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JDO support vs JPA



I am about to update the JDO metadata in the package.jdo files after moving from ObjectDB 1 to 2. However I found that there is no complete description or guide how the XML metadata should look in version 2. I found only small fragments of attributes in the description of JDO Annotations (to which XML element is the given annotation equivalent).

So my questions to this are:

1. Is there some description of XML metadata for ObjectDB ver2 using JDO which I did not find?

2. Is the combined usage of JDO annotation and XML metadata working or the enhancer takes exclusively either this or that ?

3. I found there is only API documentation for JDO and no manual at all as there is for JPA. Does this mean that the support of JDO in ObjectDB 2 is already in some legacy mode ? So is JPA the preferred technology above JDO ?

4. If I would decide to move to JPA from JDO, is it possible to access the same database with JPA what is using at the moment JDO ? Or should it be somehow transferred using a utility ?




1. You can find the full description in the JDO specification document. Some information can also be found on DataNucleus (the JDO reference implementation) website.

2. You can combine annotations and XML. The rules are described in the JDO specification document.

3. JPA is more popular and generally it is more recommended for new projects. However there are no plans to stop supporting JDO in future versions of ObjectDB.

4. You can use the same databases with JPA and JDO concurrently. The use of API does not affect the database file format.

ObjectDB Support
ObjectDB - Fast Object Database for Java (JPA/JDO)

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