Creating Continuous Queries Using Spring Data GemFire

To create continuous queries with the Spring Data GemFire library, you must have the following:

• Spring Data GemFire v2.0.1 release
• Spring Boot v2.0.0+

To create continuous queries, do the following items:

• Specify attributes subscriptionEnabled and readyForEvents for the ClientCacheApplication annotation. Apply this annotation to the Spring Boot client application class:

  @ClientCacheApplication(name = "GemFireSpringApplication", readyForEvents = true,
    subscriptionEnabled = true)
  

  The annotation for a durable event queue for continuous queries also sets the durableClientId and keepAlive attributes. For example:

  @ClientCacheApplication(name = "GemFireSpringApplication",
    durableClientId = "durable-client-id", keepAlive = true,
    readyForEvents = true, subscriptionEnabled = true)
  

• Annotate the method that handles the events to specify the query. To make the event queue durable across server failures and restarts, include the durable = true attribute in the annotation, as is done in the example:

  @Component
  public class ContinuousQuery {
  
      @ContinuousQuery(name = "yourQuery",
         query = "SELECT * FROM /yourRegion WHERE someAttribute == true",
         durable = true)
      public void handleChanges(CqEvent event) {
        //PERFORM SOME ACTION
      }
  }
  

  The class that contains the method with the @ContinuousQuery annotation must have the @Component annotation, such that the continuous query is wired up correctly for the server.

For more information, see the Spring Data GemFire documentation.