Master Microservices with Spring Boot and Spring Cloud : Part 1 - Restful Web Services with Spring Boot

Context

Formation: https://www.udemy.com/course/microservices-with-spring-boot-and-spring-cloud
Resources de la formation: GitHub et FAQ

Instructor:

Ranga Rao Karanam

Udemy Certificate of completion

https://www.udemy.com/certificate/UC-ed0e4498-34b0-485f-bce4-54782fc08206

Content

What is a RESTful Web Service?
How to implement RESTful Web Services with Spring and Spring Boot?
What are the best practices in designing RESTful Web Services?
How to design Resources and GET, POST and DELETE operations?
How to implement Validation for RESTful Web Services?
How to implement Exception Handling for RESTful Web Services?
What is HATEOAS? How to implement HATEOAS for a Resource?
What are the different approach in versioning RESTful Services?
How to use Postman to execute RESTful Service Requests?
How to implement basic authentication with Spring Security?
How to implement filtering for RESTful Services?
How to monitor RESTful Services with Spring Boot Actuator?
How to document RESTful Web Services with Swagger?
How to connect RESTful Services to a backend with JPA?

Keywords

Service Definition :
- OData (standard for REST Service Definition), pas très utilisé, à voir si curieux…sinon en rester aux formats alternatifs (mais non standards) : WADL (pas populaire), et surtout Swagger.
- Swagger : just put one dependency (springfox-swagger2) and a @Configuration (see SwaggerConfig class in this project) to get doc in json via endpoint /v2/api-docs , and another one (springfox-swagger-ui) to get Swagger UI via /swagger-ui.html
Exception handling : ResponseEntityExceptionHandler, @ControllerAdvice, ResponseEntity
Validations : @Valid, javax.validation.constraints.* (@Size, @Past etc)
HATEOAS : Hypermedia as the Engine of Application State; With HATEOAS, a client interacts with a network application whose application servers provide information dynamically through hypermedia
Internationalization : LocaleContextHolder, AcceptHeaderLocaleResolver
Content Negociation : just add jackson-dataformat-xml to support response in xml (just an example)
Monitoring : actuator, hal browser, management.endpoints.web.exposure.include
Static Filtering : simply put an @JsonIgnore on each field to filter
Dynamic Filtering : wrap the POJO into a MappingJacksonValue and pass it in to the RestTemplate (the biggest issue for me is the hardcoded fields name); SimpleBeanPropertyFilter, SimpleFilterProvider, @JsonFilter in the POJO.
- As a user commented, @JsonView could be a good/better alternative; the biggest advantage of @JsonView is that there is no hardcoding of field names to filter, see https://spring.io/blog/2014/12/02/latest-jackson-integration-improvements-in-spring
Versioning : 2 main strategies: URI/REQUESTPARAM versioning or CUSTOMHEADER/MEDIATYPE versioning, the first one is maybe the best
- STARTING BUILDING OF AN API: CHOOSE YOUR VERSIONING STRATEGY !
Security / Basic Authentification : just add spring-boot-starter-securityas a dependency
REST best practices : See Octo Technology Reference Card, a MUST READ!!
- Richardson Maturity Model
  - Level 0 : exposer les webservices SOAP en REST-style
  - Level 1 : exposer les RESOURCES avec les URI qui conviennent (sans encore utiliser les bonnes méthodes HTTP)
    - http://server/accounts
    - http://server/accounts/10
  - Level 2 : Level 1 + utilisation correcte des méthodes HTTP
    - (GET|POST) http://server/accounts
    - (GET|PUT|DELETE) http://server/accounts/10
  - Level 3 : Level 2 + HATEOAS
    - return DATA + NEXT POSSIBLE ACTIONS
- Le client doit comprendre les WS
  - avoir une documentation suffisante et compréhensible
- Utiliser au mieux les possibilités offertes par HTTP
  - Notamment en utilisant ses méthodes (GET, PUT, POST, DELETE) de façon appropriée
  - Renvoyer le satut de réponse le plus approprié (pas juste un 200, mais un 201 par exemple lors d’une création)
    - 200 - success
    - 404 - resource not found
    - 400 - bad request
    - 201 - created
    - 401 - unauthorized
    - 500 - server error
  - Pas d’informations sensibles dans les URI
  - Préférer le PLURIEL au SINGULIER
    - Préférer /users à /user
    - Préférer /users/1 to /user/1
  - Préférer des NOMS plutôt que des VERBES pour les resources
    - Préférer DELETE /users/1 plutôt que DELETE /deleteUser/1
    - PUT /posts/{id}/star // pour ajouter une étoile à un post
    - DELETE /posts/{id}/star // pour supprimer une étoile à un post

Startup

In IntelliJ, run maven goal spring-boot-run
Enable Devtools with IntelliJ : https://mkyong.com/spring-boot/intellij-idea-spring-boot-template-reload-is-not-working

Reference Documentation

For further reference, please consider the following sections:

Guides

The following guides illustrate how to use some features concretely: