Spring DATA for RDBMS and NoSql

Question

是否有可能使用Spring DATA编写具有通用代码的应用程序，该代码同时支持RDMS和Nosql（MongoDb）作为后端数据存储。它应在某个时间点支持其中之一，并且应是可配置的。

Answer 1

I have just pushed a new Spring-Data project named spring-data-gremlin which aims to do exactly this. It uses JPA annotations to map to any Tinkerpop blueprints graph database (OrientDB, TitanDB, etc). This means that switching between RDBMS and nosql graph databases should be a matter of configuration for any Spring-Data-JPA project.

Note: The project is in early stages of development and therefore not all JPA annotations are implemented yet.

Answer 2

I don't know for sure for MongoDB but we currently have projects configured with Spring Data JPA and Spring Data Neo4J simultaneously. I can't think of any obstacles why you could not make this work with Spring Data JPA and Spring Data MongoDB.

Be aware of transaction management : as far as I know MongoDB does not support transactionability so any kind of writing to both data sources can not be done as atom operation. If this is not an issue, you're good to go.

Our example snippet:

<neo4j:config storeDirectory="${neo4j.storeDirectory}"
        base-package="app.model.neo4j" />
<neo4j:repositories base-package="app.neo4j.repo" />
<tx:annotation-driven transaction-manager="neo4jTransactionManager" />

And Spring Data JPA in Configuration annotated class:

@Configuration
@EnableJpaRepositories(value = "app.dao", entityManagerFactoryRef = "emf", transactionManagerRef = "tm")
@ComponentScan("app")
@EnableTransactionManagement
public class ConfigDao {

        protected final String  PROPERTY_DB_MODEL_PACKAGESTOSCAN    = "db.model.packagesToScan";
        protected final String  PROPERTY_DB_DRIVER_CLASSNAME        = "db.driver.className";
        protected final String  PROPERTY_DB_URL                     = "db.url";
        protected final String  PROPERTY_DB_USERNAME                = "db.username";
        protected final String  PROPERTY_DB_PASSWORD                = "db.password";
        protected final String  PROPERTY_DB_ADDITIONAL_DDL          = "hibernate.hbm2ddl.auto";
        protected final String  PROPERTY_DB_ADDITIONAL_DIALECT      = "hibernate.dialect";
        protected final String  PROPERTY_DB_ADDITIONAL_EMF_NAME     = "hibernate.ejb.entitymanager_factory_name";

        @Bean
        public DataSource dataSource() {
            DriverManagerDataSource dataSource = new DriverManagerDataSource();
            dataSource.setDriverClassName(PROPERTY_DB_DRIVER_CLASSNAME);
            dataSource.setUrl(PROPERTY_DB_URL);
            dataSource.setUsername(PROPERTY_DB_USERNAME);
            dataSource.setPassword(PROPERTY_DB_PASSWORD);
            return dataSource;
        }

        @Bean
        public PlatformTransactionManager transactionManager() {
            JpaTransactionManager transactionManager = new JpaTransactionManager();
            transactionManager.setEntityManagerFactory(entityManagerFactory().getObject());
            return transactionManager;
        }

        @Bean
        public EntityManager entityManager() {
            return entityManagerFactory().getObject().createEntityManager();
        }

        @Bean
        public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
            LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
            em.setDataSource(dataSource());
            em.setPackagesToScan(PROPERTY_DB_MODEL_PACKAGESTOSCAN);
            JpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
            em.setJpaVendorAdapter(vendorAdapter);
            em.setJpaProperties(additionalJpaProperties());
            return em;
        }

        @Bean
        protected Properties additionalJpaProperties() {
            Properties properties = new Properties();
            properties.setProperty(PROPERTY_DB_ADDITIONAL_DDL);
            properties.setProperty(PROPERTY_DB_ADDITIONAL_DIALECT);
            properties.setProperty(PROPERTY_DB_ADDITIONAL_EMF_NAME);
            return properties;
        }

}

Hope it helps.