packages
Icon Types: FontAwesome brand (fab), regular (far), solid (fas), PatternFly icons
Return Type: PredefinedIcon (extends SVG builder for customization)

Icon generation: icons/pom.xml59-93

Sources: core/pom.xml30-63 tokens/pom.xml icons/pom.xml30-41

UI Component Layer

The UI layer builds on the foundation to provide user-facing components:

patternfly-java-layouts

Layout Components: Grid, GridItem, Flex, Stack, Split, Bullseye, Gallery
Dependencies: Only depends on patternfly-java-core
Purpose: Provides container components for page structure

Layout module: layouts/pom.xml30-40

patternfly-java-components

Component Count: 62 out of 86 PatternFly components implemented
Dependencies: Core, Layouts, Icons, Tokens
Component Categories: Forms, navigation, data display, overlays, feedback
Examples: Button, Menu, Table, Modal, Navigation, Wizard

Component dependencies: components/pom.xml35-51

patternfly-java-charts

Unique Approach: Uses web components wrapping PatternFly React Charts
Java API: Type-safe Java classes with J2CL externs
NPM Dependency: Requires @patternfly-java/charts package
Chart Types: Donut, Bullet, Pie (with utilization variants)

Charts approach documented: README.md89-103

Sources: components/pom.xml30-57 layouts/pom.xml30-40 charts/pom.xml

Extension Layer

Extensions provide specialized components that build on the base component library:

patternfly-java-codeeditor

Purpose: Code editor component (without Monaco integration)
Dependency: patternfly-java-components
GWT Module: org.patternfly.extension.CodeEditor

Code editor module: extensions/codeeditor/pom.xml30-40

patternfly-java-finder

Purpose: Hierarchical navigation component (macOS Finder style)
Dependency: patternfly-java-components
GWT Module: org.patternfly.extension.Finder

Finder module: extensions/finder/pom.xml30-40

Sources: extensions/codeeditor/pom.xml30-40 extensions/finder/pom.xml30-40

Integration Layer

Integration modules aggregate dependencies for different JavaScript compilation targets:

patternfly-java-gwt

Packaging: gwt-lib with GWT module descriptor
Dependencies: Components and Layouts with sources classifiers
GWT Module: org.patternfly.PatternFly (inheritable by GWT applications)
Resource Injection: Automatic injection of Popper.js via GWT module

GWT module configuration: gwt/pom.xml47-70

patternfly-java-j2cl

Packaging: Standard JAR (no GWT module descriptor needed)
Dependencies: Components and Layouts (standard dependencies)
JavaScript Resources: Includes .js files for J2CL externs and Popper.js
Build Configuration: Special resource configuration to include JS files

J2CL resource configuration: j2cl/pom.xml46-61

Sources: gwt/pom.xml30-83 j2cl/pom.xml30-62

Module Dependency Graph

The following diagram shows actual Maven dependencies between modules using the <dependency> declarations from each POM:

Key dependency patterns:

Foundation Dependencies: All modules eventually depend on patternfly-java-core, which depends on Elemento
Component Dependencies: Components depends on Core, Icons, Tokens, and Layouts
Extension Dependencies: Both CodeEditor and Finder depend only on Components
Integration Dependencies: Both GWT and J2CL depend on Components and Layouts (but use different mechanisms)
Showcase Dependencies: Aggregates all user-facing modules plus the J2CL integration

Sources: components/pom.xml35-51 gwt/pom.xml47-70 j2cl/pom.xml35-44 showcase/pom.xml57-103

Packaging Types and Build Tools

PatternFly Java uses two packaging types that determine how modules are compiled and consumed:

`gwt-lib` Packaging

Modules with gwt-lib packaging are compiled by the gwt-maven-plugin:

Characteristics:

Contains a .gwt.xml module descriptor in src/main/resources
Produces JAR with .gwt-lib classifier
Includes both Java sources and compiled classes
Can be inherited by GWT applications using <inherits> directive
Processed by GWT compiler for JavaScript generation

Module Descriptor Pattern: Each gwt-lib module defines a module name in its POM: core/pom.xml103-108

Modules Using gwt-lib:

patternfly-java-core org.patternfly.Core
patternfly-java-tokens org.patternfly.Tokens
patternfly-java-icons org.patternfly.Icons
patternfly-java-layouts org.patternfly.Layouts
patternfly-java-components org.patternfly.Components
patternfly-java-charts org.patternfly.Charts
patternfly-java-codeeditor org.patternfly.extension.CodeEditor
patternfly-java-finder org.patternfly.extension.Finder
patternfly-java-gwt org.patternfly.PatternFly

Standard JAR Packaging

Modules with standard JAR packaging are used for J2CL compilation:

Characteristics:

No GWT module descriptor required
Standard Maven JAR lifecycle
Includes JavaScript externs for J2CL (in src/main/resources/META-INF/externs/)
Consumed as regular JAR dependencies
Processed by j2cl-maven-plugin for JavaScript generation

J2CL Resource Configuration: j2cl/pom.xml47-60

Modules Using JAR:

patternfly-java-j2cl (aggregation module)
patternfly-java-showcase (J2CL application)
patternfly-java-apidoc (documentation aggregation)
patternfly-java-build-config (build configuration)

Sources: core/pom.xml103-108 components/pom.xml59-68 j2cl/pom.xml30-62

The patternfly-java-build-config module provides shared configuration files for code quality tools:

Configuration Resources:

etc/license.txt - Apache 2.0 license header template
etc/checkstyle-suppressions.xml - Checkstyle rule suppressions

Usage Pattern: Code modules declare a dependency on build-config in their plugin configurations: code-parent/pom.xml70-87

This pattern allows shared configuration to be versioned and distributed with the project without duplication.

Sources: build-config/pom.xml30-52 code-parent/pom.xml70-101

Code Generation Strategy

Several modules use code generation during the generate-sources phase to create Java classes from external resources:

Version Generation (`patternfly-java-core`)

Script: core/version.java (JBang script) Generated: org.patternfly.core.Version.java Input: POM version, PatternFly version from properties Trigger: core/pom.xml81-100

Icon Generation (`patternfly-java-icons`)

Script: icons/generate-icons.js (Node.js script) Generated: org.patternfly.icon.IconSets.java, org.patternfly.icon.IconSpecs.java Input: SVG files from @patternfly/patternfly and @fortawesome/* NPM packages Trigger: icons/pom.xml59-93

Token Generation (`patternfly-java-tokens`)

Script: tokens/generate.mjs (Node.js script) Generated: org.patternfly.token.Token.java Input: JSON from @patternfly/tokens NPM package Trigger: Similar pattern to icons using frontend-maven-plugin

Showcase Generation (`patternfly-java-showcase`)

Scripts:

showcase/code.java - Generates org.patternfly.showcase.Code.java (code snippets)
showcase/doc.java - Generates org.patternfly.showcase.Documentation.java (descriptions)

Input: Demo files from src/demo/java/**/*Demo.java Trigger: showcase/pom.xml126-156

All generation happens during the generate-sources phase, ensuring generated files are available for compilation.

Sources: core/pom.xml81-100 icons/pom.xml59-93 showcase/pom.xml126-156

Profile-Based Module Activation

The root POM uses Maven profiles to conditionally activate documentation modules:

`apidoc` Profile

Activates the patternfly-java-apidoc module for generating aggregated API documentation: pom.xml458-463

`showcase` Profile

Activates the patternfly-java-showcase module for building the demo application: pom.xml557-562

`release` Profile

Configures release-specific plugins (GPG signing, source/javadoc JARs, Central publishing): pom.xml483-556

These modules are excluded from the default build to speed up development cycles, as they are typically only needed for releases or documentation updates.

Sources: pom.xml457-562

Project Architecture

Module Overview

Parent POM Hierarchy

patternfly-java-parent (Root)

patternfly-java-code-parent

patternfly-java-bom

Layered Architecture

Foundation Layer

UI Component Layer

Extension Layer

Integration Layer

Module Dependency Graph

Packaging Types and Build Tools

gwt-lib Packaging

Standard JAR Packaging

Build Configuration Sharing

Code Generation Strategy

Version Generation (patternfly-java-core)

Icon Generation (patternfly-java-icons)

Token Generation (patternfly-java-tokens)

Showcase Generation (patternfly-java-showcase)