Windows NT and UNIX Interoperability

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Updated : October 1, 1997


This White Paper highlights how committed Microsoft and industry partners are to Microsoft Windows NT and UNIX interoperability. Key features of interoperability are addressed in the context of Network, Data, Applications, and Management.

On This Page

Network Connectivity and Services
Universal Data Access
Distributed, Heterogeneous Business Applications
Systems and Network Management
For More Information


Interoperability is essential in today's increasingly heterogeneous computing environments. As the enterprise capabilities of the Microsoft Windows NT Server operating system evolve, corporations that once relied on UNIX systems for large, processing-intensive applications and end user time-sharing are embracing Windows NT. Industry analysts cite high performance, application availability, low computing costs and ease of administration as factors spurring the popularity of Windows NT. Microsoft is committed to helping organizations achieve interoperability. Rather than advocate "rip and replace," the company helps customers evolve their information technology infrastructures in a way that leverages new technologies and products. This solution improves information sharing, reduces computing costs, and capitalizes on past investments.

Interoperability begins with network protocols and directory-security, and extends to heterogeneous, distributed enterprise applications and network and system management. Layered in the middle are data access and sharing, application porting and cross-platform application access.

These features of interoperability fall within a Network, Data, Applications, and Management (NDAM) framework. Using products and technologies mapped to NDAM, Microsoft and industry partners are totally committed to Windows to UNIX interoperability.

This White Paper describes Microsoft's interoperability strategy in four major areas:

  1. Network connectivity and services, including low-level protocols, directory services, and distributed security.

  2. Access to relational databases and to Windows-based applications for file transfer, file sharing, and printer sharing.

  3. Distributed, heterogeneous business applications, including cross-platform application development and support for UNIX clients in Microsoft BackOffice family applications.

  4. Cross-platform user, system, and network management.

Network Connectivity and Services

Achieving the most basic level of integration between Windows-based PCs and UNIX workstations requires reliable network connectivity between the two environments. Windows NT provides this foundation through built-in support for TCP/IP, the standard suite of network transport protocols used in UNIX environments. By featuring TCP/IP support, a Windows NT-based server is able to communicate with UNIX systems natively over enterprise networks and the Internet. Built-in support for services such as a Domain Name System (DNS) server, Dynamic Host Configuration Protocol (DHCP), BootP, and Remote Procedure Call (RPC)the building blocks of TCP/IP-based enterprise networksensures that Windows NT-based servers can provide the necessary infrastructure to deploy and manage these networks.

This infrastructure becomes even easier to manage through the use of enterprise directory and security services. Windows NT includes advanced directory-security services today, enabling users to log on once to gain access to all servers and services on the network and administrators to maintain a single, centralized database of all user/group accounts. Windows NT 5.0 will extend this functionality to a fully interoperable distributed services infrastructure allowing cross-platform directory access and synchronization via the Lightweight Directory Access Protocol (LDAP) and interoperable authentication via Kerberos.

Another benefit of the common TCP/IP infrastructure across Windows NT and UNIX systems is support for services such as FTP, HTTP, and TELNET. Via FTP and HTTP services, users can copy files across networks of heterogeneous systems and then manipulate them locally as text files or even Microsoft Word documents. In addition to copying UNIX files, PC users can access character-based UNIX applications through the Windows NT support for remote logon, a UNIX service enabled by TCP/IP's network terminal protocol (TELNET). By running terminal emulation software built into the Windows 95 and Windows NT operating systems, a Windows-based PC user can log on to a UNIX timesharing server in a manner similar to a dialup connection. After entering an authorized user name and password, PC users will be able to use character-based applications residing on the remote UNIX workstation as if he were logged on to the system directly.

Universal Data Access

Copying files and sharing character-based applications are a start toward achieving Windows-based PC-to-UNIX integration, but many organizations need to find ways to let end usersregardless of the desktop systems they are runningaccess expensive networked resources, such as network printers and file servers, across mixed environments.

Cross-Platform File Sharing

By supporting the TCP/IP suite of protocols and utilities, Windows NT lets organizations take full advantage of their investments in expensive UNIX and Windows NT-based network printers. Windows NT has built-in support for TCP/IP that lets employees use the printers of their choice, regardless of which system they are running. UNIX users can print to Windows NT-based printers simply by employing "lpr," a TCP/IP printing utility. Similarly, any clients connected to a Windows NT-based server can print documents, spreadsheets, e-mail, and so forth on a printer connected to a UNIX system.

PC users also can take advantage of UNIX systems as file servers, allowing organizations to take advantage of UNIX disk space. By running Network File System (NFS) client software on their PCs, end users can see and access a UNIX file system as if it were a local drive. Developed by Sun Microsystems, NFS is a file system used on most UNIX systems, and it has become the de facto standard for sharing resources across multivendor UNIX platforms. NFS client software for Windows-based PCs is available from a wide range of vendors including Intergraph and Hummingbird Communications.

To allow UNIX users access to files on a Windows NT-based server, organizations can install Intergraph's DiskShare NFS server on Windows NT and it will appear on the network like a UNIX server running NFS protocols. And for the ultimate in cross-platform file server access, Intergraph's NFS Gateway can be installed on A Windows NT-based server, allowing Windows clients using the native Windows networking software access to UNIX servers running NFS. This has the added benefit of requiring no additional software to be installed on the client, minimizing cost and hassle.

While NFS is a traditional protocol used to share files across Windows and UNIX environments, an upgraded PC file-sharing protocol promises to extend heterogeneous file sharing across the Internet. Microsoft, in conjunction with more than 40 other vendorsincluding AT&T Corp., Hewlett-Packard Co., IBM Corp., and Sun Microsystems Inc.has proposed the Common Internet File System (CIFS) protocol as a standard for remote file-sharing over the Internet and corporate intranets. Based on protocol standards built into the Windows operating systems, and therefore widely used in corporate networks, CIFS defines a common access protocol for sharing files and data of all typesincluding Windows and UNIXsecurely over the Internet and corporate intranets. Microsoft submitted the CIFS specification to the Internet Engineering Task Force (IETF) as an Internet Draft document in June 1996 and is working with the industry to publish CIFS as an informational RFC (Request for Comment). CIFS, an evolution of the high-performance SMB protocols, is the native file-sharing protocol in Windows NT. It is available on UNIX servers through AT&T's Advanced Server for UNIX.

Author's note smb/cifs is significantly faster than nfs because it allows write ahead and has native support for locks.

Database Access

Sharing expensive network printers and disk storage across mixed environments helps save companies money. But what about making use of the important business data residing on different systems throughout the organization? Again, rather than moving the data, often a difficult and costly endeavor, organizations need the ability to access this information from key enterprise business applications. Somehow, they need to make the data sitting on a UNIX workstation or IBM DB2 database accessible to the business applications running on PCs. And they need to make this happen in a way that is transparent to the PC user. Providing universal access to data is vital to developing powerful distributed solutions for running the business.

Two fundamental components of Microsoft's universal data access strategy are the Open Database Connectivity (ODBC) standard and the OLE DB standard. ODBC provides a unified way to access relational data from heterogeneous systems; any application that supports ODBC can access information stored in any database that houses relational data. For example, a Microsoft Excel spreadsheet, Microsoft Access database or any other ODBC-enabled application could pull and use data from an ORACLE, SYBASE, Informix, or any other UNIX relational database without installing any software on the UNIX system. A finance specialist using Microsoft Excel to track quarterly shipments of sweatshirts could pull inventory data from an Oracle database running on UNIX to generate a report.

With ODBC, developers do not need to write separate client/server applications to access individual UNIX databases; simply by supporting ODBC, a single application can access a variety of UNIX relational or host databases.

Exchanging datanot just accessing italso is possible among heterogeneous databases, allowing organizations to deploy Windows NT platforms in distributed business units while keeping UNIX workstations, midrange systems or mainframes in a centralized location. For example, through heterogeneous replication, a SQL Server 6.5 database running on Windows NT can automatically send data to an Informix database running on a UNIX system.

If all of your data were stored in relational databases, integration could largely be solved with ODBC alone. But most data is nonrelational, or unstructured. For example, audio and video clips, e-mail messages, and Notes documents represent a few of the types of unstructured data stored in various formats throughout most organizations. To simplify integration of unstructured data across the enterprise, Microsoft offers OLE DB. Analogous to ODBC in the relational world, OLE DB is a set of OLE interfaces that provides applications with uniform access to unstructured data regardless of type or location on the network. OLE DB is technology for software vendors whose products either use or provide unstructured data. Developers can write applications that connect to any OLE DB data providerwhether a file system, Oracle database, Excel spreadsheet or DB2 databaseand let PC users running Windows desktop applications share and manipulate data stored there.

To tap the vast potential of the Internet and intranet to run business applications, organizations need access to information residing in UNIX and host databases from a Web browser. With the Internet Information Server running on Windows NT, organizations can build Web sites that access information from any database that supports ODBC, such as Sybase or Oracle. The Internet Information Server supports ODBC through an Internet Database Connector, enabling developers to build Web pages that make dynamic queries to UNIX, IBM, or any other ODBC-compliant databases.

Developers also can give browser users the ability to alter, add, and delete data they have queried and retrieved from UNIX or host databases; end users are not restricted to staring at static HTML results tables. Microsoft's Advanced Data Connector (ADC), introduced in December 1996, is a high-performance, Web-based technology that enables developers to build Internet and intranet applications with database connectivity and corporate data publishing capabilities. Users can access and update data from any ODBC-compliant database management system.

Distributed, Heterogeneous Business Applications

Microsoft's goal is to offer customers the most extensive interoperability possible between UNIX and Windows environments. Beyond file transfer, printer sharing and universal data access, Microsoft strives to let organizations build distributed, heterogeneous business applications that integrate the various data, languages and systems they have invested in throughout the enterprise. This capability is delivered in two primary ways: 1) by providing customers a set of tools and technologies for powerful, cross-platform application development, and 2) by supporting UNIX desktop clients in BackOffice server applications, such as the Microsoft Exchange Server messaging platform and the Microsoft Proxy Server.

Active Server Platform

Microsoft has developed a set of technologies that enable developers to build powerful, cross-platform business solutions for the enterprise while taking advantage of their investments in tools, languages, data and systems. Collectively known as the Active Server platform, these technologies let developers integrate Web technology, Windows, UNIX and host data into distributed, enterprise business solutions, such as back-office accounting, point-of-sale or decision support systems. The Active Server Platform is delivered on Windows NT and the Internet Information Server.

Active Server Pages (ASP)a core component of the Active Server platformfacilitates the development of these heterogeneous business solutions. With ASP, an application development environment, developers can use the scripting language of their choiceVisual Basic, Scripting Edition (VBScript), Perl, JScript, and so forthto rapidly build dynamic Web-based business applications. Developers can combine HTML, scripts and ActiveX components developed in any language (C++, COBOL, Visual Basic, Java, and so forth) to create Web front-ends to existing legacy applications, or to build new Web applications that connect to backend UNIX, Microsoft SQL Server, and other enterprise databases.

DCOM, the Distributed Component Object Model, represents another ASP core component that enables distributed, heterogeneous business applications for the Internet or corporate intranets. DCOM is a protocol that manages communications between software components across a network, providing the foundation for distributed, interoperable applications. DCOM's design enables it to be used across multiple network transports, including popular Internet protocols such as HTTP.

Industry leaders have joined Microsoft in extending these Active Server technologies to multiple environments, making it easier for developers to build truly integrated, enterprise applications across Windows NT, Windows 95, UNIX and Macintosh environments. Software AG, for example, has introduced an implementation of Microsoft's DCOM for Sun Microsystems's Solaris UNIX platform, and plans to extend the distributed component software architecture to other varieties of UNIX, including Digital UNIX.

X Windows

But asking PC users with Windows to give up an intuitive, graphical interface for character-based applications might not be an appealing solution for sharing data in UNIX environments. In this case, rather than resort to porting UNIX applications to Windows NT, many organizations use the X Windows system to integrate the two environments. Under the X Windows system, any type of desktop client can run graphical applications running on any type of server, though X Windows servers typically are UNIX workstations using TCP/IP. So, in a Windows NT and UNIX environment running the X Windows system, a user of Windows can display multiple graphical UNIX applications locally. PC users can manipulate data between applications running in separate windows on their display, or they can cut and paste from an X Windows-based drawing package into a Windows application, such as Microsoft Word for Windows. To enable the X Windows capability, PC users must run PC X server software from Digital Equipment, Hummingbird Communications, Network Computing Devices (NCD), WRQ or other connectivity vendor.

BackOffice Support for UNIX

The second way that Microsoft helps customers build distributed, heterogeneous business applications is by supporting UNIX in its desktop and server applications. For example, working with Parker Software, Microsoft is developing UNIX clients for its SNA Server gateway, allowing UNIX users to connect through Microsoft SNA Server to access IBM mainframe and AS/400 systems. Microsoft will deliver a UNIX version of its popular Internet Explorer Web browser application. And UNIX users who require simple messaging, scheduling and address book functionality can use the Microsoft Exchange Web Client to meet their needs.

Today, via a product called "WinFrame" from Citrix Corporation, and next year via a product from Microsoft code-named "Hydra", Windows, Macintosh, UNIX, and even network computer clients can take advantage of the Windows NT operating system through the multiuser capabilities that WinFrame and "Hydra" provide. That means that UNIX clients can run Win32-based applications like Microsoft Office and the Microsoft Outlook e-mail client without the need to run bulky and incompatible emulation software. And because this environment is actually running locally on the Windows NT-based computer, administrators gain the centralized control they are looking for to reduce administrative costs.

Application Migration/Integration

Some organizations see greater long-term benefits in standardizing on one operating system rather than getting heterogeneous systems to work together. For example, standardization can yield cost savings in training, hardware, and systems administration over time. For these customers, porting UNIX applications and data to the Windows NT platform is critical, and there are several ways to migrate and integrate these applications from UNIX to Windows NT:

  • Rewrite as a Win32-based application

  • Recompile a UNIX application as a Win32 binary

  • Run UNIX binaries natively on Windows NT

Rewriting the application with Win32 has the benefit of the rich services and high performance of the native Win32 environment on Windows NT. While this option is not the shortest path to application migration, it has the most long-term benefits. As the application portfolio for the Windows NT environment has grown to exceed that of UNIX, the majority of commercial applications have been written from the ground up as Win32-based applications.

Whether companies chose to recompile a UNIX application as a Win32 binary or run UNIX binaries natively on Windows NT-based systems depends on the specific plans each has to ensure Windows NT and UNIX interoperability. Either way, NuTCRACKER from DataFocus and OpenNT from Softway Systems have solutions that work. Conceptually, there are similarities between two these products. Each aims to deliver a comprehensive set of UNIX APIs, commands, and utilities on Windows NT. But the similarities end there.

NuTCRACKER enables UNIX software to port to, integrate with, and evolve on Windows NT. It is a Win32-based UNIX compatibility environment that essentially creates native Win32-based applications that behave like and interoperate with other Win32-based applications. NuCRACKER provides UNIX tools, UNIX libraries, and an X Server on Win32 so developers can compile their C and C++ source code and link it against the NuTCRACKER dynamic link librariescreating a native Win32 application that takes advantage of rich Windows features like ActiveX, COM, DCOM, MAPI, and others. For example, a stock-trading application needs to get integrated with Microsoft Excel in order to provide a seamless financial analysis environment for stock traders.

OpenNT can be categorized as an "operating system product" that is also a software development tool, which allows developers to port their own their own tools and applications and host them side-by-side Softway tools and Windows programs. OpenNT's enhanced POSIX/UNIX subsystem makes this possible. It provides a UNIX execution environment on a Windows NT-based system that allows the UNIX application to run exactly the same way it ran on UNIX system. So, Windows NT becomes another UNIX server operating system and customers are able to deploy their application on a Windows NT-based system in exactly the same way they deploy it on UNIX servers. That means they can use existing hardware, such as character terminals and X terminals, and the same methods for hosting the multiuser application.

Systems and Network Management

Managing heterogeneous environments has long been a challenge for corporate IT departments. As demand for Windows NT increases and organizations deploy these systems alongside their existing UNIX infrastructure, heterogeneous systems and network management will become even more critical. Fortunately the availability of tools from Microsoft and third parties has increased significantly, enabling cross-platform management to become a reality.

Microsoft and Hewlett-Packard are striving to simplify the jobs of IT administrators in mixed Windows NT and UNIX environments by integrating Microsoft Systems Management Server and HP OpenView enterprise management products. Using HP's new Service Management Strategy's tools and services, including Systems Management Server, HP will enable predictable service levels based on explicit cost and service agreements between business end users and IT organizations.

Across the board, support for the Simple Network Management Protocol (SNMP) in Windows NT has reached critical mass with HP OpenView, Ca UniCenter TNG, and IBM Tivoli now available on the Windows NT platform. In addition, Windows NT Server and Windows NT Workstation both include complete support for SNMP MIBs, allowing them to be managed via these consoles.

Microsoft's agreement with Cisco Systems to jointly develop extensions to Active Directory to integrate advanced management of network elements and services will have a profound effect on overall network management. Products developed as a result of this agreement will make it possible for network managers to unify their network infrastructures and to accelerate the development of richer network services via Cisco IOS software.

For administrators who have been trained in the management of UNIX systems, Windows NT can now offer the same management paradigm via tools from MKS and Softway Systems. Both vendors offer UNIX style command and utilities and shell environments that make a Windows NT system look, act, and feel like a UNIX system. Administrators uncomfortable without tools like awk, grep, and ps, can now be immediately productive managing a Windows NT system. And Windows NT 5.0 will offer a full range of built-in command-line and scriptable management capabilities providing true "lights out" management of a Windows NT system.


Windows NT and UNIX interoperability is prerequisite in today's increasingly common heterogeneous computing environments. From the network, data, applications, and management layers, tools and technologies to allow these systems to interoperate are either built into Windows NT or are readily available from increasing numbers of third-parties. Allowing customers to benefit from their investment in UNIX systems while taking advantage of the rich services that the Windows NT platform offers is a high priority for Microsoft. Customers will see continued advances in these technologies, making it even easier to deploy and manage heterogeneous UNIX and Windows NT-based networks.

For More Information

For more information about achieving complete integration of Windows NT and UNIX environments, check out: .

The information contained in this document represents the current view of Microsoft Corporation on the issues discussed as of the date of publication. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information presented after the date of publication.

This White Paper is for informational purposes only. MICROSOFT MAKES NO WARRANTIES, EXPRESS OR IMPLIED, IN THIS DOCUMENT.