Learn to use Oauth2 to add third-party authentication in Spring web applications.

Web Authentication and Authorization

This module will show you what Oauth2 is, why it's important, and how to use it effectively. We'll start with an overview of Oauth2 in general and then explore its different types of grants, including password, authorization, refresh token, and more. All these concepts are backed by hands-on exercises. We'll get to practice creating cross-origin resource sharing policies and custom user-principal. We’ll also learn about the configuration of the authorization server to send login credentials via JSON. By the end of this module, we will have the foundations to add a proper authentication system to our application.

Oauth2 with Spring Security

You need to set a couple of things before you can use JavaScript for the client-side in an agile way.

## CORS policies	

If you want to use JavaScript and XML HTTP Request (XHR) requests for the client-side,  you will need to create a filter on your authorization server that sets the Cross-Origin Resource Sharing (CORS) policies for every request.

How you do this will differ depending on the Spring version you use.

For Spring Boot 1.5, you might need to create a custom bean for the `WebMvcConfigurer` class like so:

```java
@Configuration
public class WebConfig {
    @Bean
    public WebMvcConfigurer corsConfigurer() {
        return new WebMvcConfigurer() {
            @Override
            public void addCorsMappings(CorsRegistry registry) {
                registry.addMapping("/oauth/**");
            }
        };
    }
}
```

However, for Spring Boot 2.1.x we need to use better artillery.

We are going to create a bean that extends `OncePerRequestFilter`:



You need to set a couple of things before you can use JavaScript for the client-side in an agile way.

# CORS policies	

If you want to use JavaScript and XML HTTP Request (XHR) requests for the client-side,  you will need to create a filter on your authorization server that sets the Cross-Origin Resource Sharing (CORS) policies for every request.

How you do this will differ depending on the Spring version you use.

For Spring Boot 1.5, you might need to create a custom bean for the `WebMvcConfigurer` class like so:

```java
@Configuration
public class WebConfig {
    @Bean
    public WebMvcConfigurer corsConfigurer() {
        return new WebMvcConfigurer() {
            @Override
            public void addCorsMappings(CorsRegistry registry) {
                registry.addMapping("/oauth/**");
            }
        };
    }
}
```

However, for Spring Boot 2.1.x we need to use better artillery.

We are going to create a bean that extends `OncePerRequestFilter`:



Learn how to set JavaScript for the client-side in an agile way.

Theory

Practice

Conclusion

XHR Requests (JavaScript client-side scenario)

CORS policies