Resolved issue #1323 Two-Step View pattern

microservices-idempotent-consumer/src/test/java/com/iluwatar/idempotentconsumer/AppTest.java

@@ -1,3 +1,27 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
 package com.iluwatar.idempotentconsumer;
 
 import org.junit.jupiter.api.Test;

microservices-idempotent-consumer/src/test/java/com/iluwatar/idempotentconsumer/RequestStateMachineTests.java

@@ -1,3 +1,27 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
 package com.iluwatar.idempotentconsumer;
 
 import org.junit.jupiter.api.BeforeEach;

pom.xml

@@ -218,6 +218,7 @@
     <module>function-composition</module>
     <module>microservices-distributed-tracing</module>
     <module>microservices-idempotent-consumer</module>
+      <module>two-step-view</module>
   </modules>
   <repositories>
     <repository>

two-step-view/README.md

@@ -0,0 +1,79 @@
+# Book Data Processing and Presentation
+
+This example demonstrates a simple pipeline for processing book data and rendering it as an HTML view. It involves three main steps: **data preparation**, **business logic processing**, and **presentation**. The structure of the program aligns with the principles of the **Presentation-Abstraction-Control (PAC)** design pattern.
+
+---
+
+## Problem Addressed
+This implementation solves the issue described in [Issue #1323](https://github.com/iluwatar/java-design-patterns/issues/1323) of the [java-design-patterns repository](https://github.com/iluwatar/java-design-patterns). The goal is to showcase how to split application logic into phases while keeping the layers loosely coupled.
+
+---
+
+## Overview of the Solution
+The program is divided into the following parts:
+
+1. **Data Layer**
+    - The `Book` class represents the raw data for a book.
+    - The `BookStore` class holds the processed book data for display.
+
+2. **Logic Layer**
+    - The `DataPreparation` class handles the business logic. It computes whether a discount is applied and checks stock availability.
+
+3. **Presentation Layer**
+    - The `Presentation` class generates an HTML view of the book data.
+
+---
+
+## How to Run the Code
+
+1. Clone the repository:
+   ```bash
+   git clone https://github.com/iluwatar/java-design-patterns.git
+   cd java-design-patterns
+   ```
+
+2. Compile and run the `App` class:
+   ```bash
+   javac com/iluwatar/*.java
+   java com.iluwatar.App
+   ```
+
+3. Expected Output:  
+   The program generates an HTML representation of the book data and prints it to the console:
+   ```html
+   <div class='book'>
+       <h1>Batman Vol. 1: The Court of Owls</h1>
+       <p>Price: $11.6</p>
+       <p>Discounted Price: $8.7</p>
+       <p>Status: In Stock</p>
+   </div>
+   ```
+
+---
+
+## Code Structure
+
+- `Book`: Represents raw book data with fields like `name`, `price`, `discount`, and `stock`.
+- `BookStore`: Represents processed data including `discountPrice` and `inStock` status.
+- `DataPreparation`: Contains logic to calculate the discount price and determine stock status.
+- `Presentation`: Generates the HTML view of the book data.
+- `App`: Entry point that orchestrates the flow.
+
+---
+
+## Key Features
+
+- **Layered Architecture**: The application is divided into layers for better separation of concerns.
+- **Scalable Design**: The modular approach makes it easier to extend functionality, such as adding new data preparation rules or presentation formats.
+- **Reusability**: Each layer operates independently, promoting code reuse.
+
+---
+
+## Related Resources
+
+- **GitHub Issue**: [Issue #1323](https://github.com/iluwatar/java-design-patterns/issues/1323)
+- **Repository**: [java-design-patterns](https://github.com/iluwatar/java-design-patterns)
+- **Design Pattern**: [Two-Step-View-Pattern](https://martinfowler.com/eaaCatalog/twoStepView.html)
+
+
+

two-step-view/pom.xml

@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+    This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+
+    The MIT License
+    Copyright © 2014-2022 Ilkka Seppälä
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>com.iluwatar</groupId>
+        <artifactId>java-design-patterns</artifactId>
+        <version>1.26.0-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>two-step-view</artifactId>
+
+    <properties>
+        <maven.compiler.source>17</maven.compiler.source>
+        <maven.compiler.target>17</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+</project>

two-step-view/src/main/java/com/iluwatar/App.java

@@ -0,0 +1,47 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar;
+
+import java.util.logging.Logger;
+
+/** Main class. */
+public class App {
+  private static final Logger logger = Logger.getLogger(App.class.getName());
+
+  /** Main function. */
+  public static void main(String[] args) {
+    // Create a Book instance with sample data
+    Book book = new Book("Batman Vol. 1: The Court of Owls", 11.60, true, 10);
+
+    // Convert raw book data into a structured format
+    BookStore preparedData = DataPreparation.prepareBook(book);
+
+    String htmlOutput = Presentation.presentBook(preparedData);
+
+    // Output the rendered HTML
+    logger.info(htmlOutput);
+  }
+}
+

two-step-view/src/main/java/com/iluwatar/Book.java

@@ -0,0 +1,47 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar;
+import lombok.Data;
+
+/** Represents a Book. */
+@Data
+public class Book {
+  String name;
+  double price;
+  boolean discount;
+  int stock;
+  Book(String name, double price, boolean discount, int stock) {
+    if (!name.isEmpty()) { // Make sure is not empty
+      this.name = name;
+    }
+    if (price > 0) { // Make sure price is set with a realistic value
+      this.price = price;
+    }
+    if (stock >= 0) { // Make sure stock is not negative
+      this.stock = stock;
+    }
+    this.discount = discount;
+  }
+}

two-step-view/src/main/java/com/iluwatar/BookStore.java

@@ -0,0 +1,39 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+/** Represents the processed book data used for display purposes. */
+@AllArgsConstructor
+@Data
+public class BookStore {
+  String name;
+  double price;
+  double discountPrice; // Calculates price if the book is discounted
+  boolean inStock; // Indicates if the book is in stock
+
+}

two-step-view/src/main/java/com/iluwatar/DataPreparation.java

@@ -0,0 +1,43 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar;
+
+
+
+/** class representing phase 1. */
+public class DataPreparation {
+
+  private DataPreparation() {}
+  /**
+   * Prepares book data for the store.
+   * Calculates the discount price if applicable and checks stock availability.
+   */
+
+  public static BookStore prepareBook(Book book) {
+    double discountPrice = book.isDiscount() ? book.getPrice() * 0.75 : book.getPrice();
+    boolean inStock = book.getStock() > 0;
+    return new BookStore(book.getName(), book.getPrice(), discountPrice, inStock);
+  }
+}