Implementing a Custom Callback Class

SourcePro : DB Interface Module User’s Guide : PART IV Using Open SQL : Using the Open SQL Classes : The Data Callback Classes : Implementing a Custom Callback Class

To use the data callback feature:

1. Create a derived class from one of the three callback interface classes.

2. Implement the necessary callback methods in the derived class.

3. Provide an instance of the derived class to an RWDBOSql instance.

4. Execute the RWDBOSql.

To fetch or insert character data, derive from the base class RWDBCharCallback; for binary data, derive from RWDBBinaryCallback; and for UTF-16 data, derive from RWDBUChar16Callback. Note that only LOB data types are supported. Then define both of the pure virtual methods onFetch() and onSend(), and if needed, getLength().