feat: microkernel architecture pattern (#1086)

[KishalayP]

#1086: Implementation of the Microkernel Architecture Pattern as described in the issue

What does this PR do?

This PR introduces a complete, interactive implementation of the Microkernel Architecture Pattern (also known as the Plug-in architecture) to the repository. It uses a text editor simulation to demonstrate how to effectively separate a minimal core system from optional, specialized processing features.

This implementation demonstrates:

• Core System & IPC: A centralized MicroKernel that controls the state (a document buffer) and an IpcRouter that dispatches messages between the core and isolated plugins.
• Dynamic Plugin Management: A PluginCatalog (acting as a factory/store) and a PluginRegistry to handle the installation, tracking, and uninstallation of active plugins at runtime.
• Distinct Plugin Lifecycles: Abstract base classes demonstrating two types of plugins:
  • Lifecycle-driven plugins that execute automatically upon installation (e.g., NeonThemePlugin).
  • Event-driven (On-demand) plugins that wait for explicit IPC messages to execute (e.g., UppercasePlugin, RemoveSpacesPlugin).
• Clear Separation: An interactive CommandLineInterface (CLI) that is entirely decoupled from the core logic, allowing users to dynamically install/uninstall plugins and transform text and see the pattern working.
• The PR also includes comprehensive Unit Tests for all components, a complete README.md, and PlantUML diagrams illustrating the structural architecture and message-routing process flow.

[github-actions]

PR Summary

Started implementation of the Microkernel Architecture Pattern as a new module. Adds a Core MicroKernel with IPC-based plugin communication, a PluginCatalog for dynamic plugin creation, a PluginRegistry, lifecycle abstractions, built-in plugins, a CLI, and comprehensive tests and documentation. Includes architecture diagrams and README to illustrate concepts and usage.

Changes

File	Summary
microkernel-architecture/README.md	Documentation describing the Microkernel Architecture pattern, its motivation, components, usage, and references. Includes architecture diagrams and references.
microkernel-architecture/etc/microkernel-architecture.png	New architecture diagram image illustrating class roles and relationships.
microkernel-architecture/etc/microkernel-architecture.puml	PlantUML diagram of the architecture's class structure and component interactions.
microkernel-architecture/etc/microkernel-flow.png	Flow diagram image showing runtime message flow between kernel, CLI, registry, and plugins.
microkernel-architecture/etc/microkernel-flow.puml	PlantUML flow diagram detailing message routing in the microkernel.
microkernel-architecture/pom.xml	Defines a new Maven module with build plugins, dependencies, and Java 21 compatibility.
microkernel-architecture/src/main/java/com/iluwatar/microkernel/App.java	Main entry that wires MicroKernel and CommandLineInterface and starts the CLI.
microkernel-architecture/src/main/java/com/iluwatar/microkernel/cli/CommandLineInterface.java	CLI to install/uninstall plugins, open a text editor, and transform text via the IPC router.
microkernel-architecture/src/main/java/com/iluwatar/microkernel/core/AbstractLifecyclePlugin.java	Abstract base for lifecycle plugins providing start/stop hooks.
microkernel-architecture/src/main/java/com/iluwatar/microkernel/core/AbstractOnDemandPlugin.java	Abstract base for on-demand plugins that react to IPC messages.
microkernel-architecture/src/main/java/com/iluwatar/microkernel/core/MicroKernel.java	Core component managing plugin registry, IPC, and a document buffer; supports load/start/unload and transform.
microkernel-architecture/src/main/java/com/iluwatar/microkernel/core/Plugin.java	Plugin contract interface defining lifecycle and message handling.
microkernel-architecture/src/main/java/com/iluwatar/microkernel/ipc/IpcRouter.java	IPC router dispatching messages to registered, started plugins with fault isolation.
microkernel-architecture/src/main/java/com/iluwatar/microkernel/ipc/Message.java	Record representing a message exchanged between kernel and plugins.
microkernel-architecture/src/main/java/com/iluwatar/microkernel/plugins/JavaLanguagePlugin.java	On-demand plugin applying Java-like formatting for TRANSFORM actions.
microkernel-architecture/src/main/java/com/iluwatar/microkernel/plugins/NeonThemePlugin.java	Lifecycle plugin that applies neon theme on start and resets on stop.
microkernel-architecture/src/main/java/com/iluwatar/microkernel/plugins/PluginCatalog.java	Catalog providing plugin metadata and factories; creates fresh plugin instances.
microkernel-architecture/src/main/java/com/iluwatar/microkernel/plugins/RemoveSpacesPlugin.java	On-demand plugin removing whitespace in TRANSFORM payloads.
microkernel-architecture/src/main/java/com/iluwatar/microkernel/plugins/UppercasePlugin.java	On-demand plugin converting text to uppercase for TRANSFORM actions.
microkernel-architecture/src/main/java/com/iluwatar/microkernel/registry/PluginRegistry.java	Registry to store and look up plugins by name.
microkernel-architecture/src/test/java/com/iluwatar/microkernel/AppTest.java	Tests verifying App can be instantiated and starts/exits.
microkernel-architecture/src/test/java/com/iluwatar/microkernel/cli/CommandLineInterfaceTest.java	CLI tests covering install, uninstall, and document editing/transform flow.
microkernel-architecture/src/test/java/com/iluwatar/microkernel/core/MicroKernelTest.java	Tests for loading, starting, transforming, and unloading plugins in MicroKernel.
microkernel-architecture/src/test/java/com/ iluwatar/microkernel/ipc/IpcRouterTest.java	IpcRouter tests for missing recipient, stopped plugin, success, and fault isolation.
microkernel-architecture/src/test/java/com/iluwatar/microkernel/plugins/PluginCatalogTest.java	Tests listing built-in plugins and creating fresh plugin instances.
microkernel-architecture/src/test/java/com/iluwatar/microkernel/plugins/PluginImplementationsTest.java	Tests for plugin implementations including lifecycle and transform behavior.
microkernel-architecture/src/test/java/com/iluwatar/microkernel/registry/PluginRegistryTest.java	Tests for registry operations including replace and deregister.
pom.xml	Root pom.xml updated to include the microkernel-architecture module in the build.

---

autogenerated by presubmit.ai

[github-actions]

🚨 Pull request needs attention.

Review Summary

Commits Considered (12)

• ddba2f6: Adding Details for microkernel-architecture
• 6b1a0d8: Adding Plugin
• 6d7d86a: Reformatted as per style guide
• 29f5c0d: Reformatted as per style guide
• 24387f9: Adding Unit Tests
• b1dea43: Adding CLI and main app
• a9b0455: Adding Plugins
• 812b14f: Adding Core Plugin Functions
• d03adea: Adding Core Functions
• a16a161: Merge branch 'iluwatar:master' into #1086-microkernel-architecture-pattern
• 29d82bb: Merge branch 'iluwatar:master' into master
• e48fdf3: #1086: Init commit adding module

Files Processed (28)

• microkernel-architecture/README.md (1 hunk)
• microkernel-architecture/etc/microkernel-architecture.png (0 hunks)
• microkernel-architecture/etc/microkernel-architecture.puml (1 hunk)
• microkernel-architecture/etc/microkernel-flow.png (0 hunks)
• microkernel-architecture/etc/microkernel-flow.puml (1 hunk)
• microkernel-architecture/pom.xml (1 hunk)
• microkernel-architecture/src/main/java/com/iluwatar/microkernel/App.java (1 hunk)
• microkernel-architecture/src/main/java/com/iluwatar/microkernel/cli/CommandLineInterface.java (1 hunk)
• microkernel-architecture/src/main/java/com/iluwatar/microkernel/core/AbstractLifecyclePlugin.java (1 hunk)
• microkernel-architecture/src/main/java/com/iluwatar/microkernel/core/AbstractOnDemandPlugin.java (1 hunk)
• microkernel-architecture/src/main/java/com/iluwatar/microkernel/core/MicroKernel.java (1 hunk)
• microkernel-architecture/src/main/java/com/iluwatar/microkernel/core/Plugin.java (1 hunk)
• microkernel-architecture/src/main/java/com/iluwatar/microkernel/ipc/IpcRouter.java (1 hunk)
• microkernel-architecture/src/main/java/com/iluwatar/microkernel/ipc/Message.java (1 hunk)
• microkernel-architecture/src/main/java/com/iluwatar/microkernel/plugins/JavaLanguagePlugin.java (1 hunk)
• microkernel-architecture/src/main/java/com/iluwatar/microkernel/plugins/NeonThemePlugin.java (1 hunk)
• microkernel-architecture/src/main/java/com/iluwatar/microkernel/plugins/PluginCatalog.java (1 hunk)
• microkernel-architecture/src/main/java/com/iluwatar/microkernel/plugins/RemoveSpacesPlugin.java (1 hunk)
• microkernel-architecture/src/main/java/com/iluwatar/microkernel/plugins/UppercasePlugin.java (1 hunk)
• microkernel-architecture/src/main/java/com/iluwatar/microkernel/registry/PluginRegistry.java (1 hunk)
• microkernel-architecture/src/test/java/com/iluwatar/microkernel/AppTest.java (1 hunk)
• microkernel-architecture/src/test/java/com/iluwatar/microkernel/cli/CommandLineInterfaceTest.java (1 hunk)
• microkernel-architecture/src/test/java/com/iluwatar/microkernel/core/MicroKernelTest.java (1 hunk)
• microkernel-architecture/src/test/java/com/iluwatar/microkernel/ipc/IpcRouterTest.java (1 hunk)
• microkernel-architecture/src/test/java/com/iluwatar/microkernel/plugins/PluginCatalogTest.java (1 hunk)
• microkernel-architecture/src/test/java/com/iluwatar/microkernel/plugins/PluginImplementationsTest.java (1 hunk)
• microkernel-architecture/src/test/java/com/iluwatar/microkernel/registry/PluginRegistryTest.java (1 hunk)
• pom.xml (1 hunk)

Actionable Comments (3)

• microkernel-architecture/src/main/java/com/iluwatar/microkernel/ipc/IpcRouter.java [51-80]

  best_practice: "Logger naming consistency"

• microkernel-architecture/src/main/java/com/iluwatar/microkernel/plugins/JavaLanguagePlugin.java [49-54]

  best_practice: "Consistency: logger naming for JavaLanguagePlugin"

• microkernel-architecture/src/main/java/com/iluwatar/microkernel/plugins/UppercasePlugin.java [46-52]

  best_practice: "Consistency: logger naming for UppercasePlugin"

Skipped Comments (3)

• microkernel-architecture/src/main/java/com/iluwatar/microkernel/core/MicroKernel.java [0-0]

  best_practice: "Logging consistency across core module"

• microkernel-architecture/src/main/java/com/iluwatar/microkernel/core/AbstractLifecyclePlugin.java [0-0]

  best_practice: "Lifecycle hooks idempotency"

• microkernel-architecture/src/main/java/com/iluwatar/microkernel/plugins/RemoveSpacesPlugin.java [32-36]

  best_practice: "Logger usage consistency in RemoveSpacesPlugin"

[codecov]

Codecov Report

❌ Patch coverage is 99.58848% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 84.31%. Comparing base (4cabb20) to head (46ce10a).

Files with missing lines	Patch %	Lines
...ava/com/iluwatar/microkernel/core/MicroKernel.java	96.96%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #3610      +/-   ##
============================================
+ Coverage     84.06%   84.31%   +0.24%     
- Complexity     4353     4449      +96     
============================================
  Files          1133     1146      +13     
  Lines         15400    15643     +243     
  Branches        739      759      +20     
============================================
+ Hits          12946    13189     +243     
+ Misses         2158     2156       -2     
- Partials        296      298       +2     

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[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• 46ce10a: Adding Unit Tests

Files Processed (0)

Actionable Comments (0)

Skipped Comments (0)