/kotlin-microservices-lab

Primary LanguageKotlin

kotlin-microservices-lab

Annotations

Core Spring Framework annotations

  • @Bean - Works as a bean ID. It creates and returns the actual bean within @Configuration classes;
  • @Configuration - Used on classes that define beans. Its analog to XML config files;
  • @ComponentScan - Allow spring to know which packages to look for components;

SpringBoot annotations

  • @EnableAutoConfiguration - Tells spring to start adding beans based on classpath settings, other beans, and property settings;
  • @SpringBootApplication - Does a component scan through its subpackages;
    • Includes the following annotations: @Configuration, @EnableAutoConfiguration, @ComponentScan;

Content negotiation

Internationalization

To do this we have to add 2 instances to the execution env:

  • LocaleResolver
  • ResourceBundleMessageSource

All messages should go within a file named as messages.properties, messages_pt.properties

ps: The client should specify in the header the attribute Accept-Language and a value. Eg.: pt, en.

HATEOAS (Hypermedia As The Engine Of Application State)

Describes what can be done with resources;

Api documentation

Add two dependencies:

  • springfox.swagger2 -> http://localhost:9000/v2/api-docs
  • springfox.swagger-ui -> http://localhost:9000/swagger-ui.html

Monitoring

  • SpringBoot Actuator: Provides maintenance endpoints for checking application health;
  • SpringBoot Hal (Hypertext Application Language) Browser: Lets us see actuator in the browser;
    • To open hal browser navigate to http://localhost:9000/browser/index.html

Properties filtering

We can do this statically at the Bean level with the annotation @JsonIgnore; Or dinamically with a FilterProvider and MappingJacksonValue

Resources versioning

  • URI: @GetMapping("/v1/users"). Client: http://localhost:9000/v1/users
  • Request Parameter versioning: @GetMapping("/users", param = "version=1"). Client: http://localhost:9000/v1/users?version=1
  • Header: @GetMapping("/users", headers="X-API-VERSION=1"). Client Header: key(X-API-VERSION), value(1)
  • Produces (Accept Header Versioning/MimeType Versioning): @GetMapping("/users", produces="application/vnd.company.app-v1+json"). Client Header: key(Accept), value(application/vnd.company.app-v1+json)

What to consider when choosing:

  • URI Polution;
  • Missuse of HTTP Headers;
  • Caching;
  • Can we execute the request from a browser?
  • How easy is it to generate docs?

Security

Just add to your main application the annotation @EnableWebSecurity.

This will add the following properties:

security.basic.authorize-mode
security.basic.enabled
security.basic.path
security.basic.realm
security.enable-csrf
security.headers.cache
security.headers.content-security-policy
security.headers.content-security-policy-mode
security.headers.content-type
security.headers.frame
security.headers.hsts
security.headers.xss
security.ignored
security.require-ssl
security.sessions

Richardson Maturity Model

  • Level 1: Expose soap web services in a rest style: http://server/getPosts (Actions)
  • Level 2: Expose resources with proper URI: http://server/posts (Resorces)
  • Level 3: Implementation of HATEOAS. Data + next possible actions;

Microservices concerns

  • Bounded Contexts
  • Configuration management
  • Dynamic scale UP and scale DOWN
    • Naming server (Eureka)
    • Ribbon (Client side load balancer)
    • Feign (Easier REST APIS)
  • Monitoring
    • Zipkin Distributed Tracing
    • Netflix Zuul API Gateway