AccessPlatform 2.1 : Getting Started

DataNucleus AccessPlatform implements the JDO and JPA specifications. These specifications define how Java classes can be persisted to a datastore and how they can be queried. By choosing AccessPlatform you can select which of these APIs you feel most comfortable with. Time for you to get started and use AccessPlatform!

What is required?
  1. DataNucleus AccessPlatform 2.1 requires a JDK of 1.5 or above.
  2. The first thing to do is Download DataNucleus Access Platform. Download the bundle that is most appropriate to your needs so, for example, if you are going to be developing for access of RDBMS data download the accessplatform-rdbms zip. If you want instead to just download the individual DataNucleus plugins that make up Access Platform then please refer to the list of dependencies for details of what other packages are required.
  3. You also need a datastore. DataNucleus AccessPlatform 2.1 supports many datastores, including RDBMS, DB4O, LDAP, Excel, XML, JSON, ODF. Please refer to the linked pages for full details of the datastore required.
  4. Depending on what development environment you use, you could also download a DataNucleus plugin for Eclipse or Maven.

That should be enough to get you going. You have the necessary components to start investigating use of DataNucleus.

Starting up

The next thing to do is to learn about JDO and JPA. You need to understand the basic concepts involved. The JDO Overview is one place to start but there is plenty of reading on the internet, starting with the JDO or JPA specifications of course.

The best thing to do after some reading is to try the JDO Tutorial or the JPA Tutorial. This explains the basic steps of applying JDO/JPA (and DataNucleus) to your own application. The source code from the Tutorial is available for download. Please download it and start up your development environment with the Tutorial classes and files.

Once you have completed the Tutorial you should be ready to start applying DataNucleus to your own application and benefiting from what it offers.

Key Points

There are some key points to bear in mind when starting using JDO/JPA for java persistence.

  • To persist objects of classes you need to define which classes are persistable, and how they are persisted . Look under the JDO Mapping and JPA Mapping sections
  • Use of JDO or JPA requires a datastore-controlling factory : PersistenceManagerFactory for JDO, EntityManagerFactory for JPA. You can define many properties to define the capabilities of this
  • The persistence of objects is controlled by an API. Look under JDO API and JPA API for more details
  • During the persistence process objects are in different lifecycle states and you ought to be aware of what they are
  • You retrieve objects either by their identity, or using a query. With JDO you can use JDOQL, SQL or JPQL. With JPA you can use JPQL or SQL