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OCR for page 18
Review of Relevant Commercial Technologies
In this chapter, the committee describes trends in
commercial multimedia building block technologies.
The technologies that are described were selected
by the committee in the context of a layered archi-
tecture that is relevant to generic multimedia appli-
cations. In addition, there is discussion of some
commercial, system-level applications of multimedia
information technologies and some important les-
sons learned in the application of multimedia tech-
nologies in commercial venues. This chapter serves
as a technical foundation for recommendations made
later in this report.
MULTIMEDIA ARCHITECTURE
The committee configured a generic layered archi-
tecture as a basis for identifying building block tech-
nologies that are relevant to Army multimedia
communications. This multimedia architecture is de-
picted in Figure 3-1.
The purpose of the committee's generic architecture
is primarily for discussions of how a set of relevant
building block technologies relate to each other. It does
V. Specific Applications
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IV. Generic Applications/Enablers
III. Middleware
II. System Software
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I. Physical Platforms
FIGURE 3-1 Generic architecture for multimedia
communications.
18
not represent a fully fleshed-out technical architecture.'
The importance of a technical architecture is discussed
in Chapters 4 and 6 and in the related recommendations
in Chapter 7 of this report.
The committee's architecture consists of several ge-
neric layers. The naming of the various layers of the
architecture explicitly reflects the fact that multimedia
technologies are strongly dependent upon software. With
the generic architecture as a framework, the committee
selected relevant multimedia technologies and overlaid
them onto the various layers of the architecture (see
Figure 3-21. Generally, but not always, higher layer
technologies employ the services of lower layer tech-
nologies. Note that the building block technologies are
numbered in Figure 3-2 from bottom layers to top layers
in order to facilitate later discussions.
The bottom layer of Figure 3-2 (Layer I) includes
physical devices, subsystems, and systems (e.g., light-
weight portable terminals, storage systems, and com-
munications subsystems and systems to support
people on the move). The next level (Layer II) provides
protocols for interconnecting subsystems, systems, net-
works and gateways, operating systems for managing
computational resources, and distributed computing
environments for managing distributed software proc-
esses. The middleware (Layer III) is built on top of the
lower level system software and provides capabilities
such as information filtering, database management,
and user-friendly multimedia user interfaces. Layer IV
provides generic applications/enablers such as multi-
media teleconferencing capabilities and groupware,
iA fully fleshed-out technical architecture would not merely say that
certain building block technologies lie in certain levels of the architec-
ture. It would specify, for illustration, the Internet protocol or one or
more alternative protocols as the protocols to be used for specific
applications; it would specify a graphical user interface (e.g., Motif or
one or more alternatives) as the graphical user interface to be used.
Where more than one alternative is specified as acceptable for a specific
building block, the documentation supporting the technical architecture
would explain why there is more than one acceptable alternative,
provide guidance regarding which alternatives should be used in which
types of applications, and explain how interoperability is to be achieved
between applications using different building block alternatives.
OCR for page 19
REVIEW OF RELEVANT COMMERCIAL TECHNOLOGIES
Layer V Specific Applications
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14. Simulation: systems and applications
Layer IV Generic Applications/Enablers
13. Multimedia messaging capabilities
12. Decision support tools, groupware,
multimedia teleconferencing
11. Multimedia information access capabili-
ties
Layer II0~Iiddleware
10. Multimedia information analysis and
processing building blocks and middle-
ware services
9. User-friendly multimedia user interfaces
8. Multimedia database management sys-
tems
7. Information filtering systems
Layer System Software
6. Distributed computing environments
and operating systems
Protocols and related Functionality to
support communications
Layer I Physical Platfonr~s
Information capture technologies
3. Communications platforms that support
people on the move
2. Storage systems for multimedia informa-
tion
1. Lightweight, rugged, portable appli-
ances and terminals
FIGURE 3-2 Building block technologies in the generic multimedia
architecture.
which can be tailored for specific applications (e.g.,
simulation) at the top layer (Layer V). Woven through
the architecture are network management and security
technologies to provide reliable, secure information
processing (Layer VI).
The description of building block technologies in the
sections below follows the arrangement of Figure 3-2.
The value of doing this will become more apparent in
Chapter 4, where it will be shown that these technologies
and layered architecture concepts can be used to clarify
the recommendations for how the Army should proceed
to acquire the technologies to meet its operational needs
and functional requirements.
19
The building block technologies described range
from physical technologies, such as hand-held multi-
media appliances and physical storage subsystems, to
technologies that are embodied in algorithms and soft-
ware (e.g., speech recognition and distributed computing
technologies). They are discussed in the order of the six
layers of the generic technical architecture (Figure 3-29.
In the discussions of these building block technolo-
gies, the focus is on the current status and likely trends
in each technology, with particular emphasis on how
large the respective commercially driven research and
development (R&D) efforts are likely to be. These dis-
cussions have been kept brief to avoid unnecessary
technical detail and include only what is needed to
support the recommendations in Chapter 4.
BUILDING BLOCK TECHNOLOGIES
(LlYER I—PHYSICAL PLATFORMS)
Building block technologies discussed under
Layer I Physical Platforms of the generic architecture
(Figure 3-2) include lightweight, rugged, portable
appliances and terminals; storage systems for multime-
dia information; communications platforms that sup-
port people on the move; and information capture
technologies.
Lightweight, Rugged, Portable Appliances
and Terminals
During the first half of this decade, portable laptop
and palmtop computers have grown into a multibillion
dollar industry (based on sales of these computers in
19941. At the same time, these appliances have shrunk
to the point where laptop computers provide the full
functionality of bulkier desktop computers, except for
the smaller display and keyboard, and weigh less than
five pounds. Personal digital assistants (PDAs) for
general purpose and special purpose applications are
emerging in the marketplace. For example, they are
being used by rental car agencies to expedite check-in
and by delivery services to track the real-time status of
packages in transit. In this section we examine the
hardware component technologies- the processing
chips, memories, storage devices, displays, and batter-
ies- underlying these portable computing appliances
and terminals to illustrate the rapid technological evo-
lution of these appliances and terminals that is enabled
by the underlying technology trends and driven by
commercial market opportunities.
OCR for page 20
20
Processors
At the heart of every computing device is a central
processing unit (CPU), a processing chip that "executes"
the instructions the computer is programmed to perform.
While CPU capabilities can be characterized by various
metrics, the MIPS (millions of instructions per second)
that a processor can execute is one commonly accepted
measure of performance. In 1994, microprocessor CPUs
were announced with a rating of 1,200 MIP~an impres-
sive figure given that CPUs found in many personal
computers produced in the late 1980s and early 1990s
were rated in tens of MIPS. Such remarkable, order-of-
magnitude increases in processor speeds have been
commonplace over the past decade, and there is every ,
indication that processor capabilities will continue to (Geppert, 1995~.
increase in the foreseeable future.
Memory
The increasingly sophisticated operating systems
and application programs used in today's computers
are often characterized as being "memory hungry."
They require more dynamic random access memory
(DRAM) than their earlier counterparts in order to
operate efficiently. One indication of this trend is the
fact that the average amount of DRAM memory used
in a personal computer has grown from 0.5 megabytes
in 1984 to 8 megabytes in 1994, a 1 6-fold increase
(Geppert, 19951. Fortunately, this increase in memory
needs has been matched by a 20-fold decrease in
memory costs over the 1982-1992 period.
Trends in increasing memory density (i.e., the number
of bits on a single chip) are expected to continue for the
foreseeable future, with a factor-of-four increase every
few years. Sixteen-megabit DRAM chips are now com-
mon, and memory chip producers are assembling manu-
facturing facilities for 64-megabit chips. Hitachi and NEC
announced early designs for a 1-gigabit memory chip at
a conference in February 1995. While such gigabit
DRAMs are not expected to be produced in volume until
the first years of the next century, a continued dramatic
trend in increasing memory densities is evident.
Permanent Storage: Disk Drives and Flashcards
The miniaturization trends for CPUs and memory
noted above are also evident in the area of disk drives,
the traditional storage media for data that must be stored
for extended periods of time. Disk drives for laptops are
now available in so-called PCMCIA cards (Personal Com-
puter Memory Card International Association), which are
COMMERCIAL MULTIMEDIA TECHNOLOGIES FOR TWENI-Y-FlRST CENTURYARMYBA 1 IS
lightweight, credit-card-sized devices that can be easily
plugged into a laptop computer.
Disk drives have mechanical parts and thus require
sophisticated technology (such as liquid-bearing mo-
t`>r.s~for~.se in laptops, where ruggedness is a concern.
A recent competitor to disk drive technology, and one
that is based on semiconductor technology containing
no movable parts, is the so-called PCMCIA "flashcard."
Currently, flashcards have less storage capacity than
disk drives and are significantly more expensive, cost-
ing about 15 times more than comparable disk drives.
However, as flashcard technology is relatively new,
prices may fall as the technology matures. Current
flashcards can store 16 megabytes of data; 256-mega-
hvre flashcards are expected to be available in 1997
Display Technology
The need for lightweight and rugged displays for
portable computers and the quest for flat screen televi-
sion sets are the driving forces behind display technol-
ogy. Laptop display technology can broadly be classified
into passive liquid crystal display (LCD) technology and
active LCD technology. Active matrix LCD (AMLCD)
technology is the more recent of the Do and was
developed to overcome some of the difficulties associ-
ated with passive displays. Companies have spent an
estimated $3 billion to commercialize AMLCDs. The cost
of a manufacturing facility for AMLCDs is very substantial;
it is estimated that a single state-of-the-art AMLCD pro-
duction line exceeds $100 million (Werner, 19939.
In addition to ongoing commercial AMLCD research,
there is continuing commercial research on developing
portable displays by improving upon passive LCD tech-
nology. Another commercial initiative of interest is a push
to develop lightweight and durable displays based on
plastic LCDs.
The emergence of high definition television (HDTV)
as a consumer technology will fuel consumer demand
for low-cost high resolution displays, particularly in the
larger sizes usually associated with television viewing.
This demand should, in turn, further stimulate invest-
ments by commercial display manufacturers in all types
of high resolution displays, including flat panel displays
using the technologies described above. The large physi-
cal size of conventional cathode ray tube (CRT) HDTV
receivers (particularly the depth) will make them imprac-
tical for many households. The commercial market op-
portunity available to any company that can create a large
flat panel display technology suitable for residential
entertainment applications is enormous, and this drives
the large investments being made with respect to re-
OCR for page 21
RENEW OF COEVAL CO~CIAL ~CHNOLOGI~
search on new manufacturing methods and entirely new
approaches to creating displays.
The underlying display technologies described above
are being incorporated into novel commercial products
such as virtual reality glasses or goggles and automotive
"heads-up" displays. Virtual reality glasses or goggles use
small liquid crystal elements and combinations of lenses
and mirrors to create a virtual image that appears to the
wearer to be projected in front of the wearer as a large
image at a distance of several feet. In some cases, these
virtual reality glasses or goggles are used to immerse the
viewer in a visual environment that fills the viewer's
sensory visual field of view and thus creates the sensation
that the viewer is part of the three-dimensional environ-
ment perceived. Heads-up displays use projected images
to superimpose information on a window or screen
through which the viewer can observe other important
information (e.g., instrumentation information superim-
posed on an automobile windshield). These emerging
technologies tend to be at the high end of normal mass
market consumer price points (e.g., more than several
hundred dollars) but are expected to experience rapidly
declining prices as mass production and competition take
hold.
Power and Batteries
Power consumption and better battery technology are
also key technology factors in lightweight, portable
computing, devices. Many microprocessors and applica-
tion-specific integrated circuits and memory chips are
now being manufactured with decreased power require-
ments. Many now run at almost half the power require-
ment of previous chips, and many processors have a
sleep mode in which only a minimum amount of power
is consumed.
Batteries are used in a wide variety of applications
ranging from small batteries in toys and hand-held
consumer appliances to large storage batteries in auto-
mobiles and for backup power systems. Although not as
dramatic as the progress that occurs each year in the
performance of semiconductor-based components, there
has been a steady improvement in battery technology
and associated performance over the last several dec-
ades. Alkaline batteries have become very popular as
primary sources for small appliances. A variety of new
battery types, such as nickel-cadmium and lithium-ion
batteries, have emerged as rechargeable power sources
for appliances such as cellular telephones, cordless tele-
phones, and notebook computers. Recent advances,
such as plastic lithium-ion batteries, show promise of
increased energy densities, improved safety and environ-
mental friendliness, ruggedness, and low cost. Research
21
continues on fuel cells and alternative large energy-stor-
age batteries for automobiles and industrial applications.
The worldwide market for batteries is $26 billion per
year, of which almost 40 percent is for consumer single
use batteries. Because of the economic impact of battery
technology on automobiles, telecommunications, con-
sumer electronics, and ultimately trade, the major indus-
trialized countries have been funding battery research via
national consortia. As an example, the United States
Advanced Battery Consortium, which includes General
Motors, Ford, Chrysler, and the U.S. Department of
Energy, is a $260 million (total over several years) joint
government-industry effort to develop advanced batter-
ies for electric vehicles (Shokoohi, 19951.
Personal Digital Assistants
Personal digital assistants (PDAs) are extremely light-
weight and compact hand-held computers. Rather than
relying on a keyboard, PDAs use a stylus together with
a touch-sensitive screen for input. Long-term data storage
is provided via PCMCIA cards. PDAs can be used to
maintain a small database (e.g., an address book), write
and store notes, and send or receive electronic mail and
facsimiles when plugged into a phone jack (or connected
via a wireless modem).
PDAs were introduced to the marketplace in 1993.
Difficulties with the handwriting recognition system in
the first PDA may have limited its widespread accep-
tance. Other PDAs were introduced into the market in
1994 by many of the major international commercial
consumer electronics, computer, and communications
companies.
PDA technology is still relatively immature. No stand-
ard chip sets or common architectures have yet been
adopted in the computer industry. From a user's point of
view, PDAs also have a way to go. It has been predicted
that it will take 10 years for PDA technology to meet its
expectations (Halfhill, 19931.
Epilogue: The Personal Computer industry
The component hardware in portable laptop and
palmtop computers is closely tied with developments in
the larger personal computer industry. In order to indi-
cate the momentum and scale of the resources being
invested in this area, the section concludes with some
brief figures indicating the current and projected size of
the personal computer market.
It is estimated that 16 million personal computers will
be sold in the United States in 1995, with 34 million more
machines being sold worldwide. The estimated installed
OCR for page 22
22
COMMERCIAL MULTIMEDIA TECHNOLOGIES FOR 7.WEN7Y-FIRST CENTURYARMYBA i 1LF~I~S
base of personal computers in the United States is 80
million (approximately one personal computer for every
three people) as of 1994, with 200 million worldwide. It
has been estimated that the annual sales of personal
computers will surpass 100 million units worldwide by
the end of this decade (see Juliessen, 1995~.
Storage Systems for Multimedia Information
Storage systems are used to store information that is
needed for performing computational tasks, the results
of which may be displayed or presented to end users or
re-stored for subsequent use. As discussed above, storage
systems are used in lightweight, portable appliances and
terminals. They are also used as the physical platform for
storing information in distributed, networked applica-
tions and for archiving information.
Storage systems range from archival storage systems
such as magnetic tapes and associated tape drives (whose
information may take relatively long to access) to mag-
netic disks and optical disks
OCR for page 23
REVIEW OFRELLEVANT COMMERCIAL TECH~JOLOG1~
educational applications, interactive games, and other
applications that involve multimedia information are
being driven by a perceived market measured in billions
of dollars per year in server and storage system sales.
These developments include the compact, rugged multi-
media storage systems needed by notebook computers
(discussed above), personal compact disk players, set top
boxes (as described under Residential Information
Systems later in this chapter), and other consumer
appliances.
Communications Platforms That Support
People on the Move
"Wireless personal communications" is a commercial
telecommunications industry term for networking serv-
ices and associated applications that support people on
the move (IEEE, 19951. Cordless telephones, cellular
telephony, and paging systems are the most popular
current manifestations of wireless personal communica-
tion systems.
Cordless telephony started as a low-cost, low-power,
short-range (a few hundred feet) home appliance in-
tended to eliminate the tether to the telephone network.
The concept has blossomed into cordless telephones that
people can carry away from home and operate anywhere
within reach of a compatible base station. The CT2
Common Air Interface is a standard used in the United
Kingdom, Canada, and Hong Kong and other parts of
Southeast Asia. These systems have been optimized for
cost, and the handsets are extremely light and portable.
The Digital European Cordless Telecommunications
system provides an advanced design that supports higher
user densities. It uses small "picocells" and resembles a
cellular system as much as it does a cordless system. It
supports data transmission as well as voice.
The Personal Handyphone System is specific to Japan.
The system is designed to provide a single, small, port-
able phone that can be used at home or office (already
launched) or as a public access device (to be launched
this year). The system will support fax as well as voice.
The potential subscriber base is estimated at 5.5 million
in 1998 with up to 39 million by 2010 (Padgett et al.,
19951.
In the United States, Bell Communications Research
has developed an air interface for a Wireless Access
Communications System (WACS). By combining parts of
the Personal Handyphone System with WACS, the pro-
posal is now called Personal Access Communications
Services. The goal is to provide wireless access to the
wireline networks of local exchange carriers. Base sta-
tions are expected to be shoe-box-sized enclosures
mounted on telephone poles about 600 meters apart.
23
In contrast to cordless systems that were developed
for people walking around, cellular systems were origi-
nally intended for vehicle applications. The first genera-
tion systems, called Advanced Mobile Phone Service
(AMPS), use analog modulation for speech and base
stations with coverage of 10 km or less in some cases
as little as 0.5 km. These systems have been widely
deployed (see discussion of cellular elsewhere in this
report).
As the cost of digital electronics has continued to drop
and low-rate digital speech coding techniques have
continued to improve, digital versions of cellular have
begun to appear. The European Global System for Mobile
Communications (GSM) is expected to improve quality
over systems like AMPS and to provide pan-European
roaming. The GSM standard also includes specifications
for synchronous and asynchronous data services at 9.6,
4.8, and 2.4 kbps.
In the United States, the Electronic Industries Association
and the Telecommunications IndustIy Association adopted
a standard called IS-54, where IS stands for Interim Stand-
ard. IS-54 equipment is operational in most of the top U.S.
cellular markets, and customer adoption is increasing. A
second Interim Standard, IS-95, is based on a different
frequency sharing scheme called code division multiple
access (CDMA), which was originally developed to increase
jamming resistance for military applications. This is a
relatively new approach, with the first systems expected to
be deployed in California this year.
Manufacturers of cellular hand-held units must ad-
dress Ho fundamental markets. The first, sometimes
called the "road warrior," is a user whose livelihood
actually depends on phone contacts made while on the
move. Sales people are an obvious example. These users
demand high quality voice transmission and reliable
connections. They are also the leading buyers of pre-
mium services and features, and they are relatively
insensitive to prices. The second major group is the
"casual user." They are more concerned about price and
are more tolerant of lower voice quality or occasional
dropped connections. Manufacturers sell far more cas-
ual-user phones than road-warrior phones, but the latter
are very important to carriers because they generate
many more minutes of usage. The net result is that
manufacturers are driven to produce both a simple,
high-volume, low-cost product line and a lower-volume,
higher-cost, feature-rich line of handsets.
In contrast to voice, there are fewer systems and
standards (so far) for wireless data services. Wireless local
area networks (LANs) are usually privately owned and
operated and cover very small areas. These are generally
intended for high data rates (greater than 1 Mbps) and
operate in unlicensed spectrum. Standards for wireless
LANs are being developed under the Institute for Electri-
OCR for page 24
24
COMMERCIAL 31ULTIMEDL`4 TECHNOLOGIES FOR 7-WEN7Y-FIRST CEI~I-URYARMYBATILEFIELDS
cat and Electronics Engineers (IEEE) 802.11 committee in
the United States and under the European Technical
Standards Institute RES10 committee in Europe (HIPER-
LAN). Wireless LANs can be used to form ad hoc and
quasi-static networks, although full roaming mobility is
not yet available. Generally, the subscriber units require
a hub with which to communicate although there are
exceptions. Some operate at data rates of several mega-
bits per second, approaching that of a wired Ethernet.
Many are sized to fit on a PCMCIA card.
The Advanced Radio Data Information Service
(ARDIS) in the United States covers much wider areas
using specialized mobile radio (SMR) frequencies in the
800 to 900 MHz range. There are over 50,000 subscribers
today, and service is offered in over 400 metropolitan
areas. The prevailing data rate is 4.8 kbps, with 19.2 kbps
available in some areas. Cellular digital packet data is
another approach that reuses existing analog cellular
networks. It is a transparent overlay to AMPS systems,
taking advantage of idle time on analog channels. The
European GSM infrastructure, already digital, is develop-
ing the General Packet Radio Service to handle data.
Satellite communications systems allow for a rapid
expansion of communications infrastructure and provide
connectivity to isolated locations. Commercial satellite
services are designed to provide coverage to predeter-
mined geographic areas, and their ability to redirect or
expand this capacity is very limited.
More Ku-band (14/12 GHz) systems are being de-
ployed to augment those at C-band (6/4 GHz). Also,
Ka-band (30/20 GHz) has been set aside for commercial
satellite communications, and equipment for this band is
in the experimental stage in the United States. Utilization
of Ka-band began in Japan and Italy in 1990. These trends
imply that significantly more capacity will be available in
orbit (IEEE, 1990; Manders and Wu, 19911.
Very Small Aperture Terminal systems are being used
to provide two-way data services (T1 rates, 1.544 Mbps)
to small terminals. Direct Broadcast Services (DBS) now
transmit data at rates of tens of megabits/second to small
terminals (less than about 2 feet in size). However, both
of these latter services are available only in selected
coverage areas.
There are several commercial satellite systems for
personal communications currently in planning and de-
velopment phases; examples are IRIDIUM, Odyssey,
Globalstar, and Inmarsat-P. These systems are intended
to support users anywhere in the world. The Teledesic
system of low-orbiting satellites would provide a very
large number of medium-to-high data rate links (several
megabits/second) to small terminals. These emerging
satellite systems will represent more than $10 billion in
development and construction (including launch) costs
when deployed (CDMA, 1994~.
In addition to providing wireless links to end users,
communications platforms that support people on the
move must include backbone and feeder transmission
and switching facilities that interconnect the wireless
access nodes. Terrestrial nodes (e.g., cell sites) are typi-
cally connected with cable-based fiber optic or copper
cable facilities and occasionally with point-to-point mi-
crowave facilities. The cable-based facilities that have
been used to date have relatively low bit-error rates. The
point-to-point microwave facilities used in commercial
applications generally have relatively low bit-error rates
as well (10-6 or lower) (Ivanek, 1989~. Recently, there has
been a great deal of commercial interest in the use of
upgraded cable television systems to interconnect small
cell sites in emerging personal communications net-
works. Since the cable systems carry combinations of
frequency-division-multiplexed analog television, digit-
ized television, and other digital information streams, and
because of the characteristics of the existing cable facili-
ties, the digital error rates on these systems are expected
to be somewhat higher than in other commercial facili-
ties. As a result, certain protocols like the asynchronous
transfer mode (ATM) protocol that was designed for low
bit-error rate transmission facilities will not work properly
unless steps are taken to encapsulate these protocols
inside an error-tolerant transmission format.
Steps are being taken by a number of standards bodies
to create a transmission format that will allow ATM to be
carried over facilities with relatively high error rates, like
cable television facilities. This is considered a high prior-
ity issue because of the investments that existing cable
system operators have in their current facilities and
because of the announced plans of some local exchange
carriers to deploy new multipurpose broadband net-
works based on combinations of fiber optic and coaxial
cable. The ATM protocol is discussed at length later in
this chapter under Protocols and Related Functionality to
Support Communications.
Information Capture Technologies
Information capture technologies interface to the
physical world to capture (sense) sounds, images, mov-
ing scenes, etc., electronically and to convert the cap-
tured information to digital forms that can be used by
automated information systems.
In the past ten years, information capture technologies
have become consumer products in the form of sophis-
ticated, but moderately low-priced and highly usable,
camcorders. These commercial devices can operate in a
wide range of light levels under control of their internal
micro-processor based systems and can provide features
such as zooming and integrated sound capture (micro-
phones and associated electronics). These devices can
OCR for page 25
REVIEW OF RELEVANT COMMERCIAL ~CHNOLOGIES
also communicate to videocassette recorders via inter-
faces provided for that purpose, and it is anticipated that
next-generation camcorders will appear shortly with their
video and audio outputs encoded in standard digital
formats (e.g., the Motion Picture Experts Group (MPEG)
MPEG-2 standard). Camcorders are generally priced in
the range of several hundred to a thousand dollars,
although advances in mass production techniques and
the desirability of reaching price points below $300 to
address mass consumer markets will lead to lower prices
in the future. The emergence of desktop multimedia
teleconferencing, including video and image capture,
have led to the appearance of low-cost charge-coupled
device (CCD) video and still image cameras on the
commercial market in the $50 price range.
Associated with the emergence of these consumer
devices, and with the continued demand for sophisti-
cated multimedia programming by movie and television
audiences as well as users of multimedia computers (e.g.,
games), is the continuing evolution of video processing
systems that can be used to perform such functions as
editing video and still images and combining video with
superimposed text and images. Some of these are tran-
sitioning into consumer products as increasingly power-
ful computer technologies allow these functions to be
performed on general purpose personal computers with
appropriate software.
Another example of a sensor that has found wide-
spread commercial use is the infrared sensor technology
used in such things as motion detectors. These devices
are available commercially in products costing only a few
dollars and are used by consumers in applications includ-
ing home security systems and automated driveway
lighting.
Analog-to-digital conversion and other specialized
sampling and data conversion tasks associated with
sensors can now be performed easily with one or a few
low-cost commercial chips, and associated signal proc-
essing can be accomplished with commercial single-chip
digital signal processors. This development means that
analog multimedia information such as audio, image, and
video can be captured and converted to digital form
easily and cheaply using commercial technologies. For
example, IBM recently announced low-cost encoder
($700) and decoder ($30) chip sets that implement the
MPEG-2 video compression coding standard.
BUILDING BLOCK TECHNOLOGIES
(LAYER II - YSTEM SOFTWARE)
Building block technologies discussed under
Layer II System Software of the generic architecture
25
(Figure 3-2) include (a) protocols and related functional-
ity to support communications, and (b) distributed com-
puting environments and operating systems.
Protocols and Related Functionality
to Support Communications
Network protocols are the system-level standards for
formatting information, controlling information flows,
reserving communications paths, authorizing access to
communications resources, managing congestion, recov-
ering from communication or equipment failures, deter-
mining routing, and other processing tasks needed to
transfer or access data between remote end systems (e.g.,
users) in a network. Since even a brief overview of
network protocols could fill an entire report, we focus
here on two leading protocol architectures: the Internet
protocol suite and the emerging ATM high-speed net-
work standards. For each, we begin with a brief history
and architectural overview and then consider the types
of network services they support, with an emphasis on
multimedia communication. Also, a "technology fore-
cast" is provided for each. This section concludes with a
discussion about software support for mobility.
The Internet Protocol Suite
The Internet protocol suite is the result of 25 years of
evolutionary development, much of which has been
sponsored by the Advanced Research Projects Agency
(ARPA). In the Internet architecture, there is a clear
distinction between the services to be provided by the
network-level infrastructure and the services to be built
on top of these network services by the communicating
end systems. The division of functionality between the
network and the end systems has proven to be a remark-
ably robust and prescient one.
At the heart of the Internet architecture is a design
philosophy in which the network-level infrastructure
provides only a simple, minimal packet delivery service.
The Internet Protocol (IP) and the associated route
selection protocols that provide this net~vork-level serv-
ice make no guarantees that (a) the packets sent by one
end system will be received by the other end system, or
(b) the network will deliver transmitted packets to the
destination in the order in which they were sent. IF does
not recognize any notion of a "connection" between two
endpoints.
Any additional functionality (e.g., reliable data trans-
fer) required by an end application is provided by
"end-to-end" protocols which execute on the end sys-
tems. For example, the Transmission Control Protocol
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26
COMMERCIAL MULE ~CHNOLOGI~ FOR -FIRST CE~YA~YBA EMITS
(TCP) is an end-to-end service which uses IP to provide
in-order, reliable delivery of data between two end
systems.
From a service standpoint, the Internet protocol suite
provides for both reliable (via TCP) and unreliable (via
the user datagram protocol (UDP)) data transfer between
two end systems. Multicasting of data (i.e., the copying
and delivery of a single data packet to multiple receivers)
is also supported. All Internet applications (e.g., file
transfer protocol, remote login (telnet), E-nail, World
Wide Web (WWW)) are built upon either TCP or UDP
data transfer.
The Internet protocols provide no explicit support for
real-time communication (e.g., interactive audio or
video) or for applications that send information at a
constant bit rate, and they require the stream of bits to
be delivered with a very low delay variability among the
bits in the stream. It should be noted, however, that
several efforts are under way in the Internet Engineering
Task Force (IETF), the Internet standards body, on
developing protocols for supporting such services. Nota-
ble among these efforts is the RSVP resource reservation
protocol (Zhang et al., 19939. It should also be noted that
several efforts have demonstrated the possibility of mul-
timedia teleconferencing over the current Internet (Cas-
ner and Deering, 1992; Macedonia, 19941. In principle,
even the current Internet protocols can provide for
teleconferencing services, as long as the network's traffic
load remains low.
Since there is increasing interest in extending the use
of the Internet to applications that require guaranteed
packet delivery within a specified range of delays, such
as real-time interactive multimedia teleconferencing, it is
anticipated that the next-generation Internet protocol (IP
version 6) will include mechanisms that enable network
resources to be reserved and packets to be assigned
priorities for transport through intermediate routers. Thus
the Internet protocol suite is moving from its traditional
connectionless "best effort" delivery approach toward a
set of approaches that includes the equivalent of connec-
tion-oriented transport.
Internet protocols were initially developed for rela-
tively low speed (e.g., 56 kbps) communication links.
However, they have been shown to be able to handle
traffic at rates of hundreds of megabits per second
(Borman, 1989~.
The current Internet protocols were developed for
fixed-terminal (i.e., nonmobile) network users; this is
reflected in the design of IP (and to a lesser extent, TCP
and UDP). However, there has been considerable recent
activity and interest in developing a new IP that will
support mobility. Several efforts are currently under way
in the IETF to develop Internet standards in support of
mobility.
Nineteen ninety-tour can well be characterized as the
year that the Internet moved into the public conscious-
ness. The reach of the Internet and the installed base is
indeed impressive. There were 3,864,000 host computers
in 154 countries connected to the Internet as of December
1994; almost 100 billion packets passed through a single
National Science Foundation (NSF) net site in a single
month (Bell, 19951. Industry and commerce are now
relying on the Internet for services.
Security is also now a serious and legitimate concern
for the Internet. Commercial needs and the increasing
reliance on the Internet as part of our national infrastruc-
ture are fueling efforts in the area of network security
both from the network standpoint (i.e., protecting the
network from tampering) and from the end-user point of
view
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RENEW OF ~EVA~ CO~=C~ ~CHNOLOGI~
recting mechanisms for transport over facilities with
relatively high bit-error rates.
Before 1994, ATM products and prototypes were
being supplied by only a handful of vendors and installed
primarily in research institutions and government labs.
In 1994, however, more than two dozen vendors brought
ATM switching products to market. Membership in the
ATM Forum (the standards body most aggressively push-
ing ATM forward) has grown considerably. Nonetheless,
ATM is a new technology that has not yet been demon-
strated on nearly the same scale as the Internet protocols
(ATM Forum, 19951.
Two visions exist regarding the use of Intemet tech-
nology and ATM networks in the emerging national
information infrastructure. In one view, interconnected
ATM networks will provide seamless, uniform, end-to-
end transport of ATM cells between any two endpoints.
In the other view, ATM wide area networks will be used
to connect islands of local area or campus networks, with
the individual islands running Intemet (or other) com-
munication protocols. Both views are likely to be correct,
in that applications exist in which the solutions implied
within both views are viable. The balance between the
use of one approach over the other will be determined
in the emerging commercial marketplace, more by the
speed at which commercial products emerge that meet
user needs than by any fundamental advantage of one
approach over the other.
Software Support for Mobility
One can consider three phases in the evolution toward
the support of mobility in commercial telecommunica-
tions networks. The first, associated with traditional
"plain old telephone service (POTS)," supports essen-
tially no mobility at all. In this case the terminal equip-
ment has a fixed relationship to the network to which it
is attached, and the user has a fixed relationship to the
terminal (i.e., one attempts to call a specific person by
dialing a number associated with a specific physical
location). There is limited support for mobility via exten-
sion telephones and cordless telephones, but these do
not require any network-based intelligence. The second,
the familiar case of today's cellular services, allows one
of the relationships to be dynamic namely, the physical
location of the telephones is dynamic. However, the
relationship between user and terminal equipment re-
mains fixed (i.e., a particular cellular telephone and
associated telephone number are still used to attempt to
reach a specific user). In the third phase, the relationship
between the user and the terminal is also allowed to vale,
and it is the user, rather than a specific terminal, to whom
calls are directed. This is called "personal mobility." The
27
latter two phases require that software-controlled func-
tionality be added to both the terminal equipment and
the network.
Smart-card technology offers still further flexibility to
personal mobility. Smart cards contain user-specific data
that turn a terminal into a de facto peripheral for the card.
With the smart card, the terminal takes on the personality
and behavior that the user wishes (and has paid for),
including feature sets, custom dialing control, and
authentication passwords.
For systems in phase two, represented by today's
cellular telephony, the approach to locating users (i.e.,
their moving terminals) who move from place to place
is to maintain a system of home and visited databases
called Home Location Registers (HLRs) and Visited Loca-
tion Registers (VLRs). The HER is the place to which an
incoming call for a roaming user is initially directed based
on the user's telephone number. The HER will contain
an entry that shows the VLR associated with the network
in which the user is currently known to be located. This
VLR knows that the user is in its domain because the
user's telephone has communicated recently with one of
its cellular nodes. The call will be forwarded to that
network, where the OR will arrange to have the call
delivered to the proper roaming user, based on its stored
information regarding the user's current location in its
associated network. The VLRs will also notify the FILRs
when roaming users move in and out of their domains.
To support full personal mobility, including smart
cards, commercial network-based software will be up-
graded and supplemented to include functionality not
required in traditional fixed-terminal networks. In par-
ticular, fast inquiry and response database systems will
be deployed to (a) interrogate terminal units and data-
bases for user authentication, (b) interrogate databases
for number translations, and (c) transfer service profile
information from one information database to another as
users and their terminals travel from place to place.
Networks will be (reprogrammed to recognize mobility-
related numbers and respond to personal feature profiles
associated with individual users.
Distributed Computing Environments
and Operating Systems
Operating Systems Oeve/opment
Operating systems are software systems that manage
the hardware resources of a computer system to provide
seIvices needed by applications. They evolved from
earlier input-output control systems, which were loaded
into early computer systems before an application began
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28
COMMERCIAL MULTIMEDIA TECHNOLOGIES FOR 7 WEN7-Y-FIRST CEN71~YARMYBA T7ZEFIFI DS
to run; this was typically done with a deck of punch cards
placed immediately ahead of the cards used for the
application. It became clear that there was a common set
of functions needed by many applications, and this gave
rise to early operating systems. Early machines in many
cases were dedicated to a single use. Later machines were
multipurpose, but the input-output control system
scheme made for sequential execution of jobs, one after
another.
A major advance came from the idea of multiprogram-
ming, which took advantage of the fact that the expensive
processor was often wasted as slow input and output
devices (such as printers, card punches, and tape ma-
chines) were accessed by an application. Multiprogram-
ming used the idle periods of the processor to perform
other computational work until the input and output
were completed. A variety of multiprogramming tech-
niques were developed, with fixed and variable numbers
of tasks, priorities, etc. Timesharing is a multiprogram-
ming technique that allows interactive access to the
multiprogrammed resources.
Multiprogramming also involves sharing of processor
memory resources. Modern multiprogramming technolo-
gies have almost uniformly emnlc~ved the technique
, . . .. . .
-- J - ~~-r - - J - ~
called demand-paging." Demand-paging divides the
storage of the machine into fixed-size units called pages.
Application storage is also divided up into page-sized
address ranges, which are mapped to the machine's
storage through a technique known as virtual memory.
All commercial operating systems for workstation or
larger computers (e.g., MVS~, UNITY and its derivatives)
now incorporate these techniques. Smaller systems, such
as personal computers, have been evolving in the same
fashion; the popular Windows application support soft-
ware is essentially a single-user multiprogramming sys-
tem overlaid on an extremely simplistic device-
management core (MS-DOS~. Newer generations of
personal computer software will support more advanced
memory management techniques, such as demand-
paged virtual memory. The lack of modern memory
management technology in the popular MS-DOS soft-
ware has been a major limitation in using these commod-
ity machines for more complex applications and a major
source of failures. These difficulties have provided op-
portunities for alternative personal computer operating
systems (e.g., OSLO), as well as penetration of the
personal computer market by UNITE technology.
A major challenge remaining for operating systems is
the efficient processing of multimedia data (Nahrstedt
and Steinmetz, 19951. Multiprogramming systems have
embedded assumptions about scheduling jobs that they
inherited from their predecessor technologies. For exam-
ple, they often schedule job execution in a "round-robin"
fashion to preserve a fair allocation of processing
resources between jobs. This scheduling creates a "virtual
time" model where each job's real processing time (wall-
clock time) is dilated in proportion to the amount of
competition for processing resources.
Unfortunately, continuous media such as voice and
video are characterized by their real-time requirements;
30 frames per second of video are required to preserve
perceptual smoothness in spite of competing demands
for resources. These real-time constraints suggest that the
requirements of multiprogramming must be balanced
against the application requirements for effective multi-
media support in operating systems (Nahrstedt and Ste-
inmetz, 19951. Substantial commercial R&D effects are
underway to improve the support for multimedia appli-
cations in commercial operating systems. Examples in-
clude the XMedia(~) toolkit from DEC and the Hewlett
Packard(~) MPower(D toolset.
nteroperability and Distributed Computing Environments
In the 1970s and before, computer programs were
usually written for only one hardware and software
platform at a time. "Porting" a large application to another
platform was a difficult task, rarely undertaken. The
UNION operating system, which blossomed in the 1970s,
owes much of its popularity to the fact that it was
explicitly designed to run on multiple platforms and was
closely wedded to the C programming language, which
was also designed for portability. In the 1980s, portability
was among the most desirable of attributes sought for
computer applications.
In the 1990s, portability remains an important issue,
but interoperability (the ability of computer applications
developed by different vendors to cooperate on the same
or different computing endeavors, and to share data
between such applications) across software and hard-
ware platforms has become the more sought-after attrib-
ute. Interoperability and the improving price-
performance trend of small computer systems have led
to intense interest in what is known as a distributed
computing environment—a set of standard interfaces,
software components, and tools that permit computer
applications developed by different vendors to cooperate
on the same or different computing environments inter-
connected by appropriate communication links.
In the past, incompatible software applications have
proliferated. This has occurred because of (a) mixing
programs written in different languages, and (b) the use
of different ways to communicate between programs
running on the same or different computers that are
connected by a communications system. Cooperation
across incompatible platforms was so difficult to achieve
that applications were commonly designed with no
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REVIEW OF RELEVANT COMMERCIAL TECHNOLOGIES
come closest to meeting them (Zeigler, 1990; Ruiz-Mier
and Talavage, 19893.
BUILDING BLOCK TECHNOLOGIES
(LAYER Vl MANAGEMENT~ECURITY)
Building block technologies discussed under
Layer VI- Management/Security of the generic architec-
ture (Figure 3-2) include security technologies; network
management systems; and general purpose languages,
tools, development environments.
Security Technologies
Security is a major issue and a major concern among
all providers and users of information networking appli-
cations and services. In the United States, privacy is one
of our most cherished rights, and privacy concerns are a
major impediment to successful realization of the vision
of a national information infrastructure. Health care
providers and patients are concerned about the protec-
tion of patient-identifiable patient records. Educators are
concerned about the unauthorized disclosure of student
records and also about the uncontrolled or unauthorized
access of students to pornographic materials. Individuals
do not want their messages and real-time communica-
tions to be disclosed, nor do they want information about
their buying habits, what they read, their tax records, or
other personal information to become available without
their permission. Electronic commerce cannot flourish
without the ability to conduct secure transactions and
protect intellectual property from unauthorized uses.
Security includes:
.
Protection of stored information or information in
transit through a network from unauthorized access
in usable form (eavesdropping);
· Protection of stored information or information in
transit from unauthorized modification;
Authentication that what has been received over a
network has not been modified, and that the source
of the information is who he or she claims to be;
Protection of resources from unauthorized access;
Protection of users' identities from those who are
not authorized to know their identities;
· Protection of information about users' usage pat-
terns: what they access, how often, from where;
and
Protection against denial-of-service attacks that pre-
vent authorized users from accessing resources and
information when they need to do so.
.
37
Recent trends in commercial systems and applications
have been to enhance security. There is a tradeoff be-
tween the level of protection that can be provided and
the ease with which legitimate users can use the services
they are authorized to use. This tradeoff is shifting in time
as advances in technology are making such things as
powerful smart cards available. Standards are the pacing
factor here, because the industry recognizes that users
will not wish to carry around a variety of different types
of smart cards for different purposes. Thus, much effort
is currently being employed to identify the broad range
of applications and the corresponding capabilities that
must be embedded in smart cards. Smart cards are
essentially credit-card-sized miniature computers that
contain secret encryption keys, the ability to execute
security (encryption) algorithms, and input/output capa-
bilities to interface with terminals or appliances. They can
store personal information such as medical records, and
they can also be loaded with electronic money.
To illustrate the trends in commercial practice, one can
consider the following examples.
First-generation cellular networks are relatively sus-
ceptible to eavesdropping. Next-generation digital cellu-
lar networks will employ encryption techniques to make
eavesdropping more difficult. Emerging wireless per-
sonal communications networks will, in some cases,
employ spread-spectrum code division multiple access
(CDMA) techniques and even more powerful encryption
algorithms. These networks may also employ public key
cryptography algorithms to allow accessing users to
authenticate themselves to the network without disclos-
ing their identities to eavesdroppers. CDMA systems are
not only intrinsically eavesdrop-resistant but also resis-
tant to direction finding because their low-power signals
are spread over a broad range of frequencies, which are
shared by all other users.
When remote users log on to their host terminals over
networks, there are opportunities for passwords to be
compromised to eavesdroppers, particularly with wire-
less networks. This has led to the use of special credit-
card-sized tokens that generate and display
pseudo-random numbers that are used as one-time pass-
words. Using a variety of approaches, the passwords
generated by these tokens can be authenticated by host
security systems that know the secret information resid-
ing in the token that generates the passwords. Eavesdrop-
pers cannot make use of these passwords after their initial
use by authorized users. The use of these single-purpose
tokens may be eliminated when their functionality is
absorbed into general-purpose smart cards in the future.
Standards for digital signatures, based on public key
cryptography, make it possible to not only verify the
source of a piece of multimedia information that has been
stored or transmitted in digital form, but also to validate
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38
COMMERCIAL MULE ~CHNOLOGI~ FOR -FIRST CE~YA~YBA EMITS
that no change has been made to the digital multimedia
object subsequent to being signed by the originator.
Extensions of this approach have resulted in the ability
to also authenticate the exact time that a document was
signed (digital notary service) in ways that are acceptable
in legal settings.
In general, cryptography makes it possible to make
multimedia information inaccessible to unauthorized us-
ers by placing it in a form that is not usable without the
secret cryptographic decoding key. Commercial methods
for implementing cryptography are widely available,
although export restrictions, difficulties in negotiating
terms with respect to the use of patented methods, and
certain federal government initiatives with respect to
encryption methods, which contain "back doors" to allow
government access under specified circumstances, have
temporarily hampered progress in converging on com-
mercial standards for strong encryption methods.
There are initiatives under way to create cryptographic
methods to support electronic commerce, including the
exchange of credit information over public networks.
Several vendor-specific approaches are currently being
employed in commercial networks to support electronic
shopping and the sale of intellectual property over
networks.
Firewalls to prevent attacks on network enclaves (i.e.,
networks within a specified administrative domain, such as
those of a company or a university) from determined
intruders are available and are continually being upgraded
as more sophisticated attacks are developed and em-
ployed. Applications exist for automatically detecting net-
work security vulnerabilities against known attacks due to
improper configurations of networks and their attached
hosts. However, protection of networks against determined
attackers remains an ongoing problem for commercial and
institutional system administrators. It has been described as
a joumey, rather than a destination, where the objective is
to minimize risks and to detect quickly and limit the damage
associated with attacks.
In summary, with network and information security as
one of the pacing factors in the successful realization of
the applications associated with a national information
infrastructure, which represent a commercial market op-
portunity measured in hundreds of billions of dollars per
year by most estimates, there is a very large commercial
R&D effort under way to create, standardize, and deploy
easy-to-use, powerful, and inexpensive security technolo-
gies and methodologies.
Network Management Systems
Network management systems are used to manage
large, distributed, heterogeneous information systems.
Management functions range from authorizing users to
have access to specific services and applications to
recovering from faults or attacks. Typically, management
is accomplished in a layered fashion to make the man-
agement process itself manageable. Individual network
components such as communications nodes (e.g.,
switches, multiplexers, routers) and links (e.g., fiber optic
systems), servers, and end systems contain self-diagnostic
functionality and the ability to remotely configure or
reconfigure their capabilities.
The network management functionality that is de-
voted to monitoring and controlling these individual
components is referred to as residing in the element
management layer. Collections of components work
together to perform such functions as the provision of
communications paths or accessible databases. While
individual components may fail, redundancies can make
it possible to maintain these functions. For example, a
communication path can be maintained by using an
alternative route through a multiconnected network. A
backup server can be used to take over for a damaged
server. The network management layer that is responsi-
ble for maintaining such things as communications paths
and database capabilities is known as the resource man-
agement layer. Higher layers in the network management
stack are responsible for providing specific types of
services and applications to specific users and user
classes.
As distributed, multipurpose, multiprovider, heterogene-
ous networks have proliferated in the commercial world,
network management has become a major commercial
market. Downsizing and reengineering of commercial firms
and industries have placed ever more importance on the
elimination of manual tasks and the use of automated
systems to configure, troubleshoot, and control networks.
The increasing dependence of society on information
networks in such areas as commerce, health care, and air
traffic control places a premium on reliable systems that can
quickly control and isolate problems.
General Purpose Languages, Tools,
Development Environments
Any piece of computer software, whether used in an
operating system, a multimedia database, multimedia
teleconferencing software, or a network management
system, is a program. Any such program, in turn, must
be written in a programming language. While the pro-
gramming language in which software is written may be
unimportant to a user of an application embodied in a
program, if the software is to be extended, modified, or
customized, the programming language in which this is
done becomes critically important.
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REVIEW OF RFLEVA~ CO~ERCIAL ~CHNOLOGI~
Early computer programming languages such as FOR-
TRAN were designed primarily for numerical calculation
and were aimed at freeing the programmer from having
to consider the details of a computer's hardware when
writing a program. Modern computer programming lan-
guages such as C++ and Ada were designed to support
a spectrum of application domains. They also recognize
large-scale software development as a continuing group
process involving many individuals and thus support
widely recognized software engineering principles:
(a) programming is a human activity, and (b) software
should be maintainable, portable, modular, and reusable.
Hundreds of computer programming languages have
been developed, and yet only a relatively small handful
have found widespread use. Rather than provide a
comprehensive survey of languages, the committee ex-
amines here two of the most important languages in use
today for application programming and system software
development: Ada95 and C++.
Ada traces its birth back to 1975, when the Department
of Defense (DoD) established requirements for a high-
level language that could be used in all defense projects.
In 1976, 23 existing languages were formally reviewed
and none were found to meet the requirements. It was
concluded that a new language was needed, and the Ada
language was born. Ada became an American National
Standards Institute (ANSI) standard in 1983 and an Inter-
national Standard Organization (ISO) standard in 1987.
The 1983 Ada standard was updated in early 199j and,
like the original Ada, is intended for embedded and
real-time systems. It also has a number of built-in features
to support distributed computing. A major improvement
found in Ada95 is its support for object-oriented program-
ming and enhanced support for real-time systems.
The so-called "Ada mandate," Public Law 101-511 Sec.
8092, states that Ada should be used for all DoD software:
"Notwithstanding any other provisions of law, after June
1, 1991, where cost effective, all Department of Defense
software shall be written in the programming language
Ada, in the absence of special exemption by an official
designated by the Secretary of Defense." Thus, Ada has
considerable visibility within the defense contracting
industry. The extent to which Ada is used in non-gov-
ernment-sponsored software development is the subject
of continual debate. Numerous commercial uses of Ada
are documented (IIT, 1995~.
C++ is another modern general-purpose language of
roughly similar power to Ada. It is object-oriented and
also has many features that modern software engineering
practice considers important. It is a descendant of the C
programming language, which was developed in the
early 1970s at Bell Laboratories, and has found wide-
spread use since then. Standardization efforts are under-
way in both the ANSI (American) and ISO (International)
39
groups to develop a C++ standard. It has been stated that
C++ is by far the most popular object-oriented program-
ming language and that the number of C++ users is
doubling every 7.5 to 9 months. Trade magazines contain
numerous reviews of compilers and development envi-
ronments for C and C++, thereby attesting to the wide-
spread interest in this language.
Associated with these languages are a number of tools
and development environments. These are attempts to
ease the programming task, organize teams of program-
mers for large projects, and "debug" programs effectively.
Examples of such tools include syntax-directed editors,
source-code control systems, and symbolic debuggers.
A syntax-directed editor provides programming lan-
guage syntax checking and language-specific structuring as
the program is typed in by the programmer. The advantage
of this approach is that many of the "bugs" common in early
stages of program development can be eliminated before
the first trial compilation of the program.
Systems for controlling source code, such as the
Source Code Control System (SCCS) and Revision Control
System (RCS), serve as repositories for the source code
comprising a program. There are facilities provided for
change management, which is critical in management of
large-scale software projects.
Symbolic debuggers allow a failed program to be
analyzed in the form of the symbols used by the pro-
"rammer to write the program. The advantage of this
technology is that the programmer is able to more quickly
isolate conceptual errors because the form of the error
report is in the semantic structures used by the program-
mer rather than those of the lower-level "object code"
used by the machine.
SYSTEMS
In this section the committee gives examples of sys-
tem-level applications of multimedia information tech-
nology existing or emerging in the commercial domain.
These examples will provide substantiation for the rec-
ommendations in Chapter 4 as to which building block
technologies the Army should adopt or adapt from the
commercial domain and which building blocks are can-
didates for Army-specific development to produce pro-
prietary advantages over its adversaries. This section
covers four major systems: cellular and wireless, elec-
tronic commerce, intelligent transportation systems, and
residential information services.
Cellular and Wireless Telecommunications Systems
Revenue growth and subscriber growth in cellular
systems have exceeded even the most optimistic projec-
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40
COMMERCIAL MULTIMEDIA TECHNOLOGIES FOR 7~ FIRST CENTURYARMYBA 771~EFIELDS
tions of its early proponents. Yearly revenues in North Electronic Commerce
America have grown from $500 million in 1985 to over
$4.6 billion by year-end 1993 (Leeper, 19959. This is an
average annual revenue growth of 32 percent. Revenue
growth rates are retreating slightly but are still expected
to exceed 20 percent annually through 1996.
Globally, in 1993 alone, the number of subscribers
went from 21.1 million to 33.1 million, a growth of 56
percent. In North America, the growth was 47 percent,
going from 12.1 million to 17.7 million (Leeper, 1995~.
Note that revenues are not growing as fast as subscribers
because of declining prices.
With more advanced electronic, battery, and antenna
technologies, there has been a marked move toward
personal, portable handsets. In 1987 only 5 percent of
handset sales could be called "portable"—vehicular sets
accounted for 78 percent of all sales, and "transportable"
units 17 percent. In 1993, portable sales had jumped to
a 36 percent share of the total, transportables to 35
percent; vehicular sales had declined to 29 percent of the
overall market (Leeper, 19959.
Prices on cellular subscriber units have dropped to
well within the means of mass market consumers. In
1993, portable units in the United States had an average
"walk-away" price of $343 with some units sold for as
little as $43. Vehicular units averaged $264 and transport-
ables $187. Despite their higher average price, portables
remain the fastest growing segment of the market
(Leeper, 19959.
Customers appear willing to pay a premium for port-
ability and convenience, and technology has made very
small and lightweight phones possible. The leading
handset manufacturer has recently introduced a "flip-
phone" model weighing only 3.9 ounces. The phones are
becoming as small as is practical for human fingers to
operate; further reduction in size may require a paradigm
shift in packaging and other means of input and output.
Since it is still inconvenient in many circumstances
to "wear" a phone and to answer it every time it rings,
many users today wear a vibrating pager and use it to
screen calls. The portable cellular phone stays in the
briefcase until it is actually needed. This practice
portends the day when a person may "wear" a per-
sonal, wireless, LAN (local area network) that links a
pager, phone, and PDA.
Cellular and wireless users, particularly business
users, are increasingly demanding more reliable, se-
cure, nearly ubiquitous service with the ability to move
around freely. They are demanding lighter, more reli-
able handsets with longer operation between battery
charges. They are also demanding multipurpose units
that can operate as cordless telephones, cellular tele-
phones, and telephones that can access emerging
personal communication networks.
Electronic commerce refers to the conduct of business
using distributed information networks that connect geo-
graphically distributed locations of the same firm, firms
and their suppliers, firms and their customers, and mul-
tiple firms jointly creating and marketing products.
The banking industry is at the leading edge of elec-
tronic commerce in its use of information networks to
conduct billions of dollars of transactions on a daily basis.
The banking industry uses information networks to move
money among accounts distributed worldwide and to
monitor critical information needed to make financial
decisions, such as the granting of loans and lines of credit.
These networks are also used to collect and process
credit and debit card information from hundreds of
thousands of merchants who accept these cards, to clear
hundreds of millions of checks on a daily basis, and to
operate automatic teller machine networks on a world-
wide basis.
All major stock exchanges depend upon information
networks to conduct hundreds of millions of trades each
day. This dependency has become increasingly evident
during recent outages at the NASDAQ exchange.
For more than a decade, electronic data interchange
(EDI) has been used between firms and their suppliers
to place orders, send invoices, and make payments on
accounts payable. Some large firms will not deal with
suppliers who cannot conduct their business using EDI.
Recently, there have been successes in various forms
of electronic shopping (e.g., the Home Shopping Chan-
nel), and this success is fueling the emergence of on-line
shopping services over which purchases can be trans-
acted. Such transactions may involve the use of credit
cards, debit cards, electronic checks, or anonymous
electronic money.
In all of these existing and emerging applications,
network integrity, network reliability, and security are
major, ongoing concerns. Not only are these networks
susceptible to theft of services, fraud, compromise of
private information, and attempts to steal or counterfeit
electronic funds, but they are also susceptible to disrup-
tive attacks and accidents that can cause billions of dollars
per day of economic damage.
Intelligent Transportation Systems
Departments of transportation at the federal and state
levels have concluded that it will be increasingly difficult,
if not impossible, to construct new roads to accommodate
increasing traffic loads over the next several decades.
Meanwhile, there is a need to increase highway safety,
to improve traffic flows to decrease congestion resulting
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REVIEW OF REIEVANT COMMERCIAL TECHNOLOGI~
from accidents and stochastic traffic surges, and to track
the locations of commercial and public vehicles. In
response to this realization, an initiative known as
Intelligent Transportation Systems (ITS, formerly known
as Intelligent Vehicle/Highway Systems) has been
established.
Consensus estimates are that government and private
investments in ITS cumulatively up to the year 2011 will
be $210 billion (IMPS, 19923. In fiscal year 1995, the U.S.
Department of Transportation budget includes $227.5
million in funds allocated to ITS research and develop-
ment, operational tests, and other ITS-related initiatives
and applications. These applications include highway
sensors (including cameras) that will monitor traffic and
send traffic information over wireless and wired commu-
nications networks to centralized traffic control nodes;
traveler information systems that will distribute traffic
reports to travelers in automobiles, trucks, and their
homes and offices; positioning systems that will allow
vehicles to track and report their locations to centralized
nodes; 911-emergency systems that will allow travelers
to report problems, including their precise locations
(currently a serious problem in cellular emergency calls);
map delivery systems that will guide travelers to their
destinations; and others that are less relevant to this
report.
These distributed systems and their associated appli-
ances and applications will have to be reliable, secure,
easy to use, and affordable in mass market applications.
Residential Information Services
In 1994 the sales of home-based personal computers
equaled that of television sets ($8 billion) (Markoff,
19951. It is anticipated that, over the next decade and
beyond, the use of residential multimedia computers to
access information (education, health care, personal
finance) and to shop for and purchase information and
consumer products will become commonplace. In order
for this vision to become a reality, residential applications
must be intuitive and easy to use. There is an increasing
awareness in government and industry that universal
service will not be solely a matter of financial means but
also a matter of the usability of information services and
applications by those members of society who are not
technologically oriented and have limited time to invest
in learning how to use new technologies. Thus there is
an ongoing, major R&D effort to achieve increasingly
user-friendly graphical (and other) user interfaces and
so-called plug-and-play capabilities.
For example, there is a large amount of commercial
activity related to the design of set top boxes for interac-
tive multimedia applications in the home. The terminol-
41
ogy "set top box" refers to a piece of equipment, used in
conjunction with a standard television set, which acts as
an interface between an interactive or noninteractive
multimedia communication service being provided via
a coaxial cable, a pair of copper wires, a satellite or
terrestrial microwave antenna, or an optical fiber and
the standard antenna input of the television set. The set
top box may contain powerful processing and informa-
tion storage capabilities, and it may provide a sophisti-
cated user interface that allows the user to do such things
as navigate menus of available programs and other
information and to interact with the application the user
has selected. Much of this current activity relates to the
design of a user interface that is easy and intuitive to use
for the more than 95 percent of the general population
that owns television sets. In addition, since the upstream
(user-to-net~vork) bandwidth is very limited in many
architectures for connecting end users to the information
servers that provide multimedia to these set top boxes,
yet the response time to user requests (e.g., program
changes) must be very short, there is a big emphasis on
maximizing performance in the context of bandwidth
limitations.
LESSONS LEARNED IN THE
COMMERCIAL WORLD
The major focus of this section is on lessons learned
in the commercial world in the application of multimedia
information technologies. These lessons support the
committee's recommendations that appear later in this
report. The following sources of lessons learned will be
addressed: architecture, standards, vertical versus hori-
zontal structures, leveraging commercial off-the-shelf
(COTS) technology, how business meets special technol-
ogy requirements, leveraging legacy investments and
fostering rapid acceptance of information technology,
and adopting a spiral model of development.
Architecture
Because we can observe its entire life cycle, the IBM
System 360 serves as an excellent case history from which
to draw a few essential lessons about architecture.
In the late 1950s and early 1960s, IBM was facing a
problem. IBM was fielding an ever-widening variety of
systems, few of them compatible with one another and
each separately optimized for a particular set of applica-
tions. Further, each system required a separate training
regimen for IBM's field support staff, leading to very high
maintenance costs.
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42
COMMERCIAL MULTIMEDIA TECHNOLOGIES FOR TWEN7-Y-FIRST CE~YA~YBA EMITS
To solve the growing problem, IBM's executives com-
missioned the design of a single, logical architecture from
which an integrated family of systems could be built. The
result was the now famously successful System 360 (and
its follow-on, System 370) family of systems.
What are the lessons to be learned from this successful
commercial experience with architecture? Fred Brooks,
System 360 Development Manager, says (Brooks, 19759:
System 360 architects had two almost unprecedented advan-
tages: enough time to work carefully, and political clout equal
to that of the implementors. The provision of enough time came
from the schedule of the new technology; the political equality
came from the simultaneous construction of multiple implemen-
tations. The necessity for strict compatibility among these served
as the best possible enforcing agent for the specifications.
Regarding the architecture design, Brooks writes:
I will contend that conceptual integrity is ';the" most important
consideration in system design. It is better to have a system omit
certain anomalous features and improvements, but to reflect one
set of design ideas, than to have many good but independent
and uncoordinated ideas. Conceptual integrity does require that
a system reflect a single philosophy and that the specification as
seen by the user flow from a few minds.
The principal lessons here are that creation of a
communications and computing architecture requires
that (a) a few resonant minds create the architecture, (b)
they be given time to work, and (c) the architecture be
enforced not only by edict but also by simultaneously
constructing several of the system implementations that
use the architecture.
The committee notes that cultural separations among
existing functional groups, profit centers, divisions, etc.,
exist in all commercial companies and other institutions.
Pride and esprit de corps within these are typically
long-standing and well cultivated, and they typically have
produced very positive results in the past. Unfortunately,
they are also major obstacles to developing an integrated
"enterprise" or"information" architecture. The challenge
is to overcome these obstacles by taking steps like those
taken at IBM in the context of system 360. Such successes
are, to date, quite rare.
Standards
The commercial world places great value on the
existence and widespread use of standards. Standards
consist of sets of rules with which conformance to the
standard can be evaluated. These rules can be applied at
many layers in systems, ranging from physical connectors
to the graphical user interfaces discussed elsewhere in
this chapter.
Standards have the business advantage that, once
defined, all commercial enterprises that wish to compete
for the provision of components of an integrated system
can exploit whatever competitive advantages they pos-
sess or can create without having to be vertically inte-
grated suppliers of the end-to-end system. Thus,
standards are pro-competitive. The consumer derives
advantage from the fact that technologies adhering to a
standard are interoperable. Interoperability means that
one of a set of interoperable components can be pro-
cured or upgraded independently of others. For example,
all compact disc players use the same compact disc,
although significantly different sampling schemes and
signal processing technologies can be applied, resulting
in a variety of consumer choices, from low quality to
audiophile quality.
Industry standards emerge in two ways, which can be
interrelated and often are. First is through the use of a
standards body. The purpose of the standards body is to
provide an impartial design and selection of a standard.
The most effective standards bodies rely on groups of
technical experts in an area to define a useful and
effective standard. Examples are the Institute for Electri-
cal and Electronics Engineers (IEEE), the International
Standards Organization (ISO), and the ATM (Asynchro-
nous Transfer Mode) Forum. IEEE Standards usually
relate to computer and communications devices and their
functions. Examples include standard formats `~or com-
puter representation of floating point numbers (IEEE 754)
and standard interfaces for a portable operating system
(IEEE 1003, POSIX).
ISO standards include the Open Systems Interconnect
standard or OSI; this standard defines a multilayer pro-
tocol model which was carefully defined and accepted
as a standard before implementation was begun. This
latter case illustrates a risk with standardization by com-
mittee. The risk is that the committee will be bypassed
with a second form of standardization, the de facto
standard based on user preference. In the case of OSI,
implementation of the Internet protocol described earlier
in this chapter proceeded without a complete formal
standardization process, and yet it has become the de
facto standard for Internet communications.
De facto standards are a result of market dynamics. If
a clear standard is not established when a company
wishes to enter a market, it can either wait for a standards
body to put forth a standard to which it will adhere, or
it can take its own approach and presume that it will
achieve sufficient market share to become one of a small
set of accepted solutions. An example where this has
occurred is in the design of command sets for asynchro-
nous modems, where a manufacturer (Hayes) developed
a command set that is a de facto standard. Such standards
are sometimes developed as a byproduct of other com-
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REVIEW OF RELEVANT COMMERCIAL TECHNOLOGIES
petitive advantages possessed by a company. In the
Hayes case it was a flexible microprocessor-augmented
modem called the SmartModem~, which was a huge
commercial success; the Hayes command set has outlived
the company. Once established, such standards are
violated at considerable commercial risk.
Official standards and de facto standards can be the
same if the official standard is available early enough so
that companies see an advantage in adhering to it, or if
the de facto standard becomes officially recognized by a
standards body. The former case is exemplified by the
ATM Forum, which specifies standards for a variety of
protocol layers in ATM networks. The latter case, while
pragmatic, can be fraught with difficulty as the company
that originated the de facto standard may be given a
further advantage by ratification of its technology as a
standard. Standards bodies have traditionally been reluc-
tant to ratify a situation that might, by giving advantage
to a particular vendor, give the appearance that they may
not be impartial, although recently there has been a trend
toward the adoption of de facto standards by standard
forums like the Open Software Foundation.
Companies address their concerns with standards by
becoming active participants in standards bodies when
technological standards may affect them or be positively
influenced by their input. Companies put their concerns
into the deliberative process of the standards body. For
example, computer manufacturers were highly influen-
tial in the design of the ATM Adaptation Layer 5 standard,
which allowed for overlapped operation of check-sum
computation and data movement that is highly desirable
in computer networking environments.
Vertical Versus Horizontal Industry Structures
In the first several decades of its existence, the com-
puter industry was vertically integrated. Each firm (e.g.,
IBM, Digital Equipment Corporation) designed, devel-
oped, and sold all of the hardware and software needed
by its customers to implement their computing applica-
tions. In the past 15 years, the computer industry has
assumed a horizontal structure. Intel, Motorola, and
others make microprocessors and memory chips. Com-
paq, IBM, Apple, and many others make personal com-
puters and a wide variety of plug-in boards and
peripherals. Microsoft, IBM, Apple, and others make
operating systems. A large number of firms sell middle-
ware and application software (The Economist, 19933.
The transition to a horizontal structure has been driven
by several factors. Customers demanded open system
solutions that would allow them to mix and match
products from multiple suppliers; this necessitated the
opening of interfaces, which allowed competing firms to
43
sell horizontally structured products. Economies of scale
and a very competitive marketplace made it necessary to
focus on one's core strength and to sell into as large a
market as possible.
This same transition from a vertical structure to a
horizontal structure is affecting many other industries.
Global competition is causing firms to focus on their
differentiating advantages and to outsource what they
can get better or cheaper from others. For example, an
airline may determine that its reservation system should
be a separate business rather than a vertically integrated
part of a business that includes the component that
actually flies passengers. The airline may also outsource
its maintenance and meal preparation service. It is not
clear that each airline needs to maintain its own baggage
handling staff. What to keep and what to outsource is a
critical decision regarding where one wants to differen-
tiate from competitors.
In the long distance telephone industry, competing
firms have been differentiating themselves via the capa-
bilities of their billing systems to support complex dis-
count plans. It is conceivable that someday telephone
companies will outsource their networks and differenti-
ate themselves on the basis of marketing and customer
support services.
A lesson learned is that to achieve superiority (beat
the competition) in information-technology-intensive
businesses, one should focus development efforts on
areas where one intends to achieve a differentiating
advantage and should outsource everything else.
Leveraging Commercial Off-the Shelf Technology
The commercial telecommunications industry is one
of the largest consumers of multimedia information tech-
nologies. It is therefore useful to examine recent trends
within the telecommunications industry in leveraging
COTS multimedia information technologies. Much can be
learned from successful companies in this industry.
For example, MCI and SPRINT, two of the largest
providers of inter-exchange ("long distance") telecommu-
nications services ("carriers") in the United States, conduct
only limited R&D activities. They focus on defining the
overall architectures of the networks they wish to deploy,
the associated management systems, and tracking technol-
ogy trends. They carefully determine how they wish to
differentiate themselves from their competitors (e.g., in such
areas as billing systems and customer service), and they
commission the development of those differentiating capa-
bilities using commercial-off-the-shelf technologies (i.e.,
they focus on implementing applications of commercial
off-the-shelf technologies, not the underlying technolo-
gies themselves).
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44
COMMERCIAL MUl COMEDY ~CHNOLOGI~ FOR -FIRST CE~YA~YBA WHIFF DS
The providers of cellular telecommunications services
have relied on their suppliers to produce innovations in
technology, while they (the providers) have focused on
applying that technology in their networks. When mem-
bers of the cellular telecommunications industry deter-
mine the need for a new capability (e.g., inter-net~vork
signaling to enable nationwide roaming), they call upon
their supplier community to produce proposals for how
this might be implemented. Cable television companies
follow a similar strategy to that of the cellular companies,
maintaining only a modest R&D effort focused on defin-
ing requirements for new system architectures and
capabilities.
Recently, the local exchange carriers (Ameritech, Bell
Atlantic, and others) have been moving their R&D focus
more toward applications of technology and differentia-
tion from their competitors based on lower cost struc-
tures and superior customer service enabled by the
skilled application of commercial-off-the-shelf technolo-
gies obtained from their suppliers. They are placing less
emphasis on investing in the creation of the underlying
technologies themselves and are relying instead on their
suppliers to make those investments. However, they do
spend considerable effort in understanding technology
trends in order to anticipate both opportunities and
competitive threats that might result from lower costs or
new capabilities enabled by advances in underlying
technologies in all of the layers of the generic technical
architecture described earlier in this chapter.
In the telecommunications marketplace, a specific
example of this approach involves the introduction of
new fiber optic systems based on Synchronous Optical
Network (SONET) standards. These systems are more
cost-effective and more easily reconfigured than the
prior generation of fiber optic systems. The supplier
community produces these systems and makes them
available to all carriers. The carriers focus on applying
these systems in their evolving network architectures
to reduce their costs and to obtain the benefits of more
flexible and reliable networks. Where carriers attempt
to differentiate themselves is in the use of management
systems that allow them to be more responsive than
their competitors in filling orders for new services that
are carried on their networks and in quickly respond-
ing to service interruptions caused by cable cuts and
equipment failures.
How Business Meets Special Technology Requirements
Business tends to solve problems using as much
commercial technology as possible, since business is
loathe to engage in R&D to solve immediate problems.
It is worth studying an example in detail to understand
the approach. A major investment bank, Morgan Stanley,
needed a system to support trading operations in its New
York City trading areas. The reliability requirements of
the system were extremely high.
The Morgan Stanley approach to this problem was at
the system level (i.e., a system of systems to provide high
reliability using commercial components). In this case,
the commercial systems were redundant engineering
workstations connected by dual Ethernet LANs. System
software was written to automatically reroute work and
network traffic in the case of failure. Thus the system was
created from commercial technology using redundant
commercial components in a nonstandard way. The
nonstandard result was almost exactly twice as expen-
sive, but it achieved a multiplicative gain in reliability for
this cost plus the addition of a small amount of software
and some management discipline.
Thus a somewhat ad hoc and opportunistic ap-
proach led to a solution that met Morgan Stanley's
needs via the innovative application of COTS technolo-
gies. The key to success was in focusing on meeting
the need, while leaving the solution (detailed require-
ments) flexible.
Leveraging Legacy Investments and
Fostering Rapid Acceptance of Information Technology
Corporations and institutions have been deploying
computer based systems and applications for 40 years.
These systems are based on a wide variety of diverse
technologies and architectures and were typically not
designed to interoperate with each other in the context
of an overall enterprise-wide architecture. Collections of
such systems, which represent an embedded investment
by the organization or enterprise, are typically referred
to as "legacy systems." The issue of "what to do with
legacy systems" is an old one in the commercial world,
but it is growing in importance as the number and
complexity of legacy systems increase and as the accom-
panying maintenance costs and update backlog grow. In
addition, the allure of more modern systems with up-
dated technologies has made the weaknesses of legacy
systems more prominent.
The technical problem of designing a new system to
replace a legacy system is usually the easiest part of a
problem. Much more difficult is the cost justification of
replacement, management of risk (at first, the new system
might not work as well as the old), and reluctance of
users and system operators to learn the way a new system
works. On the other hand, most engineers prefer to work
on new-systems design rather than upgrading old sys-
tems, and legacy-system expertise becomes more and
more scarce as time goes by.
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REVIEW OF RELEVANT COMICAL ~CH.YOlOGI~
While there is no single preferred method of dealing
with the legacy system dilemma, the following are sug-
gested alternatives.
Alternative 1
The first alternative would develop a new-technology,
wholesale replacement for the legacy system, with no
change in functionality or user interface. This approach
has the advantages that the requirements may be well
understood (see below) and there is minimal retraining
for end users. Ostensibly there will be attractive future
savings in maintenance costs, and the new system will
accept upgrades more quickly and gracefully.
The difficulty is that, in any given year, it is always
cheaper to carry the legacy system a bit further than to
undertake a new development. In addition, all of the
requirements that are being met by the old system may
not be well documented. Therefore, the new system may
initially fall short of meeting all current business require-
ments. In addition, for large systems, such "big bang"
approaches to the replacement of legacy systems have
almost always failed to meet schedules and budgets and
have often resulted in major project failures where
hundreds of millions of dollars of development have
been "written off."
Alternative 2
This alternative would develop a new-technology
replacement for the legacy system, with new features and
capabilities. This approach is similar to alternative 1
above, except it has the additional advantage of offering
new features that may answer long-standing requests for
legacy system upgrades. Such new features may add risk,
delay, cost, and new user-training requirements.
Alternative 3
The third alternative would freeze changes to the
legacy system and "surround" or encapsulate it within a
new system. Over time, legacy system functions can be
replaced by new-technology elements until the legacy
system is totally replaced. This approach has the advan-
tage of leveraging capabilities already present in the
legacy system without making further direct investments
in it. It has the disadvantage that few legacy systems can
be subsumed easily within a new system.
An example of this approach is to make existing legacy
system data accessible via modem graphical user inter-
faces, which can access multiple legacy systems and new
45
systems in an intuitive, easy-to-use manner. This approach
has been successfully employed to transition large legacy
systems used to manage and automate telephone company
operations.
Alternative 4
The last alternative would (a) continue to use and
maintain a legacy system but "cap" the number of users,
and (b) develop a new system for new users (or some
subset of the old users) and develop interworking ar-
rangements with the legacy system as required. This
approach has the advantage of limiting the expansion of
the legacy system while simultaneously limiting the risk
associated with wholesale replacements. If the new
systems truly offer lower costs and increased capabilities,
then it becomes easier to plan for the legacy system
replacement because the benefits will be known in
advance. This approach has the disadvantage that it may
not be appropriate for large, tightly integrated systems.
In particular, the inte~vorking problems with the legacy
system could be substantial.
Deciding which path to pursue is ultimately based on
such things as cost-benefit trades and the culture of the
organization facing the problem. In any given budget-
year, it is almost always cheaper and politically safer to
"get one more year" out of a legacy system than to
attempt replacing it. Alternatives 3 and us above can be
used to control risk, but ultimately it takes farsighted
managers who encourage risk taking by subordinates to
pursue a legacy system replacement program.
Adopting a Spiral Model
In recent years, industry has moved from its traditional
model of software development, sometimes pejoratively
referred to as a "waterfall" model, to a new model of
Selfware development referred to as a "spiral" model
(Boehm, 19871.
In the traditional waterfall model. development pro-
ceeds in one sequence through the following phases:
system requirements specification, system design, soft-
ware coding, and system tesiin~with any problems
found in system testing generally repaired by iterating
back to the design or coding phases. The waterfall
metaphor derives from the one-way flow of this process
down a sequence of, for the most part, irreversible steps.
The difficulty with this process is that, in complex
systems, requirements that are set early on may not
adequately capture the needs of real users. In addition,
some requirements may imply development difficulties
and corresponding costs that are out of proportion to
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46
their user benefits. Those who formulate the require-
ments may not be aware of the latest emerging technolo-
gies and their associated or potential capabilities, and
thus they may specify requirements that cannot leverage
these capabilities. As a result, large systems may be
developed that fail to meet user needs, take longer to
develop, and are more costly than necessary.
To address this problem, a "spiral" model of develop-
ment has been adopted by most developers of large,
complex software systems. In the spiral model, one
iterates quickly through a cycle of requirements specifi-
cation, development of a prototype that captures the
most important aspects of the requirements (prototyp-
ing), and testing with real users. In this iterative process,
one can quickly discover user needs that are not met
(e.g., the system is hard for real users to use), and one
can quickly discover requirements that drive cost and
total development time out of proportion to their in-
tended benefits. The spiral metaphor derives from the
rapid cycling that occurs through the phases of require-
ments specification (and respecification), prototype de-
velopment, and testing.
Experience shows that the spiral model of develop-
ment leads to lower development costs, more rapid
development, and substantially greater satisfaction of real
user needs. Key to this process is the use of prototypes
that simulate the most important aspects of the system
under development but do not implement all of the
detailed requirements on each cycle through the spiral
model. As an illustration, an early mock-up of a user
interface could be done with something as simple as
Post-it notes stuck on a board to simulate pull-down
menus. A simulation of a database access capability need
not be connected to the real database system. It could,
instead, be connected to a simulated database system that
imitates the delays that will occur in returning an answer
to a query and illustrates how the answer will be
presented to the user.
Process Improvement
For all its importance, the production of software,
especially large-scale system software, is still as much art
as it is science. To address the problem, the Software
Engineering Institute (SKI) of Carnegie-Mellon University
developed a Capability Maturity Model for software
organizations wishing to improve their proficiency
(Humphrey, 19891. The approach provides an explicit
road map for change and a way for an organization to
keep score on its progress.
Specifically, the SKI Capability Maturity Model allows
an organization to rate itself and track its progress
through five successive "levels" of proficiency. Level 1,
COMMERCIAL MULTIMEDIA TECHNOLOGIES FOR 7~WEN7Y-FIRST CEN7-URYARMYI3A T~EFIELDS
the lowest level, is characterized by chaos and unpre-
dictability in cost, schedule, and quality. Level 5, the
highest level, is one in which cost, schedule and, quality
have become highly predictable based on quantitative,
repeatable measurements and well-established proce-
dures. The intermediate levels allow an organization to
track its evolution toward Level 5. The SKI Capability
Maturity Model has become well-established in the soft-
ware industry. Most large software organizations conduct
self-evaluations, and many are evaluated by outside
consultants who specialize in doing so.
The approach the SKI took is quite general- it is based
on the writings of P. B. Crosby and the "quality maturity
structure" that he defined (Crosby, 19791. The fundamen-
tal (and common sense) notion taught by Crosby is that
an organization wishing to make a positive change in the
way it does business "must" find a way to treat its
processes as measurable, trackable, and controllable.
SUMMARY
This chapter has outlined commercial multimedia
technologies to provide support for the analysis con-
tained in Chapter 4. The principle was to examine
building block technologies selected on the basis of a
generic layered architecture, which was introduced at the
beginning of this chapter. The intent was to describe each
of these building blocks, with a focus on their current
status and likely trends.
In addition, there was discussion of examples of
commercial, system-level applications of multimedia
technologies. Finally, there was a review of some impor-
tant lessons learned in the commercial world with respect
to these technologies.
This chapter has shown that multimedia information
technologies and the capabilities they enable are evolv-
ing rapidly under the pressure of commercial market
forces and underlying technological advances. This status
portends well for the availability of solutions from the
commercial world that will be addressed in Chapter 4.
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Representative terms from entire chapter:
block technologies
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