I am a bit confused about the difference between Spring Data-JPA and JPA. I know about JPA that it is a specification for persisting the Java Objects to a relational database using popular ORM technology.
In other words, JPA provides interfaces and other ORM technologies, implements those interfaces known as JPA provider e.g Hibernate.
Now, what exactly is Spring Data JPA?
Is Spring Data JPA has added some more functionality (Interfaces) over JPA and still it is specified only or it is also a JPA provider?
I saw Spring Data JPA works around repositories (DAO layer: if I am not wrong). So, I mean, how it is different using 'Spring Data JPA + Hibernate' or only using 'Hibernate' directing?
I saw Spring, JPA works around repositories (DAO layer: if I am not wrong). So I mean how it is different using 'Spring JPA + Hibernate' or only using 'Hibernate' directly?
As you said, JPA is an specification while Hibernate is a particular implementation of that specification (these implementations are usually referred to as Providers). By using Hibernate you tie yourself to that provider restricting your freedom to switch to another option when required (for example, you want to use EclipseLink or ObjectDB instead because Hibernate has a bug that halts your development process).
Quoting Spring Data JPA's documentation:
Implementing a data access layer of an application has been cumbersome for quite a while. Too much boilerplate code had to be written. Domain classes were anemic and haven't been designed in a real object oriented or domain driven manner.
Using both of these technologies makes developers life a lot easier regarding rich domain model's persistence. Nevertheless the amount of boilerplate code to implement repositories, especially is still quite high. So the goal of the repository abstraction of Spring Data is to reduce the effort to implement data access layers for various persistence stores significantly.
To sum it up, it is on top of JPA adding another layer of abstraction, kind of defining a standard-based design to support Persistence Layer in a Spring context. Those defined interfaces (known to Spring) provide the services that the framework handles using JPA to serve the results. You define a repository in a way Spring can scan the project and find it:
<repositories base-package="com.acme.repositories" />
Thus, allowing you to use it in the context of a container or outside of it.
Now what exactly is Spring, JPA. Is Spring, JPA has added some more functionality (Interfaces) over JPA and still it is specified only or it is also a JPA provider?
Spring Data JPA provides a definition to implement repositories that are supported under the hood by referencing the JPA specification, using the provider you define.
The Java Persistence API, sometimes referred to as JPA, is a Java framework managing relational data in applications using the Java Platform, Standard Edition (JavaSE) and Java Platform, Enterprise Edition(JavaEE).
Persistence in this context covers three areas:
The API itself, defined in the javax.persistence package.
The Java Persistence Query Language (JPQL).
Object-Relational metadata.
Spring Data JPA is part of the umbrella Spring Data project that makes it easier to implement JPA based repositories.
Features:
Sophisticated support to build repositories based on Spring and JPA
Support for QueryDSL predicates and thus type-safe JPA queries
Transparent auditing of domain class
Pagination support, dynamic query execution, ability to integrate custom data access code
Validation of #Query annotated queries at bootstrap time
Support for XML based entity mapping
JavaConfig based repository configuration by introducing #EnableJpaRepositories
JPA
JPA is a specification that standardizes the way Java Objects are mapped to a relational database system. Being just a specification, JPA consists of a set of interfaces, like EntityManagerFactory, EntityManager, and annotations that help you map a Java entity object to a database table.
There are several JPA providers, like HIbernate, EclipseLink, or Open JPA which you can use.
Spring Data JPA
Spring Data JPA is a JPA data access abstraction. Just like JPA, Spring Data JPA cannot work without a JPA provider.
Spring Data JPA offers a solution to the DDD Repository pattern or the DAO (Data Acess Object) pattern. It can also generate JPA queries on your behalf through method name conventions.
Spring Data JPA can work with Hibernate, Eclipse Link, or any other JPA provider. A very interesting benefit of using Spring or Java EE is that you can control transaction boundaries declaratively using the #Transactional annotation.
Jpa is a specification of java.it is used to persist data between java obect and relational database.
Spring data jpa- it is same like jpa means we can describe in below way.
Spring Data Jpa is jpa data abstraction access which means it likes a jpa but it add some extra functionality, Without jpa we can not implement the spring data jpa.
Related
In the Spring Data JPA documentation, they are often referring to the word store. One such line from documentation is:
If you use the repository abstraction for any other store, you need to change this to the appropriate namespace declaration of your store module. In other words, you should exchange jpa in favor of, for example, mongodb.
What is the actual meaning of store?
Does jpa represent only relational databases in the context of store?
Similarly we can have annotations based on store like #EnableJpaRepositories and #EnableMongoRepositories. Why do we have seperate annotations? I will appreciate clarification.
A "Store" is where you "store" (save) your data.
It's a more generic term covering both databases and non-databases.
Also commonly called a "Data Store", e.g. see Wikipedia:
A data store is a repository for persistently storing and managing collections of data which include not just repositories like databases, but also simpler store types such as simple files, emails etc.
JPA means Java Persistence API, e.g. see Wikipedia:
The Java Persistence API (JPA) is a Java application programming interface specification that describes the management of relational data in applications using Java Platform, Standard Edition and Java Platform, Enterprise Edition.
If you look at the Spring Data site, you'll see that is supports a lot of different data access technologies:
Spring Data JDBC
Spring Data JDBC Extensions
Spring Data JPA
Spring Data LDAP
Spring Data MongoDB
Spring Data Redis
Spring Data REST
Spring Data for Apache Cassandra
Spring Data for Apache Geode
Spring Data for Apache Solr
Spring Data for Pivotal GemFire
Spring Data Couchbase
Spring Data Elasticsearch
Spring Data Envers
Spring Data Neo4J
Spring for Apache Hadoop
JDBC and JPA can both be used to access relational databases.
I'm trying to create a Java Distributed Application, where i have two parts:
1) A Java EE running over Tomcat WebServer that have all business rules, JPA beans and crud operations. This part of architecture also have a RestFul layer that delegate all operations to a Service Layer, where all business lives.
2) A Java SE (Swing) that don't have any business logic and don't know JPA or any orm framework, a thin client. This just have Swing Forms and DTO (Data Transfer Object) Java Class. When this part need any database operation, it call Java EE RestFul (First part), passing DTO as JSON and this DTO is converted in Java Bean (JPA) in WebServer.
This is just a ideia of project but i have some doubts:
1) my biggest problem is convert DTO to Java Bean. I think this will be a trouble, because i need re-find the Bean in JPA (to attatch it in JPA PersistenceContext) and set property by property from DTO to JPA. There is any easy way to do it ? OBS: my dto is equal Java Bean but don't have JPA annotations. Is like a Class clone.
2) JSON is more faster way to Transfer data between RestFul?
3) can i control sessionScoped from Swing to Java EE ?
I need to migrate my application from JDBC programing model to use Hibernate. As part of this I would like to use the Annotation based configuration of hibernate. For this I want to generate JPA entities from database. I know how to do this(Using Eclipse Link), but How can I ensure the data is secured when I create JPA entities from my IDE(Eclipse)? Because Ecplise Link is a third party tool, Is there some extra configuration to prevent my database access.
Is there a way achieve this through coding?
You could generate the model from an empty database which contains the structure only and no data.
What I have,
I have a DB schema with 10 tables and basic relationships (one to one, one to many ) between the tables.
What I need,
I need to create webservices to access this DB Data (Lets ignore the business logic layer as of now) with basic CRUD operations
What I know,
I know we have JPA to generate entities, and jackson to map between json and POJO classes.
Now is there a tool which takes the DB Schema as input and generates the RESTful service classes, JPA entities with jackson annotations
Note:
We can use Spring to achieve most of it. But I dont want to use Spring or any J2EE framework for various other reasons.
I think NetBeans is the Best and the easiest.
Just right click on your web project and click on new as the picture
and if you want to create restfull web services from entity classes
Just right click on your entity classes package and click on new
Getting Started with RESTful Web Services
Have you considered JBoss Forge?
It's a tool that allows you, amongst many other things, to generate JPA entities from table and generate REST services as well (I've personally tested the JPA entities generation only). It doesn't rely on any framework, only on Java EE standard such as JPA and JAX-RS.
After creating the new project you have to call
jpa-generate-entities-from-table
to generate the entities (JPA classes) and then
rest-generate-endpoints-from-entities
to generate the REST endpoints.
In your case I think the IDE which you are using or you have option to use that is very important.
For MyEclipse
If you have option to use MyEclipse then you can expose JPA Entities via REST Web Services very easily without installing any plugins. Here is the link
Exposing JPA Entities via REST Web Services
Texo
You can also go for Texo if you think that is suitable for you
or if you are using Oracle WebLogic Server 12c (12.1.2) or later then
Oracle® Fusion Middleware Solutions will be a good choice
I am planning to build a web application with Java Server Faces but i am unsure how to handle the persistence of my entities. For php projects i am using the Symfony framework with Doctrine 2. I call the persist method of the entity manager mainly in the controllers. So there are no seperate classes for business logic. I tried Hibernate and i think that is a good replace for Doctrine. ;)
The java project is for university and i want to transfer the business logic from the controllers/beans to classes for business logic.
I read articles and tutorials about the data access object and repository pattern (http://docs.spring.io/spring-data/jpa/docs/1.3.0.RELEASE/reference/html/jpa.repositories.html).
In the data access object pattern i have a class for my Entity and an interface and a class for my DAO object/entity, in the repository pattern i have a class for my entity and a class for the repisitory.
But where goes my business logic? Do I have to write an interface and a class per entity for the business logic layer and inside the classes i simply call my dao/repository methods? If so, what is the difference between both patterns?
If I am totally wrong: What is the (industry) standard for data persistence (with Hibernate/JPA) with Java Server Faces?
The architecture of the project must be well organized according to principle "low coupling and high cohesion"
The system layers should be well seperated. The basic architecture have 3 layers.
Presentation Tier: JSF managed beans are in this layer. The task of this layer is to correspond user actions, hold user data and show the data to the user. Basically, its responsibility is bounded by MVC pattern regardless of which implementation you use (JSF, Spring MVC or Struts)
Bussimess Logic Tier: The data and actions which was collected from page was sent to this layer to operate on data. You should not manipulte the data and prepare the response inside Presentation Tier. It is the responsibility of Bussiness Logic Tier.(Spring, CDI)
Integration Tier: Database access should be done in this layer regardless of the library technology used (Hibernate, JPA, JDBC).
As you can see in the pic. your JSF managed beans should only be capable of requests from the pages(controller) and page data (model). You can have a look to this answer to understand JSF MVC. Therefore, It is better to not to connect DB inside JSF managed beans. It is not a good practice.
The second part of your question. All technologies, Hibernate, JPA, Spring JDBC, uses JDBC driver of the related DB. JDBC Drivers is the just thing which connects to the DB. However, it is beter to select a method how to connect to DB, Hibernate, JPA or Spring JDBC.
You can download my example application which implements this architecture basically.