Case Studies and Examples of Design Patterns

Below are some case studies and examples of design patterns:

1. Singleton Pattern for Database Connections

• Context: The database is accessed through many requests in web applications which might slow down the response time for the user.
• Design Pattern: The Singleton pattern is an example of one class that realizes one instance of the placement of the database connection.
• Impact: Through this approach, the system serves one connection to the database allowing it to reuse resources while performing better. While it is possible, getting concurrency in case the Singleton instance is accessed at the same time by various threads needs careful treatment.

2. Observer Pattern for Event Handling

• Context: In the case of a GUI application where various elements like buttons and so on respond to events caused by user clicks.
• Design Pattern: The Observer pattern is used to disconnect the event’s publisher ( e.g., button) from the event’s subscribers(e.g., text fields, labels).
• Impact: This approach brings about necessary improvements in maintenance and scalability by ensuring every group can respond independently of others. But if there are many observers, the pattern will introduce the latency in a non-transforming manner, as each entity should be notified one by one.

3. Proxy Pattern for Remote Method Invocation

• Context: In the case of a distributed system, the client needs to call methods, which are on the remote machine.
• Design Pattern: The logic of the Proxy is to implement a local proxy, which will do the communication with the server should it be remote.
• Impact: The model Automates backend issues and thus facilitates their user interaction with the server by eliminating the complexity of backend communication. On the other hand, it may lead to performance weaknesses associated with network latency as well as serialized and deserialized data.

4. Factory Pattern for Object Creation

• Context: The target software systems of objects must be created based on different criteria.
• Design Pattern: The Factory method pattern allows developers to decouple the object creation process and postpone the class initialization of objects to runtime, avoiding the specification of concrete classes.
• Impact: This is a good pattern because it makes the object creation process transparent which makes the code more flexible and maintainable. The downside may be seen in creating this transparency which requires one additional layer of indirection which may increase the overhead. Creating a sustainable design is a way of counteracting such effects.

5. Strategy Pattern for Algorithm Selection

• Context: In a sorting algorithm library already exists, various sorting algorithms for different data types and a large scale are available.
• Design Pattern: The strategy decorator allows selecting a sorting algorithm at runtime rather than compile time.
• Impact: To illustrate, such pattern engineers performance via computationally the most suitable algorithm’s selection in terms of the contextual factors. In addition, it provides for the easy management of the code and testing purposes.

Design patterns are a means of handling common software design problems in a structured way so that software will be easier to implement. The systematic use of patterns can of course positively impact such aspects as maintainability, scalability, and legibility of the code, consequently improving the quality of the system in its own right.