This guide describes how to use Spring Session to transparently leverage a relational to back a web application’s HttpSession with XML based configuration.

The completed guide can be found in the httpsession-jdbc-xml sample application.

1. Updating Dependencies

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

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

	<dependency>
		<groupId>org.springframework.session</groupId>
		<artifactId>spring-session-jdbc</artifactId>
		<version>2.1.1.BUILD-SNAPSHOT</version>
		<type>pom</type>
	</dependency>
	<dependency>
		<groupId>org.springframework</groupId>
		<artifactId>spring-web</artifactId>
		<version>5.1.1.RELEASE</version>
	</dependency>
</dependencies>

Since we are using a SNAPSHOT version, we need to ensure to add the Spring Snapshot Maven Repository. Ensure you have the following in your pom.xml:

pom.xml
<repositories>

	<!-- ... -->

	<repository>
		<id>spring-snapshot</id>
		<url>https://repo.spring.io/libs-snapshot</url>
	</repository>
</repositories>

2. Spring XML 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. Add the following Spring Configuration:

src/main/webapp/WEB-INF/spring/session.xml
(1)
<context:annotation-config/>
<bean class="org.springframework.session.jdbc.config.annotation.web.http.JdbcHttpSessionConfiguration"/>

(2)
<jdbc:embedded-database id="dataSource" database-name="testdb" type="H2">
	<jdbc:script location="classpath:org/springframework/session/jdbc/schema-h2.sql"/>
</jdbc:embedded-database>

(3)
<bean class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
	<constructor-arg ref="dataSource"/>
</bean>
1 We use the combination of <context:annotation-config/> and JdbcHttpSessionConfiguration because Spring Session does not yet provide XML Namespace support (see gh-104). This creates a Spring Bean with the name of springSessionRepositoryFilter that implements Filter. The filter is what is in charge of replacing the HttpSession implementation to be backed by Spring Session. In this instance Spring Session is backed by a relational database.
2 We create a dataSource that connects Spring Session to an embedded instance of H2 database. We configure the H2 database to create database tables using the SQL script which is included in Spring Session.
3 We create a transactionManager that manages transactions for previously configured dataSource.

For additional information on how to configure data access related concerns, please refer to the Spring Framework Reference Documentation.

3. XML 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, we need to instruct Spring to load our session.xml configuration. We do this with the following configuration:

src/main/webapp/WEB-INF/web.xml
<context-param>
	<param-name>contextConfigLocation</param-name>
	<param-value>
		/WEB-INF/spring/*.xml
	</param-value>
</context-param>
<listener>
	<listener-class>
		org.springframework.web.context.ContextLoaderListener
	</listener-class>
</listener>

The ContextLoaderListener reads the contextConfigLocation and picks up our session.xml configuration.

Last we need to ensure that our Servlet Container (i.e. Tomcat) uses our springSessionRepositoryFilter for every request. The following snippet performs this last step for us:

src/main/webapp/WEB-INF/web.xml
<filter>
	<filter-name>springSessionRepositoryFilter</filter-name>
	<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter>
<filter-mapping>
	<filter-name>springSessionRepositoryFilter</filter-name>
	<url-pattern>/*</url-pattern>
	<dispatcher>REQUEST</dispatcher>
	<dispatcher>ERROR</dispatcher>
</filter-mapping>

The DelegatingFilterProxy will look up a Bean by the name of springSessionRepositoryFilter and cast it to a Filter. For every request that DelegatingFilterProxy is invoked, the springSessionRepositoryFilter will be invoked.

4. httpsession-jdbc-xml Sample Application

4.1. Running the httpsession-jdbc-xml Sample Application

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

$ ./gradlew :spring-session-sample-xml-jdbc:tomcatRun

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

4.2. Exploring the httpsession-jdbc-xml Sample Application

Try using the application. Fill out the form with the following information:

  • Attribute Name: username

  • Attribute Value: rob

Now click the Set Attribute button. You should now see the values displayed in the table.

4.3. How does it work?

We interact with the standard HttpSession in the SessionServlet shown below:

src/main/java/sample/SessionServlet.java
public class SessionServlet extends HttpServlet {

	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		String attributeName = req.getParameter("attributeName");
		String attributeValue = req.getParameter("attributeValue");
		req.getSession().setAttribute(attributeName, attributeValue);
		resp.sendRedirect(req.getContextPath() + "/");
	}

	private static final long serialVersionUID = 2878267318695777395L;
}

Instead of using Tomcat’s HttpSession, we are actually persisting the values in H2 database. Spring Session creates a cookie named SESSION in your browser that contains the id of your session. Go ahead and view the cookies (click for help with Chrome or Firefox).

If you like, you can easily remove the session using H2 web console available at: http://localhost:8080/h2-console/ (use jdbc:h2:mem:testdb for JDBC URL)

Now visit the application at http://localhost:8080/ and observe that the attribute we added is no longer displayed.