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Difference between revisions of "EclipseLink/Development/DBWS/oNmMetadata"
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* generated persistent model classes must work when mapped simultaneously by both an OR and OX metadata model. <br/> i.e. an instance of a generated class must support the following: a row is retrieved from the database, built into an instance object and that very same object is serialized to XML - and vice-versa. | * generated persistent model classes must work when mapped simultaneously by both an OR and OX metadata model. <br/> i.e. an instance of a generated class must support the following: a row is retrieved from the database, built into an instance object and that very same object is serialized to XML - and vice-versa. | ||
− | ==== | + | ==== OR new-format metadata requirements ==== |
− | * | + | * direct mappings with sufficient attribute information to support the range of datatypes used by XML |
+ | * session-level settings: database platform information, container settings, etc. | ||
+ | * queries whose arguments use complex types (advanced JDBC types; PL/SQL records, collections) | ||
+ | ** [https://bugs.eclipse.org/bugs/show_bug.cgi?id=211299 211299], [https://bugs.eclipse.org/bugs/show_bug.cgi?id=221876 221876] | ||
==== OXM new-format metadata requirements ==== | ==== OXM new-format metadata requirements ==== |
Revision as of 11:29, 4 June 2009
Contents
DBWS and new-format metadata
Issues Summary
At some point in the future, DBWS will switch from using 'native' EclipseLink metadata (a.k.a. Project deployment xml) to using 'oxm' and 'orm' (a.k.a JPA-style) metadata formats. In addition to using the new-format metadata, DBWS typically operates without persistent model classes; thus at runtime, a dynamic solution is required for the generation of persistent model classes.
General Solution
Similar to the current DBWS support, the new-format metadata files will be produced at design time by a DBWS utility. Later DBWS will at runtime read-in the new-format metadata files, dynamically generate persistent model classes, and realize an environment that bridges between representation in a relational database and in an XML document.
Requirements
- the new-format 'oNm.xml' metadata must support the majority of EclipseLink features (see below)
- as there are no persistent model classes on the classpath, processing the new-format metadata must use only simple scalar objects (Strings, booleans, numbers, etc.) for all capabilities and settings.
- an in-memory model of the new-format metadata can be read in from an file (or stream, URL, etc.) without persistent model classes on the classpath.
- an in-memory model of the new-format metadat can be serialized to a file (or stream, URL, etc.) without persistent model classes on the classpath.
- an in-memory model of the new-format metadata can be realized into runtime artifacts, including generating persistent model classes.
- generated persistent model classes must work when mapped simultaneously by both an OR and OX metadata model.
i.e. an instance of a generated class must support the following: a row is retrieved from the database, built into an instance object and that very same object is serialized to XML - and vice-versa.
OR new-format metadata requirements
- direct mappings with sufficient attribute information to support the range of datatypes used by XML
- session-level settings: database platform information, container settings, etc.
- queries whose arguments use complex types (advanced JDBC types; PL/SQL records, collections)
OXM new-format metadata requirements
Open Issues
- there are multiple solutions for dynamic generation of persistent model classes (SDO -
o.e.p.sdo.helper.DynamicClassWriter
; DBWS -o.e.p.internal.dynamicpersist.BaseEntityClassLoader
). A separate functional spec should be created to examine the requirements and work required to refactor the multiple solutions into a common solution.