PRB: DAO Can't Be Used in an ISAPI DLL

• The DAO SDK included with: Microsoft Visual C++, 32-bit Edition, versions 4.0 and 4.1

SYMPTOMS

DAO fails inside an ISAPI DLL. A call to CoGetClassObject() or CoCreateInstance() for the database engine will fail. You may receive the following HRESULTS:

E_OUTOFMEMORY                  (    0x8007000EL )
REGDB_E_IIDNOTREG            (    0x80040155L )

CAUSE

DAO wasn't tested or designed to work in an ISAPI DLL. The problem lies within the way the Internet Information Server handles OLE.

RESOLUTION

Do one of the following:

• Don't use DAO. Because DAO is non-thread safe, Microsoft recommends that you not use it in an ISAPI DLL. The SQL Server ODBC driver works well with an ISAPI DLL and is a good choice for scaleable solutions.

  -or-

• Use the Internet Data Connector feature of the Microsoft Internet Information Server to connect to the database file. See the online documentation for the Microsoft Internet Information Server for more information about the Internet Data Connector.

  -or-

• Write a CGI application to get to DAO rather than calling DAO in an ISAPI DLL.

STATUS

This behavior is by design.

REFERENCES

Tech note 67 (TN067), "Database Access from an ISAPI Server Extension"