Persistent Systems Module Lead Interview Questions, Process, and Tips

Liskov Principle is a principle of object-oriented programming that states that objects of a superclass should be replaceable with objects of its subclasses without affecting the correctness of the program.

• Named after Barbara Liskov, a computer scientist who introduced the principle in 1987

• Also known as Liskov Substitution Principle (LSP)

• Helps in designing classes that are easy to extend and maintain

• Violation of LSP ca...read more

Factory Design Pattern is a creational pattern that provides an interface for creating objects in a superclass, but allows subclasses to alter the type of objects that will be created.

• Factory Design Pattern is used to create objects without exposing the creation logic to the client.

• It provides a way to delegate the instantiation logic to child classes.

• It promotes loose coupling by eliminating the need to bind applicati...read more

Runtime polymorphism is the ability of an object to take on multiple forms during runtime.

• It is achieved through inheritance and method overriding.

• The method called depends on the actual object type at runtime.

• Example: Animal class with a speak() method, and Dog and Cat classes that inherit from Animal and override the speak() method.

• When a Dog object calls speak(), the overridden method in the Dog class is executed.

• Wh...read more

Dependency injection is a design pattern where objects are passed as dependencies rather than being created within a class.

• Reduces coupling between classes

• Increases testability and maintainability

• Allows for easier swapping of dependencies

• Examples: Constructor injection, Setter injection, Interface injection

Yes, I have worked with nUnit framework.

• I have used nUnit for unit testing in C# projects.

• I am familiar with its syntax and assertions.

• I have integrated nUnit with Visual Studio for continuous testing.

• I have used nUnit to test both simple and complex scenarios.

• For example, I used nUnit to test a payment processing system.

• I also used nUnit to test a complex algorithm for data analysis.

Endpoints are URLs that clients use to access resources in a WebAPI.

• Endpoints are the entry points for a WebAPI.

• They define the resources that can be accessed by clients.

• Endpoints are identified by a URL and HTTP method.

• Examples of endpoints include /api/users and /api/products.

• Endpoints can have parameters that are passed in the URL or request body.

WebService is a software system designed to support interoperable machine-to-machine interaction over a network. WebApi is a framework for building HTTP services that can be consumed by a broad range of clients.

• WebService uses SOAP protocol for communication while WebApi uses HTTP protocol.

• WebService is platform-independent while WebApi is platform-dependent.

• WebService supports only XML format while WebApi supports XML...read more

Singleton and static are both design patterns used to create objects with global access, but they differ in their implementation.

• Singleton restricts the instantiation of a class to a single object, while static allows multiple instances.

• Singleton provides a global point of access to the object, while static members are accessed through the class name.

• Singleton can be lazy-loaded, while static members are initialized at...read more

Entity framework supports left/right join to pull details from joinee table.

• Use LINQ to perform left/right join in Entity framework

• Use DefaultIfEmpty() method to perform left join

• Use join...into statement to perform right join

• Example: var result = from employee in context.Employees

• join department in context.Departments on employee.DepartmentId equals department.Id into empDept

• from department in empDept.DefaultIfEmpty()

DI can be achieved through method, constructor, and property level patterns.

• Method level DI involves passing dependencies as method parameters.

• Constructor level DI involves passing dependencies as constructor parameters.

• Property level DI involves setting dependencies as properties of an object.

• Examples of DI frameworks that use these patterns include Spring and Unity.

• Choosing the appropriate pattern depends on the spec

Select alternate rows from SQL

• Use the modulo operator to filter alternate rows

• Add a WHERE clause with the modulo operator

• Example: SELECT * FROM table WHERE id % 2 = 0

• Example: SELECT * FROM table WHERE MOD(id, 2) = 0

Clustered index determines physical order of data while non-clustered index has separate structure.

• Clustered index determines the physical order of data in a table while non-clustered index has a separate structure.

• Clustered index is faster for retrieval of data while non-clustered index is faster for retrieval of specific data.

• A table can have only one clustered index while multiple non-clustered indexes can be create...read more