2.15 Contents of RWDBSystemHandle

The RWDBConnection::systemHandle() method returns a pointer to a base class from which a family of implementation-specific classes are derived. To use the database API directly, you can downcast this pointer to the appropriate type, and use its implementation-specific features. Naturally, this usage reduces an application's portability.

For the Oracle access library, the implementation-specific system handle has the datatype RWDBOracleSystemHandle. It contains a pointer to the Logon Data Area (LDA) and to the Host Data Area (HDA). These provide access to the server. The handle also maintains control parameters used when accessing the database. The production of a new RWDBConnection creates a new RWDBOracleSystemHandle. The handle starts the session and maintains the LDA and HDA. The following functions may be used to retrieve these components:

Lda_Def* lda();
ub1* hda();

NOTE: The following function has been eliminated:
Hda_Def* hda();
The type Hda_Def is not available on all clients and is functionally identical to ub1.

2.15.1 Obsolete Functions

The following functions were made obsolete by changes in DBTools.h++ 4.0. These functions have been removed from the API:

size_t
fetchSize() const;
void
fetchSize(size_t number);

size_t
parameterSize() const;
void
parameterSize(size_t number);

size_t
maxStoredProcParameterSize() const;
void
maxStoredProcParameterSize(size_t newSize);

The fetchSize() functions became redundant when caches were added to RWDBReader. Please see the caching chapter in the User's Guide for information on how to alter the size of a fetch. Existing programs that use fetchSize() should change the cache size of their RWDBReaders instead.

The function parameterSize() was superseded by the function maximumNumberOfParameters(). Calls to parameterSize() can safely be replaced with equivalent calls to maximumNumberOfParameters().

The function maxStoredProcParameterSize() was superseded by the function maximumBlobSize(). Calls to maxStoredProcParameterSize() can safely be replaced with equivalent calls to maximumBlobSize().

2.15.2 Number of Parameters

Class RWDBOracleSystemHandle allows you to set and to access the maximum on the number of parameters in a stored procedure. The functions to use are:

size_t
maximumNumberOfParameters() const;
void 
maximumNumberOfParameters(size_t number);

The maximum number of parameters is used to allocate buffers for the call to odessp. The default value is 32.

2.15.3 Blob Size

Class RWDBOracleSystemHandle allows you to set and access the size of the buffer used for retrieving LONG and LONG RAW data. The functions to use are:

size_t 
maximumBlobSize();
size_t 
maximumBlobSize(size_t newSize);

The default blob size is 32k - 1 bytes.

2.15.4 Using RWDBSytemHandle

If it is necessary for your application to make calls directly to OCI, proceed as in the following example:

#include <rw/db/orasrc/orasysh.h>
RWDBConnection oraConnect = myDbase.connection();
RWDBOracleSystemHandle* handle = (RWDBOracleSystemHandle*)oraConnect.systemHandle();
Lda_Def* lda = handle->lda();
// use the LDA pointer for Oracle OCI calls

Please be aware that there are complications associated with making direct OCI calls, which do not use the internal logic of the Oracle access library.

Also note that your application must be compiled with an include path to the Oracle library include files.