30+ H2A Architect Interview Questions and Answers

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.

• When a Cat object calls speak(), the overridden method in th...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

Indexing in SQL is a way to optimize database performance by creating a data structure that allows for faster retrieval of data.

• Indexing is a technique used to quickly locate and access the rows in a database table.

• It works by creating an ordered list of values from one or more columns in a table.

• By using indexes, the database engine can quickly find the rows that match a certain condition without having to scan the entire table.

• Indexes are especially useful for tables with a...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() select new { employee.Name, department.Name }

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.

Partitions in Informatica help in parallel processing and improving performance.

• Partitions in databases and Informatica serve different purposes

• Informatica partitions help in parallel processing of data

• Improves performance by distributing data processing across multiple nodes

• Allows for better resource utilization and faster data processing

• Example: Partitioning in Informatica can be used to process large volumes of data efficiently

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 specific use case and design considerations.

Various types of joins in SQL include inner join, left join, right join, and full outer join.

• Inner join: Returns rows when there is a match in both tables.

• Left join: Returns all rows from the left table and the matched rows from the right table.

• Right join: Returns all rows from the right table and the matched rows from the left table.

• Full outer join: Returns rows when there is a match in either table.

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 can lead to unexpected behavior in the program

• Example: If a ...read more

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, JSON, and other formats.

• WebService is used for enterpris...read more

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

Interconnect between microservices involves communication protocols, service discovery, load balancing, and fault tolerance.

• Use communication protocols like HTTP, gRPC, or messaging queues for inter-service communication

• Implement service discovery mechanisms to locate and connect to other microservices dynamically

• Utilize load balancing techniques to distribute incoming requests evenly across multiple instances of a service

• Implement fault tolerance strategies such as circuit b...read more

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 created.

• Clustered index is created on the primary key by default...read more

A recursive query is a query that refers to itself in order to retrieve data from a database.

• A recursive query is used to retrieve hierarchical data such as organizational structures or family trees.

• It typically involves a common table expression (CTE) in SQL.

• The query continues to execute until a specific condition is met, such as reaching the root node in a tree structure.

• Example: Finding all employees and their managers in a company hierarchy.

To change the port in Spring Boot, modify the application.properties file or use command line arguments.

• Modify application.properties file with 'server.port=XXXX'

• Use command line argument '--server.port=XXXX'

• Update port in embedded server configuration in code

SQL query for updating data in a database table.

• Use the UPDATE statement in SQL to modify existing records in a table.

• Specify the table name, column names, and values to be updated in the query.

• Use WHERE clause to specify the condition for which records to update.

• Example: UPDATE table_name SET column1 = value1, column2 = value2 WHERE condition;

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 application-specific classes into the code.

• Examples include: Simple...read more

A program to find if a given string is a palindrome or not.

• Create a function that takes a string as input

• Reverse the string and compare it with the original string

• If they are the same, then the string is a palindrome

Hashmap uses hashing to store key-value pairs, while linkedlist is a data structure used to store a collection of elements.

• Hashmap uses a hash function to map keys to indices in an array, where the values are stored.

• Linkedlist is a collection of nodes, where each node contains a value and a reference to the next node.

• Hashmap can have collisions, where multiple keys map to the same index, which is resolved using separate chaining or open addressing.

• Linkedlist can be singly lin...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 compile-time.

• Singleton can be used to maintain state acro...read more

Junit testing for rest services involves testing the functionality and performance of RESTful APIs using Junit framework.

• Write test cases to validate the input and output of REST services

• Use Junit annotations like @Test, @Before, @After for setup and teardown

• Mock external dependencies using frameworks like Mockito for isolated testing

• Verify HTTP status codes, response body, headers in test cases

• Use tools like RestAssured for making HTTP requests and validating responses

System design involves creating a high-level architecture of a software system based on requirements and design principles.

• System design focuses on structuring software components and their interactions.

• Design principles like SOLID, DRY, and KISS help in creating scalable and maintainable systems.

• Consider factors like performance, scalability, security, and maintainability during system design.

• Use design patterns like MVC, Observer, and Factory to solve common design problems...read more