This guide describes how to use Spring Session along with Spring Security when you use Hazelcast as your data store. It assumes that you have already applied Spring Security to your application.

You cand find the completed guide in the Hazelcast Spring Security sample application.

1. Updating Dependencies

Before you use Spring Session, you must update your dependencies. If you use Maven, you must add the following dependencies:

pom.xml
<dependencies>
	<!-- ... -->

	<dependency>
		<groupId>com.hazelcast</groupId>
		<artifactId>hazelcast</artifactId>
		<version>3.12.1</version>
	</dependency>
	<dependency>
		<groupId>org.springframework</groupId>
		<artifactId>spring-web</artifactId>
		<version>5.2.0.M3</version>
	</dependency>
</dependencies>

Since we are using a Milestone version, we need to add the Spring Milestone Maven Repository. You must have the following in your pom.xml:

pom.xml
<repository>
<id>spring-milestone</id>
<url>https://repo.spring.io/libs-milestone</url>
</repository>

2. Spring Configuration

After adding the required dependencies, we can create our Spring configuration. The Spring configuration is responsible for creating a servlet filter that replaces the HttpSession implementation with an implementation backed by Spring Session. To do so, add the following Spring Configuration:

@EnableHazelcastHttpSession (1)
@Configuration
public class HazelcastHttpSessionConfig {

	@Bean
	public HazelcastInstance hazelcastInstance() {
		MapAttributeConfig attributeConfig = new MapAttributeConfig()
				.setName(HazelcastSessionRepository.PRINCIPAL_NAME_ATTRIBUTE)
				.setExtractor(PrincipalNameExtractor.class.getName());

		Config config = new Config();

		config.getMapConfig(HazelcastSessionRepository.DEFAULT_SESSION_MAP_NAME) (2)
				.addMapAttributeConfig(attributeConfig)
				.addMapIndexConfig(new MapIndexConfig(
						HazelcastSessionRepository.PRINCIPAL_NAME_ATTRIBUTE, false));

		return Hazelcast.newHazelcastInstance(config); (3)
	}

}
1 The @EnableHazelcastHttpSession annotation creates a Spring bean named springSessionRepositoryFilter that implements Filter. The filter is in charge of replacing the HttpSession implementation to be backed by Spring Session. In this instance, Spring Session is backed by Hazelcast.
2 In order to support retrieval of sessions by principal name index, an appropriate ValueExtractor needs to be registered. Spring Session provides PrincipalNameExtractor for this purpose.
3 We create a HazelcastInstance that connects Spring Session to Hazelcast. By default, the application starts and connects to an embedded instance of Hazelcast. For more information on configuring Hazelcast, see the reference documentation.

3. Servlet Container Initialization

Our Spring Configuration created a Spring bean named springSessionRepositoryFilter that implements Filter. The springSessionRepositoryFilter bean is responsible for replacing the HttpSession with a custom implementation that is backed by Spring Session.

In order for our Filter to do its magic, Spring needs to load our SessionConfig class. Since our application is already loading Spring configuration by using our SecurityInitializer class, we can add our SessionConfig class to it. The following listing shows how to do so:

src/main/java/sample/SecurityInitializer.java
public class SecurityInitializer extends AbstractSecurityWebApplicationInitializer {

	public SecurityInitializer() {
		super(SecurityConfig.class, SessionConfig.class);
	}
}

Last, we need to ensure that our Servlet Container (that is, Tomcat) uses our springSessionRepositoryFilter for every request. It is extremely important that Spring Session’s springSessionRepositoryFilter is invoked before Spring Security’s springSecurityFilterChain. Doing so ensures that the HttpSession that Spring Security uses is backed by Spring Session. Fortunately, Spring Session provides a utility class named AbstractHttpSessionApplicationInitializer that makes this doing so easy. The following example shows how to do so:

src/main/java/sample/Initializer.java
public class Initializer extends AbstractHttpSessionApplicationInitializer {

}
The name of our class (Initializer) does not matter. What is important is that we extend AbstractHttpSessionApplicationInitializer.

By extending AbstractHttpSessionApplicationInitializer, we ensure that the Spring Bean named springSessionRepositoryFilter is registered with our servlet container for every request before Spring Security’s springSecurityFilterChain.

4. Hazelcast Spring Security Sample Application

This section describes how to work with the Hazelcast Spring Security sample application.

4.1. Running the Sample Application

You can run the sample by obtaining the source code and invoking the following command:

$ ./gradlew :spring-session-sample-javaconfig-hazelcast:tomcatRun
By default, Hazelcast runs in embedded mode with your application. However, if you want to connect to a standalone instance instead, you can configure it by following the instructions in the reference documentation.

You should now be able to access the application at http://localhost:8080/

4.2. Exploring the Security Sample Application

You can now try using the application. To do so, enter the following to log in:

  • Username user

  • Password password

Now click the Login button. You should now see a message indicating that your are logged in with the user entered previously. The user’s information is stored in Hazelcast rather than Tomcat’s HttpSession implementation.

4.3. How Does It Work?

Instead of using Tomcat’s HttpSession, we persist the values in Hazelcast. Spring Session replaces the HttpSession with an implementation that is backed by a Map in Hazelcast. When Spring Security’s SecurityContextPersistenceFilter saves the SecurityContext to the HttpSession, it is then persisted into Hazelcast.

When a new HttpSession is created, Spring Session creates a cookie named SESSION in your browser. That cookie contains the ID of your session. You can view the cookies (with Chrome or Firefox).

4.4. Interacting with the Data Store

You can remove the session by using a Java client, one of the other clients, or the management center.

4.4.1. Using the Console

For example, to remove the session by using the management center console after connecting to your Hazelcast node, run the following commands:

	default> ns spring:session:sessions
	spring:session:sessions> m.clear
The Hazelcast documentation has instructions for the console.

Alternatively, you can also delete the explicit key. Enter the following into the console, being sure to replace 7e8383a4-082c-4ffe-a4bc-c40fd3363c5e with the value of your SESSION cookie:

	spring:session:sessions> m.remove 7e8383a4-082c-4ffe-a4bc-c40fd3363c5e

Now visit the application at http://localhost:8080/ and observe that we are no longer authenticated.

4.4.2. Using the REST API

As described in the section of the documentation that cover other clients, there is a REST API provided by the Hazelcast node(s).

For example, you could delete an individual key as follows (being sure to replace 7e8383a4-082c-4ffe-a4bc-c40fd3363c5e with the value of your SESSION cookie):

	$ curl -v -X DELETE http://localhost:xxxxx/hazelcast/rest/maps/spring:session:sessions/7e8383a4-082c-4ffe-a4bc-c40fd3363c5e
The port number of the Hazelcast node is printed to the console on startup. Replace xxxxx with the port number.

Now you can see that you are no longer authenticated with this session.