Acts as a registry of JDO metadata so that metadata files don't need to be parsed multiple times. MetaData is stored as a FileMetaData, which contains PackageMetaData, which contains ClassMetaData, and so on. This maps exactly to the users model of their metadata. The users access point is getMetaDataForClass() which will check the known classes without metadata, then check the existing registered metdata, then check the valid locations for metdata files. This way, the metadata is managed from this single point.
When the MetaData is requested for a class, if it isn't already found, the valid file locations are checked for that class and the file containing it will be read. The MetaData for all classes, queries, sequences etc in that file are loaded at that point. In addition, all classes will be "populated" (meaning that their superclasses are assigned, and unspecified fields are added, and any related objects are linked). The MetaData of these classes are only initialised when they are absolutely needed - to avoid generating circular references in the initialisation process.
Each NucleusContext typically will have its own MetaDataManager so allowing Meta-Data to be for different datastores. In addition, each PMF can allow MetaData files to use a particular suffix, hence we allow the JDO/ORM file suffices to be specifiable at construction.
Acts as a registry of JDO metadata so that metadata files don't need to be parsed multiple times. MetaData is stored as a FileMetaData, which contains PackageMetaData, which contains ClassMetaData, and so on. This maps exactly to the users model of their metadata. The users access point is getMetaDataForClass() which will check the known classes without metadata, then check the existing registered metdata, then check the valid locations for metdata files. This way, the metadata is managed from this single point.
When the MetaData is requested for a class, if it isn't already found, the valid file locations are checked for that class and the file containing it will be read. The MetaData for all classes, queries, sequences etc in that file are loaded at that point. In addition, all classes will be "populated" (meaning that their superclasses are assigned, and unspecified fields are added, and any related objects are linked). The MetaData of these classes are only initialised when they are absolutely needed - to avoid generating circular references in the initialisation process.
Each OMFContext typically will have its own MetaDataManager so allowing Meta-Data to be for different datastores. In addition, each PMF can allow MetaData files to use a particular suffix, hence we allow the JDO/ORM file suffices to be specifiable at construction.
Acts as a registry of JDO metadata so that metadata files don't need to be parsed multiple times. MetaData is stored as a FileMetaData, which contains PackageMetaData, which contains ClassMetaData, and so on. This maps exactly to the users model of their metadata. The users access point is getMetaDataForClass() which will check the known classes without metadata, then check the existing registered metdata, then check the valid locations for metdata files. This way, the metadata is managed from this single point.
When the MetaData is requested for a class, if it isnt already found, the valid file locations are checked for that class and the file containing it will be read. The MetaData for all classes, queries, sequences etc in that file are loaded at that point. In addition, all classes will be "populated" (meaning that their superclasses are assigned, and unspecified fields are added, and any related objects are linked). The MetaData of these classes are only initialised when they are absolutely needed - to avoid generating circular references in the initialisation process.
Each PMFContext typically will have its own MetaDataManager so allowing Meta-Data to be for different datastores. In addition, each PMF can allow MetaData files to use a particular suffix, hence we allow the JDO/ORM file suffices to be specifiable at construction.
@version $Revision: 1.31 $
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