NeoDatis ODB

Layer 1: The instance layer

This layer works with Instances. This is the entry point of ODB. This layer is the user interface to ODB. It is implemented by the following package:

• org.neodatis.odb.main: public interfaces and factories
• org.neodatis.odb.core.io: contains internal implementation for this layer.

Layer 2: a meta representation of the objects and classes

package : com.neodatis.odb.meta

This layer is a Meta representation layer. It holds all the data and definition in a language independent way. Main classes are ClassInfo (Meta representation of a class), NonNativeObjectInfo (Meta representation of an instance), NativeObjectInfo (Meta representation of a native value, like int, long, String, …). More details about Object Infos.

Class ClassInfo

The ClassInfo is a meta representation of a class. It has the following attributes:

• The OID of the class
• The OID of the previous class info
• The OID of the next class info
• The class type : user class or system class
• Class Name
• Package name
• List of attributes
• The number of objects of this class.
• The OID of the first object of this class
• The OID of the last object of this class
• The list of indexes defined on this class

The class org.neodatis.odb.core.introspector.ClassIntrospector is the class that uses reflection to transform a class into a ClassInfo meta representation

Class NonNativeObjectInfo

The NonNativeObjectInfo is a meta representation of an object. It has the following attributes:

• The object
• The type of the object (org.neodatis.odb.core.meta.ODBType)
• The ClassInfo of the object
• The list of attributes (list of AbstractObjectInfo)
• The ObjectInfoHeader that holds :
  • The object position (in the ODB file)
  • The Object OID
  • The previous Object OID
  • The next object OID
  • The ClassInfo OID
  • The ids (local id, to idenitfy the attribute) of the attributes
  • The OID or position of the attributes

Layer 3 : The file(s) where data are physically stored.

ODB stores all data in a unique binary file. This file will contain:

• The database meta-model : All the classes already stored in the base
• The instances
• The indexes
• …

Check this page to learn more about the ODB file format