M i c r o s o f t ' s W i n d o w s C E , P o c k e t P C , a n d W i n ...
W12Chapter 4Computer SoftwareThe market for mobile device operating systems includes software for a variety of de-
vices, such as handheld computers, set-top boxes, subnotebook PCs, mobile tele-
phones, and factory-floor equipment. In the past, each device used its own operating
system (although the software may have been written by an independent software
vendor that licensed it to the device manufacturer). The buyer had no choice but to
use the operating system the maker put into it. This situation created a fragmented
market for mobile device operating systems. It also prevented a large market for ap-
plications from developing, in sharp contrast to the PC industry. The mobile device
operating system market has begun to consolidate around a handful of high-volume
operating systems, including:• Microsoft’s Windows CE, including the Pocket PC variant of CE• Palm OS from Palm• Symbian’s EPOC operating system• Embedded Linux, an OS originally developed for servers and desktop computersFor discussion of these operating systems, see the material below.M i c r o s o f t ’ s W i n d o w s C E , P o c k e t P C ,
a n d W i n d o w s N T E m b e d d e d 4 . 0Microsoft offers three operating systems for embedded and mobile devices. These op-
erating systems allow developers to create customized versions of the OS that let
them omit unneeded capabilities and functions but include those necessary to exploit
a particular device. All are aimed at 32-bit devices only.MOBILE DEVICE OPERATING SYSTEMS Table W4.1Operating SystemsMobile Device Operating Systems
• Microsoft Windows CE• Palm Operating System• Microsoft Pocket PC• Embedded Linux• Microsoft Windows NT Embedded 4.0Desktop and Notebook Computer Operating Systems
• MS-DOS• IBM’s OS/2• Windows 95, Windows 98• UNIX• Windows Millennium Edition (ME)• Linux• Windows NT• Mac OS X• Windows 2000• JavaOS• Windows XPDepartmental Server Operating Systems
• UNIX• Windows XP• Linux• Novell NetWare• Windows 2000Enterprise Server Operating Systems
• IBM’s OS/400• IBM’s z/OS (formerly OS/390)Supercomputer Operating Systems
• Cray Unicos• IBM’s AIX(page 98)(page 98)Chapter 4Computer SoftwareW13The main differences among the three systems are that Windows NT Embeddedis more powerful and is designed to build server appliances and systems that need to
provide or consume services typically associated with a server, such as printer and file
sharing, log-in and authentication, and Web page serving. Thus, the NT product
would be used for such devices as set-top boxes, Web-server appliances, and possibly
ATMs or Web-pad devices. Windows CE is an appropriate product for PDAs, Web-
access devices, video-game platforms, mobile phones, and intelligent appliances.
(Pocket PC is a variant of Windows CE.) Microsoft plans to replace Windows CE,
Pocket PC, and Windows NT Embedded with Windows XP.W i n d o w s C EWindows CE is Microsoft’s information appliance operating system that has been in-
corporated into entertainment devices, subnotebook products, handheld PCs, palm-
size PCs, cordless and mobile phones, Windows terminals, some set-top boxes, and an
automobile information and entertainment system (AutoPC). Windows CE is the
modular embedded OS for the new generation of highly connected 32-bit devices that
seamlessly integrate with both Windows and the Internet. The standard Windows CE
software package for handheld PCs includes scaled-down versions (known as pocket
versions) of Microsoft Word, Excel, and PowerPoint; Pocket Internet Explorer; an e-
mail client; a personal information manager (PIM) that synchronizes with Microsoft
Schedule ; and Outlook.Using these pocket applications to edit documents originating on a PC and thensending them back to the PC often causes loss of most formatting and is therefore
somewhat problematic. The package has a program that automatically detects when
the handheld PC is docked with a Windows computer and initiates synchronization
and replication between Information Manager and Microsoft Schedule .Future versions of Microsoft’s embedded operating systems for handhelds willcontain voice-recognition and pen software. Another technology in future versions
will be “Tap and Talk,” which lets the user point at a place on the screen with a stylus
or pen and then speak to supply input for that area of the screen.P o c k e t P CIn early 2000, Microsoft introduced a version of its Windows mobile operating system
called Pocket PC. The Pocket PC operating system is a version of Windows CE 3.0
with features and an interface designed specifically for PDAs and handheld comput-
ers. (Pocket PC is a specific implementation of Windows CE optimized for these de-
vices.) Pocket PC solves many problems that held back the success of previous
versions of Windows CE, such as an overly complicated interface, slow performance,
and poor power management that shortened battery life. Pocket PC supports natural
handwriting recognition with a variety of programs. A utility named Transcriber takes
words or phrases entered anywhere on the screen and translates them into text. Ana-
lysts say that using fuzzy logic with an integrated dictionary yields high accuracy.Microsoft added new features to Pocket PC—devices with Pocket PC containminiversions of Internet Explorer (which offers full Web access), Word, Excel, Out-
look, the Microsoft Reader, Windows Media Player, and Money. One cannot usually
alter documents using these versions and expect formatting to be preserved—indeed
some allow no editing—but existing documents and attachments can be read.W14Chapter 4Computer SoftwareP a l m O p e r a t i n g S y s t e mPalm developed this operating system for its PalmPilot handheld, pen-input PDAs.
Palm OS includes a graphical user interface and an interapplication drag-and-drop
feature. Users must learn a stylized alphabet, called Graffiti, to make the device re-
ceive handwritten input. Palm OS is optimized for mobile computing and takes less
memory and runs faster than Windows CE, Java, and EPOC. Many industry experts
consider Palm OS the best for small devices, because of its speed and modest power
requirements.The Palm OS has many features:• An agenda view where people can see both their schedule and a “to-do” list at thesame time• A shortcut command bar to access features such as cut, copy, paste, delete, andbeam• Tappable menus, so people can activate menus with a quick tap on the menu text atthe top of their screens• New privacy protections• A faster way of creating Address Book entries, so that records of people from thesame company or group can have common information duplicated more quickly• Faster HotSync capabilities• A “sleep” button that allows the user to delay an appointment alert from the calen-dar while continuing to use other product features• Infrared HotSync capabilities that eliminate the need for a docking cradleS y m b i a n ’ s E P O CThe Symbian operating system, EPOC-32, has been powering Psion handheld devices
for several years. It is a full 32-bit operating system written for ARM (Advanced
RISC Microprocessor) processors, which constitute the majority of processors used in
mobile phones.Hewlett-Packard’s Chaiis an integrated suite of software products, developmenttools, and support services. Chai is intended to help device manufacturers design in-
formation appliances. With Chai, a manufacturer can select components from the
Chai Appliance Platform and drop them into a device. Any class of Java-enabled de-
vices can be developed, including handheld phones, digital set-top boxes, high-speed
network routers, factory automation controllers, and intelligent products.Qualcomm’s BREW (Binary Runtime Environment for Wireless)platform al-lows developers to create applications that operate on all handsets with Qualcomm
CDMA chip sets. BREW sits between the chip system software and the application,
making the phone’s functionality available to the application without requiring the
developer to have the chip system source code or even a direct relationship with a
handset manufacturer. BREW allows rapid development of a variety of small, trans-
portable handset applications that users can download over carrier networks onto any
BREW-enabled phone. BREW enables consumers to download, update, and delete
applications from their handsets, thereby bringing to wireless handsets the same
choice and control that users have on their desktop computers. BREW supportsMOBILE DEVICE OPERATING ENVIRONMENTS(page 98)Chapter 4Computer SoftwareW15e-mail and instant messaging, real-time navigation services, group chat, group games,
and news and information services tailored to the individual.Sun’s Java Embedded Environment is Sun Microsystems’ operating environmentfor embedded platforms and is based on the company’s Java technology.T h e H i s t o r y o f M S - D O S a n d W i n d o w sDesigned for the ClientMS-DOSWindows 1.0 through Windows 3.1 (operating environments)Windows 95Windows 98Windows Millennium Edition (ME)Designed for Workstations and ServersWindows NT 1.0 through Windows NT 4.0Windows NT 5.0 (renamed Windows 2000)Windows 2000Professional
Standard Edition Server
Advanced Server
Datacenter ServerWindows XPHome Edition
Professional (32-bit)
Professional (64-bit)BlackcombW i n d o w s F a m i l y O v e r v i e wEach of the current Windows desktop products is part of one of the two major Win-
dows product families: Windows 95/98/Millennium, sometimes referred to collectively
as “Windows 9x,” and Windows NT/2000.Windows 9x is software that has its origins in MS-DOS and the early versions ofWindows. Although Windows 95 was a new development effort rather than an up-
date to earlier versions of Windows, it retained many attributes of the earlier ver-
sions. For example, it lacked preemptive multitasking capability and protected
memory and still contained some 16-bit code. Windows 98 and Windows Millennium
Edition (typically referred to as “Windows ME”) are based on Windows 95 and have
inherited these attributes.Windows Millennium Edition (Windows ME)is the first major update to theWindows 95 product family since Windows 98 was released in June 1998. Windows
ME offered improvements for home computing in the areas of PC reliability, digi-
tal media, home networking, and the online experience. Highlights of Windows
ME include:DESKTOP AND NOTEBOOK COMPUTER
OPERATING SYSTEMS(page 100)W16Chapter 4Computer Software• In the area of PC reliability, Windows ME provides such features as System Re-store, which enables users to roll back to a previous PC configuration that worked
properly.• System File Protection, which prevents the accidental or unauthorized overwritingof crucial system files.• AutoUpdate, which downloads Microsoft updates automatically without userintervention.• Faster bootup.• Digital media. Features in this area include:• Windows Image Acquisition (WIA), which helps users transfer digital imagesfrom digital scanners, cameras, and other WIA-compliant devices• Windows Movie Maker, which includes tools for editing, saving, and sharingdigital home videos• Windows Media Player
• DirectPlay Voice Chat, which allows gamers to chat across the Internet whileplaying an interactive game• Home networking:• Home Networking Wizard
• Improved Internet Connection Sharing (ICS) technology
• Simplified USB networking and universal plug-and-play technology• Online experience:• Windows ME improvements include enhanced browsing, shopping, Web pub-lishing, and chatting, as well as Internet Explorer 5.5.Windows NTand its follow-on productWindows 2000, on the other hand, werewritten from the beginning to be full multitasking operating systems based exclu-
sively on 32-bit code. As a result, Windows NT/2000 is able to run multiple pro-
grams better, less prone to systems crashes, and more secure than the Windows 9x
products. Windows 2000 Professional desktop OS and its planned upgrades, Win-
dows XP Professional and Windows XP Home Edition, all shipped during the second
half of 2001.There are two major target market segments for desktop Windows: the consumerand the business user. During the latter part of the 1990s, MS attempted to position
Windows NT as its preferred solution for the business user. In reality, however, the
vast majority of business users ran Windows 95 or 98 on their desktops. Notebook
computer users did not have much choice because Windows NT was not well-suited to
running on notebooks—it lacked the power management and plug-and-play features
notebooks need. With the release of Windows 2000 Professional (the desktop version
of Windows 2000), Microsoft had a more attractive product to offer the mainstream
business customer (including notebook users). With the release of Windows XP, the
next-generation version of Windows 2000, Microsoft is in the process of abandoning
the Windows 9x product family.Windows 2000 Professional (32-bit)is a major upgrade of Windows NT. Windows2000 was originally known as Windows NT 5.0. Four editions of Windows 2000
shipped in 2000: Professional, Standard Edition Server, Advanced Server, and Data-
center Server. Microsoft considers the Windows 2000 family its most vital operating
system upgrade.Windows 2000 is a more manageable operating system than previous desktop ver-sions of Windows and provides centralized, policy-based management, broad support
for laptops and mobile devices, and improved performance. Windows 2000 also fea-
tures the following:• Active Directory—IntelliMirror copies desktop settings automatically to a net-worked Windows 2000 server. Active Directory allows users to access applications
and configurations from any Windows 2000 Professional desktop on the network
even if the network connection fails, and makes it easier for administrators to trou-
bleshoot and repair Windows 2000 desktops.• Improvements for notebook use:• Mobile features include Hibernate, which turns off the computer and restoresprograms and settings when the user reactivates.• Offline access to files and folders and offline viewing of Web documents, whichallows users to disconnect from the network and work and view Web pages as
if still connected.• A synchronization manager for files and documents that are being used offlineso they can be kept consistent with the copies stored on the network.• A smart battery meter, which gives a more accurate view of battery life andlets users reduce power to specific functions to extend battery strength.• Hot docking and easier remote configuration features.• Direct X 7.0 improves video performance.• Distributed File System: This feature permits multiple disk drives to be groupedinto a single, virtual disk drive, allowing users to find files more easily without
searching multiple drives.• File Allocation Table 32 (FAT32) file system:• The FAT32 file system improves Windows 2000 Professional’s compatibilitywith Windows 98/Millennium Edition.• This feature is provided in addition to the NT file system and the original 16-bit FAT format.• Enhanced security:• Windows 2000 Professional provides file-level data encryption and implementsKerberos, a platform-independent security mechanism for user authentication
and access control in a networked computer environment.• Microsoft management console provides users with the ability to conduct single-interface management.• Advanced networking hardware:• Software support for new networking hardware, including digital subscriberline (DSL) modems, cable modems, wireless technologies, and improved
support for peripherals connected by means of universal serial bus (USB),
FireWire, and infrared.• Internet capabilities:• Windows 2000 Professional’s Internet features include Internet Explorer 5.01,optional Internet Information Services (IIS) 5.0, Dynamic Hypertext Markup
Language (DHTML) Behaviors and Extensible Markup Language (XML)
support for developers, and Internet connection-sharing technologies.• Faster multitasking and faster performance.• Full 32-bit architecture:• The presence of full 32-bit architecture allows users to run more programs andperform more tasks simultaneously than with Windows 95 or Windows 98.• It also provides 25 percent faster performance than with Windows 9x on sys-tems with 64 megabytes or more of memory.• Scalable memory and processor support: Supports up to 4 gigabytes of RAM andup to two processors in a symmetric multiprocessor (SMP) configuration.Chapter 4Computer SoftwareW17Windows XP Home Edition and Windows XP Professional (32-bit)is the first up-grade to Windows 2000, originally known by code name of “Whistler.” Windows XP
has three versions: a 32-bit consumer version, a 32-bit business version, and a 64-bit
business version.Windows XP will be the first product descended from Windows NT that is de-signed for both business and consumer users, and the first version of Windows that
integrates features of Microsoft’s .NET platform. Windows XP Home edition is
aimed at home users and gamers. Windows XP Home Edition is viewed primarily as
a 32-bit consumer replacement for Windows ME. Microsoft emphasizes Internet-
and network-oriented features, such as a redesigned Weblike user interface with
user-selectable Visual Styles; an emphasis on digital media; the Internet Explorer 6.0
browser; and basic support for Microsoft’s forthcoming .NET platform. For example,
Windows XP will enable users to save files to a Microsoft Internet storage site. Win-
dows XP will offer the same features as Windows ME and also feature simplified
security/log-in, an enhanced home-networking wizard, and the ability for home users
to use multiple configuration profiles simultaneously.Windows XP Professional has a 32-bit version and a 64-bit version. Windows XPProfessional is considered a minor upgrade to Windows 2000 Professional. However,
many of the features being introduced in Windows XP Professional will be of value to
business users. The user-selectable visual design will enable task-based computing,
with a task bar that provides a summary function via a pop-up that lists each e-mail
message, document, or spreadsheet currently open. Windows XP will also feature the
inclusion of smart agents, enhanced memory management, and better support for PC
companion devices such as Web pads, personal digital assistants, and mobile phones.
It also will provide support for Microsoft’s Visual Studio.NET programming environ-
ment. This support will allow developers to design applications that exploit the .NET
features of the client.Windows XP Professional (64-bit) is designed to accompany Intel’s Pentium 4 mi-croprocessor. This upgrade will feature large memory support, features designed to pro-
vide high availability, support for new floating-point numerics, and multimedia-specific
instructions. The 64-bit Windows is targeted at demanding applications, including e-
commerce, data mining, memory-intensive high-end graphics, complex mathematics,
and high-performance multimedia. The 64-bit operating system maintains backward
compatibility with current 32-bit applications.Following Windows XP, Microsoft will release its first fully .NET-enabled Win-dows operating system—code namedBlackcomb—which can be considered version3.0 of Windows 2000. On the client side, Blackcomb will provide services of interest to
both consumers and business users. For example, Blackcomb will feature what are
known as natural interfaces, including speech recognition and handwriting support.Blackcomb will also feature seamless integration with XML-based Web servicescurrently under construction by Microsoft and other firms. Over time, these Web ser-
vices, such as the authentication and digital-rights-management elements of Mi-
crosoft’s forthcoming Hailstorm services, will be able to tap into the Windows 2000
Active Directory, essentially melding Internet services with Microsoft’s back-end di-
rectory services. Blackcomb will also be modularized to support non-PC devices. Mi-
crosoft is working on services for Blackcomb: a new storage system, a series of
PC-based and non-PC-based user interfaces, building-block Web services, and a new
programming environment, C#, that will support non-Windows environments such as
Solaris and Linux and is designed to compete with Sun’s Java.W18Chapter 4Computer SoftwareL i n u x Linuxis based on UNIX and, like the Apache Web server, is open source freewarethat can be downloaded at no cost from the Internet. Linux’s designer, Linus Tor-
valds, and other freeware developers continue to enhance the core Linux operating
system kernel.As part of the GNU Network Object Model Environment (GNOME) Founda-tion, HP, IBM, and Sun are committed to developing a set of standard APIs to pro-
mote Linux as a desktop alternative to Windows, and they have embraced the
GNOME interface as a means of doing so. Leading system and software vendors an-
nounced initiatives in 2000 designed to advance Linux on the desktop to compete
with Microsoft Windows, which currently controls about 90 percent of desktops
worldwide.A number of graphical user interfaces are available for use with Linux. The twobest known are the K Desktop Environment (KDE) and GNOME, both of which are
based on the X Windows System. KDE 2.0 incorporates an office productivity suite
and an array of new technologies, such as Konqueror, a full-featured Web browser
and file manager, and Koffice, an integrated office suite. The GNOME Foundation’s
GNOME 1.4 was released in mid-2001.The GNOME Foundation is sponsoring various projects and has adopted Sun’sStarOffice productivity suite as the core of the office productivity software for
GNOME Office. Sun, which acquired Star Division’s StarOffice in 1999, has made the
office productivity suite available to the open source community.Another GNOME Foundation member, Eazel (founded by a group of formerMacintosh engineers from Apple Computer), have developed a Linux GUI and file
manager product called Nautilus 1.0 that offers a Windows-like interface, file manage-
ment services, and integrated Web services for the Linux desktop. Nautilus is a core
component of the GNOME 1.4 desktop project. The GNOME 1.4 desktop will be
bundled with Red Hat and other Linux distributions. Dell and Sun have committed
to bundling Nautilus on workstations in 2001. Sun, for example, will distribute
Eazel’s Nautilus software on the upcoming GNOME 2.0 desktop user environment
for Solaris.T h e A p p l e M a c i n t o s h O p e r a t i n g S y s t e mThe current desktop version of Apple’s flagshipMacintosh operating systemis MacOS X, released in 2001. Mac OS X, a desktop operating system, is built on an open
source, UNIX-based core operating system called Darwin. It features a new Aqua
user interface, advanced graphics, true memory protection, preemptive multitasking,
and SMP when running on the dual-processor Power Mac G4 systems.The new “liquidlike” Aqua user interface offers color, depth, translucence, andfluid motion with new controls that resemble polished gems and buttons that indicate
active or nonactive status by glowing and dimming. The GUI also offers new ease-of-
use features, including customizable toolbars, navigation aids, the ability to save docu-
ments in Adobe Systems’ Portable Document Format (PDF), and a new Dock feature
that makes it easier for users to organize applications, documents, and windows.The Dock feature contains many new user-friendly features, including pop-upmenus, customizable toolbars, navigation aids, and the ability to print PDF files. The
Dock tray holds folders, applications, documents, storage devices, minimized win-
dows, digital images, links to Web sites, and e-mail.Another major feature for end users, the redesigned Finder, offers simple naviga-tion and large buttons to applications, documents, home directories, and Internet fa-
vorites in a single window. The File Viewer gives users three options for viewing theChapter 4Computer SoftwareW19file system, including the icon and list views of Mac OS 9. By double-clicking on items
in either the icon or list view, a view of the new folder appears in place of the older
folder to reduce screen clutter and provide a single window view.Mac OS X also features a new Quartz two-dimensional graphics engine, OpenGLfor three-dimensional graphics and gaming, and QuickTime for streaming video and
audio. Quartz provides on-the-fly rendering of documents stored in PDF and dramati-
cally renders sharper graphic elements. OpenGL has become the industry’s most
widely used and supported 2-D and 3-D graphics API.Mac OS X also includes features for improved integration with UNIX systems. Itextends support to UNIX File System, the standard volume format of most UNIX op-
erating systems, and to POSIX file system semantics, which makes it easier for devel-
opers to bring server applications to the new operating system.Mac OS X also includes clients for the Apple File Protocol, Network File System(NFS, the dominant file-sharing protocol in the UNIX world), and Web-based Distrib-
uted Authoring and Versioning (WebDAV, an emerging Internet standard for access-
ing and sharing files over the Web). Mac OS X incorporates a version of the Apache
Web server for file sharing and support for the Java 2 Platform, Standard Edition.Mac OS X is a major upgrade of Mac OS 9. Mac OS X provides these major im-provements in performance and usability via the following:• Protected memory that allocates unique address space for each application orprocess on the computer• A Virtual Memory Manager that automatically allocates the amount of memoryneeded by an application• Built-in support for Point-to-Point Protocol (PPP) for remote access as well asAppleTalk support for interoperability with existing Macintosh networks• Ability to embed and manipulate PDF data in any Mac OS X application• QuickTime support• Larger icons (up to 128128 pixels)• Improved screen space management• New e-mail application• Easier switching between applications• Column views for easier navigation of rich file systemsPartitioning, also called domain support, is a method of segmenting a server’s re-
sources to allow the processing of multiple workloads on a single system. That is,
users can deploy a mixture of applications on separate partitions, each with its own
copy of the operating system. First developed by IBM for the mainframe more than
25 years ago, partitioning is becoming ubiquitous on high-end RISC servers running
UNIX and has made its debut on some of IBM’s midrange servers as well as high-end
Intel servers.As many large corporations, data centers, and service providers attempt to reducethe costs associated with running large numbers of servers, partitioning is becoming
more widespread. Partitioning offers the ability to segment system resources—CPU,
memory, and I/O—with varying degrees of isolation between the partitions. In some
cases, such as IBM’s zSeries mainframes, customers can run a combination of operat-
ing systems, such as OS/390, z/OS, and Linux, in separate partitions. For instance, aW20Chapter 4Computer SoftwarePARTITIONING (page 100)customer can run a technical/engineering application on one partition running OS/390
or z/OS, and a series of e-commerce and data-warehousing applications on Linux par-
titions. There are distinctions in the manner in which partitions are implemented, the
degree to which the application workloads are isolated, and how system resources are
allocated to each partition.S o f t v e r s u s H a r d P a r t i t i o n i n gPartitions may be implemented in software, hardware, or a combination of both.
The benefit of software partitioning is that it enables finer partitioning of a single
server than a hardware approach. The downside is that it cannot isolate application
workloads in separate partitions as neatly, or in as fault-tolerant a manner, as hard
partitions. Physical, or hard, partitions can isolate application workloads in a more
fault-tolerant manner. With physical partitioning, the hardware enforces separation
of partitions so they work as if they were separate servers. If a failure occurs in one
partition, the remaining partitions can continue to function. Additionally, hard par-
titions give customers the ability to run multiple operating systems on a single
server. The negative side is that fewer partitions can be created per system, thus
reducing the number of workloads a single server can take on. IBM’s logical parti-
tions (LPARs), which are a combined software and hardware approach, have been a
feature of IBM’s S/390 architecture since 1988.D y n a m i c v e r s u s S t a t i c P a r t i t i o n i n gThere also is a distinction in the manner in which resources—CPUs, memory, and
input/output—can be reallocated to various physical partitions in a single server. Dy-
namic partitioning refers to the ability to move resources from one partition to the
other while the system is still running. Dynamic partitioning allows users to reassign
resources between partitions on the fly without taking the system offline, or in an un-
interrupted manner. Static partitioning, on the other hand, requires operators to halt
the operation of the affected partition, reconfigure the machine as they want it, and
reboot.Vendors are enhancing dynamic partitioning by providing automatic dynamic par-titioning, which allows the system to automatically reallocate resources between parti-
tions based on application needs. In this case, the system monitors application needs
within a partition and adjusts resources accordingly, without operator intervention.H a r d P a r t i t i o n i n g v e r s u s W o r k l o a d M a n a g e m e n tVendors are also extending workload management features to high-end systems to
handle variable workloads. In this software-based model, the workload is controlled
dynamically by the operating system. The benefits are that the model enables better
resource allocation and prioritization of workloads. However, the downside is that it
allows for only one operating system image, which is a single point of failure. In con-
trast, a hard-partitioned system allows for multiple operating system images on a sin-
gle SMP server. IBM’s zSeries partitioning has been improved with the introduction
of Intelligent Resource Director, which dynamically and automatically can balance
CPU power or I/O bandwidth to the priority LPARs on the server. In this model, the
priority of an LPAR is determined by the Workload Manager, which has all business
policies defined and continually monitors the server at ten-second intervals.Chapter 4Computer SoftwareW21Introduced in 1974, Multiple Virtual Storage (MVS) was a batch-processing-oriented,
mainframe operating system that managed large (by the standards of the time) amounts
of memory and disk space. Since that time, IBM has enhanced and rewritten MVS to
offer online operations, provided by subsystems such as the Customer Information Con-
trol System (CICS), Time Sharing Option (TSO), and other system software.In 1981, the MVS family was enhanced by MVS/Extended Architecture(MVS/XA) to include 16-bit addressing, 2 GB of virtual memory, and other new fea-
tures of IBM’s System 370 XA architecture. In 1994, MVS/Enterprise System Archi-
tecture (MVS/ESA) enhanced the operating system for larger-scale mainframes by
including 31-bit addressing and 16 terabytes of virtual memory with IBM’s ESA/390
architecture. MVS also has been enhanced for lower-cost CMOS mainframe hard-
ware and can be used to run UNIX applications, including Linux, e-commerce and
e-business applications, and client/server deployments. During the mid-1990s, IBM
changed the name MVS toOS/390to reflect the fact that it no longer was limited totraditional MVS functionality. IBM also included UNIX user and programming inter-
faces and could be used to run both traditional MVS applications and UNIX applica-
tions at the same time.OS/390 runs on S/390 architecture systems from Amdahl, Hitachi, and IBM, andis designed to handle very large systems with many gigabytes of data. In September
2000, IBM introduced its z/Architecture, a new 64-bit mainframe architecture devel-
oped under the code name “Freeway” that replaces the 32-bit architecture first de-
buted in 1994. The first system implementing the new architecture is theeServerzSeries 900.W22Chapter 4Computer SoftwareIBM’S ENTERPRISE OPERATING SYSTEM:
z/OS (previously OS/390)(page 100)Manager’s Checklist W4.1 Common Groupware FeaturesWould Your Organization Benefit from These Groupware Features?• Electronic mail and messaging• File and document storage/sharing• Shared database access• Calendaring and schedulingcoordination• Desktop videoconferencing• Collaborative presentationcapabilities• Workflow/document routing• Managed security/file access• LAN or Internet-based access• Meeting-support software(page 106)The Internet is the ultimate distributed system. Internet developers cannot be sure
what types of hardware and software their customers will be using when they seek ac-
cess to company servers. Internet applications designed to let one company interact
with other companies can be complex because of the variety of hardware and software
with which they must be able to work. Furthermore, building a complete, end-to-end
integrated system is a complex task, regardless of the tools available. Most applica-
tions do not support integration sufficiently and require workarounds. More sophisti-
cated applications need middleware to link application modules developed in
different computer languages and running on heterogeneous platforms. To accom-
plish this linkage, companies must use distributed middleware systems.Components are modules of code that can serve as the building blocks for evenlarger programs. Distributed components offer two advantages over traditional one-
or two-tier programs in helping to integrate disparate systems. First, they provide
common interfaces for the applications that need to be linked to build Web applica-
tions. Second, because it shifts the labor from writing code to assembling prebuilt
modules, the use of components can significantly reduce the cost and time involved in
developing applications. Many companies already rely on the use of small compo-
nents for the rapid development of user interface screens and for tasks such as linking
applications to databases. Emphasis, however, remains on larger components and
portfolio assembly. Larger components can offer functionality similar to that of off-
the-shelf software, and portfolio assembly involves integrating multiple applications
from different vendors into a suite of the best ones.Scaling up from component-based software, middleware integrates code writtenfor heterogeneous systems. The most popular of the standards for distributed compo-
nent middleware are Microsoft’s Distributed Component Object Model, Sun’s Enter-
prise JavaBeans, and the Object Management Group’s Common Object Request
Broker Architecture. An increasingly popular middleware option is the Extensible
Markup Language (XML) coupled with a transport protocol like Simple Object Ac-
cess Protocol (SOAP).Development can be simplified if a company chooses to use a distributed compo-nent system with a component-based application server. Component Object Model orChapter 4Computer SoftwareW23MIDDLEWARE AND COMPONENT SOFTWARE Manager’s Checklist W4.2 Software Evaluation CriteriaYes NoYes NoDoes the Software Meet Our Needs in Terms of the Following Criteria?• Ease of development• Learning (fordevelopers and
for users)• Reporting capability• General functionality• Data handling• Graphic presentation• Performance• Output options• Environments andhardware• Security• Documentation• Maintenance• Vendor support• Cost(page 107)(page 117)Enterprise JavaBeans application servers provide both basic support for a distributed
component model and a wide range of integrated servers and utilities that the devel-
opers otherwise would have to create. For similar reasons, vendors are introducing
Extensible Markup Language servers.Middleware comprises two general subsets: the application server or componentenvironment, and messaging. Systems that maintain links between client/server sys-
tems or between applications in conventional distributed systems are examples of the
former. The latter applies to all types of messaging software, including XML. Middle-
ware is any system or collection of utilities that links different elements together,
whether on a single machine or over a network.When applications were maintained on mainframes, the operating system and itsutilities tracked modules and passed messages with ease. Managing the communica-
tions between the computers and the database server was also relatively straightfor-
ward in later client/server systems that simply linked computers to a single database
running on a database server.Specific interfaces between the client and server for each application, whichmaintained the software modules that the servers needed to reach, made sense for
mainframes and early client/server systems. Today, application developers rely on
middleware systems that are independent of specific applications or components
that might want to talk to one another. This independence is necessary because the
developer can no longer anticipate the location, language, or platform used at each of
the nodes in the distributed system.With the rise of the Internet, dealing with the problem of disparate systems hasbecome more urgent. Companies are building applications to be linked by the Inter-
net to clients and to other servers throughout the world. The company building the
application cannot know which kind of platform the client is running or where it is lo-
cated. This problem will only become more complex as a variety of mobile wireless
devices begin to access company sites via the Internet.In the world of networked computing, middleware must link a variety of plat-forms from an unknown number of locations. The middleware that keeps track of the
locations of the software modules that need to link to each other and that manages
the actual exchange of information is rapidly increasing in sophistication. In short,
middleware is being used to solve the two distinct problems of heterogeneity and re-
source discovery.T y p e s o f M i d d l e w a r eA major challenge in building applications that can be partitioned over distributed
systems is the creation of a uniform scheme for passing information among program
modules and for accessing data from multiple sources when programs and data may
reside on different platforms. Middleware provides developers with a uniform inter-
face through which their programs can access other applications. Each application in-
teracts only with the middleware, which performs the necessary translations to
communicate with the appropriate databases, operating systems, and applications.
The middleware thus presents the application developer with a single, consistent in-
terface (the illusion of a single underlying server) that masks the complexity of the ac-
tual computing infrastructure.Several types of middleware are often used together, because no single middle-ware approach is general enough for the full range of applications. Therefore, systems
are not uniform and single-server, but are collections of subsystems that use a variety
of middleware to interoperate. This diversity removes the pressure for an entire en-
terprise to use a single solution and encourages business data standards for integratingW24Chapter 4Computer SoftwareChapter 4Computer SoftwareW25middleware systems. In other cases, heterogeneity is unavoidable, so bridging integra-
tion solutions are necessary.In addition to providing connectivity, middleware often provides special servicesfor an application when it is desirable to isolate those services rather than build them
directly into the application. Isolation is beneficial if a service is used by multiple ap-
plications (saving money by providing a service all applications can share) or if the
software to implement those services is purchased from a middleware vendor. Some
of these services function independently, and their association with true middleware is
merely historical. (Some common examples are Common Object Request Broker Ar-
chitecture’s collections, properties, query, relationship, and time services. Although
all these are application independent, none require intimate integration with the mid-
dleware infrastructure.) Other services, however, are intertwined with the middle-
ware’s connectivity services (such as security, high availability, and load balancing).Of greatest interest to developers of distributed systems is middleware for remoteprocedure calls, messaging, transaction processing, and object and component man-
agement, as well as the dominant types of distributed middleware, such as enterprise
application integration (EAI), distributed components, and XML.Remote Procedure Call (RPC) Middleware.The RPC middleware model is basedon a synchronous approach to communication. When a procedure has initiated a call
to another procedure, it waits for the response. If a call from procedure A to proce-
dure B initiates subsequent calls from procedure B to procedure C, etc., each proce-
dure involved in the sequence waits as the call is transmitted out and back. (In
synchronous communications, data are transmitted at regular intervals and in one di-
rection. In asynchronous communications, data can be transmitted at any time and in
any direction.)The primary drawback to RPC middleware is that its programming model is at alow level of abstraction. Consequently, applications using RPCs are tedious to write.
RPCs allow point-to-point communication between machines, but they do little to
mask the details of implementation from developers. Each RPC in an exchange, as
well as control flow embedding the RPCs, must be explicitly coded, which slows devel-
opment and results in code that is more difficult to change than it would have been if
components and objects had been used. Another disadvantage of this type of middle-
ware is that it works for applications that use few RPCs, but in high-volume systems
or in cases where the function call will take a long time to complete, an asynchronous
approach works better.Message-Oriented (MOM) Middleware.MOM is a popular asynchronous model forexchanging messages between applications or modules. A MOM environment incor-
porates a queue. The initiating module sends a message to the queue, then goes on
with other processing. The queue tries to send the message to the target module, con-
tinuing to do so until the target module is available and accepts the message. Once the
target module has created a response, that response is also sent to the queue, which
then forwards it to the originator, again continuing to forward the message until it is
accepted.Queues are especially effective if the originator or the target modules receive anoverwhelming number of messages. In such cases, the queue mechanism holds the
messages and forwards them only when the target module can process them. In that
way, MOM prevents the source from blocking and prevents the target from being
overwhelmed. MOM also can add at least a second target process to read from the
same queue, increasing the rate at which the messages are processed.W26Chapter 4Computer SoftwareA common approach is to use commercial MOM software, which often providesfunctionality beyond simple message passing. For example, most MOM systems incor-
porate some way of keeping track of where modules are so that the target can be
more or less transparent to the sender. Similarly, if a MOM system is to pass messages
between modules written in different languages, it requires a neutral Interface De-
scription Language (IDL) mechanism to provide a common language for the two
modules. MOM systems have been developed to handle asynchronous calls between
procedures, between components, or between modules or applications.Transaction Processing Middleware.In database systems, a transaction represents agroup of commands that must succeed or fail as a single unit. An example is an opera-
tion that transfers funds from one bank account to another. Both halves of the trans-
action must occur before the transaction can succeed. If funds are debited from one
account, they must be credited to the other account. If one of these operations fails,
all parts of the transaction must be restored to their original states. That is, a transac-
tion processing system keeps a copy of the original state of the elements in the trans-
action and releases that copy only when all changes necessary to the transaction have
been accomplished. Transaction processing systems are essential to financial systems
and to any other applications that require transactional integrity.Transaction processing monitors, also called transaction managers, are based onmainframe processing. Examples include the Customer Information Control System
(CICS) and Information Management System, which have matured to provide
excellent performance and reliability.Modern distributed computing applications frequently use middleware to ac-cess relational database servers using Structured Query Language (SQL) (dis-
cussed in Chapter 5). Ideally, business software applications would be written as a
series of transactions. All participating application components would adhere to
the transaction-management paradigm. In reality, there are two basic approaches
to transaction management:•Without a separate transaction-processing monitor: This approach uses the trans-
action management capabilities of the relational database management system’s
server product.•With a separate transaction-processing monitor: This approach is required when
several heterogeneous databases are being updated in a single transaction. It also
can improve performance in high-volume transactional applications.C o m p o n e n t M i d d l e w a r eThe three best-known component models are Microsoft’s Component Object Model
(COM), Sun’s Enterprise JavaBeans (EJB) model, and the Object Management
Group’s (OMG’s) CORBA Component Model (CCM). The component level com-
prises interfaces and an environment with services that keep track of components and
pass messages between them. Each of these three component models (CORBA,
COM, and JavaBeans) has been extended by the creation of a new, more advanced
component model (the new CCM, COM , and EJB, respectively). One of the advan-
tages of component software is that its development is independent of how the com-
ponent is written. The only attributes of a component that a developer needs to know
are its interfaces.OMG’s CORBA.The CORBA system is transparent to the developer in that he orshe does not need to know where the target object is located. It can reside on the
same machine or on another platform with the same or different operating systems.Chapter 4Computer SoftwareW27To use CORBA, developers wrap components written in a specific object-oriented
language by creating IDL interfaces. The code that implements a CORBA environ-
ment can be object-oriented code, but it also can be written in a non-object-oriented
language like C. At the CORBA or component level, one does not care what is inside
the components. Thus, CORBA can also be used to wrap COBOL modules and inte-
grate them.Microsoft’s COM.Microsoft’s COM is another approach to components that de-fines an environment that allows a developer to create interfaces for code modules,
then allows any code modules to send messages and obtain results from other COM
modules. COM modules are not objects. They lack some of the characteristics that
have traditionally been used to define objects, specifically inheritance. COM modules
are components. They have interfaces defined in Microsoft IDL and an environment,
which is built into the various Windows operating systems, that passes messages be-
tween COM components.To pass messages to COM components on networked Windows platforms, a Win-dows developer uses DCOM, which is an RPC mechanism that moves messages be-
tween distributed COM components. COM components can be developed in
non-object-oriented languages like C. Like CORBA, the key is that at the component
level, the system is simply concerned with interfaces and passing messages and does
not concern itself with what kind of code is inside the COM components.Sun’s Enterprise JavaBeans (EJB) Model.This component system was developedby Sun to provide its Java object-oriented language with modules that would be easy
to reuse. Sun defined a specific type of Java object that it referred to as a JavaBean.
JavaBeans have interfaces written in Java. Sun also specified utilities (other objects)
that would manage message passing between JavaBeans. Java’s Remote Method In-
vocation (RMI) enables a Java program running on one computer to access the ob-
jects and methods of another Java program running on a different computer (i.e., it is
an RPC-like mechanism for accessing JavaBeans on distributed platforms).Enterprise Application Integration (EAI) Middleware.EAI-packaged middlewareis designed to allow developers to choose different levels of integration (e.g., data-
level, application interface-level, or business process-level) between existing and new
systems. As a result, many older systems that still perform valuable tasks are able to
continue. Indeed, often the return on an EAI investment is measured by how little of
the installed base needs to be changed to leverage a new system.Another driver behind EAI deployment involves sharing information betweendisparate applications that never were designed to work together. Business process
automation is the automation of tasks that an organization already might be doing
manually by integrating two or more applications. For example, a business can print a
sales report from an ERP system to cross-reference customer information for credit
checks in another system. EAI would transform this task from a manual process to an
automated one.The single-application vendor solution promises the highest degree of integrationamong applications. However, it is unlikely that this approach can satisfy require-
ments for complete integration across a portfolio of applications because, according to
various analysts, packaged applications address only about one-third of an enter-
prise’s requirements. The remaining two-thirds are satisfied by custom applications.
So, once integration spreads beyond the scope of a single application suite, planners,
designers, and architects must rely on EAI middleware. EAI middleware addresses
the uppermost three layers of services seen next.W28Chapter 4Computer SoftwareManagers Checkist W4.3Seven Levels of Application
IntegrationBusiness Integration1. Business process development—business processdesign/modeling, real-time decision support,state managementApplication Integration2. Business event processing—automatic eventnotification, flow control, content routing,
transactional integrity3. Application content transformation—formattranslation, data semantics, validation,
prebuilt templatesApplication Connectivity 4. Application bridges and gateways—for legacy,Web, database, and packaged applications5. Application interaction styles—publish/subscribe,publish/reply, file transfer, request/reply,
conversational6. Message-handling services—queuing, security,message management, administration7. Basic communications—point-to-point, reliablebroadcast, IP multicast, IIOP/ORB, database,
Web, 3270 SNAD i s t r i b u t e d C o m p o n e n t M i d d l e w a r eAlthough components are often used as a necessary part of middleware, they are not
required. Middleware systems have been built in a variety of ways, using different
technologies. As the complexity and heterogeneity of the typical enterprise’s portfolio
of applications increase, however, distributed component middleware systems may
play a role in reducing that complexity.A potential approach could be to convert all of a system’s modules into indepen-dent components with standard interfaces. Then, instead of wiring the entire system
together, a middleware system could be used to pass messages between the compo-
nents. Because the components would be uncoupled, they could be added or elimi-
nated without changing the entire system. However, the standard interfaces are not
currently provided by most widely used component models. Most commercial middle-
ware packages use the MOM model, and each package has a proprietary method for
connecting an application to the middleware. Open standards, such as the Java Cryp-
tography Architecture, are just beginning to come into use, and no major application
vendors are supporting them. Current middleware connectors are makeshift, cus-
tomized components that use the application’s native API to get the interface to
work. Some vendors are starting to standardize the connections between applications
and middleware, as Siebel is doing with its XML-based EAI bridge.Developers can reduce the complexity of developing distributed component sys-tems in other ways. Many middleware systems implement protocols, such as APIs,
and supply a few utilities, which are usually components themselves. If the informa-
tion passing between two components running on different platforms is uncompli-
cated, then a minimal middleware package can be used.However, many distributed applications and almost all e-commerce applicationsrequire more than simply passing data between two modules. For example, a distrib-Chapter 4Computer SoftwareW29A b o u t B u s i n e s sA b o u t B u s i n e s sBox W4.2:Surveillance software: How much is too much?A T W O R KA survey found that 54 percent of companies said they
monitored their employees’ Internet connections, while
38 percent said they reviewed worker e-mail messages.
Silent Watch surveillance software from Adavi
(adavi.com) allows an employer to monitor dozens of
computers from a single screen in real time, while
recording every keystroke an employee makes, even if
the data are deleted.W H I L E S H O P P I N GMany large retailers have implemented surveillance
systems that record and interpret customer movements,
using IBM BlueEyes software that tracks customer
movements and pupil, eyebrow, and mouth movement.
The software allows computers to anticipate users’
wants by gathering video data on eye movement and fa-
cial expression.The American Civil Liberties Union notes that thesoftware will be able to identify who shoppers are.
Once identity is established, it can be cross-referenced
to capture that shopper’s income and buying prefer-
ences. Interestingly, purchasers of BlueEyes unani-
mously have requested that IBM not reveal their names
to the press, or the locations where the software has
been implemented.A T S C H O O LeSniff Solution from Vericept (vericept.com) allows
schools to monitor students’ use of school computers.
ESniff detects packets of information that indicate that
proscribed activities are occurring—that a student is
visiting Web sites that offer, for example, sexual im-
ages, or copyright-violating music downloads. The soft-
ware can also “sniff” e-mail messages for signs of
out-of-bounds activities, like drug dealing. Suspect
pages and messages are captured on a computer hard
disk for review by school administrators. One high
school reports that access of unauthorized Internet sitesdropped by 98 percent after the school’s administrators
announced the implementation of the software.A T H O M EA child was playing spelling games on Reader Rabbit,
Mattel Interactive’s popular educational software pro-
gram. After she went to bed, her father logged on to the
Internet to do some work. Minutes into his session, an In-
ternet security program, or firewall, alerted him that
Reader Rabbit was attempting to secretly send data from
his computer to Mattel. Inside the child’s software he un-
covered “spyware,” a type of program that embeds itself
in a PC’s hard drive. It can then relay information to and
from over the Internet connection. Because the informa-
tion being sent was encrypted, the father could not deter-
mine what exactly was being sent to Mattel. Mattel said
that the spyware was originally designed to offer con-
sumers additional product content and to communicate
bug fixes. (Computer users concerned about potential
spyware transmission can download the ZoneAlarm 2.6
firewall, available free at zonealarm.com.)Sources: “More Employers Taking Advantage of New Cyber-
Surveillance Software,” cnn.com, July 11, 2000; “Schools Get
Tool to Track Students’ Internet Use,” nytimes.com, May 21,
2001; “Privacy Worries Arise Over Spyware in Kids’ Software,”
U.S. News and World Report, July 3, 2000, p. 55; “Behind
BlueEyes,” MIT Technology Review, May 2001, p. 32.Questions1.How would you feel about having yourself identi-
fied by surveillance software in any of the preced-
ing situations? Would some be acceptable to you
but others not acceptable? Why?2.Do you feel that surveillance software is too intru-
sive? If not, do you feel that surveillance software
has the potential for becoming too intrusive?3.What are the advantages and disadvantages of sur-
veillance software to companies?‘s‘sMKT(page 101)W30Chapter 4Computer Softwareuted application may need a transaction-processing model that ensures that updates
to data are not finally committed until all aspects of the transaction are ready to be ap-
plied. Most Internet systems need the capability to scale from one to multiple servers.
This task requires an application designed in such a way that multiple instances of it
can run without producing invalid results. It also involves load balancing to ensure
that the server is not overloaded during peak periods of activity.Distributed Component Architectures.Software architectures describe the basic el-ements and relationships used in software development. Companies that embrace dis-
tributed component middleware are adopting a component architecture. In such
cases, the key elements in the business environment are described in terms of compo-
nents, and a middleware infrastructure is included to facilitate communication be-
tween the components. The three most popular component architectures are OMG’s
CORBA architecture, Microsoft’s Distributed Internet Architecture (DNA), and
Sun’s J2EE architecture.In our example (see Figure 4.10b), ACCOUNT would be a superclass of theCHECKING-ACCOUNT subclass and the SAVINGS-ACCOUNT subclass.
Inheritance here means that the CHECKING-ACCOUNT subclass and SAV-
INGS-ACCOUNT subclass inherit data values such as customer name and account
number from the ACCOUNT class (see Figure 4.10b). Also, the CHECKING-AC-
COUNT subclass and the SAVINGS-ACCOUNT subclass inherit methods such as
add deposit and calculate balance from the ACCOUNT class. It is important to
note that the CHECKING-ACCOUNT subclass has an additional data value,
charge per check, and an additional method, subtract check. Further, the SAV-
INGS-ACCOUNT subclass has an additional data value, interest rate, and an addi-
tional method, subtract withdrawal. These additional data values and methods
serve to differentiate subclasses from their superclasses. A useful aspect of inheri-
tance is that if necessary, one can change the data values or methods in a super-
class, and the changes will be reflected in all subsequent subclasses.Table W4.2Common Modules of Enterprise Application Software• Payroll• Shipping/logistics• General ledger• Employee records• Sales-order processing• Tax accounting and planning• Cash-flow analysis• Manufacturing control• Fixed-asset accounting• Check processing• Accounts payable• Customer service• Invoicing• Sales force support• Accounts receivable(page 117)
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