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DataNucleus Access Platform 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 Access Platform you can select which of these APIs you feel most
comfortable with. Time for you to get started and use Access Platform!
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DataNucleus Access Platform 1.1
requires a JDK of 1.5 or above.
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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.
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You also need a datastore. DataNucleus Access Platform 1.1 supports
RDBMS,
DB4O,
LDAP,
Excel spreadsheets,
NeoDatis ODB,
XML,
JSON and
OpenDocument spreadsheets.
Please refer to the linked pages for full details of the datastore required.
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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.
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 JDO2 or JPA1 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.
There are some key points to bear in mind when starting using JDO/JPA for java persistence.
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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
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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
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The persistence of objects is controlled by an API. Look under
JDO API and JPA API
for more details
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During the persistence process objects are in different
lifecycle states and you ought to be aware of what
they are
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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
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