Spring Data GemFire provides support to map entities that will be stored in a GemFire data grid. The mapping metadata is defined using annotations at the domain classes just like this:

@Region("People")
public class Person {

  @Id Long id;
  String firstname;
  String lastname;

  @PersistenceConstructor
  public Person(String firstname, String lastname) {
    // …
  }

  …
}
			

The first thing you see here is the @Region annotation that can be used to customize the Region in which the Person class is stored in. The @Id annotation can be used to annotate the property that shall be used as the Cache key. The @PersistenceConstructor annotation actually helps disambiguating multiple potentially available constructors taking parameters and explicitly marking the one annotated as the one to be used to create entities. With none or only a single constructor you can omit the annotation.

In addition to storing entities in top-level Regions, entities can be stored in GemFire Sub-Regions, as so:

@Region("/Users/Admin")
public class Admin extends User {
  …
}

@Region("/Users/Guest")
public class Guest extends User {
  ...
}
		

Be sure to use the full-path of the GemFire Region, as defined in Spring Data GemFire XML namespace configuration meta-data, as specified in the id or name attributes of the <*-region> bean definition.

As alternative to specifying the Region in which the entity will be stored using the @Region annotation on the entity class, you can also specify the @Region annotation on the entity's Repository abstraction. See Chapter 9, GemFire Repositories for more details.

However, let's say you want to store a Person in multiple GemFire Regions (e.g. People and Customers), then you can define your corresponding Repository interface abstractions like so:

@Region("People")
public interface PersonRepository extends GemfireRepository<Person, String> {
…
}

@Region("Customers")
public interface CustomerRepository extends GemfireRepository<Person, String> {
...
}
		

Spring Data GemFire provides a custom PDXSerializer implementation that uses the mapping information to customize entity serialization. Beyond that it allows customizing the entity instantiation by using the Spring Data EntityInstantiator abstraction. By default the serializer uses a ReflectionEntityInstantiator that will use the persistence constructor of the mapped entity (either the single declared one or explicitly annoted with @PersistenceConstructor). To provide values for constructor parameters it will read fields with name of the constructor parameters from the PDXReader supplied.

public class Person {

  public Person(@Value("#root.foo") String firstname, @Value("bean") String lastname) {
    // …
  }

}  

The entity annotated as such will get the field foo read from the PDXReader and handed as constructor parameter value for firstname. The value for lastname will be the Spring bean with name bean.