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Windows 2000 is served
This special feature article was a one-off in addition
to my regular column. It was a review of the newly-released Windows 2000
operating system. It felt good to stretch my wings a little here.
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And so Microsoft has finally completed its biggest ever
undertaking and Windows 2000 (W2K) is now their flagship-operating platform.
The result is another massive training exercise for the worldwide community of
developers who target this platform, and the prospect of a whole host of
product upgrades to go along with it. For this article I have removed my Visual
Basic hat and will be discussing some of the wider issues that are relevant to
all developers. I'd like to start by reviewing some of the general features of
the W2K product set and then move on to have a closer look at a few of the most
important technologies and concepts that you should target as you prepare
yourself for working with this architecture.
From the day that Windows 95 emerged from Microsoft it has
been a battle for Windows NT to keep up in two key areas. While NT has always
been a more robust and, arguably, enterprise-oriented operating system it has
always lacked features that its lower-ended sibling has had from day one. In
1995 Microsoft found themselves in the uncomfortable position of having the
more powerful desktop shell only available on their low-end operating system,
whereas the old Program Manager shell still sat on their high-end, premier
operating system, Windows NT 3.51. Finally, a year later, Windows NT 4 (known
at the time as the Shell Update Release) was made available and the most
obvious shortcoming had been overcome. The second most serious shortcoming,
plug and play, has only now been finally overcome after another four years of
development.
W2K family
W2K will finally ship in four different versions:
Professional:
The standard desktop edition for users, which supports up to two processors and
4GB of memory.
Server:
Basic server edition, which supports four processors and 4GB of memory.
Provides file, print, intranet, and networking services.
Advanced Server:
As Server edition, but supports 8 processors and 8GB of memory. Also offers
two-node fail-over, and 32-node network load balancing.
Data Center Server:
Delivery date is still to be announced at the time of writing (late January
2000). As Advanced Server edition, but will support up to 32 processors and
64GB of memory. It also offers a cascading fail-over among four nodes. This is
Microsoft's high-end product for enterprise servers that need to support
intensive online transaction processing (OLTP) services.
Key features
W2K introduces so many new features that it's difficult to
know what to skip for the sake of brevity. However, the key features as I see
them are
Installation:
Windows finally understands the FAT32 partitioning scheme introduced by Windows
95 SR2. The good news here is that you can make up a boot disk from Windows 95
SR2 or Windows 98 and format the hard disk on your target machine to be greater
than 2GB. Previous versions of Windows NT would have refused to install onto
such a partition and so boot partitions were generally confined to being 2GB in
size. Therefore if you've got a machine with a single 9GB disk then you can
also have a single 9GB C: drive if you want. However, having said all that it
really is a good idea to have your boot partition separate from your data.
Service pack 4 of Windows NT 4 was notorious for failing halfway through the
update of the core system files, leaving an unbootable machine. I know of
people who shared data with their boot partition (under NTFS) that fell foul of
this and lost their data. Either way, the choice is there now.
When you install the server edition there is only so much that
you can do from the installation dialogs, although it isn't immediately obvious
at the time. For instance, under NT4 you could specify that a server would be a
domain controller. With W2K you must complete the basic installation of the
operating system first, and then after your first proper local login you are
presented with a wizard front-end application that allows you to set up
additional components and services. In the case of the domain controller
example, this is really dependent upon Active Directory services being
installed first, and only then can you specify the kind of role that the server
will take in the network.
Related to the theme of installation is that of service packs,
an area of previous criticism that Microsoft has also addressed in this
release. Despite the level of service packs available for NT 4 reaching 6a, the
generally available install disk only included the service pack 1 level fixes.
Once this had been installed then it was then necessary to subsequently apply
the latest service pack, making the whole operation take longer. Now, thanks to
a process known as service pack slipstreaming, it will be possible to create a
new W2K installation kit that contains both the latest service pack and any
subsequent hot fixes that might be available.
Disk/file system:
NTFS has been the subject of much improvement. The concept of disk partitions
is being replaced with a new concept called dynamic volumes. As the name
implies this is an operation whereby a raw area of physical disk can be added
to an existing volume dynamically (i.e. without the need for a reboot). W2K
will continue to support partition-based disks, but as of now they are
considered to be legacy configurations. Under the previous disk partitioning
mechanism it was possible to have up to 4 partitions residing within a single
physical disk, but now this option is completely configurable.
For notebook users a very useful new feature is the local
caching of network data. This is a significant improvement to the My Briefcase
concept in the way that copies of network files can be stored locally for you
to use on the move. To make it work you right-click on a network file or folder
within the Windows Explorer and select the Make Available Offline option. The
neat thing about this is that files and folders still appear to be in the same
place i.e. on the network. For example, if your F: drive is a network resource
then you would still see the F: drive when you are unplugged from the network,
and you will be able to see and work with any files that you had previously
marked to be available. Then, when you reconnect to the network, an automatic
synchronisation takes place, although quite correctly you are asked to decide
how you want to play it if both the offline and online copies have each been
updated since the previous synchronisation.
Windows File Protection:
Microsoft has become much more protective of the core system files that make up
Windows. System files are now marked as super-hidden, and efforts are made to
stop you tampering with them. For example, if you click on the Winnt folder
within the Windows Explorer then no files are initially displayed and you are
presented with a rather blunt message:
This folder contains files that keep your system working
properly. There is no need to modify its contents.
There are also safeguards in place to prevent you from
accidentally deleting core files - Microsoft claim that you could delete all
the files on your hard disk and the machine would still boot, but I strongly
suggest that you don't try this at home. Windows is also very concerned about
certain files being overwritten; Microsoft has identified around 2600 files
that are crucial to the smooth running of the full package and refers to them
as Windows Protected Files. A background task called the System File Protection
service checks whether any of the protected files have been replaced and, if
so, takes steps to restore the original.
Server features:
When the Windows NT Option Pack was made available for free a member of the
Microsoft UK team expressed the opinion that this new bundle of software really
should have pushed up the name of the underlying operating system to Windows NT
4.5, and I think with some justification. The Option Pack chiefly consisted of
Microsoft Transaction Server (MTS), Internet Information Server (IIS),
Certificate Server, and Message Queue Server (MSMQ). Now all of these features
are available as an integral part of the W2K Server family, with some aspects
available within W2K Professional as appropriate.
IIS 5.0 continues its rather rapid evolution, this time with
ease of administration being an obvious point of focus for the development
team. There are new wizards available that are specifically targeted towards
the more difficult tasks, most notably for the creation of certificates. Also
new is HTTP compression which, as the name suggests, reduces the size of
textual data being sent down the line. In order for this to work the receiving
browser must be able to handle a compressed HTTP stream, which IE4 and IE5 can,
as well as Netscape Navigator 4. The downside to this is that it does add
slightly to the load on the processor, but as the main bottleneck is usually
the speed of the data connection it is likely to be beneficial on many newer
machines.
Windows Driver Model:
As part of the continuing drive to eventually converge the NT platform and the
Windows 98 family the Windows Driver Model (WDM) has been adopted to ease the
load on the poor device driver writers. W2K and Windows 98 use the same drivers
to control hardware, thereby reducing the burden on hardware manufacturers. In
fact this burden is even more reduced because of the way that Microsoft has
redesigned the overall model. Previously a driver had to be written from
scratch, although templates were made available within the DDK to get things
started. In W2K Microsoft has split the concept of a device into two halves.
One half provides the general functionality that the class of driver provides,
such as an audio class that covers items such as sound cards. Microsoft
provides a class driver that provides the high-level features common to the
functionality of the device in question. It is then up to the hardware
manufacturer to write a minidriver that provides the specific functionality
that is unique to the device. Driver developers will be pleased to know that
the new sample DDK code - from which starting point many drivers do actually
get written - is finally a realistic representation of how a professionally
written driver should be coded.
Power management:
W2K incorporates a power management facility that features several levels of
shutdown, from simple screen blanking and hard-drive spindown to complete
hibernation. This concept was originally introduced with Windows 95 as Advanced
Power Management (APM) but now the Advanced Configuration and Power Interface
(ACPI) specification has superseded it. W2K supports both APM and ACPI, but the
APM support is a legacy feature. ACPI is actually part of an initiative called
OnNow which, according to Microsoft, "defines a hardware-level interface
that enables operating systems to implement power management in a consistent,
hardware platform-independent way".
W2K provides power management via the Power Manager, a new
kernel-mode subsystem. In order for this to work the motherboard must have a
BIOS that supports ACPI. Applications, too, must support this feature in terms
of cleaning up, closing files, and saving state data. Notification comes as a
WM_POWERBROADCAST message; initially Windows signals its intention to enter
suspend mode and all applications are given the option to vote on this. If all
applications approve then a subsequent WM_POWERBROADCAST message is despatched
stating that the suspend operation is actually about to happen - this is the
time to save your data and your state. Finally, when the PC wakes up again,
another WM_POWERBROADCAST message is sent and each application should be able
to recover itself to a stable operational state.
Plug and play:
This is one of the features that users have been waiting for the most. The Plug
and Play Manager subsystem will automatically identify any devices which
"appear" (i.e. are plugged in) as long as they conform to the ACPI
specification. Windows tends to keep quite a few of the more common device
drivers on hand and will automatically install it if it can, otherwise it will
prompt the user to make it available. As a new device is being added a
sub-component of the Plug and Play Manager (called the Arbiter) will
dynamically reassign whatever resources it and all other devices require in
order to make it all fit.
W2K Application Specification
Since the days of Windows 3.1 Microsoft has provided
guidelines for the development of Windows applications in order to provide both
a consistent experience for the end user and to promote harmony between each
application and the underlying operating environment. Originally called the
Designed for Windows logo program it has now evolved into the W2K Application
Specification. Two levels of conformance exist, one for W2K Professional and
the other for the W2K Server range.
The core specification is really aimed at ensuring that an
application doesn't use any outdated features that were found in earlier
versions of Windows. The application must be 32-bit, must support long
filenames and UNC paths, and it must also ensure that all file types have
associated file types, descriptions, and actions.
Installation requirements have been updated somewhat in that
Windows installer-based packages must be provided (see my regular column from
last January for more on this). It is also important that the product should
correctly support uninstallation. The uninstall mechanism should be accessed
via the Add/Remove Programs icon with Control Panel, rather than as a shortcut
in the Start menu. Actually, on this subject Microsoft has also become more
strict in declaring what should and shouldn't be visible from the Start menu.
It is now recommended that shortcuts to help files and readme documents be also
excluded in order to avoid cluttering up the whole Start menu area.
One of the problems that Microsoft testers found while
assessing the compatibility of existing applications with W2K is that the
location of the My Documents folder has in more than a few cases been hard
coded. In W2K the location of this folder has been moved to C:\Documents and
Settings\<username>\My Documents, so of course the full path cannot be
hard coded because it will alter for each user. Defaulting to each user's My
Documents folder for the storage of user-created data is an Application
Specification requirement, but the means by which it is achieved apparently
needs better publicising to the development community. For the record the way
to do this is to make a call to SHGetFolderPath and specify CSIDL_PERSONAL as
the folder type. Of course you should use the common dialogs whenever you can,
and these now include the relevant My Documents location for the current user
(see Figure 1).
Figure 1: Redesigned common dialog
The Application Specification also includes requirements for
the OnNow/ACPI support and Active Directory. There are also some specific
requirements for the server editions of W2K; most notably that anything which
has a need to be managed must be done so via a Microsoft Management Console
(MMC) snap-in.
Kernel changes
You might notice from the descriptions of the four editions of
W2K that are outlined above that the 4GB process space limit has now been
exceeded on the two higher-end versions. Under Windows NT 4 the 4GB limit was
determined by the 32-bit addressing scheme used on the Intel architecture, but
the more recent x86 chips include a feature known as Physical Address Extension
(PAE) that uses a 36-bit physical addressing scheme and thereby allows up to
64GB of physical memory to be addressed. To accommodate this W2K includes a new
API set (included with all four editions of the product) called the Address
Windowing Extensions (AWE) that provides support for this feature. The API
consists of just four functions: VirtualAlloc, AllocateUserPhysicalPages,
MapUserPhysicalPages, and FreeUserPhysicalPages.
Also new at the kernel level is the Job object which is a
programming feature that creates a relationship between multiple NT processes.
Sometimes it is desirable for a program to spawn a whole new process in order
to perform a task. For example Visual C++ runs within the context of a
Microsoft Developer Studio application, which is a single Win32 process.
However the main compilation routine is performed by a separate executable
called CL.EXE, which in turns spawns child processes (e.g. CL2.EXE). If it
becomes necessary for the logical task of compilation to be halted it was
previously very difficult to implement a means of killing all of the processes
together because no explicit relationship between them existed. Within W2K a
process can create a Job object using the CreateJobObject function and then
subsequent processes can be added by calls to AssignProcessToJobObject. If the
need should arise to kill all of the added processes together then a simple
call to TerminateJobObject will do the deed. Job objects can be named and
shared, and they can also be used to manipulate common attributes of all member
processes.
Active Directory
What's the most important improvement within W2K? Well, the
answer depends upon whom you ask. A typical user would probably argue the case
for Plug and Play, but anybody who actually supports Windows NT-based networks
currently will argue that it is Active Directory. The problem so far has been
that the domain model used in previous versions of Windows NT isn't suited to
the size of enterprise networks that exist today, and for Microsoft this has
been bad news since they will have undoubtedly lost corporate sales because of
it. NT 4 domains consist of a Primary Domain Controller (PDC), probably a
Backup Domain Controller (BDC), and client workstations. If you have multiple
domains then it is necessary to set up all kinds of trust relationships between
them.
Active Directory (AD) still uses domains, but the concept of a
primary domain has been replaced with a more enterprise-friendly hierarchical
model. The directory service is concerned with maintaining a database of all of
the objects that exist within the network, but within the structure of a secure
and partitioned namespace. Objects can be anything, such as users, computers,
printers, applications, and so on. In terms of the overall hierarchy, objects
exist within namespaces - that is, it is a bounded area within which a given
name can be resolved. The objects here exist hierarchically, for example
individual user objects exist within a collection object (called a container in
AD). This namespace of hierarchical objects is called a tree. On a larger scale
a collection of trees can exist as a forest, which doesn't share the same
namespace but does fall under a common schema that defines the rules and
definitions that specify the content of, and relationships between, a set of
objects within a directory service.
Every object that exists within an Active Directory namespace
has a distinguished name (DN). The name of the DN is based upon a hierarchical
path through the namespace. For example, if my web site was an Active Directory
hierarchy that existed on the Internet (it's not, before you try), then my DN
could be
/O=Internet/DC=COM/DC=jonperkins/CN=Users/CN=Jon
This DN identifies the user object Jon within the
jonperkins.com domain.
For the software developer the means by which you manipulate
Active Directory is the Active Directory Service Interface (ADSI).
Programmatically, for those of us who connect via COM Automation interfaces,
this means setting a reference to the Active DS Type Library. With Visual Basic
for instance (inevitably), I could set the value of my home page property
within the Jon object as follows:
Dim oUser As IADsUser
Set oUser =
GetObject("LDAP://O=Internet/DC=Com/DC=jonperkins/CN=Users/CN=Jon")
oUser.HomePage = "http://www.jonperkins.com/index.htm"
oUser.SetInfo
Set oUser = Nothing
COM+ and DNA2000
DNA 2000 is Microsoft's platform for supporting multi-tiered
applications (the letters stand for Distributed interNet Architecture). It is
really a collection of technologies that come together to provide the services
necessary to host applications that conform to the data/business/presentation
services model.
At the heart of DNA is COM+ Services 1.0, formerly known as
Microsoft Transaction Server (MTS) but now fully integrated into the operating
system rather than an add-on provided by an option pack. COM+ isn't just a
renaming of MTS 2.0 however, it also adds new features such as distributed
transaction support, role based security management, and thread
synchronisation. It also incorporates the message queuing services previously
available in Microsoft Message Queue Server (MSMQ). The administration of COM+
components can now be found under the Component Services icon within the
Administration Tools folder (which has been sensibly moved from the Start menu
to Control Panel). Figure 2 shows an illustration of the Component Services
folder, and Table 1 shows the new features within the COM+ Services. I intend
to provide a more thorough coverage of the creation of COM+ components within a
forthcoming Visual Basic column.
Figure 2: Component services MMC snap-in
DNA 2000 is the overall architecture that provides a suitable
environment for Web applications. Actually, that's the Microsoft definition; in
fact it is just as suitable for conventional EXE-based front ends as it is for
browser-based applications. W2K doesn't provide the final piece of jigsaw for
the great DNA 2000 plan though. While you can build proper DNA 2000
applications today with W2K there are still some products yet to appear that
will complete the picture. In my Visual Basic column this month I introduce
XML, a new standard for the transfer of both data and the definition of that
data. XML is very important to DNA 2000 and to this end a new version of SQL
Server will provide a high-degree of support for it. Similarly a new product
called Microsoft BizTalk Server will provide business process integration
within the enterprise through the exchange of XML-formatted business documents.
Finally, Microsoft AppCenter will simplify the deployment and management of
Windows DNA applications within "farms" of servers.
Last word
Microsoft has dedicated a huge amount of effort into producing
an operating system that offers so much. Finally, their high-end operating
system no longer excludes important features that can only be found in their
lower-end offering. Equally as importantly they have finally started to deliver
a platform that scales from notebook all the way up to corporate server. We
really have had to wait a long time for this upgrade, but I think it was worth
it - not that we had any choice. I don't doubt that many companies will want to
wait until the first service pack has been in circulation for a while, although
Microsoft are undoubtedly impatient for a rapid uptake so I wouldn't be
surprised to see this psychologically important milestone reached within the
next six months. Having finally produced a code base that doesn't have the
gaping holes of its predecessor I would envisage that future versions wouldn't
be so difficult to get out of the stable. And so, having overcome its greatest
technical challenge to date, we now have to wait and see if it can have a
similar success with its greatest legal challenge too!
