Re: Description Repositories at Thread level

[Armin Waibel]

Hi Sridhar,

in your case you can setup two different repository and read the second 
one at runtime (with both jdbc-connection-descriptor declared in the 
default repository, in the second one only declare object metadata - 
then you don't need to read and merge the second ConnectionRepository) 
or you can modify a copy of the default repository object metadata.

http://db.apache.org/ojb/api/org/apache/ojb/broker/metadata/MetadataManager.html

I recommend to use object metadata profiles. You can handle this stuff 
in a startup class or something similar. Say you have two 
DescriptorRepository instances one for Oracle , one forAccess

MetadataManager mm = MetadataManager.getInstance();
mm.addProfile("access", accessDescriptorRepository);
mm.addProfile("oracle", accessDescriptorRepository);
Now OJB manage three DescriptorRepository instances the "default one" 
automatic read by OJB (access or oracle) and two profiles for use in 
threaded mode.

Currently OJB allows to enable per thread mode when needed. So you can 
enable per thread mode when needed or at startup.

mm.setEnablePerThreadChanges(true);

OJB now support per thread object metadata via a ThreadLocal instance. 
But you have to tell the MM which profile to use. If you now obtain a 
PersistenceBroker instance from the PBF you will get the "default one".
BEFORE obtain the PB instance call

mm.loadProfile("oracle");
PersistenceBroker broker = PersistenceBrokerFactory.cre....;
Now the object metadata profile for "oracle" is associated with the 
obtained PB instance. All further obtained PB instance of the current 
thread will now use the oracle profile. If you want to change the 
profile for current thread call loadProfile again.

hope this will help you!

regards,
Armin
Sridhar wrote:

Hi,

I need to define a repository that needs to work both in Oracle as well as MS-
Access.  Some jdbc datatypes like BLOB and CLOB in Oracle maps to LONGVARBINARY 
and LONGVARCHAR in access. Also, on some rare occasions I need to copy data 
between Access and Oracle. In one case the table names are different (the table 
represented by class "LLEAgency").  To overcome I defined the repository for 
Oracle data types and change them to access data types when required.  This 
method is on a class that extends Thread.

    public void makeAccessCompatible()
    {
        MetadataManager mdm = MetadataManager.getInstance();
        mdm.setEnablePerThreadChanges(true);
        DescriptorRepository dr = mdm.copyOfGlobalRepository();
        Iterator ir = dr.iterator();
        while(ir.hasNext())
        {
            ClassDescriptor cd = (ClassDescriptor) ir.next();
            if(cd.getClassNameOfObject().endsWith("LLEAgency"))
            {
                System.out.println(cd.getFullTableName());
                cd.setTableName("CODES_DEPARTMENTS");
            }
            FieldDescriptor[] flds = cd.getFieldDescriptions();
            for (int i = 0; i < flds.length; i++)
            {
                FieldDescriptor fd = flds[i];
                if (fd.getColumnType().toLowerCase().equals("blob"))
                {
                    fd.setColumnType("longvarbinary");
                }
                else if (fd.getColumnType().toLowerCase().equals("clob"))
                {
                    fd.setColumnType("longvarchar");
                }
            }
        }
        mdm.setDescriptor(dr);
    }
After executing this on one of the threads, I checked the repository on both 
the threads and they are exactly same, this is how I checked, compare the 
String returned from the 2 threads using

MetadataManager.getInstance().getRepository().toXML();

I have tried setting the

        MetadataManager.getInstance().setEnablePerThreadChanges(true);

at various points, including the application startup.  But still no luck.  
Looks like I am missing something very obvious here. When I get a 
copyofGlobalRepository, I assume I get a copy entire repository tree, with the 
Class, Field descriptors everything.  Am I still working with the same object 
references or differet objects/references? Can anyone please help me with this?

Thanks & Regards
Sridhar
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]


---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]