Extended Stored Procedures in VC++? That's simple!

Although giving these benefits, the native Extended Stored Procedures API (former Open Data Services API) is rather complex in use.

It requires too much "housekeeping" work from the developer: manage memory buffers, handle I/O parameters, determine I/O datatypes, describe and produce recordsets, etc, etc, etc...

This, in turn, may require often debug.

Is there a better way?

Here is a VC++ class CXProc that hides all of that jazz from the developer and just exposes methods and properties.

It is compatible to VC++ 6 and 7.

No more dozens of srv_describe, srv_paramsetoutput, srv_rpcparams, srv_paraminfo, etc!
Just CXProc xproc(srvproc); CxpFields& fd = xproc.Fields(); fd[0].SetInt(123);

[+] This example does the following (click here to show/hide):

This code deals with two optional I/O parameters (first them is varchar and second is int), modifies first (when present), and then creates a recordset of 3 columns: int, datetime, and image.

#include "xproc.h"

using namespace XProc;

__declspec(dllexport) RETCODE xp_Class(SRV_PROC *srvproc)
{
	CXProc xproc(srvproc);				// Initialize
	CxpParams& p = xproc.Params();			// Remember the INPUT/OUTPUT params collection for future reference

	size_t cnt = 0;

	if (p.size()) {					// Check if procedure parameters are present
		char* s = p[0].GetAnsiText();		// Read first procedure parameter (assume it is VARCHAR & OUTPUT)
		
		cnt = 21 + strlen(s);
		char* answer = new char[cnt];
		memset(answer, 0, cnt);
		strcat(answer, "You've just passed: ");

		p[0].SetVarchar(strcat(answer, s));		// Send the modified text back to OUTPUT parameter
		delete answer; delete s;			// IMPORTANT!!!

	}

 	// Let's make a recordset of 20 rows and 3 columns: INT, DATETIME, and IMAGE
	CxpFields& fd = xproc.Fields();			// Remember the fields collection for future reference
    
	cnt = 300;					// Let IMAGE field's length is 300 bytes
	fd[2].SetName("300 bytes of BLOB");			// Give an arbitrary name to an IMAGE field column

 	// Just a dummy integer multiplicator value from 2nd INPUT parameter (optional)
	int nDummy = 1;	
	if ((p.size() > 1) && (p[1].DataType() == ftInteger)) {
		nDummy = p[1].GetInt();
	}

	SYSTEMTIME st;
	for (int i = 0; i < 20; i++) {
		// Field #1
		fd[0].SetInt(i * nDummy);
		// Field #2
		GetSystemTime(&st); fd[1].SetDateTime(st);		
		// Field #3
		void* p = malloc(cnt); memset(p, i, cnt); fd[2].SetImage(p, (ULONG)cnt); free(p);
		// Send a recordset row back to SQL Server
		fd.Next();
	}

	return 1;
};

This class supports the following datatypes for I/O Parameters and Recordset Fields:

bigint (recoginzed as numeric) binary bit datetime uniqueidentifier (TGUID in Delphi) float

int money numeric or decimal nvarchar varbinary varchar

Plus, it supports the following BLOB datatypes for Recordset Fields:

• image
• ntext
• text

Maximum length of varchar/nvarchar parameters data is 4000 symbols.

An arbitrary number of recordsets can be returned from a procedure.

Note: Instead of SQL Server 2000 (and later), SQL Server 7.0 does not support SELECT INTO/INSERT of text/ntext/image fields from extended stored procedure recordsets.

Download Demo (120KB) Includes: Demo DLL and its source project Header source file: CXProc.h Complete reference manual in *.CHM format

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