given that JDO's future is unclear* (at best) and JPA is unproven* (are
there any robust production tested implementations yet?), i would think
that a "wait and see" approach would be most prudent.
* = craig would know much better than i, i think
i think that all things being equal it'd be better to not have the
hibernate dependency, but it doesn't seem like now would be the right
time to switch. if you're going to do this, make sure you won't be
contemplating it again in 6 months.
now, if folks want to put start putting things together in sandbox, by
all means ... maybe by the time 3.x is ready, things will be clear
Allen Gilliland wrote:
So maybe it's time to ask the question more squarely ... who wants to
replace Hibernate as our persistence implementation?
-- Allen
Matt
-- Allen
Craig L Russell wrote:
> Hi,
>
> Here's what I propose as a starting point for the query interface
> between Datamapper Managers and Datamapper Persistence.
>
> There are enough differences between JDO, JPA, and Hibernate that I
> found it really awkward to define a set of methods on
> PersistenceStrategy that covered the functionality. In particular,
there
> are two methods in JPA that both execute the query and determine the
> result shape, and parameters are passed one by one. In JDO, there
is an
> API that determines the result shape and one method to execute the
> query, passing parameter values. It's trivial to encapsulate these
> differences in a Query instance.
>
> I've included the Query API below for discussion, along with calling
> sequence from Mapper.
>
> Craig
>
> public class DatamapperPersistenceStrategy {
> ...
> /**
> * Create query.
> * @param clazz the class of instances to find
> * @param queryName the name of the query
> * @throws org.apache.roller.RollerException on any error
> */
>
> public DatamapperQuery newQuery(Class clazz, String queryName)
> throws RollerException;
> }
>
> public class DatamapperUserManagerImpl {
> ...
> public WebsiteData getWebsiteByHandle(String handle, Boolean
enabled)
> throws RollerException {
> // XXX cache websites by handle?
> return (WebsiteData)strategy.newQuery(WebsiteData.class,
> "getByHandle&&Enabled")
> .execute(new Object[]{handle, enabled});
> }
>
> public interface DatamapperQuery {
>
> /** Execute the query with no parameters.
> * @return the results of the query
> */
> Object execute();
>
> /** Execute the query with one parameter.
> * @param param the parameter
> * @return the results of the query
> */
> Object execute(Object param);
>
> /** Execute the query with parameters.
> * @param params the parameters
> * @return the results of the query
> */
> Object execute(Object[] params);
>
> /** Remove instances selected by the query with no parameters.
> * @return the results of the query
> */
> void removeAll();
>
> /** Remove instances selected by the query with one parameter.
> * @param param the parameter
> * @return the results of the query
> */
> void removeAll(Object param);
>
> /** Remove instances selected by the query with parameters.
> * @param params the parameters
> * @return the results of the query
> */
> void removeAll(Object[] params);
>
> /** Set the result to be a single instance (not a List).
> * @result the instance on which this method is called
> */
> DatamapperQuery setUnique();
>
> /** Set the types of the parameters. This is only needed if the
> * parameter types are temporal types, e.g. Date, Time, Calendar.
> * @param the types of the parameters in corresponding positions.
> * @result the instance on which this method is called
> */
> DatamapperQuery setTypes(Object[] types);
>
> /** Set the range of results for this query.
> * @fromIncl the beginning row number
> * @toExcl the ending row number
> * @return the instance on which this method is called
> */
> DatamapperQuery setRange(long fromIncl, long toExcl);
> }
>
> Craig Russell
> [EMAIL PROTECTED] http://db.apache.org/jdo
>
>
