Prash Shirolkar, Author
Alyssa Henry, Contributor
Stephen Pepitone, Contributor
Acey J. Bunch, Contributor
David Schwartz, Contributor
Microsoft Corporation

January 2002
Revised December 2008

Summary: Learn about the past, present, and future of the Microsoft data access technologies. (6 printed pages)

Contents

Introduction
Microsoft Data Access Components (MDAC)
   Current MDAC Architecture
   Current MDAC Components
   Deprecated MDAC Components
   MDAC Releases
SQL Server Native Client
ADO.NET
Obsolete Data Access Technologies
For More Information

Introduction

This article describes the past, present, and future of Microsoft data access technologies, including DB-Library, DAO, Microsoft Data Access Components (MDAC) (including ODBC, ADO, and OLE DB), ADO.NET, and SQL Native Client. This article identifies which technologies are being enhanced, and which technologies and components are being deprecated or excluded from future releases.

Microsoft Data Access Components (MDAC)

With Microsoft Data Access Components (MDAC), developers can connect to and use data from a wide variety of relational and nonrelational data sources. You can connect to many different data sources using ActiveX Data Objects (ADO), Open Database Connectivity (ODBC), or OLE DB. You can do this through providers and drivers that either are built and shipped by Microsoft, or that are developed by various third parties.

Current MDAC Architecture

With the current MDAC architecture, client-server, n-tier, or Web browser applications can access SQL, Semi-Structured, and Legacy Data stores. Additionally, with MDAC (depending on requirements), these applications have the flexibility to access the data using ADO, OLE DB, or ODBC.

Figure 1. Current MDAC architecture

For the purposes of this document, you can divide the MDAC stack into the following components, based on technology and products:

• ADO (including ADOMD and ADOX)
• OLE DB (including SQL Server OLE DB Provider, Oracle OLE DB Provider, OLE DB Provider for ODBC Drivers, Data Shape Provider, and Remote Data Provider)
• ODBC (including SQL ODBC Driver and Oracle ODBC Driver)

Current MDAC Components

These components are supported in the current release. Use these components when you develop new applications or upgrade existing applications.

• ADO: ActiveX Data Objects (ADO) provides a high-level programming model that will continue to be enhanced. Although a little less performance than coding to OLE DB or ODBC directly, ADO is straightforward to learn and use, and it can be used from script languages, such as Microsoft Visual Basic Scripting Edition (VBScript) or Microsoft JScript.
• ADOMD: ADO Multi-Dimensional (ADOMD) is to be used with multidimensional data providers such as Microsoft OLAP Provider, also known as Microsoft Analysis Services Provider. No major feature enhancements have been made to it since MDAC 2.0.
• ADOX: ADO Extensions for DDL and Security (ADOX) enable the creation and modification of definitions of a database, table, index, or stored procedure. You can use ADOX with any provider. The Microsoft Jet OLE DB Provider provides full support for ADOX, while the Microsoft SQL OLE DB Provider provides limited support. No major enhancements are planned for ADOX in future MDAC releases; however, it is available on the 64-bit Windows operating system.
• OLE DB: OLE DB is a comprehensive set of COM interfaces for accessing a diverse range of data in a variety of data stores. OLE DB providers exist for accessing data in databases, file systems, message stores, directory services, workflow, and document stores. OLE DB core services (although not every OLE DB provider) is available on the 64-bit Windows operating system.
• SQLOLEDB: Microsoft OLE DB Provider for SQL Server (SQLOLEDB) supports access to Microsoft SQL Server. However, SQL Native Client is recommended for creating new applications or enhancing existing applications that must take advantage of new SQL Server features in Microsoft SQL Server 2005. SQLOLEDB will continue to be supported and is available on the 64-bit Windows operating system.
• Microsoft SQL Server Network Libraries: The SQL Server Network Libraries allow SQLOLEDB and SQLODBC to communicate with the SQL Server database. The following SQL Server Network Libraries have been deprecated in MDAC releases: Banyan Vines, AppleTalk, Servernet, IPX/SPX, Giganet, and RPC. TCP/IP and Named Pipes will continue to be supported and are available on the 64-bit Windows operating system.
• ODBC: The Microsoft Open Database Connectivity (ODBC) interface is a C programming-language interface that allows applications to access data from a variety of Database Management Systems (DBMS). Applications that use this API are limited to accessing relational data sources only. ODBC is available on the 64-bit Windows operating system.
• SQLODBC: Microsoft SQL Server ODBC Driver (SQLODBC) enables access to Microsoft SQL Server. However, SQL Native Client is recommended for creating new applications or enhancing existing applications that must take advantage of new SQL Server features in SQL Server 2005. SQLODBC will continue to be supported and is available on the 64-bit Windows operating system.
• MSDASQL: The Microsoft OLE DB Provider for ODBC (MSDASQL) is a technology that allows applications that are built on OLEDB and ADO (which uses OLEDB internally) to access data sources through an ODBC driver. MSDASQL is an OLEDB provider that connects to ODBC, instead of a database. MSDASQL ships with the Windows operating system, and Windows Server 2008 is the first Windows release to include a 64-bit version of the technology.

Deprecated MDAC Components

These components are still supported in the current release of MDAC, but they might be removed in future releases. Microsoft recommends, when you develop new applications, that you avoid using these components. Additionally, when you upgrade or modify existing applications, remove any dependency on these components.

• Microsoft Jet Database Engine 4.0: Starting with version 2.6, MDAC no longer contains Jet components. In other words, MDAC 2.6, 2.7, 2.8, and all future MDAC releases do not contain Microsoft Jet, the Microsoft Jet OLE DB Provider, the ODBC Desktop Database Drivers, or Jet Data Access Objects (DAO). The Microsoft Jet Database Engine 4.0 components entered a state of functional deprecation and sustained engineering, and have not received feature level enhancements since becoming a part of Microsoft Windows in Windows 2000.
  
  There is no 64-bit version of the Jet Database Engine, the Jet OLEDB Driver, the Jet ODBC Drivers, or Jet DAO available. This is also documented in KB article 957570. On 64-bit versions of Windows, 32-bit Jet runs under the Windows WOW64 subsystem. For more information on WOW64, see http://msdn.microsoft.com/en-us/library/aa384249(VS.85).aspx. Native 64-bit applications cannot communicate with the 32-bit Jet drivers running in WOW64.
  
  Instead of Microsoft Jet, Microsoft recommends using Microsoft SQL Server Express Edition or Microsoft SQL Server Compact Edition when developing new, non-Microsoft Access applications requiring a relational data store. These new or converted Jet applications can continue to use Jet with the intention of using Microsoft Office 2003 and earlier files (.mdb and .xls) for non-primary data storage. However, for these applications, you should plan to migrate from Jet to the 2007 Office System Driver. You can download the 2007 Office System Driver, which allows you to read from and write to pre-existing files in either Office 2003 (.mdb and .xls) or the Office 2007 (*.accdb, *.xlsm, *.xlsx and *.xlsb) file formats. IMPORTANT Please read the 2007 Office System End User License Agreement for specific usage limitations.
  
  Note: SQL Server applications can also access the 2007 Office System, and earlier, files from SQL Server heterogeneous data connectivity and Integrations Services capabilities as well, via the 2007 Office System Driver. Additionally, 64-bit SQL Server applications can access to 32-bit Jet and 2007 Office System files by using 32-bit SQL Server Integration Services (SSIS) on 64-bit Windows.
  
  
• MSDADS: With the Microsoft OLE DB Provider for Data Shaping (MSDADS), you can create hierarchical relationships between keys, fields, or rowsets in an application. No major feature enhancements have been made since MDAC 2.1. This Provider has been deprecated in future MDAC releases. Microsoft recommends that you use XML, instead of MSDADS.
• Oracle ODBC: The Microsoft Oracle ODBC Driver (Oracle ODBC) provides access to Oracle database servers. It provides full support for Oracle 7. Also, it uses Oracle 7 emulation to provide limited support for Oracle 8 databases. The Oracle ODBC Driver has not been tested yet with Oracle 9 databases.
• RDS: Remote Data Services (RDS) is a proprietary Microsoft mechanism to access remote ADO Recordset objects across the Internet or an intranet. No major feature enhancements have been made to RDS since MDAC 2.1. This component is being deprecated. Microsoft now ships the Microsoft SOAP Toolkit 2.0, in which applications can access remote data by using an open, XML-based standard. Applications that use RDS should migrate to SOAP.
• JRO: Jet Replication Objects (JRO) is deprecated. JRO is used within ADO with Jet (*.mdb) databases to create and compress Jet Databases (.mdb’s) and perform Jet Replication Management. MDAC 2.7 will be its last release. JRO will not be available on the 64-bit Windows operating system. JRO is not supported in the Microsoft Access 2007 file format (*.accdb).

MDAC Releases

Here is a list of the supportability scenarios of past, present, and future MDAC releases, starting with the earliest.

• MDAC 1.5, MDAC 2.0, and MDAC 2.1: These versions of MDAC were independent releases that were released through the Microsoft Windows NT Option Pack, the Microsoft Windows Platform SDK, or the MDAC Web site. These versions of MDAC no longer are supported.
• MDAC 2.5: This version of MDAC was included with the Windows 2000 operating system. Service packs of MDAC 2.5 were included with corresponding Windows 2000 service packs. However, Microsoft currently supports only MDAC 2.5 SP3 on Windows 2000 SP4.
• MDAC 2.6: MDAC 2.6 RTM, SP1, and SP2 were included with Microsoft SQL Server 2000 RTM, SP1, and SP2, respectively. Additionally, these MDAC service packs were released to the MDAC Web site in accordance with the Microsoft SQL Server 2000 service-pack release schedule. You can install this version of MDAC and its service packs on Windows 2000, Windows Millennium Edition, Windows NT, Windows 95, and Windows 98 platforms. This version of MDAC no longer is supported.
• MDAC 2.7: This version of MDAC was included with the Microsoft Windows XP RTM and SP1 operating systems. You can install this version of MDAC and its service packs on Windows 2000, Windows Millennium, Windows NT, and Windows 98 platforms. You can install this version on the Windows XP platform only through the operating system or its services packs. This version of MDAC no longer is supported.
• MDAC 2.8: This version of MDAC was included with Windows Server 2003 and Windows XP SP2 and later. You also can install this version of MDAC and its service packs on Windows 2000.
  • The 32-bit version of MDAC 2.8 also was released to the MDAC Web site at the same time that Windows Server 2003 was released to the customer.
  • The 64-bit version of MDAC 2.8 was released with the 64-bit version of Windows Server 2003 and Windows XP.
• Windows DAC 6.0: MDAC changes its name to Windows DAC - "Windows Data Access Component" starting with version 6.0. This version of MDAC is included with Windows Server 2008 and Windows Vista.
  • The 32-bit and 64-bit versions of WDAC 6.0 will be released with the Windows operating system only.

SQL Server Native Client

SQL Server Native Client is a data access technology that is new to Microsoft SQL Server 2005, and it is a stand-alone data access application programming interface (API) that is used for both OLE DB and ODBC. It combines the SQL OLE DB Provider and the SQL ODBC Driver into one native dynamic-link library (DLL), while providing also new functionality that is separate and distinct from the Microsoft Data Access Components (MDAC). SQL Server Native Client can be used to create new applications or enhance existing applications that must take advantage of new SQL Server 2005 features such as Multiple Active Result Sets (MARS), User-Defined Types (UDT), and XML data-type support.

Note   SQL Server Native Client is not supported with SQL Server versions 6.5 and earlier.

ADO.NET

ADO.NET is an evolutionary improvement over traditional ADO for creating distributed, data-sharing applications. It is a high-level application-programming interface that is targeted at loosely coupled, n-tier, Internet-based applications that support disconnected access to data. It is a core component of the Microsoft .NET Framework.

Figure 2. ADO.NET architecture

ADO.NET provides .NET-managed providers for connected access, and DataSets that read and write in XML for disconnected management of retrieved data and user interaction. The following data providers are available for ADO.NET:

• Microsoft SQL .NET Data Provider: This provider allows .NET applications to access a Microsoft SQL Server database directly.
• Microsoft OLE DB .NET Data Provider: This provider allows .NET applications to access databases by using their native OLE DB Providers.
• Microsoft ODBC .NET Data Provider: This provider allows .NET applications to access databases by using their ODBC drivers.
• Microsoft Oracle .NET Data Provider: This provider allows .NET applications to access an Oracle database.

The DataSet reads and writes XML, and the XMLDataDocument integrates relational and XML views.

Obsolete Data Access Technologies

Obsolete technologies are technologies that have not been enhanced or updated in several product releases and that will be excluded from future product releases. Do not use these technologies when you write new applications. When you modify existing applications that are written by using these technologies, consider migrating those applications to ADO.NET.

The following components are considered obsolete:

• DB-Library: This is a SQL Server–specific programming model that includes C APIs. There have been no feature enhancements to the DB-Library since SQL Server 6.5. Its final release was with SQL Server 2000, and it will not be ported to the 64-bit Windows operating system.
• Embedded SQL (E-SQL): This is a SQL Server–specific programming model that enables Transact-SQL statements to be embedded in Visual C code. No feature enhancements have been made to the E-SQL since SQL Server 6.5. Its final release was with SQL Server 2000, and it will not be ported to the 64-bit Windows operating system.
• Data Access Objects (DAO): DAO provides access to JET (Access) databases. This API can be used from Microsoft Visual Basic, Microsoft Visual C++, and scripting languages. It was included with Microsoft Office 2000 and Office XP. DAO 3.6 is the final version of this technology. It will not be available on the 64-bit Windows operating system.
• Remote Data Objects (RDO): RDO was designed specifically to access remote ODBC relational data sources, and made it easier to use ODBC without complex application code. It was included with Microsoft Visual Basic versions 4, 5, and 6. RDO version 2.0 was the final version of this technology.

For More Information

For more information, visit the following Microsoft Web site:

• Data Platform Developer Center