Migration from EclipseStore

Given the flexibility of EclipseStore and its diverse use cases, there is no universal, one-size-fits-all solution for migrating data between the two systems.

The first step is to define the appropriate entities and repositories tailored to your requirements, ensuring they align with the existing data structure in EclipseStore.

Next, the data must be transferred to the Spring-Data-Eclipse-Store storage. To facilitate this, both EclipseStore and Spring-Data-Eclipse-Store must run within the same JVM (Java Virtual Machine). This configuration enables the developer to operate both systems simultaneously and transfer data by making simple save calls to the respective repositories.

Example

0. Status Quo

Let’s say that this is the current state of the code:

package software.xdev.example.eclipse.store

public record Root(List<Owner> owners, List<Vet> vets){}
public record Owner(String name, List<Pet> pets, List<Visit> visits){}
public record Pet(String name){}
public record Vet(String name, List<Owner> clients){}
public record Visit(LocalDate date, Owner owner, Pet pet){}

In this case Root is the root-object of EclipseStore.

1. Building Repositories

Now entities with its corresponding repositories must be created in the same project:

package software.xdev.example.sdes.enitities

	public class Owner{
		@Id
		@GeneratedValue(strategy = GenerationType.AUTO)
		private long id;
		private final String name;
		private final List<Pet> pets;
		private final List<Visit> visits;
		//...
	}
	public class Vet{
		@Id
		@GeneratedValue(strategy = GenerationType.AUTO)
		private long id;
		private final String name;
		private final List<Owner> clients;
		//...
	}
	public class Visit{
		@Id
		@GeneratedValue(strategy = GenerationType.AUTO)
		private long id;
		private final LocalDate date;
		private final Owner owner;
		private final Pet pet;
		//...
	}
	public class Pet{
		@Id
		@GeneratedValue(strategy = GenerationType.AUTO)
		private long id;
		private final String name;
		//...
	}

package software.xdev.example.sdes.repositories

	public interface OwnerRepository extends CrudRepository<Owner, Long>{}
	public interface VetRepository extends CrudRepository<Vet, Long>{}
	public interface VisitRepository extends CrudRepository<Visit, Long>{}
	public interface PetRepository extends CrudRepository<Pet, Long>{}

Note that the root object is not needed in the new structure. Since we want to transfer the data in the next step, it is good practice to keep these classes in the same project but in separate packages. It is recommended that ids fields are defined to improve performance.

3. Copy Data

Now it’s time to copy the actual data. For that we need to start up the old EclipseStore storage additionally to the Spring-Data-Eclipse-Store storage. Then we simply iterate over the existing data, repackage it in our new objects and store them through the repositories.

package software.xdev.example.sdes.repositories

package software.xdev.example;

import org.eclipse.store.storage.embedded.types.EmbeddedStorage;
import org.eclipse.store.storage.embedded.types.EmbeddedStorageManager;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.event.ContextRefreshedEvent;
import org.springframework.context.event.EventListener;
import org.springframework.stereotype.Service;
import software.xdev.example.sdes.repositories.*;

@Service
public class EclipseStoreDataMigrater
{
	OwnerRepository ownerRepository;
	VetRepository vetRepository;
	VisitRepository visitRepository;
	PetRepository petRepository;

	@Autowired
	public EclipseStoreDataMigrater(OwnerRepository ownerRepository, VetRepository vetRepository, VisitRepository visitRepository, PetRepository petRepository
	)
	{
		this.ownerRepository = ownerRepository;
		this.vetRepository = vetRepository;
		this.visitRepository = visitRepository;
		this.petRepository = petRepository;
	}

	@EventListener
	public void migrateData(final ContextRefreshedEvent event)
	{
		final software.xdev.example.eclipse.store.Root root = new software.xdev.example.eclipse.store.Root(null, null);
		try(final EmbeddedStorageManager storageManager = EmbeddedStorage.start(root))
		{
			root.owners.forEach(owner -> {
				owner.pets.forEach(pet -> this.petRepository.save(new software.xdev.example.sdes.entities.Pet(pet.name)));
				//...
			});
		}
	}
}

This is very simplified but shows the general strategy to migrate data from EclipseStore to Spring-Data-Eclipse-Store.