Single Spring Application Deployment for both Local and CloudFoundry.com Servers

If you’re not using Maven, you can download Spring 3.1 M1 from the Community Download page.

Having upgraded the version in Maven, we need to change the namespaces for any application context files. This is as straightforward as changing schema locations to be xxx-3.1.xsd instead of xxx-3.0.xsd

In this XML fragment, we can see that there are embedded <beans /> elements inside the main <beans /> element.  This is a new feature of Spring 3.1 that allows different configurations to be easily specified within one configuration file. Here we’ve defined a bean called dataSource as a JDBC datasource and as a CloudFoundry.com datasource.  The profile attribute allows us to specify which profile the bean is to be instantiated in.  So, in the “default” profile, i.e. a local profile where development and testing is most likely to be performed, a JDBC datasource is defined.  The “cloud” profile specifies a datasource for CloudFoundry.com.  A bean profile can be set to cover multiple profiles, but in this example, the dataSource bean is either a local JDBC datasource or a CloudFoundry.com datasource and can never be defined in both cases.

For a detailed description of Spring’s bean definition profiles, check out Chris Beams blog post.

Choosing a Profile at Runtime

The final stage of changing an application to use the bean definition profiles defined above is to add a class that implements the org.springframework.context.ApplicationContextInitializer interface.  This interface allows the spring container to be customised before it in initialized. In our instance, we can hook into this and, depending on the environment, set the active profile to be the “default”, local JDBC datasource, or the “cloud” CloudFoundry.com datasource.

public class Initializer implements
      
  ApplicationContextInitializer<ConfigurableWebApplicationContext> {
  
  protected final Log logger = LogFactory.getLog(getClass());
  
  public void initialize(ConfigurableWebApplicationContext ctx) {
    ConfigurableEnvironment environment = ctx.getEnvironment();
  
    ApplicationInstanceInfo instanceInfo = new CloudEnvironment()
      .getInstanceInfo();
  
    if (instanceInfo == null) {
      // We are running locally.
      logger.info("Setting default profile.");
      environment.setActiveProfiles("default");
    } else {
      // We are running in the cloud.
      logger.info("Setting cloud profile.");
      environment.setActiveProfiles("cloud");
    }
  }
}