Identify Three Stakeholder Groups From The BDSS And Concussi

Identify three groups of stakeholders from the BDSS and concerns that influence architecture

This assignment explores the design and architectural considerations of the BillyDoo Software System (BDSS). It requires identifying stakeholders, their concerns, and analyzing architectural styles involved in a notification feature. It further explores design patterns, specifically the Proxy pattern, in the context of software design, including sequence diagrams and comparisons with other patterns. Additionally, it examines microservices architecture, performance scenarios, and software metrics, culminating in a comprehensive understanding of software engineering principles.

Paper For Above instruction

Introduction

The development of complex software systems necessitates careful consideration of stakeholder needs, architectural styles, and design patterns. The BillyDoo Software System (BDSS) serves as an illustrative case for analyzing stakeholder concerns, architectural decisions, and pattern applications. This paper delves into these aspects, focusing on stakeholder analysis, architectural styles for notification services, the application of the Model-View-Controller (MVC) pattern, the Proxy pattern's nuances, microservices architecture features, performance and usability scenarios, as well as code complexity metrics, providing a holistic view of modern software engineering practices.

Stakeholders and Their Concerns within BDSS

Identifying stakeholders and their concerns is fundamental to tailoring software architecture that aligns with varying interests. In the context of BDSS, three primary stakeholder groups include end-users (members of the public), event organizers, and system administrators.

  • End-users: They are primarily interested in personalized notifications about upcoming events matching their preferences such as category and location. Their concern centers on the relevance and timeliness of notifications, as well as privacy issues related to data handling and account security.
  • Event organizers: This group aims to maximize visibility for their events. Their concern revolves around the accurate delivery of event information and ensuring that their events are properly categorized and located in the system for optimal reach by interested users.
  • System administrators: They focus on system stability, security, and performance. Their concerns include maintaining system uptime, safeguarding user data, and ensuring the notification service operates efficiently under varying loads.

Architectural Styles for the Notification Service Scenario

The scenario involves users registering for event updates, receiving emails with links to customized event pages, and the system potentially employing several architectural styles. For such a feature, a multi-layered architecture with clients, web servers, and backend services is typical. An event-driven architecture could be integral, facilitating asynchronous notifications. The email notification feature might leverage a publish-subscribe pattern, where user preferences act as filters, and notification triggers are published whenever a new event meeting criteria is added.

Furthermore, employing a microservices architectural style can enhance scalability, with dedicated services managing user preferences, event categorization, and notification dispatching. RESTful services may facilitate communication between components, ensuring modularity. The style chosen would emphasize loose coupling and high cohesion, key for maintainability and scalability.

Understanding MVC Through a Chosen Application

A concrete example of the MVC pattern is the Gmail web client. The application allows users to read, compose, and manage emails via an interactive interface.

- The Model corresponds to the data layer—email messages, user data, folders stored in a database.

- The View is the graphical interface displaying the inbox, email content, and composing windows.

- The Controller manages user inputs, such as clicking a button to send an email or delete messages, coordinating actions with the model and updating views accordingly.

The MVC pattern offers clear separation of concerns, facilitating independent development and testing. It enhances flexibility, as views can change without impacting business logic, and encourages modularity, making maintenance more straightforward.

The Proxy Pattern and Its Applications

The Proxy pattern encapsulates access control, lazy loading, and remote communication by providing a surrogate for the real subject object. A virtual proxy is particularly relevant when loading resources is resource-intensive, such as large images in document editing software.

The structure involves a subject interface, a real subject implementing core functionalities, and a proxy controlling access and object instantiation. For example, in a document editor, image proxies defer loading large images until necessary, improving load times.

Sequence Diagram and Alternative Actions

The interaction sequence involves the client requesting an image via the proxy. If the real image does not exist, the proxy instantiates it, loads the image from disk, and forwards the request. If it exists, the proxy directly forwards the request. This behavior can be represented by a guard condition in the diagram, illustrating the decision point for object creation.

Comparison of Proxy and Adapter Patterns and Their Couplings

The Proxy pattern shares similarities with the Adapter pattern in that both wrap an existing object to alter or control its behavior. However, while the Proxy controls access, the Adapter transforms interfaces for compatibility.

Proxy tends to achieve looser coupling, as it implements the same interface as the real subject and can be swapped transparently. The Adapter, however, often introduces a different interface to match incompatible classes, which can increase coupling if not managed carefully.

A Factory pattern can indeed be integrated with the Proxy pattern, particularly when dynamic creation of proxies is required, such as in systems with multiple proxy types or where proxies are selected based on runtime conditions.

Microservices Architecture: Features and Benefits

Martin Fowler’s microservices paradigm emphasizes decomposition of applications into small, independent services focusing on specific functionalities. Key features include decentralized data management, autonomous development teams, and continuous deployment.

Unlike monolithic applications, which bundle all functionalities into a single unit, microservices are componentized into distinct modules, each responsible for a particular business capability. This division facilitates scalability, resilience, and technology diversity.

Teams are typically organized around services, enabling independent deployment and updates, which contrasts with monolithic structures where tight coupling complicates modifications.

Data management in microservices is decentralized, allowing each service its data store, which increases flexibility and prevents data bottlenecks. Monitoring becomes vital to detect failures early and maintain system health, aligning with designing for failure principles that encourage fault tolerance.

Microservices – Advantages and Disadvantages

Advantages include improved scalability, resilience, and faster deployment cycles. Disadvantages encompass increased complexity in managing distributed systems, challenges in data consistency, and potential overhead in inter-service communication.

Preconditions for Microservices Adoption

Organizations should have mature DevOps culture, automated deployment pipelines, and comprehensive monitoring systems before adopting microservices. Additionally, teams must be skilled in distributed system design, and the system should benefit from separation of concerns.

Performance and Usability Scenario for BDSS

Performance Scenario: When the number of users subscribing to event notifications exceeds 10,000 simultaneously, the system experiences significant latency in sending emails, leading to delayed notifications and decreased user satisfaction. This scenario tests the system’s capacity to handle high load efficiently and ensure prompt delivery of notifications.

Applying Black Box Testing Principles

Test planning involves analyzing input parameters—such as email address length, event category validity, and location data—to define boundary conditions and typical cases. Principles include partitioning input data into equivalence classes, covering valid, invalid, and edge cases. For example, testing maximum and minimum weight limits for a letter, or invalid dimensions exceeding allowed sizes, adheres to the Design by Contract precondition requirements. Estimating minimal test cases requires identifying representative classes and boundary values; typically, a set of five to ten tests suffices to cover the critical input space.

Java Method Precondition Assertion

An example assertion to verify preconditions could be:

assert weight > 0 && weight

Impact of Design by Contract on Unit Testing

Design by Contract simplifies unit testing by explicitly defining preconditions and postconditions, which serve as clear fail points for invalid inputs and incorrect outputs, enabling automated verification of method correctness with minimal supplementary tests.

Code Metrics and Complexity Analysis

Sample codes—a method with multiple conditionals and loops—are chosen to illustrate differences in LOC and cyclomatic complexity. Calculations show that code with nested conditionals increases complexity, guiding refactoring decisions towards smaller, more maintainable units.

Conclusion

In summary, understanding stakeholder concerns, architectural styles, design patterns, and quality metrics is essential for developing robust, scalable, and maintainable software systems. Employing patterns like MVC and Proxy, alongside microservice architecture, supports these goals, while metrics inform ongoing improvements in code quality.

References

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  • Richardson, C., & Ruby, S. (2007). RESTful Web Services. O'Reilly Media.
  • Martin, R. C. (2008). Clean Code: A Handbook of Agile Software Craftsmanship. Prentice Hall.
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