Support for "Interface Based Design"

Question

I would like two PC classes that implement a common interface, but the two
PC classes are not related by inheritance, and would not be stored in the
same table. For example,
public interface VersionNumber {
int getNumber();
boolean isComparableTo( VersionNumber vn );
/** PC class **/
public class BasicVersionNumber implements VersionNumber {
/** PC class **/
public class CustomVersionNumber implements VersionNumber {
/** PC class **/
public class Paper {
VersionNumber vn;
Since "BasicVersionNumber" and "CustomVersionNumber" are not related via
inheritance, they would not generally reside in the same database table.
It would mean that the table containing "Paper" would need both the target
table for this instance of "vn", and the primary key for "vn". It appears
that KODO assumes the target table is available in the Meta-Data file, but
with interface-based design, that is not known until run time and could be
different for different instances of class "Paper".
Is it possible to do this with KODO? Where can I go to understand how.
Keith L. Musser
Integrated Dynamics, Inc.
812-371-7777
email: [email protected]
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Answer 1

Kodo supports interfaces as fields (in Kodo 3, we support interfaces for
more relation types). Kodo will store the toString () of the JDO
identity for the actual concrete instance in the column as there is no
formal O/R relation between the table and the interface field type.
Keith Musser wrote:
I would like two PC classes that implement a common interface, but the two
PC classes are not related by inheritance, and would not be stored in the
same table. For example,
public interface VersionNumber {
int getNumber();
boolean isComparableTo( VersionNumber vn );
/** PC class **/
public class BasicVersionNumber implements VersionNumber {
/** PC class **/
public class CustomVersionNumber implements VersionNumber {
/** PC class **/
public class Paper {
VersionNumber vn;
Since "BasicVersionNumber" and "CustomVersionNumber" are not related via
inheritance, they would not generally reside in the same database table.
It would mean that the table containing "Paper" would need both the target
table for this instance of "vn", and the primary key for "vn". It appears
that KODO assumes the target table is available in the Meta-Data file, but
with interface-based design, that is not known until run time and could be
different for different instances of class "Paper".
Is it possible to do this with KODO? Where can I go to understand how.
Steve Kim
[email protected]
SolarMetric Inc.
http://www.solarmetric.com