Windows 2000 is the most exciting and important product that Microsoft has ever created, a family of operating systems aimed at the corporate server and desktop markets that combines the latest technology with ease-of-use and simplicity features. As the first major upgrade to Windows NT since version 4.0 shipped in July 1996, Windows 2000 represents the next generation of the reliable, scalable, and secure operating system we've all come to know and respect. Originally titled Windows NT 5.0, Windows 2000 was so renamed in late 1998 when it became clear that this release would extend past its NT roots to embrace markets currently dominated by the mainstream Windows products such as Windows 98.
Today, each Edition of Windows 2000--including the desktop-based Professional Edition as well as the various members of the Server family-- targets a specific portion of the business market, making a compelling case for complete Windows 2000-based solutions. Windows 2000 Professional now bests Windows 98 as the obvious choice for mobile users with its advanced power management features, offline prowess, and integration with Windows 2000 networks. On the high-end, Windows 2000 DataCenter Server scales to heights previously unknown to Windows NT, offering support for 64 GB of RAM, multiple processors, and advanced clustering. Windows 2000 scales up--and down--into markets that are new for a Windows NT product. In this way, Microsoft has greatly increased the number of possible usage scenarios for Windows 2000.
But Windows 2000 Server is the true high point in the Windows 2000 Product line. Encompassing a family of products that includes Server Standard Edition, Advanced Server, and DataCenter Server, Windows 2000 Server scales from small office/home office duty to the largest data warehouses on the planet. In this chapter, we'll take a look at the history, design, and usage scenarios of Windows 2000 Server to gain a better understanding of where we've been and where we're headed.
The Evolution of Windows NT and Windows 2000
In 1988, Microsoft Corporation wooed David Cutler away from Digital Equipment Corporation, where he had spearheaded the development of the popular VMS operating system. Given carte blanche to pursue his dream of a next-generation operating system, Cutler and small group of coders began work on NT ("New Technology"), a micro kernel-based operating system that was architecturally similar to VMS. NT was to be a fully 32-bit operating system that sport a modular design, memory protection, and pre-emptive multithreading in a day and age when PCs operating systems offered none of these features. Microsoft just had two requests: It had to run applications designed for the then command line-based OS/2 operating system, which it was co-developing with IBM, and it had to achieve POSIX compliance, a key feature for US government use.
| Windows NT/2000 timeline |
| Click here to see a table of the Windows NT/2000 timeline. |
Then Microsoft shipped Windows 3.0 in late 1990. And everything changed: As millions of copies of Windows flew off of store shelves, Microsoft realized that the future of computing was Windows, not OS/2. The company cut its ties with IBM and OS/2 and directed Cutler to make NT at least look like Windows. So Windows NT was born, with a graphical user interface that was almost identical to the regular Windows product. And even though Windows NT had nothing in common with Windows under the hood, Cutler's team also built in the ability to run Windows applications so that users could easily upgrade when needed. The plan for marketing Windows NT was finally coming together.
Finally, in late 1993, David Cutler and the Windows NT team shipped their first product, Windows NT 3.1, which was given an identical version number as the latest version of Windows at the time. Windows NT 3.1 included the new NTFS file system, the domain-based networking scheme used by NT until Windows 2000, and a 32-bit interface for programmers. Windows NT 3.1 landed with a collective thud, however, because of its lofty hardware requirements and lack of native software. Still, the idea was sound and as hardware finally caught up with the design of Windows NT, future versions began to sell well. In September 1994, Windows NT 3.5 was released with faster performance and better administration tools. The watershed release, however, was Windows NT 3.51, which arrived in June 1995, just two months before Microsoft's pseudo 32-bit Windows 95, the next major upgrade to Windows 3.x. Windows NT 3.51 included the first version of what was to become COM, the Component Object Model, Microsoft's vision for distributed computing that is finally realized with Windows 2000. It also included Windows 95 application compatibility, which became extremely important when Windows 95 went on to sell more copies than any operating system ever created.
The release of Windows 95, however, with its new user interface, caused a bit of problem for Windows NT users, who were still stuck with the clunky old Windows 3.x-style interface. Responding to user concerns, Microsoft began working on a version of Windows NT that would look and feel like Windows 95. Windows NT 4.0--featuring the Windows 95 user interface--shipped in July 1996, after only six months in beta. Though largely a re-skinned version of NT 3.51 with few other real-world improvements, Windows NT 4.0 was a resounding success, and quickly sold millions of copies (Indeed, Microsoft has sold over 30 million copies of Windows NT 4.0 at the time of this writing). Reliable, secure, and scalable, Windows NT 4.0 was just about everything the corporate market was looking for. And with the rise of the Web, NT's prowess as a Web server soon made it the platform of choice for an entire generation of systems. Windows NT quickly outpaced then replaced UNIX at all but the highest-end systems. And its only competition on the low-end was Windows 95, which ran better on older desktops and mobile computers, and later, Windows 98, the successor to Windows 95. Microsoft had literally captured the minds--and pocketbooks--of virtually the entire computer industry.
The success of Windows NT 4.0 caused a bit of a conundrum for the NT team at Microsoft, then still lead by the demanding David Cutler. The future of computing--as seen from a late 1996 standpoint--was clearly Web-based, but there were other issues as well. Computing had become too complicated. Windows NT required too many reboots, such as when networking components were reconfigured. And UNIX pundits were beginning to complain that NT's popularity made little sense when UNIX systems were known to scale higher and run more reliably. And the rise of open source solutions, such as the UNIX-like Linux, caused IT managers to begin exploring alternatives.
During the entire lifetime of Windows NT 4.0--basically 1996 to 2000---the operating system came under constant attack from hackers as new security flaws were found. Critics saw this as evidence of NT's vulnerability, but it can more accurately be described as a right of passage as NT became far more popular and thus more logical for hackers to attack. In the 1970's and 1980's, VMS and UNIX came under constant attack themselves, as they were virtually the only connected systems available. But the rise of Windows NT brought a new target to the mix. Microsoft responded with several service packs--designed to supply bug fixes in a single collection--and hundreds of hot-fixes that fixed individual issues as they arose. Windows NT had its trial by fire and emerged as a more secure system as a result. Indeed, the fact that Microsoft hasn't had to make any drastic changes to the design of Windows NT attests to its fundamental strength and adaptability.
When it came time to design Windows 2000, the NT team knew it had its work cut out for it. Windows 2000 would need to be more secure, reliable and scalable than Windows NT 4.0. But it would also need to be easier to use and more manageable, despite the fact that NT 4.0 was already outpacing the competition. And Windows 2000--then known simply as Windows NT 5.0--would have to scale from a typical desktop or laptop to the largest Intel and Alpha systems in the world. In short, it would have to be the greatest version of NT ever created.
In September 1997, Microsoft released the first beta of Windows NT 5.0. They should have waited: The first beta was almost completely unusable and included none of the exciting new features that Microsoft was promising for the final release. Almost a year passed and Beta 2 was finally released in August 1996, offering testers a glimpse at the future. Finally, on April 29, 1999, Microsoft released the feature-complete Beta 3, offering it up to an unprecedented 500,000 testers, the largest beta test Microsoft has ever created. And Beta 3 was a huge success: Most users found it acceptable for production environments and Microsoft itself quickly moved all of its production servers to the new OS. In late 1999, Microsoft announced that Windows 2000 would become available on February 17, 2000. Windows NT, finally, had come full circle as a mass-market phenomenon. And though the NT name dies with this latest release, it's spirit lives on as the tag line for Windows 2000: Built on NT technology.
Meanwhile, Microsoft is busy working on 64-bit versions of Windows 2000 and the next Windows. David Cutler stepped down as the Windows 2000 project lead so that he could focus on the 64-bit version of Windows 2000 instead, which he sees as the true future of the product.
Design Goals for Windows 2000
When the Windows NT team sat down in late 1996 to determine the features that should be included in Windows 2000, they took a hard look at the changing landscape of the PC industry and the way that computers are used, managed, and administrated. The set of design goals for Windows 2000 was honed over time with the input of key customers and partners. And when Microsoft surveyed their top customers, they discovered that two improvements were overwhelming required of Windows 2000:
- Windows 2000 systems must be more reliable and available.
- Windows 2000 must be easier to manage while lowering the Total Cost of Ownership (TCO).
Windows 2000 Is More Reliable
Though Windows NT is overwhelmingly considered far more reliable than other Microsoft operating systems, it falls short of the industrial strength UNIX systems from vendors such as Sun Microsystems. A "reliable" system should stay up and running 24 hours a day, 7 seven days a week. Network disruptions should cause backup systems to kick in automatically, so that the user doesn't notice a problem. Windows NT 4.0, in particular, was vulnerable to the so-called "Blue Screen of Death" (BSOD), which usually brought the system to a halt when a poorly written device driver overran the protected memory area of the system kernel.
In Windows 2000, reliability is increased in a number of ways. The kernel and other key OS subsystems are now protected so that applications and device drivers cannot violate system integrity. And a new feature called Windows File Protection (WFP) prevents applications from overwriting key system files with its own, older versions. A new version of NTFS--Windows 2000's file system--is more fault-tolerant than previous versions so that the system can be returned to a known state in the case of a hardware failure. In the case of a complete system failure, Windows 2000 reboots much more quickly than Windows NT 4.0 and does so without the intervention of the user if desired. This maximizes system uptime.
Windows 2000 also supports a new Safe Mode Boot so that problem hardware and software can be isolated and removed if needed. The number of actions that require reboots has been reduced dramatically as well: Microsoft has reduced the number of required reboots in Windows 2000 to 16, compared to over 75 in Windows NT 4.0.
Windows 2000 Is More Available
"Availability" refers to a client's ability to access that system. A system that is available is online, running properly, and accessible to others. Windows 2000 Server is classified as "high availability," meaning that a properly configured Windows 2000-based system should be available 99.9% of the time. And other members of the Server family achieve even higher availability with such features as clustering and fail-over support. If you're looking for truly stellar availability, you'll want to look into Advanced Server or DataCenter Server.
Windows 2000 Is More Manageable
Windows NT 4.0 offered an almost ridiculous number of management tools, each designed to handle a single administrative task. While the number of tools available to the Windows 2000 administrator isn't any smaller, Microsoft has at least provided a central shell for admin tools--the Microsoft Management Console (MMC)--that gives each of these tools a consistent look and feel.
Microsoft has also made the old DOS-like command prompt superfluous in Windows 2000 with the addition of Windows Scripting Host (WSH), a VBScript and Jscript-based scripting environment that makes it easy to automate management tasks.
For system administrators, one of the biggest headaches in Windows NT 4.0 was managing a Microsoft domain-based network. In Windows 2000, Microsoft has finally provided a true Directory Service, the Active Directory, which gives administrators a single point of administration for every resource on the network. Using a single data store, the Active Directory uses a simple "tree of trees" organizational model for network design, bypassing the old Windows NT SAM database. And the Primary Domain Controller (PDC)/Backup Domain Controller (BDC) model of old has been replaced by a simple Domain Controller (DC) model where all DCs are peers. A change made to any DC is automatically replicated to every other DC on the network.
Everything in Windows 2000 is easier to manage: Users (Figure), groups, security (Figure), and other resources (Figure).
Windows 2000 Is More Scalable
In the Windows NT 4.0 world, there were initially two target machines, workstations and servers, which were served by the Workstation and Server Editions, respectively. As Windows NT matured, however, other markets opened up and Microsoft introduced Enterprise Edition for high-end servers with limited clustering capabilities and Terminal Server Edition for networks of legacy machines that needed to easily run newer applications using a graphical terminal emulation system similar to X Window on UNIX.
With Windows 2000, the range of target systems has grown dramatically. Windows 2000 now scales from a standard corporate laptop or desktop system with the Professional Edition all the way up to multi-machine, multi-processor server giants with the DataCenter Server Edition. As a scalable operating system, Windows 2000 has moved both up and down into new markets for NT, providing support for a wide range of systems. This means that a relatively humble single processor system can be easily upgraded in the future without the need to reinstall the operating system. It also means that Windows 2000 can exist at virtually any tier of an enterprise network. And with a 64-bit version of Windows 2000 expected sometime in 2000, the circle will be complete. Windows everywhere, indeed.
Windows 2000 Is More Secure
The security subsystem in Windows 2000 has been improved at virtually every level. A single secure logon to a Windows 2000 network can be protected with Kerebos v5 (which replaces the old NTLM authentication from NT 4) or even public key authentication. A new Encrypting File System (EFS) can be used to encrypt data stored on an NTFS volume. System and network security can be easily managed with group policy objects in Active Directory.
If desired, Windows 2000 systems can even be protected with smart card logon, which provide a partially hardware-based security where users swipe a card then provide a password to gain access to the network.
What's New in Windows 2000 Server?
If you're familiar with Windows NT 4.0, the new features in Windows 2000 might be somewhat overwhelming. The Windows 2000 Server family represents a stunning upgrade to the previous generation of NT, with an extensive list of features that are covered throughout this book. The following list summarizes the new features in Windows 2000 Server.
Setup and Configuration
Administrators that need to perform multiple identical installations of Windows 2000 will be pleasantly surprised by the new scriptable unattended setup option that requires no interaction during installation. Once a server is installed, you can choose from a list of pre-set server configurations, each of which automatically installs any required services. Available configurations include Active Directory Server (Figure), Networking Server, File Server, Print Server, Web Server, and Clustering Server.
One huge improvement to Windows 2000 is the new Repair Command Console, a utility that allows administrators to access NTFS volumes from a boot floppy so that system recovery can more easily be performed. This is the first time Microsoft has authorized a way to access an NTFS volume from outside of Windows NT/2000. It also means that you stalwart NT administrators out there can do away with those small FAT boot partitions!
In Windows NT 4.0, the application of Service Packs was a painful and experimental affair. For Windows 2000, administrators can now "slipstream" Server Pack fixes into a network installation share so that future installations will include all of the new Service Pack files automatically. This means no more re-applications of Service Packs.
Active Directory
Active Directory represents Microsoft's first true Directory Service, and unlike add-on products such as Netware, Active Directory is fully integrated into the base operating system.
Security
Security in Windows 2000 has been enhanced with the addition of the Security Configuration Manager (SCM), a one-stop security management utility that provides access to the entire range of security parameters (Figure). Windows 2000 logons now use Kerebos v5 authentication or public key certificates. Windows 2000 provides an optional Certificate Server for managing deployment of public key certificates.
Windows 2000 also implements IPSEC (IP Security Protocol) for encrypted TCP/IP network traffic and the Encrypting File System (EFS) for protecting data on NTFS volumes (Figure).
Management
The biggest change to management in Windows 2000 is the move to the Microsoft Management Console (MMC), a centralized shell used for all of the management tools. Windows 2000 also offers management automation with the Windows Scripting Host (WSH) and the new Task Scheduler, which provides a GUI front-end for scheduling specific tasks.
Microsoft also includes the Windows Installer in Windows 2000, a system-wide installation service that is used by new applications such as Microsoft Office 2000. The Windows Installer provides a standard way for applications to install and uninstall, and repair themselves if files are accidentally deleted. Windows Installer works with the Add/Remove Programs applet in Control Panel.
File and Print Services
A new MMC snap-in, File Service Management, provides a central location to manage network shares, sessions, and connections. A new version of Index Server, dubbed Indexing Services, provides faster query and indexing with a nicer user interface (Figure). An integrated (though somewhat limited) disk defragmenting utility will defragment FAT, FAT32, and NTFS volumes (Figure).
Microsoft has improved printing services in Windows 2000 with the Internet Printing Protocol (IPP), which allows users to access a printer over the Internet using a standard URL address. And printers are far easier to find with Active Directory, using the new Publishing Printers node.
Networking
Microsoft has finally promoted TCP/IP to the default networking protocol in Windows 2000 while improving its performance. A new version of DNS, Dynamic DNS, automates many DNS-related tasks that previously required manual intervention. And Windows 2000 machines can share a single dial-up or network connection with other machines using Internet Connection Sharing (ICS, also called Network Address Translator, NAT), which hides internal network addresses from external networks using the host IP address (Figure). This provides a free and relatively secure way to get numerous machines onto the Internet using a single connection.
Networking and dial-up networking configuration has been vastly improved in Windows 2000, using a simplified common interface.
Application Services
One of the most exciting additions to Windows 2000 Server is Terminal Services (Figure), a terminal emulation service that allows legacy systems (such as Windows 3.1, Macintosh, or UNIX) to run full screen or windowed Windows 2000 sessions remotely as if they were directly connected to the server. Terminal Services can be used to run the latest applications (such as Office 2000), virtually, from older hardware or as an administration tool that effectively replaces (and surpasses) third-party tools such as PC Anywhere.
Also new to Windows 2000 is COM+, the latest version of Microsoft's distributed application service (Figure). COM+ allows developers to write distributed, componentized, n-tier applications in a language-neutral manner. COM+ provides the infrastructure for transactions and scalability that would otherwise need to be hand-coded by developers. And the addition of Message Queuing Services means that COM+ applications can run reliably over unreliable network connections, such as a dial-up account.
No overview of Windows 2000 could be complete without a mention of its superb Web application capabilities. Microsoft had already established its Internet Information Server (IIS) as the market and performance leader with Windows NT 4.0, but the integrated IIS in Windows 2000 ups the ante even further. Scriptless Active Server Pages (ASP) in IIS 5.0 execute far more quickly and the new ASP engine now features error handling and server "scriptlets" for the creation of script-based COM objects.
How To Use Windows 2000 Server
After you've successfully installed Windows 2000, you can optionally choose one of five roles, or usage scenarios, for that server. These choices are available from the "Configure Your Server" application that runs automatically when you start Windows 2000 Server (Figure); if you've turned this off, you can also access it from the Administrative Tools group in the Start menu.
Choosing a usage scenario simplifies the management and configuration of the server, as each choice will automatically install and configure the services required by the usage scenario. In this section, we'll take a look at these usage scenarios and explore the reasons why you might want to take advantage of these preset configurations.
File Server
The most basic usage scenario, File Server, doesn't really require much configuration. By default, Windows 2000 Server acts as an excellent file server with easy share resource configuration through the Shared Folder wizard (Figure). In Windows NT 4.0, it was relatively easy to create shares using Explorer, and while you can still do this in Windows 2000, this new wizard makes it much simpler. And with Novell Netware and Apple Macintosh client support, Windows 2000 works great in a heterogeneous networking environment.
Using the Distributed File System (DFS) in Windows 2000, you can create a single namespace for a large number of different file systems on the same network. DFS is automatically installed with Windows 2000 Server, and it uses a tree-based root structure similar to Active Directory. DFS automatically resolves addressing issues to the physical locations of shares on the network, giving users a simplified view of available resources, with no need to understand the underlying complexity (Figure).
In short, you don't have to do anything to make Windows 2000 function as a file server. This capability is built into the base operating system.
Print Server
Sharing printers is one of the most obvious benefits to a networked environment and Windows 2000 improves NT's support for network printer sharing while providing unique new services such as Internet printer sharing (Figure). In Windows 2000, all of the printing properties are set through the Printers folder, which has been moved from the root of My Computer to the Control Panel folder. You can manage every conceivable printing option from this folder (Figure).
But the biggest change for printing services in Windows 2000 has to be the Add Printer wizard, which makes adding a local or remote printer fairly painless (Figure).
Like the File Server scenario, using Windows 2000 as a print server is straightforward and doesn't really require any special software installation. Many Windows 2000 Servers are used for both file and printer sharing simultaneously.
Web/Media Server
Windows 2000's integrated Web services, called Internet Information Services (IIS), is one of the platform's greatest strengths. Built on the solid foundation of Windows NT 4.0/IIS 4.0, the Web services in Windows 2000 are designed to make it easier to publish information to the Web while adding a host of new features and performance improvements. Windows 2000 makes it easier to host multiple Web sites, for example, and task that wasn't very straightforward in Windows NT 4.0 (Figure).
Web and FTP servers are managed through the ubiquitous MMC, while new wizards such as the Virtual Directory wizard make it easy to publish information on the Web (Figure). And a host of new security features, including new security wizards, make IIS the most secure Web server available for Windows 2000 (Figure).
Microsoft has also added streaming media capabilities to Windows 2000 Server, allowing developers to easily publish streaming audio and video to the Internet. Windows Media Services even allows for real-time audio and video presentations over the Internet.
When you choose the Web/Media Server role, you will need to install IIS (if you didn't do so during Setup) and/or Windows Media Services. Both of these choices represent a fairly significant commitment on your part as they each include numerous, sometimes arcane, configuration options. If you actually intend to use your Server for either of these roles, be sure you understand what you're getting into.
Networking Server
Windows 2000 Server includes a vast suite of networking-related services, so using it as a networking server is an obvious choice. The services you choose, however, will determine the complexity of configuration. At its most basic level, a Windows 2000 Server can provide file and printer sharing over a network, typically with the TCP/IP protocol. From that point, things get a little complicated.
If you'd like to dynamically assign IP addresses to TCP/IP clients on the network, you can install DHCP, the Dynamic Host Configuration Protocol (Figure). You can also use DHCP in tandem with Internet Connection Sharing to share a single dial-up or network connection to the Internet with all of the users on your internal network.
If you'd like to provide your own Internet naming services, where Internet names are mapped to IP addresses locally, rather than at your ISP, you can install the Domain Naming System (DNS) service. Active Directory, for example, requires the installation of DNS so that domain controllers on the network can be more easily located.
You can also provide remote access to your server for users with dial-up connections, if desired, and allow for Virtual Private Networks (VPNs) that can be accessed remotely.
Each of these options--and a host of other miscellany--requires a thorough understanding of networking, so setting up Windows 2000 as a networking server is going to require some preparation, planning, and understanding. But Windows 2000 excels at networking: The hard part is just figuring out the principals behind the technology. This book devotes a large section to Windows 2000 networking.
Application Server
Windows NT 4.0 provided excellent application server facilities, with support for powerful BackOffice applications such as SQL Server and Exchange Server (Figure). And like Windows NT 4.0, Windows 2000 provides an excellent platform for database and email serving, though this will require the installation of separate products. But Windows 2000 takes application serving to the next level with its integrated Terminal Services, which allows users on older Windows machines to run the latest Windows 2000 applications in a remote terminal session that looks and acts like the local system. Terminal Services is available as an installation option during Setup or you can install it at any time using the Configure Your Server application.
In general, I recommend using Terminal Services on a dedicated server. In other words, you shouldn't run IIS or Windows Media Services on the same server as Terminal Services, which requires some serious hardware resources for a large number of users.
Windows 2000 also offers a host of application hosting infrastructure services, such as application load balancing for distributing network loads transparently across numerous servers, and the new Component Services, which combines the distributed application development environment of COM with the transactional capabilities of Microsoft Transaction Server.
Introducing the Windows 2000 product family
One of the more confusing aspects of Windows 2000 is the name change from Windows NT and the numerous changes Microsoft has made to the Server family.
In short, Windows 2000 is simply Windows NT 5.0. The name change was made to indicate a commitment to the Windows name going forward: After a final update to the Windows 9x line in late 2000, Microsoft will base all of its future desktop and server operating systems on the Windows NT core, not Windows 9x. So Windows 2000 is really just a first step in what can only be called a marketing vision, if you will, of the way these products should be named. Unfortunately, this has created some confusion in the marketplace, as many Windows 98 home users will assume that "Windows 2000" is the next upgrade for them. It isn't.
And Microsoft has renamed and consolidated the various editions of Windows NT with the move to Windows 2000. Windows NT Workstation, which was so named because of its lofty hardware requirements when it first shipped, is now renamed as Windows Professional, as it will run on most mainstream business desktops (and mobile computers). The "workstation" moniker just doesn't make sense anymore (Figure).
But the big moves, of course, come with the Server family.
Windows 2000 Server products
With Windows NT 4.0, Microsoft initially offered a single Server Edition. In 1997, Windows NT Server, Enterprise Edition was introduced to serve higher-end server systems with heady memory requirements and limited clustering support. Then, Microsoft released Windows NT Terminal Server in 1998, its first terminal services product and the first version of NT to support multiple simultaneous users with full access to all of NT's capabilities.
With the release of Windows 2000, Microsoft has changed the lineup a bit. The Terminal Server product is no more, but integrated Terminal Services are now available as a free option on any member of the Server family (Figure). And the basic Server, sometimes referred to as Windows 2000 Server Standard Edition, has been scaled back a bit to focus on the low-end of the market, such as home office/small office servers with a limited number of users (Figure). Server supports four microprocessors.
For the more demanding needs of database, departmental and application servers, Microsoft has replaced Enterprise Edition with Windows 2000 Advanced Server (Figure), which scales to eight processor symmetrical multiprocessing (SMP). Advanced Server supports clustering and load balancing services.
At the absolute high-end, Microsoft is introducing the new Windows 2000 DataCenter Server. This behemoth supports 16-way SMP, and up to 64 GB of RAM. DataCenter Server provides both clustering and load balancing services and is optimized for large data warehouses, large-scale science and engineering simulations and the like.
