Hi,
Current RDB DAS(deprecated SDO), by using, SDOUtil.createTypeHelper(); is
creating
new TypeHelper instance for each SELECT query (GraphBuilderMetadata()). But
this way
we end up in creating many TypeHelpers.
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The new SDO API, gives another way where we can use the same TypeHelper
instance, through,
HelperContext context = HelperProvider.getDefaultContext();
TypeHelper th = context.getTypeHelper().
With this the existing RDB DAS code needs a bit of caution, like -
A> first check typeHelper.getType() , and only if it is null, then call
SDOUtil.createType(hc,...)
(because directly calling createType() on pre-existing Type, returns null)
B> Also, create property in DataObject only when it is missing, like
if(root.getProperty(tableName) != null &&
root.getProperty(tableName).getType().getName().equals(
tableType.getName())){
//dont do anything
}
else{
property = SDOUtil.createProperty(root, tableName, tableType);
SDOUtil.setMany(property, true);
SDOUtil.setContainment(property, true);
}
But when tried with this approach, in cases of ApplyChange() {UPDATE}, what
is seen is SET clause
gets NULL values and WHERE clause gets correct values. WHERE clause is
derived from ChangeSummary
old values and is coming correct. In case of SET clause, what is seen is,
below line from RDB DAS
returns NULL-
DataObject parent = dataObject.getDataObject(parentRef);
Where serialized dataObject is -
<?xml version="1.0" encoding="ASCII"?>
<dObj:dObj xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
xmlns:dObj="dObj"
xmlns:das="http:///org.apache.tuscany.das.rdb/das";
xsi:type="das:ORDERDETAILSDESC">
<ID>3</ID>
<ORDERID>1</ORDERID>
<PRODUCTID>2</PRODUCTID>
<DESCR>Descr 3,1,2</DESCR>
<orderDetailsDesc_opposite>root.xml#//@ORDERDETAILS.0
</orderDetailsDesc_opposite>
</dObj:dObj>
And parentRef is -
orderDetailsDesc_opposite
Question here is, when the serialized dump shows that there is
orderDetailsDesc_opposite
available, why dataObject.getDataObject() is not able to fetch it?
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On the other hand, when the new SDO API, is used in the old way, i.e. keep
creating new
instances of TypeHelper (do not reuse the one from DefaultContext), the
above problem does
not occur. So, when done like below,
HelperProvider helperProvider = HelperProvider.getInstance(); //this is a
new instance each time
HelperContext defHc = helperProvider.getDefaultContext();//and so are the
others
TypeHelper typeHelper = helperProvider.typeHelper();
Surprisingly, here the DataObject serialization dump and parentRef value are
exactly the same as above, and dataObject.getDataObject(parentRef) is able
to fetch NOT NULL DataObject.
So, what is going on inside SDO/EMF? Why the same (at least from serialized
string), DataObject's
getDataObject() method behaves differently in these two cases?
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Regards,
Amita
