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The idea is to support buffer handles more naturally and to support converted, buffer-related methods, attributes, and language statements as direct method calls on DMO proxy objects.

Today, converted business logic references DMOs by their schema interfaces, which include only getter and setter methods for their database fields. This means that any buffer-related 4GL methods and attributes must be invoked as second-class citizens, typically by invoking a static method call and passing the proxy object into that call (e.g., RecordBuffer.recordID(myDMO)).

Going forward, business logic will reference DMOs by an interface which extends both the schema interface as well as a new Buffer interface, which includes APIs for all converted 4GL methods and attributes. That interface will extend WrappedResource, so that instances of these objects can be used within instances of the handle class. This means that business logic can invoke both schema-specific methods, and 4GL-style methods and attributes, as direct method calls on a DMO proxy object.

Each converted DMO interface will include a new, public, static, inner interface which extends both the enclosing interface, as well as the new Buffer interface:

public interface SomeDMO
{
   // getter and setter methods
   ...

   public static interface Buf
   extends SomeDMO, Buffer
   {
   }
}

This grouping interface does not define any methods of its own; its only purpose is to group the enclosing interface and the Buffer interface, so that DMO proxies in converted business logic can access the methods of both, without requiring any casting.

DMO implementation classes will continue to implement only the schema-specific, DMO interface (i.e., not the one that extends Buffer).

BufferImpl is the concrete implementation of the Buffer interface. It also implements BufferReference, which has one method, buffer, used to access the RecordBuffer instance associated with a DMO proxy object. Internally, BufferImpl uses the buffer method to delegate much of its work to the RecordBuffer class. The implementation of the buffer method in this class throws an exception; at runtime, we rely on a proxy implementation of the buffer method to override this implementation to get us an actual RecordBuffer instance. However, it needs to be present in BufferImpl to satisfy the Java compiler.

This new implementation requires a number of conversion changes in addition to the schema conversion change described above. Everywhere a DMO is defined or declared today, the data type must change from {DMO interface} to {DMO interface}.Buf. This affects all calls to:

• RecordBuffer.define
• TemporaryBuffer.define (overloaded)
• TemporaryBuffer.useShared
• SharedVariableManager.lookupBuffer

In addition, a number of existing constructs must change:

RecordBuffer.recordID(dmo)      --> dmo.recordID()
RecordBuffer.rowID(dmo)         --> dmo.rowID()
RecordBuffer.isAvailable(dmo)   --> dmo.available()
RecordBuffer._isAvailable(dmo)  --> dmo._available()
RecordBuffer.wasLocked(dmo)     --> dmo.locked()
RecordBuffer._wasLocked(dmo)    --> dmo._locked()
RecordBuffer.wasAmbiguous(dmo)  --> dmo.ambiguous()
RecordBuffer._wasAmbiguous(dmo) --> dmo._ambiguous()
RecordBuffer.isNew(dmo)         --> dmo.newlyCreated()
RecordBuffer._isNew(dmo)        --> dmo._newlyCreated()
TemporaryBuffer.clear(dmo)      --> dmo.deleteAll()

Note that since there is now the opportunity to encounter naming collisions with DMO-specific method names, we have to ensure that no method defined by the Buffer interface begins with is, get, or set. These prefixes are reserved for DMO-specific interface method names, and in fact, such methods will not use any other prefixes, so as long as we follow this rule, we will avoid collisions.

This change presents some problems for hand-written code. Specifically, there is now a body of hand-written Java code which relies on the old APIs, most notably RecordBuffer.isAvailable/_isAvailable, RecordBuffer.recordID, and a handful of others. For the time being, these methods are marked deprecated so that this code will still compile, though it requires testing to make sure it still works. Ultimately, this code should be edited to comply with the new architecture.

I have gotten very far with this change over the weekend, but I'm still working out issues getting converted Majic to compile. I hope to finish tomorrow and get it into testing very soon.

For those of you currently working on issues that will be affected by this change, please ask any questions you may have.

Will buffer parameters change to {DMO interface}.Buf?

public class ExternalProc
{
   SomeDMO.Buf buf;

   public void execute(final SomeDMO.Buf buf)
   {
      ...

Stanislav Lomany wrote:

Will buffer parameters change to {DMO interface}.Buf?

Yes, any access to a DMO from business logic will be via this new interface.

Updated the Buffer interface to accommodate the following, additional changes:

RecordBuffer.create(dmo)   --> dmo.create();
RecordBuffer.delete(dmo)   --> dmo.delete();
RecordBuffer.release(dmo)  --> dmo.release();
RecordBuffer.validate(dmo) --> dmo.validate();

In addition, I've added the following at Stanislav's request for trigger support, though currently the runtime backing is only stubbed out:

   public void openReadOnlyScope();

I am running conversion now, cleaning up, adding javadoc and comments; hope to be able to go into regression testing tomorrow.

Methods RecordBuffer.copy() and RecordBuffer.openScope() are not deprecated, but compiler makes warnings

compile:
    [javac] Compiling 1006 source files to /home/vmn/p2j/build/classes
    [javac] /home/vmn/p2j/src/com/goldencode/p2j/persist/BufferImpl.java:354: warning: [deprecation] copy(com.goldencode.p2j.persist.DataModelObject,com.goldencode.p2j.persist.DataModelObject,boolean) in com.goldencode.p2j.persist.RecordBuffer has been deprecated
    [javac]       RecordBuffer.copy((BufferImpl) bufHandle.get(), this, true);
    [javac]                   ^
    [javac] /home/vmn/p2j/src/com/goldencode/testcases/Vadim22.java:52: warning: [deprecation] openScope(com.goldencode.p2j.persist.DataModelObject...) in com.goldencode.p2j.persist.RecordBuffer has been deprecated
    [javac]             RecordBuffer.openScope(btest, hbuffer);
    [javac]                         ^
    [javac] Note: Some input files use unchecked or unsafe operations.
    [javac] Note: Recompile with -Xlint:unchecked for details.
    [javac] 2 warnings

Possible it takes “deprecated” keyword from some commented lines above these methods.

Yes, I should have removed the commented methods once I got everything compiling. I didn't notice this when I built the regression testing application, as I just saw that the build was successful, but missed the summary lines:

    [javac] Note: Some input files use or override a deprecated API.
    [javac] Note: Recompile with -Xlint:deprecation for details.

Thanks for pointing this out. This means the javadoc will likely be wrong, too. I'll remove these commented, deprecated methods in the final update.

Eric, please be aware that define parameter buffer is not converted properly:

   Book.Buf buf1;

   public void execute(final Book buf1)
   {
      externalProcedure(new Block()
      {
         public void body()
         {
            RecordBuffer.openScope(buf1);
            ExternalProc.this.buf1 = buf1;  /* different types */
          }
      });
   }

I confirm for temp-tables too, please check the buffer_test2a.p and buffer_test2b.p (they are in bazaar).

Stas, Constantin, thanks for letting me know about this. I have an update which fixes this for me locally, but it needs to go through testing still. I'll post it here for your temporary use, once I've cleaned it up.

• Errorable
• DatabaseInfo
• ADMData
• UniqueID
• NamespaceURI

I'm putting this through conversion regression testing.

Passed conversion regression testing.

I'm taking this back, wrong task: this has some regressions in terms that is too aggressive when bracketing the deleteAll call, there are other cases when it doesn't need to.

I'll fix this and re-test.

The om_upd20130304b.zip and ecf_upd20130305a.zip updates have gotten through conversion regression testing. However, Majic requires an update to hand-written Java code which implements the WrappedResource interface. See #2081.

Please commit and distribute the combined update.

ca_upd20130306b.zip has passed conversion regression testing (no changes in generated sources).

0306b.zip was committed to bzr revision 10253.