feat: add publisher-subscriber design pattern (#2898)

[sanurah]

This PR is adding the publisher subscriber design pattern for feature #2898

[github-actions]

PR Summary

This PR implements the Publisher-Subscriber design pattern. It introduces a Publisher that manages topics and Subscribers that listen to specific topics. The implementation includes classes for Message, Topic, Publisher, and various Subscribers (WeatherSubscriber, DelayedWeatherSubscriber, CustomerSupportSubscriber). Unit tests are also included.

Changes

File	Summary
pom.xml	The pom.xml file was modified to include the newly added publish-subscribe module.
publish-subscribe/README.md	This README file provides a comprehensive explanation of the Publisher-Subscriber design pattern, including real-world examples, a detailed description of the implementation, and usage scenarios. It also includes an architectural diagram.
publish-subscribe/etc/pub-sub.png	New file: Architectural diagram for the Publisher-Subscriber pattern.
publish-subscribe/pom.xml	This file defines the dependencies for the publish-subscribe module, including junit-jupiter-engine for testing and logback-classic for logging.
publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/App.java	This is the main application class demonstrating the Publisher-Subscriber pattern. It creates topics, registers subscribers, publishes messages, and waits for message processing.
publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/Message.java	This class represents a message that holds the published content. It uses a record to define a simple immutable data structure.
publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/Topic.java	This class represents a topic with a name and a set of subscribers. It includes methods to add, remove, and publish messages to subscribers.
publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/publisher/Publisher.java	This interface defines the contract for a Publisher, including methods to register topics and publish messages.
publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/publisher/PublisherImpl.java	This class implements the Publisher interface, managing a set of topics and publishing messages to the appropriate subscribers.
publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/CustomerSupportSubscriber.java	This class implements a subscriber that handles customer support messages. It logs a message when a new support request is received.
publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/DelayedWeatherSubscriber.java	This subscriber simulates a delayed processing scenario by introducing a 2-second delay before processing a message.
publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/Subscriber.java	This interface defines the contract for a Subscriber, which includes a method to handle incoming messages.
publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/WeatherSubscriber.java	This class implements a subscriber that handles weather-related messages. It logs a message when a new weather event is received.
publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/AppTest.java	This test class verifies that the main application runs without throwing any exceptions.
publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/LoggerExtension.java	This class is a JUnit extension that captures log messages for testing purposes.
publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/model/MessageTest.java	This test class contains unit tests for the Message class.
publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/model/TopicTest.java	This test class contains unit tests for the Topic class, including adding and removing subscribers.
publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/publisher/PublisherTest.java	This test class contains unit tests for the Publisher class, including registering topics and publishing messages.
publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/subscriber/SubscriberTest.java	This test class contains unit tests for the Subscriber class, including subscribing to multiple topics, receiving messages, and unsubscribing.

---

autogenerated by presubmit.ai

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• c535bb7: feat: add publisher-subscriber design pattern (Publish/Subscribe pattern #2898)

Files Processed (19)

• pom.xml (1 hunk)
• publish-subscribe/README.md (1 hunk)
• publish-subscribe/pom.xml (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/App.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/CustomerSupportContent.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/Message.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/Topic.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/TopicName.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/WeatherContent.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/publisher/Publisher.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/publisher/PublisherImpl.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/CustomerSupportSubscriber.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/Subscriber.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/WeatherSubscriber.java (1 hunk)
• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/LoggerExtension.java (1 hunk)
• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/model/MessageTest.java (1 hunk)
• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/model/TopicTest.java (1 hunk)
• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/publisher/PublisherTest.java (1 hunk)
• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/subscriber/SubscriberTest.java (1 hunk)

Actionable Comments (0)

Skipped Comments (0)

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• 8fcbb85: fix: check styles on publisher-subscriber design pattern (Publish/Subscribe pattern #2898)

Files Processed (11)

• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/App.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/CustomerSupportContent.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/Message.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/Topic.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/TopicName.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/WeatherContent.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/publisher/Publisher.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/publisher/PublisherImpl.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/CustomerSupportSubscriber.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/Subscriber.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/WeatherSubscriber.java (1 hunk)

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Skipped Comments (0)

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• d00524e: fix: check styles on publisher-subscriber design pattern (Publish/Subscribe pattern #2898)

Files Processed (9)

• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/CustomerSupportContent.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/Message.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/Topic.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/TopicName.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/WeatherContent.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/publisher/Publisher.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/publisher/PublisherImpl.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/Subscriber.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/WeatherSubscriber.java (1 hunk)

Actionable Comments (0)

Skipped Comments (0)

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• 208ca21: fix: check styles on publisher-subscriber design pattern (Publish/Subscribe pattern #2898)

Files Processed (1)

• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/CustomerSupportSubscriber.java (1 hunk)

Actionable Comments (0)

Skipped Comments (1)

• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/CustomerSupportSubscriber.java [5-16]

  redundancy: "Redundant logger initialization."

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• d5ac9d4: fix: improve coverage on publisher-subscriber design pattern (Publish/Subscribe pattern #2898)

Files Processed (1)

• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/AppTest.java (1 hunk)

Actionable Comments (0)

Skipped Comments (1)

• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/AppTest.java [9-12]

  enhancement: "Add more comprehensive tests to verify core functionality."

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• 7fdc594: Merge branch 'master' into master

Files Processed (0)

Actionable Comments (0)

Skipped Comments (0)

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• 92bc114: fix: fix dependancy on publisher-subscriber design pattern (Publish/Subscribe pattern #2898)

Files Processed (1)

• publish-subscribe/pom.xml (1 hunk)

Actionable Comments (0)

Skipped Comments (0)

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• bb5f9a6: fix: fix documentation on publisher-subscriber design pattern (Publish/Subscribe pattern #2898)

Files Processed (12)

• publish-subscribe/README.md (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/App.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/CustomerSupportContent.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/Message.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/Topic.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/TopicName.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/WeatherContent.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/publisher/Publisher.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/publisher/PublisherImpl.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/CustomerSupportSubscriber.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/Subscriber.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/WeatherSubscriber.java (1 hunk)

Actionable Comments (0)

Skipped Comments (0)

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• fd0d33b: fix: apply spotless on publisher-subscriber design pattern (Publish/Subscribe pattern #2898)

Files Processed (11)

• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/App.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/CustomerSupportContent.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/Message.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/publisher/Publisher.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/CustomerSupportSubscriber.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/WeatherSubscriber.java (1 hunk)
• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/AppTest.java (1 hunk)
• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/LoggerExtension.java (1 hunk)
• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/model/MessageTest.java (1 hunk)
• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/publisher/PublisherTest.java (1 hunk)
• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/subscriber/SubscriberTest.java (1 hunk)

Actionable Comments (0)

Skipped Comments (0)

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• 24ca271: fix: changes after review on publisher-subscriber design pattern (Publish/Subscribe pattern #2898)

Files Processed (12)

• publish-subscribe/README.md (1 hunk)
• publish-subscribe/etc/pub-sub.png (0 hunks)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/App.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/Topic.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/publisher/PublisherImpl.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/CustomerSupportSubscriber.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/DelayedWeatherSubscriber.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/WeatherSubscriber.java (1 hunk)
• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/model/MessageTest.java (1 hunk)
• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/model/TopicTest.java (1 hunk)
• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/publisher/PublisherTest.java (1 hunk)
• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/subscriber/SubscriberTest.java (1 hunk)

Actionable Comments (0)

Skipped Comments (0)

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• 1813b99: fix: changes after review on publisher-subscriber design pattern (Publish/Subscribe pattern #2898)

Files Processed (4)

• publish-subscribe/README.md (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/App.java (1 hunk)
• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/DelayedWeatherSubscriber.java (1 hunk)
• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/subscriber/SubscriberTest.java (1 hunk)

Actionable Comments (0)

Skipped Comments (0)

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• 0f6b3b4: fix: fix sonar on publisher-subscriber design pattern (Publish/Subscribe pattern #2898)

Files Processed (1)

• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/subscriber/SubscriberTest.java (1 hunk)

Actionable Comments (0)

Skipped Comments (1)

• publish-subscribe/src/test/java/com/iluwatar/publish/subscribe/subscriber/SubscriberTest.java [175-181]

  enhancement: "Improve waiting mechanism in tests."

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• f68c624: fix: fix sonar on publisher-subscriber design pattern (Publish/Subscribe pattern #2898)

Files Processed (1)

• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/DelayedWeatherSubscriber.java (1 hunk)

Actionable Comments (0)

Skipped Comments (1)

• publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/subscriber/DelayedWeatherSubscriber.java [28-36]

  performance: "Performance impact of artificial delay."

[sonarqubecloud]

Quality Gate passed

Issues
9 New issues
0 Accepted issues

Measures
0 Security Hotspots
91.4% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[iluwatar]

Looks good! Thank you for the contribution 🎉

@all-contributors please add @sanurah for code

[allcontributors]

@iluwatar

I've put up a pull request to add @sanurah! 🎉