Introduction to High Level Design

High level design is an architectural approach to designing software systems that focus on the overall structure and organization of the system. It involves defining the major components of the system, their relationships, and the interfaces between them.

In high level design, we take a holistic view of the system and consider the system as a whole rather than individual parts. This helps us understand how different components of the system interact with each other and how they contribute to the overall functionality of the system.

High level design is typically done before the detailed design and implementation phase. It helps in identifying the key features and functionalities of the system and provides a blueprint for the development team to follow.

Let's take an example to understand the concept of high level design better:

1  class Main {
2    public static void main(String[] args) {
3      // Replace with your Java logic here
4      System.out.println("High level design is an architectural approach to designing software systems that focus on the overall structure and organization of the system. It involves defining the major components of the system, their relationships, and the interfaces between them.");
5    }    
6  }

In this example, we have a Java program that prints out the definition of high level design. This is a simplified example to demonstrate the concept. In practice, high level design involves much more complex systems with multiple components and interactions.

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class Main {

    public static void main(String[] args) {

      // Replace with your Java logic here

      System.out.println("High level design is an architectural approach to designing software systems that focus on the overall structure and organization of the system. It involves defining the major components of the system, their relationships, and the interfaces between them.");

    }    

}

Defining the Problem

In order to design an effective solution, it is crucial to first have a thorough understanding of the problem statement and the requirements. This involves analyzing the problem statement, identifying the key objectives and constraints, and clarifying any ambiguities.

When defining the problem, it is essential to consider various factors:

• Input: What input data is available or required to solve the problem?
• Output: What is the expected output or desired outcome?
• Constraints: Are there any limitations or restrictions that need to be considered?
• Use Cases: What are the different scenarios or use cases that the solution should cater to?

Let's take a look at an example to illustrate the importance of defining the problem:

1<<code>>

In this example, we have a simple Java program that prints out a statement emphasizing the need to understand the problem before designing a solution. This serves as a reminder to always start by clearly defining the problem statement and requirements.

By properly defining the problem, we can ensure that our design and implementation align with the desired objectives and constraints, leading to a more effective and efficient solution.

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class Main {

  public static void main(String[] args) {

    // replace with your Java logic here

    System.out.println("In order to define a problem effectively, it is important to first understand the problem statement and the requirements.");

  }

}

Identifying Components

When designing a system, one of the key steps is to identify the major components that make up the system. These components are the building blocks of the system and play a crucial role in its overall functioning.

In the context of high-level design, components can be thought of as modules or classes that encapsulate a specific set of functionality. They can be independent entities or can interact with other components to achieve the desired behavior.

When identifying components, it is important to consider the following factors:

• Functionality: What specific functionality does each component provide?
• Responsibilities: What are the responsibilities of each component?
• Dependencies: Which components depend on or interact with each other?

Let's consider an example to illustrate the process of identifying components. Suppose we are designing a social media platform. Some possible components of this system could be:

• User Management: Handles user registration, authentication, and profile management.
• News Feed: Aggregates and displays posts from users' connections.
• Messaging: Enables communication between users through private messages.
• Analytics: Collects and analyzes data related to user engagement and platform performance.

By identifying these components, we can gain a high-level understanding of the system structure and its various functionalities. This helps in further refining the design and ensuring modularity and maintainability.

1<<code>>

In this example, we have a simple Java code snippet that illustrates the identified components and their interactions. The code demonstrates the basic structure of the social media platform and how different components collaborate to provide the desired functionality.

When designing a system, it is important to carefully analyze the requirements and break down the system into appropriate components. This allows for better organization, easier maintenance, and scalability of the system.

Designing Classes

In the process of high-level design, one of the crucial steps is designing the classes that will make up the system. Classes play a significant role in encapsulating the behavior and data of different entities within the system.

When designing classes, it is essential to consider the following aspects:

• Responsibilities: What are the responsibilities of each class? Each class should have a clear purpose and should be responsible for a specific set of behaviors and data.
• Relationships: How do the classes relate to each other? A well-designed system will have well-defined relationships between classes, such as composition, inheritance, or association.
• Abstraction: How can we abstract the common behavior and attributes of related classes? By designing classes with appropriate inheritance and interfaces, we can achieve abstraction and create reusable code.

Let's take an example to illustrate the process of designing classes. Suppose we are designing a sports team management system. We can start by designing two classes: Player and Team.

1<<code>>

In this example, we have a Player class that represents a player in a sports team. It has attributes like name, age, and jersey number, as well as getter methods to access these attributes. We also have a Team class that represents a sports team and contains a list of players. It has methods to add and remove players from the team, as well as a getter method to retrieve the list of players.

By designing the classes in a well-defined and organized manner, we can create a robust and maintainable system. The classes should have clear responsibilities, well-defined relationships, and appropriate abstraction to ensure code reusability and modularity.

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}

class Player {

    private String name;

    private int age;

    private int jerseyNumber;

​

    public Player(String name, int age, int jerseyNumber) {

        this.name = name;

        this.age = age;

        this.jerseyNumber = jerseyNumber;

    }

​

    public String getName() {

        return name;

    }

​

    public int getAge() {

        return age;

    }

​

    public int getJerseyNumber() {

        return jerseyNumber;

    }

}

​

class Team {

    private List<Player> players;

​

    public Team() {

        players = new ArrayList<>();

Defining APIs

In high-level design, one of the crucial steps is defining the APIs for interaction between components. APIs, or Application Programming Interfaces, provide a way for different components of a system to communicate and exchange data.

When defining APIs, it is important to consider the following aspects:

• Functionality: What functionality should the API provide? The API should expose necessary methods or endpoints to perform specific tasks or actions.
• Input and Output: What are the inputs required by the API, and what will be the output? Define the data format and structure for inputs and outputs.
• Error Handling: How will errors be handled in the API? Define how the API will handle and communicate errors or exceptions.

Let's take an example to illustrate the process of defining APIs in the context of a sports team management system. One of the APIs we can define is the getPlayerDetails API, which takes a player ID as input and returns the details of the player. Here's an example Java code snippet:

1<<code>>

In this example, the getPlayerDetails API takes a playerId as input and is responsible for fetching the player details from the database. This API provides a way for other components to retrieve player information.

By carefully defining APIs, we enable seamless interaction between different components of the system. APIs serve as the contract between components, allowing them to work together effectively and efficiently.

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class Main {

  public static void main(String[] args) {

    // replace with your Java logic here

    // Define APIs for interaction between components

    // Example: API to get player information

    Player getPlayerDetails(String playerId) {

      // Logic to fetch player details from the database

    }

  }

}

Handling Data Storage

When designing a high-level system, one of the important aspects to consider is how to handle data storage. Data storage is crucial for storing and retrieving data efficiently.

There are several ways to handle data storage, depending on the requirements of the system:

1. Relational Databases: Relational databases provide a structured way to store data using tables and relationships between tables. They ensure data integrity and support complex querying using SQL. Popular relational databases include MySQL, PostgreSQL, and Oracle.

2. NoSQL Databases: NoSQL databases are non-relational databases that are designed to handle large volumes of unstructured or semi-structured data. They provide flexible schemas and horizontal scaling. Examples of NoSQL databases include MongoDB, Cassandra, and Redis.

3. File Systems: File systems are used to store data in files and directories. They provide a simple way to organize and manage data but may not be suitable for complex querying or high scalability.

4. Cloud Storage: Cloud storage services, such as Amazon S3 and Google Cloud Storage, provide scalable and durable storage options with easy accessibility. They are ideal for storing large amounts of data and serving it over the internet.

The choice of data storage depends on factors such as data volume, query patterns, scalability requirements, and cost considerations. It's important to evaluate the pros and cons of different storage options and choose the one that best fits the system's needs.

Let's consider an example in the context of a job portal system. The system needs to store job listings, user profiles, and application data. A relational database like MySQL can be used to store structured data with relationships between tables. Here's a Java code snippet to illustrate the usage of MySQL:

1import java.sql.Connection;
2import java.sql.DriverManager;
3import java.sql.ResultSet;
4import java.sql.Statement;
5
6class Main {
7  public static void main(String[] args) {
8    try {
9      // Establish a connection to the MySQL database
10      Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/job_portal", "user", "password");
11
12      // Create a statement to execute SQL queries
13      Statement statement = connection.createStatement();
14
15      // Execute a query to fetch job listings
16      ResultSet resultSet = statement.executeQuery("SELECT * FROM job_listings");
17
18      // Iterate over the result set and process the data
19      while (resultSet.next()) {
20        int jobId = resultSet.getInt("id");
21        String jobTitle = resultSet.getString("title");
22
23        System.out.println("Job ID: " + jobId + ", Job Title: " + jobTitle);
24      }
25
26      // Close the resources
27      resultSet.close();
28      statement.close();
29      connection.close();
30    } catch (Exception e) {
31      e.printStackTrace();
32    }
33  }
34}

In this example, we establish a connection to a MySQL database, execute a query to fetch job listings, and process the result set. The data is stored and retrieved using SQL queries.

By carefully selecting and implementing the appropriate data storage solution, we can ensure efficient and reliable data management in our high-level system.

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class Main {

  public static void main(String[] args) {

    // replace with your Java logic here

    // Data storage implementation code

  }

}

Considerations for Scalability

When designing a high-level system, it's important to consider scalability aspects to ensure that the system can handle growing demands and increasing workload. Scalability refers to the system's ability to handle higher loads without compromising performance or user experience.

There are several key considerations to keep in mind when designing for scalability:

1. Horizontal Scalability: Horizontal scalability involves adding more machines or instances to the system to distribute the workload. This approach allows the system to handle increased traffic by scaling out rather than scaling up. For example, in a web application, adding more servers to a load balancer can help distribute incoming requests and prevent any single server from becoming a bottleneck.

2. Vertical Scalability: Vertical scalability involves increasing the resources of a single machine to handle increased workload. This may include upgrading the CPU, memory, or storage capacity of the machine. Vertical scalability can provide improved performance for individual requests, but it may have limitations in terms of the maximum capacity that a single machine can handle.

3. Caching: Caching is a technique used to store frequently accessed data in memory or a cache layer to minimize the load on the backend systems. By caching data at strategic points in the system, the overall response time can be significantly improved. Caching can be implemented at various levels, such as application-level caching, database query caching, or distributed caching using tools like Redis.

4. Asynchronous Processing: Asynchronous processing involves decoupling time-consuming or resource-intensive tasks from the main request-response flow. By offloading these tasks to background processes or queues, the system can handle requests more efficiently and improve overall scalability. Asynchronous processing can be used for tasks such as sending emails, generating reports, or processing large datasets.

5. Database Optimization: The choice of database and its optimization play a crucial role in the scalability of a system. Techniques such as indexing, denormalization, and sharding can optimize database performance and improve scalability. Additionally, considering the use of distributed databases or NoSQL databases can be beneficial for handling large volumes of data and high traffic.

6. Monitoring and Load Testing: Regular monitoring and load testing are essential for identifying bottlenecks and performance issues in the system. By monitoring system metrics, such as CPU usage, memory usage, and response times, you can proactively identify areas that require optimization. Load testing helps simulate high traffic scenarios and identify how the system behaves under increased load.

By considering these scalability considerations during the design phase, you can ensure that the system is prepared to handle growing demands, maintain performance, and provide a seamless user experience.

Let's illustrate the concept of scalability with an example. Consider a scenario where you have to solve the classic FizzBuzz problem. The problem is to print the numbers from 1 to 100, but for multiples of 3, print "Fizz" instead, and for multiples of 5, print "Buzz" instead. For numbers that are multiples of both 3 and 5, print "FizzBuzz".

Here's a Java code snippet that solves the FizzBuzz problem:

1class Main {
2    public static void main(String[] args) {
3     for(int i = 1; i <= 100; i++) {
4       if(i % 3 == 0 && i % 5 == 0) {
5           System.out.println("FizzBuzz");
6       } else if(i % 3 == 0) {
7           System.out.println("Fizz");
8       } else if(i % 5 == 0) {
9           System.out.println("Buzz");
10       } else {
11           System.out.println(i);
12       }
13     }    
14   }
15 }```

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class Main {

    public static void main(String[] args) {

     for(int i = 1; i <= 100; i++) {

       if(i % 3 == 0 && i % 5 == 0) {

           System.out.println("FizzBuzz");

       } else if(i % 3 == 0) {

           System.out.println("Fizz");

       } else if(i % 5 == 0) {

           System.out.println("Buzz");

       } else {

           System.out.println(i);

       }

     }    

   }

 }

Designing for Performance

When it comes to designing high-level systems, optimizing for performance is a critical factor to consider. Performance refers to how efficiently a system can execute its operations, handle high workloads, and respond to user requests in a timely manner.

To achieve a high-performance design, here are some key considerations:

1. Efficient Algorithms: Choosing efficient algorithms is paramount to achieving optimal performance. Algorithms with better time and space complexity will significantly improve the system's overall efficiency. As a developer with a strong background in data structures and algorithms, you are well-versed in identifying and implementing efficient algorithms to solve various problems.

2. Scaling Techniques: Employing scaling techniques can help distribute the workload and improve system performance. Horizontal scalability, where additional machines or instances are added to handle increased traffic, and vertical scalability, which involves upgrading resources of a single machine, can both be utilized to optimize performance for different scenarios.

3. Caching: Caching frequently accessed data can reduce the load on backend systems and improve response times. By implementing caching mechanisms at various levels, such as application-level caching or distributed caching, you can effectively enhance performance by minimizing redundant computation or data retrieval operations.

4. Optimized Database Queries: Efficiently querying databases is crucial for performance optimization. By using appropriate indexes, avoiding unnecessary joins or subqueries, and optimizing database schema design, you can significantly improve query execution times and overall system performance. Your experience with MySQL and understanding of its optimization techniques will be beneficial in this regard.

5. Handling I/O Operations: Efficiently handling input/output (I/O) operations, such as reading from or writing to files or network connections, can have a substantial impact on system performance. Properly managing buffering, reducing disk I/O, or utilizing asynchronous I/O techniques can contribute to better performance.

6. Identifying Bottlenecks: Profiling and identifying performance bottlenecks in the system is essential for optimization. Using tools like Java VisualVM or JProfiler, you can analyze CPU usage, memory consumption, and other system metrics. With your experience in Java and Spring Boot, you are familiar with these profiling tools and can identify and resolve performance bottlenecks.

Optimizing for performance requires a combination of efficient algorithms, scalable design, caching strategies, optimized database queries, thoughtful handling of I/O operations, and effective bottleneck identification. By applying these principles in your high-level design, you can create systems that deliver superior performance and meet the demands of modern applications efficiently.

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class Main {

    public static void main(String[] args) {

        // Replace with your Java logic here

    }

}

Security and Privacy

Addressing security and privacy concerns in the design of high-level systems is of utmost importance. It involves implementing measures to protect sensitive data, ensure secure access and communication between components, and address potential vulnerabilities.

Encryption and Data Protection

Encryption plays a vital role in securing sensitive data. It involves transforming data into an unreadable format using encryption algorithms and requires a secret key to decrypt the data back into its original form. Algorithms like AES (Advanced Encryption Standard) or RSA (Rivest-Shamir-Adleman) can be used to encrypt data.

Here's an example of secure encryption in Java:

1// Example of secure encryption
2class Main {
3  public static void main(String[] args) {
4    String plaintext = "This is sensitive data";
5    String key = "secretpassword";
6    String ciphertext = encrypt(plaintext, key);
7    System.out.println("Encrypted data: " + ciphertext);
8  }
9
10  private static String encrypt(String plaintext, String key) {
11    // replace with encryption logic
12    return ciphertext;
13  }
14}

Access Control

Implementing secure access control is critical to ensure that only authorized users can interact with sensitive data or perform specific actions. It involves defining roles, permissions, and authentication mechanisms to enforce access restrictions.

Here's an example of secure access control in Java:

1// Example of secure access control
2class User {
3  private String name;
4  // ... other user properties
5  
6  public User(String name) {
7    this.name = name;
8  }
9  
10  public boolean hasPermission(String action, String resource) {
11    // replace with permission logic
12    return true;
13  }
14}
15
16User user = new User("John Doe");
17if (user.hasPermission("read", "sensitive_data")) {
18  System.out.println("User has permission to read sensitive data");
19} else {
20  System.out.println("User does not have permission to read sensitive data");
21}

By implementing strong encryption mechanisms and secure access control, high-level designs can ensure the security and privacy of sensitive data and protect against unauthorized access and breaches.

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class Main {

  public static void main(String[] args) {

    // replace with your Java logic here

    System.out.println("Designing for security and privacy is crucial in high-level systems. It involves implementing measures to protect sensitive data and ensure secure access and communication between components.");

    // Example of secure encryption

    String plaintext = "This is sensitive data";

    String key = "secretpassword";

    String ciphertext = encrypt(plaintext, key);

    System.out.println("Encrypted data: " + ciphertext);

    // Example of secure access control

    User user = new User("John Doe");

    if (user.hasPermission("read", "sensitive_data")) {

      System.out.println("User has permission to read sensitive data");

    } else {

      System.out.println("User does not have permission to read sensitive data");

    }

  }

​

  private static String encrypt(String plaintext, String key) {

    // replace with encryption logic

    return ciphertext;

  }

}

Testing and Validation

Testing and validation are essential components of the software development lifecycle. They help ensure that the system functions as expected, meets the requirements, and is free from errors and bugs.

Types of Testing

Various types of testing are performed to validate the system:

1. Unit Testing: This type of testing involves testing individual components or units of code to ensure they work correctly in isolation. It helps identify and fix issues at an early stage.

2. Integration Testing: Integration testing is conducted to verify the proper functioning of different components when integrated or combined together. It tests the interaction and communication between components.

3. System Testing: System testing is performed on the complete and integrated system to validate that it meets the specified requirements and functions as expected. It ensures the system works as a whole and all components work together seamlessly.

4. Acceptance Testing: Acceptance testing is the final testing phase and is performed by end-users or stakeholders. It checks if the system meets the user requirements and if it is ready for deployment.

Test-Driven Development (TDD)

Test-driven development is an approach where tests are written first before writing the actual code. It follows the Red-Green-Refactor cycle, where tests are written, the code is developed to make the tests pass, and then the code is refactored for better design.

Here's an example of test-driven development in Java using JUnit:

1import org.junit.Test;
2import static org.junit.Assert.*;
3
4public class FizzBuzzTest {
5   @Test
6   public void testFizzBuzz() {
7       FizzBuzz fizzBuzz = new FizzBuzz();
8       assertEquals("1", fizzBuzz.fizzBuzz(1));
9       assertEquals("2", fizzBuzz.fizzBuzz(2));
10       assertEquals("Fizz", fizzBuzz.fizzBuzz(3));
11       assertEquals("4", fizzBuzz.fizzBuzz(4));
12       assertEquals("Buzz", fizzBuzz.fizzBuzz(5));
13       assertEquals("Fizz", fizzBuzz.fizzBuzz(6));
14       assertEquals("Buzz", fizzBuzz.fizzBuzz(10));
15       assertEquals("FizzBuzz", fizzBuzz.fizzBuzz(15));
16   }
17}
18
19public class FizzBuzz {
20   public String fizzBuzz(int n) {
21       if (n % 3 == 0 && n % 5 == 0) {
22           return "FizzBuzz";
23       } else if (n % 3 == 0) {
24           return "Fizz";
25       } else if (n % 5 == 0) {
26           return "Buzz";
27       }
28       return String.valueOf(n);
29   }
30}

Automated Testing and Continuous Integration

Automated testing and continuous integration are practices that support testing and validation. Automated tests can be run repeatedly to ensure that changes or new additions to the system do not introduce regressions or break existing functionality. Continuous integration ensures that the code changes made by multiple developers are integrated and tested frequently, reducing the chances of conflicts and issues later on.

In conclusion, testing and validation are crucial steps in the software development process. They help identify and fix issues early, ensure the system meets the specified requirements, and provide confidence in the system's functionality and reliability.

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class Main {

  public static void main(String[] args) {

    // replace with your Java logic here

    for(int i = 1; i <= 100; i++) {

      if(i % 3 == 0 && i % 5 == 0) {

          System.out.println("FizzBuzz");

      } else if(i % 3 == 0) {

          System.out.println("Fizz");

      } else if(i % 5 == 0) {

          System.out.println("Buzz");

      } else {

          System.out.println(i);

      }

    }

  }

}

Documentation and Communication

In software development, documentation and communication play a crucial role in the overall design process. They facilitate effective collaboration, knowledge sharing, and understanding among team members.

Importance of Documentation

Documentation serves as a comprehensive source of information about the system, its components, and their functionalities. It acts as a reference for developers, designers, and stakeholders, ensuring everyone is on the same page. Good documentation helps in:

• Understanding the System: Documentation provides insights into the system's architecture, design decisions, and implementation details. It helps new team members get up to speed quickly and assists in maintaining and modifying the system.

• Ensuring Consistency: Consistent documentation ensures that everyone follows the same standards, conventions, and best practices. It helps maintain code quality and readability, making it easier to identify and fix issues.

• Enhancing Collaboration: Documentation encourages collaboration and effective communication between team members. It provides a common platform for sharing ideas, discussing design decisions, and resolving issues.

Types of Documentation

Various types of documentation are typically created during the design process:

• Requirements Documentation: This captures the system's functional and non-functional requirements. It defines what the system should do and the constraints it needs to adhere to.

• Design Documentation: Design documentation includes architectural diagrams, class diagrams, sequence diagrams, and other design artifacts. It helps understand the system's structure, components, and their interactions.

• Technical Documentation: Technical documentation focuses on the technical details of the system, including APIs, data models, algorithms, and implementation specifics. It provides guidelines and instructions for developers and maintains a record of design decisions.

• User Documentation: User documentation aims to assist end-users in understanding and using the system. It includes user manuals, guides, FAQs, and troubleshooting information.

Importance of Communication

Effective communication is essential for successful software design. It ensures that all stakeholders have a clear understanding of the system's requirements, design choices, and progress. Communication facilitates:

• Requirements Gathering: Communication helps in eliciting and understanding the system's requirements from stakeholders. It ensures that all necessary information is captured accurately and avoids any misunderstandings.

• Collaborative Design: Communication enables collaboration among team members, allowing them to share ideas, provide feedback, and collectively make design decisions. Regular meetings, discussions, and reviews facilitate a smooth design process.

• Alignment with Stakeholders: Communication helps ensure that the design aligns with the expectations and needs of stakeholders. Regular updates, demos, and feedback loops keep stakeholders engaged and informed about the design progress.

• Issue Resolution: Effective communication aids in resolving design issues and conflicts. It encourages open discussions and allows team members to address concerns, propose solutions, and reach consensus.

In conclusion, documentation and communication are vital aspects of the design process. They promote collaboration, knowledge sharing, and understanding, leading to well-designed software systems.

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class Main {

public static void main(String[] args) {

    System.out.println("Hello World!");

}

}

Putting It All Together

In this tutorial, we explored the concepts and principles of high-level design in software development. We discussed the importance of high-level design and its various aspects, such as defining the problem, identifying components, designing classes, defining APIs, handling data storage, considering scalability, designing for performance, addressing security and privacy concerns, testing and validation, and the significance of documentation and communication.

By following a structured high-level design process, we can effectively plan and create software systems that meet the desired requirements and are scalable, maintainable, and performant.

To summarize, high-level design involves:

• Understanding the problem and its requirements
• Identifying the major components of the system
• Designing classes and their relationships
• Defining APIs for component interaction
• Handling data storage
• Considering scalability and performance
• Addressing security and privacy concerns
• Testing and validating the design
• Documenting the design process

Now that we have covered the fundamentals of high-level design, you are ready to apply these concepts and principles in real-world scenarios. Remember to practice and explore more examples to enhance your understanding of high-level design!

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class Main {

  public static void main(String[] args) {

    // Replace with your Java logic here

    System.out.println("Hello, World!");

  }

}