1. Spring Framework

• The Spring framework provides comprehensive support for developing Java applications.
• Provides the plumbing
• OOP best practices built-in
• DRY Principle

2. Why Spring Boot:

• Supports rapid development
• Removes boilerplate of application setup
• Many uses
• Cloud-native support, but also traditional

Reference to explore more on this topic.

The meaning of Integration testing is quite straightforward- Integrate/combine the unit tested module one by one and test the behaviour as a combined unit. The main function or goal of this testing is to test the interfaces between the units/modules.

1. Bottom Up:

2. Top Down:

Why Service Layer:

• Separation of concern
• Loose coupling
• Orchestration
• Caching

e.g: Steps for rest controller:

• URL Mapping
• Deserialize Input
• Validate Input
• Bussiness Logic
• Serialize Onput
• Translate Exceptions

Following is the order we do things in this guide:

• Bootstrap a project using Spring Initializr.
• Implement a Business Service for our API - StudentService.
• Implement the API - using StudentController. First, we implement the GET methods and then the POST methods.
• Write Integration Tests for our API.

Spring Initializr http://start.spring.io/ is great tool to bootstrap your Spring Boot projects.
image for spring analyzer
As shown in the image above, the following steps have to be done

• Launch Spring Initializr and choose the following:
  • Choose com.ECSE429.springboot as Group
  • Choose student services as Artifact
  • Choose the following dependencies
    • Web
    • Actuator
    • DevTools
• Click Generate Project.
• Import the project into Eclipse.

Please update your POM file with this sample POM file.

All applications need data. Instead of talking to a real database, we will use an ArrayList - kind of an in-memory data store.
A student can take multiple courses. A course has an id, name, description and a list of steps you need to complete to finish the course. A student has an id, name, description and a list of courses he/she is currently registered for. We have StudentService exposing methods to

• public List retrieveAllStudents() - Retrieve details for all students
• public Student retrieveStudent(String studentId) - Retrieve a specific student details
• public List retrieveCourses(String studentId) - Retrieve all courses a student is registered for
• public Course retrieveCourse(String studentId, String courseId) - Retrieve details of a specific course a student is registered for
• public Course addCourse(String studentId, Course course) - Add a course to an existing student

Refer to these files at the bottom of the article for exact implementation of the Service StudentService and the model classes Course and Student.

• src/main/java/com/ECSE429/springboot/model/Course.java
• src/main/java/com/ECSE429/springboot/model/Student.java
• src/main/java/com/ECSE429/springboot/service/StudentService.java

github for the source code.

The Rest Service StudentController exposes a couple of get services.

• @Autowired private StudentService studentService : We are using Spring Autowiring to wire the student service into the StudentController.
• @GetMapping("/students/{studentId}/courses"): Exposing a Get Service with studentId as a path variable
• @GetMapping("/students/{studentId}/courses/{courseId}"): Exposing a Get Service for retrieving specific course of a student.
• @PathVariable String studentId : Value of studentId from the uri will be mapped to this parameter.

github for the source code.

When we are writing an integration test for a rest service, we would want to launch the entire spring context.

• @SpringBootTest(classes = StudentServicesApplication.class, webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT) : Launch the entire Spring Boot Application on a Random Port
• @LocalServerPort private int port;: Autowire the random port into the variable so that we can use it to create the url.
• createURLWithPort(String URL): Utility method to create the url given an uri. It appends the port.
• HttpEntity entity = new HttpEntity(null, headers);: We use entity so that we have the flexibility of adding in request headers in future.
• restTemplate.exchange(createURLWithPort("/students/Student1/courses/Course1"),HttpMethod.GET, entity, String.class): Fire a GET request to the specify uri and get the response as a String.
• JSONAssert.assertEquals(expected, response.getBody(), false): Assert that the response contains expected fields.

github for the source code.
Now run and test the service.