Lesson 1

Question 1

Spring

Answer 1

• It is a framework
• Used for building Java applications and services
• Hosts java libraries
• Has very useful and essential web development “components”, i.e. DB access, security, cloud deployment, web services
• Streamlines the experience of writing code in Java
• It’s fast

Question 2

Web development basics (3 parts)

Answer 2

1) Data storage
2) Services (application logic)
3) Client

Question 3

Spring beams/services

Answer 3

Spring beams/services are used to write application logic. They are basically Java classes that Spring knows about

Question 4

H2

Answer 4

H2 is an in-memory SQL database that Spring Boot will run alongside our business logic.

Question 5

Controller beam

Answer 5

The client interacts with the controller beam, which will then send an HTML request and usually expects HTML in return

Question 6

Spring Boot

Answer 6

• Spring boot is part of the Spring framework. Internally, spring boot is built on top of the Spring framework.
• Helps in rapid application development
• Helps to develop stand alone and enterprise web applications
• Used by all SDLC stakeholders
• Powerful tool for building servers (to connect simultaneous users on different clients)

Question 7

Thymeleaf

Answer 7

Thymeleaf is an HTML template engine, which gets populated using Spring Boot. Thymeleaf allows you to show web pages to a client and populate data on the page using server code.

Question 8

When should you use Java versus another coding language?

Answer 8

Java should be used to build any web application, but should not be used to build anything high-performance (such as a graphics processing application)

Question 9

Maven

Answer 9

Maven is a java dependency manager

Question 10

HTTP

Answer 10

HTTP is a binary format of data. It’s used for communication between programmes over the web. It can be broken down into requests and responses.

Question 11

What is the role of a web server?

Answer 11

A web server’s primary role is to listen for an HTTP request, then sending a response to the client.

Question 12

Java Application server

Answer 12

An application server is used to process concurrent requests and send response messages out to many clients.
Examples of application servers are: Apache Tomcat, Glassfish, Netty, Wildfly. Spring boot has an embedded application server which includes Apache Tomcat by default.
Java Application Server is a pluggable architecture that can host many deployed applications at once.

Question 13

Multi-threading, request filtering, resource sharing to each application are all things done by the Java application server. What are multi-threading and threading?

Answer 13

Threading is basically one track of computation.

Multi-threading is running multiple threads in parallel.

Question 14

Application server

Answer 14

A programme that hosts other (and multiple) applications. It forwards requests to the correct application according to a filter.

Question 15

Pluggable architecture

Answer 15

A pluggable architecture refers to any piece of software that can be added, replaced or removed.
More often than not, every pluggable component has a common interface.

Question 16

Servlet

Answer 16

A servlet is the interface connection between the app that has been developed and the app server that it runs on.
The server sends requests to endpoints in your application. Each servlet represents a configurable endpoint for client connections.

Question 17

How does the server find servlets in an application?

Answer 17

1)deploy the application to the server
2)server scans the application files for a web.xml file
The web.xml file tells the server which servlets are in the application and which urls they match to.
3)The server uses Java’s reflection API to load the relevant servlet classes and prepares to manage them

Question 18

What is the life cycle of a servlet?

Answer 18

1) Java’s reflection API loads the relevant servlet classes
2) This instance of our Servlet is what the app server will use to process incoming requests. It will remain in memory until the app server shuts it down.
3) The app server calls the .init() method. This triggers any initialisation logic we gave this method.
4) for an incoming request, the app server calls the .service() method which triggers our servlet’s request handling logic.
5) when the servlet is ready to be shut down, the app server calls the .destroy() method