Web Application Architecture

Question 1

What external system do you know?

Answer 1

An external system is something that lives outside your application, like a database, some remote web service, the system’s clock, the file system, and so on.

Question 2

What are the differences between infrastructure and core code?

Answer 2

Infrastructure code - it’s all external system and low-level system things.

Core code - It’s a domain logic ( just business requirements)

Question 3

How to avoid direct interaction with database?

Answer 3

We can create a separated class/method which will encapsulate DB interaction and we can use this method instead (send us dependency). ( Something like Command in our project)

Question 4

What main rules we need to use to build a clean web application?

Answer 4

1) Core code doesn’t directly depend on external systems

2) Core code doesn’t need a specific environment to run in ( can be run in console/api/admin)

Question 5

What is Table Data Gateway?

Answer 5

Table Data Gateway is a design pattern in which an object acts as a gateway to a database table. It hides the SQL statements and other implementation details behind a single interface per database table. (It’s like class for one table with methods which can wrap your SQL statement get/insert/update)

Question 6

What is Repository?

Answer 6

“Object savers” are usually called repositories. Repository is the name of a design pattern which provides a solution to a common problem: the need to save a domain object, and later reconstitute it.

Question 7

What is Data Mapper pattern?

Answer 7

DataMapper “moves data between objects and a database while keeping them independent of each other and the mapper itself” ( send params -> save records to DB). DataMappers to serve their main function, mapping domain objects to the database and vice versa.

Question 8

What is service locator pattern?

Answer 8

Class which contains all depency that we need to run the service.

class Sample
        Service service = ServiceLocator.getService("ServiceOne");
        service.execute();

    service = ServiceLocator.getService("ServiceTwo");
    service.execute();

    service = ServiceLocator.getService("ServiceOne");
    service.execute();

    service = ServiceLocator.getService("ServiceTwo");
    service.execute(); end

Question 9

What main layers ( folders ) we can use?

Answer 9

• Entity
• Repository
• Domain Event
• Event Subscriber
• Service
• Input object (form, parameter object)