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BOX 1 Information Infrastructure—Shared
Resources
The analogy between information infrastructure and
the interstate highway system has helped bring the concept of the
NII into the popular consciousness. The analogy is apt, and not
only because of the role Vice President Gore's father played in
drafting the legislation that led to the interstate highway
system.
The fundamental commercial utility of the highway
system (and the railroads) is the substitution of transportation
for local production, enabling new economies of scale and resource
sharing in many industries. Economies of scale in manufacturing
industries can be such that the cost of large-scale remote
manufacture combined with transport can be significantly less than
the cost of local production.
The highways are infrastructural in that they make
entire industries more efficient, resulting in better value for the
customer and expanded markets for producers. It is this value that
justifies the public investment in the infrastructure.
More importantly, it explains why public
investment and policy support are necessary stimuli for
infrastructure development: because shared infrastructure provides
advantage to all who use it, there is no particular competitive
incentive for specific infrastructure users (producers or
consumers) to invest directly in its creation. On the other hand,
expanded markets benefit all users, and so user investment in
infrastructure is justified if it is distributed equitably. For
example, public highways may receive their initial funding from
bond issues combined with direct taxpayer support, with operating
costs and loan service costs funded by users through tolls and
licensing.
The highway system infrastructure is sustained
through a continually evolving set of interrelated infrastructure
elements, such as roadbed engineering standards, speed limits,
roadside amenities, interstate trucking regulations, tolls, and
routing architecture. National-scale users are able to rely on this
structure and thus commit the success of their enterprises to its
continued existence without expanding their risks.
Information infrastructure development involves an
analogous set of elements. Network protocols, application
interfaces, interoperability standards, and the like define the
class of mechanisms through which value is delivered. Value comes
from high-level services such as electronic mail, information
services, remote access, and electronic commerce all supporting a
rich variety of information objects. Reliance and commitment from
national-scale users depend on breadth and uniformity of access,
common architectural elements, interoperability, and a reasonably
predictable and manageable evolution
The importance of common architectural elements to
infrastructural utility must not be understated. Rail-gauge
standardization is a canonical example. But commitment to common
architectural elements must also include commitment to a process
for evolving them. Achieving the right balance is a principal
challenge to creating an adoptable national information
infrastructure.
Finally, acting in the interest of government applications, the
government can take a proactive role as consumer of NII
technologies to stimulate its suppliers to respond effectively in
delivering information infrastructure that supports government
applications. Possible government applications include systems for
government information, crisis response, and environmental
monitoring.
The gigabit testbeds in the HPCC program offer a model for
research partnerships among government, industry, and academe and
represent a resource on which to build prototype implementations
for national applications. Each testbed is cost-shared between
government and the private sector and embraces the computer and
telecommunications industries, university research groups, national
laboratories, and application developers. The key function of the
testbeds is to experiment with new networking technology and
address interoperability and commonality concerns as early as
possible.
Relationship Between High-Performance
Technologies and the NII
The federal HPCC program supports the research, development,
pilot demonstration, and early evaluation of high-performance
technologies. HPCC's focus in its initial years was on the
grand
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challenges of science and engineering, with a strategy of
developing a base of hardware and software technologies that can
scale up to large-scale processing systems, out to wide-area
distributed systems, and down to capable yet portable systems
(FCCSET, 1994; CIC, 1994). These scalable technologies will
contribute strongly to the NII, as will the legacy of cooperation
between government, industry, and academia. These can greatly
accelerate the establishment of an evolvable information
infrastructure architecture, with testbed development, protocol and
architecture design, interoperability experiments, and benchmarking
and validation experiments. This legacy has helped facilitate
adoption of HPCC-fostered technologies by independent users by
significantly reducing their costs and risks of adoption.
This twofold HPCC stimulus, of research and cooperation,
combines with a program emphasis on demonstration, validation, and
experimental application to create a framework for government
technology investment in NII. For this reason, HPCC was expanded in
FY1994 to include a new major program component, Information
Infrastructure Technology and Applications (IITA), focusing
directly on creation of a universally accessible NII, along with
its application to prototype NC applications. (These activities are
described in more detail in the section below titled ''The Federal
HPCC Program and the NII.")
Each of the other HPCC program activities contributes to IITA.
For example, emerging large-scale information servers designed to
provide information infrastructure services are based on
HPCC-developed, high-performance systems architectures, including
architectures based on use of advanced systems software to link
distributed configurations of smaller systems into scalable server
configurations. The microprocessors used in these large-scale
systems are the same as those found in relatively inexpensive
desktop machines. High-performance networking technologies, such as
communications network switches, are increasingly influenced by
processor interconnection technologies from HPCC. Networking
technologies are also being extended to a broad range of wireless
and broadcast modalities, enhancing mobility and the extent of
personal access. Included in this effort are protocols and
conventions for handling multimedia and other kinds of structured
information objects.
NII can be viewed as built on a distributed computing system of
vast scale and heterogeneity of an unprecedented degree. HPCC
software for operating systems and distributed computing is
enhancing the interoperability of computers and networks as well as
the range of information services. The software effort in the HPCC
program is leading to object management systems, methodologies for
software development based on assembly of components, techniques
for high assurance software, and improvements to programming
languages. These efforts will contribute to the development and
evolution of applications software built on the substrate of NII
services.
Three-Layer National Information
Infrastructure Architecture
Within the HPCC community, a much-discussed conceptual
architecture for the National Information Infrastructure has three
major interconnected layers: National Challenge Applications,
supported by diverse and interdependent NII communication and
computation Services, built on heterogeneous and ubiquitous NII
bitways (see Figure 1). Each layer sustains a diverse set of
technologies and involves a broad base of researchers and
technology suppliers, yielding a continuously improving capability
for users over time. By delivering utility to clients in the layers
above through common mechanisms or protocols, a rapid rate of
evolution of capability can be sustained in a competitive
environment involving diverse suppliers. Thus, developments in each
of these layers focus both on stimulating the creation of new
technologies and on determining common mechanisms or
protocols—the commonality—through which that capability
can be delivered. For example:
•
The keys to scaling up in national challenge
applications are often in the choice of common application-specific
protocols. For example, manufacturing applications require shared
representations for product and process descriptions to support
widespread interoperability among design systems and tools.
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•
Services such as multimedia multicast can be
provided to developers of Application capabilities through proper
adherence to common protocols. With well-designed protocols and
interfaces, rapid growth in multimedia capability and capacity can
be delivered to end users and applications developers without
requiring major reengineering of the whole applications-level
systems. Services are also interdependent and themselves evolve in
this manner.
•
The diverse bitways technologies deliver
communications capability in a uniform manner through use of
standard protocols, such as SONET/ATM. This has the effect of
insulating developers of NII services from the details of the
rapidly evolving communications technologies used to deliver
information capabilities to end users and applications.
This architecture addresses directly the challenge of scale-up
in capability, size, and complexity within each of the three
layers. Ongoing validation of concepts can be achieved, in each
layer, through large-scale testbed experimentation and
demonstration conducted jointly with industry, users, and suppliers
of new technologies and information capabilities. If the evolution
of the NII architecture proceeds as envisioned, the result will be
the integration of new capabilities and increased affordability in
the national challenge applications. Each layer supports a wide
range of uses beyond those identified for the specific national
challenge applications. For example, generalized NII service and
bitway technologies can also support applications on a very small
scale, extensions of existing services, ad hoc distributed
computing, and so on.
The national challenge applications are described in more detail
in the next section, with the issues addressed by the services
layer in the succeeding section titled "Services." Bitways
technologies are well covered in other sources, such as
Realizing the Information Future (CSTB, 1994), and are not
discussed here.
Figure 1
A model three-layer architecture for the NII. Bitways provide the
communications substrate, the applications layer
supports the implementation of the NCs, and the services layer
provides the bridge between communications and
information. (a) Despite the need for similar application-enabling
services, each NC sector might reimplement these
from scratch, yielding overly expensive stovepipe systems if there
were no common services layer. (b) A common
services layer coupled to toolkits for building applications.
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National Challenge Applications
Numerous groups have developed lists of critical applications,
characterized by the potential for a pervasive impact on American
society and exploitation of extensive communications and
information processing capabilities. For example, in 1993 the
Computer Systems Policy Project identified design and
manufacturing, education and training, and health care as the
national challenges (CSPP, 1993). A more exhaustive list has been
developed by the Information Infrastructure Task Force,
representing the union of much of what has been proposed (IITF,
1994). Among these NC applications are the following:
•
Crisis Management: Crisis management
systems exploit information technology to ensure national and
economic security through various kinds of crises. This is
accomplished by providing timely data collection and intelligence
fusion, advanced planning tools, rapid communications with defense
forces spread around the globe, and a command and control ability
to respond quickly to crises. The same basic capabilities can be
deployed on a smaller scale to respond to local emergencies, such
as devastating hurricanes, earthquakes, or fires.
•
Design and Manufacture:These systems
integrate engineering design with product manufacturing, to reduce
the time to create new products, to lower production costs, and to
increase product quality. In a wider sense, a pervasive design and
manufacturing system should couple suppliers to their customers
throughout the production chain. Goals are more responsive product
design, manufacture, and just-in-time warehousing and product
delivery.
•
Education and Training: These systems
provide access to online instructional and research materials,
anywhere and anytime, as well as more direct communication among
students and educators. Once created and made accessible,
instructional materials may be reused and evolved by instructors
around the country. For example, educational use of the information
infrastructure can enable distance learning, where students in
remote locations can gain access to specialized instruction.
Training could exploit simulation coupled with remote access to
actual apparatus.
•
Environmental Monitoring: These systems
integrate data from ground, airborne, and space-based sensors to
monitor (and potentially respond to) environmental changes. They
may be used to discover a nuclear accident in progress, oncoming
climatic effects such as smog conditions, or can be exploited for
longer-term studies such as climate change.
•
Government Information Delivery: Citizens
have a right to ready, low-cost access to government information
that they have already paid for, including economic statistics,
trade information, environmental and land use information, and
uniform one-stop shopping for government services such as veterans'
and social security benefits.
•
Health Care: These systems use information
technologies to improve the delivery of health care, by providing
ready access to patient records, remote access to medical
expertise, support for collaborative consultations among health
care providers, and rapid, paperless claims adjustment that can
help reduce health care costs.
There are two additional applications that sit at the interface
of the national challenges and the underlying service layer:
digital libraries and electronic commerce. In a sense, these are
fundamental enablers for information access and electronic exchange
of value and will be extensively used by virtually all of the other
NC applications described above.
•
Digital Libraries: A digital library is a
knowledge center without walls, accessible from anywhere through
networked communications. These systems are leading to significant
advances in the generation, storage, and use of digital information
of diverse kinds. Underlying services and technologies range from
advanced mass storage, online capture of multimedia data,
intelligent information location and
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filtering, knowledge navigation, effective human
interfaces, system integration, and prototype and technology
demonstration.
•
Electronic Commerce: Electronic commerce
integrates communications, data management, and security services
to allow business applications within different organizations to
automatically interchange information. Communications services
transfer the information from the originator to the recipient. Data
management services define the interchange format of the
information. Security services authenticate the source of
information, verify the integrity of the information received by
the recipient, prevent disclosure of the information to
unauthorized users, and verify that the information was received by
the intended recipient. Electronic commerce applies and integrates
these infrastructure services to support business and commercial
applications, including financial transactions such as electronic
bidding, ordering and payments, and exchange of digital product
specifications and design data.
In each of these applications there is an unmet challenge of
scale: How can the service be made ubiquitously available with
steadily increasing levels of capability and performance? The
applications communities depend on information technology for
solutions but are facing scaling barriers, and hence the NII goal
of crossing the threshold of ubiquity. In the absence of common
architectural elements, such as interfaces, methods, and modules,
it may be possible to demonstrate prototype solutions to specific
applications problems through monolithic stovepipes. But these
solutions may not give any means to pass this threshold of
pervasiveness and dependability.
Services
Overview
As we have noted, information infrastructure is more than
bandwidth, switching, and ubiquitous communications access. It is
(1) the common service environment in which NC applications are
built. All applications share generic service needs: human
interfaces (e.g., graphical user interaction, speech recognition,
data visualization), application building blocks (e.g., planning
subsystem, imaging subsystem), data and process management (e.g.,
search and retrieval, hyperlink management, action sequencing), and
communications (e.g., IPC, mobile computation). Also, the
engineering of applications requires (2) tools in the form of
development environments, toolkits, operational protocols, and data
exchange and action invocation standards from which service
solutions can be combined, integrated, and reused. Finally, the
engineering of applications becomes more efficient (as is already
occuring for shrink-wrap software running on personal computers) in
the presence of (3) a marketplace of reusable subsystems; in this
manner, applications systems can be assembled from competitively
acquired subsystems rather than built directly from the raw
material of lines of code.
We elaborate slightly some of the elements of the common service
environment:
•
Tools, Libraries, and Databases: There
already exist major, complex software systems that provide
implementations for portions of the national challenge
applications. For example, large collections of computer-aided
design (CAD) software are already used extensively in engineering
design domains. Similarly, relational and object-oriented database
management systems provide extensive capabilities for structured
data storage, indexing, and management. Diverse sets of software
tools and subsystems can be integrated into coherent applications
development environments to form the development base with which to
assemble the national challenge applications. Similarly, diverse
libraries of program components and databases of data elements can
be composed and integrated into the development environment.
•
Composition and Integration Frameworks:
Toolkits already exist in certain specific domains to assist in the
composition and integration of tools, libraries, and databases. For
example, the CAD
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Framework Initiative (CFI) accomplishes this by
providing interface specifications for tool-to-tool communications
and tool-to-database communications. In addition, the CFI has
developed prototype implementations of these capabilities. These
can form the basis of value-aided and commercially supported
packages and software toolsets. Commercial vendors of applications
software for desktop computers are developing a variety of
frameworks (such as CORBA, OLE, OpenDoc, and others) for
integration of software applications. Users expect that commercial
pressures will eventually result in some degree of integration of
these various frameworks. This issue of multiple standards is
discussed further below.
•
Building Block Object Sets: The commonality
that characterizes many of the service needs of the national
challenge applications naturally yields an evolving shared market
of software objects (that is, actions, operations, and protocols as
well as data structures) to emerge that can be reused across
multiple application development efforts. For example, a schedule
object, which provides operations for allocating limited resources
to critical tasks, could be used as a component of several
different applications.
•
Application Customized Objects: Leveraging
the evolving building block object sets, we expect the objects from
which the applications are implemented to be customized and
extended for the application at hand. For example, though there is
much in common in terms of command, control, communications, and
intelligence (C3I) for an
intensive care unit and an environmental spill, we would expect the
details of sensor integration, strategies for alerting, and demands
for real-time response to be somewhat different. The elements of
the underlying object base will need customization for their use in
specific national challenge applications. The degree of commonality
across applications, which we hope is large, remains to be
discovered.
Considerations in Constructing the
National Information Infrastructure
Common architectural elements. The national
challenge applications obtain service capabilities delivered
through common protocols or interfaces (known commercially as APIs,
or applications portability interfaces). Though service
capabilities may evolve rapidly, to the benefit of users, they are
delivered through particular interfaces or protocols that evolve
more slowly. This insulates the client architecturally from the
rapid pace of change in implementations, on the one hand, but it
enables the client to exploit new capabilities as soon as they
appear, as long as they are delivered through the accepted
interface. A competitive supply of services hastens the processes
of convergence to common protocols and evolution therefrom.
Industry standards, stovepipes, and risk. We have
asserted that commonality among the protocols, interfaces, and data
representations used in the services layer of the NII will be
critical for its success. To the extent that emerging or evolving
industry-standard commonalities are replaced by ad hoc or
proprietary stovepipe approaches for the national challenge areas,
applications developers place themselves at risk with respect to
delivery of capability and future evolution path. In particular, in
return for complete ownership or control of a solution, they may
give up the opportunity to ride the curves of growth in rapidly
growing underlying technologies, such as multimedia, digital
libraries, and data communication. The challenge of the national
challenge applications is how the applications constituencies can
have both control of applications solutions and participation in
the rapid evolution of underlying technologies. Government,
supported by research, can invest in accelerating the emergence of
new common architectural elements, and in creating technologies
that reduce the risk and commitment associated with adoption of
rapidly evolving standards.
Evolution of commonalities. Accepted protocols
naturally manifest a certain stickiness independent of their merit,
because they become a stable element in determining systems
structure and
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develop associated transition costs and risks. The history of
TCP/IP and OSI is a good example of this well-known phenomenon, as
is the recent introduction of de facto standards relating to the
World Wide Web (URLs and HTML). In particular, research and
government can take a leading role in establishing new
commonalities that foreshadow industry standards.
Rapid evolution and multiple standards. There are
numerous standards presently in use for image representation. Most,
but not all, are open standards; several are proprietary or
otherwise encumbered. Regardless of the degree of acceptance of any
one these standards, the pace of change is such that it would be
foolish for a major software application developer to lock itself
into accepting or producing images according to just one of these
standards. Indeed, most major software applications building-blocks
accept multiple such standards, thus increasing the robustness of
the client applications with respect to either the technical
characteristics or market acceptance of any one of the particular
standards for bitmaps. In addition, tools are readily available for
converting among the various representations for images. Thus, from
the standpoint of applications architecture, a robust design can be
created that does not depend on the fate of any one of the many
standards, but rather on the evolution of the entire suite. The
multiple commonalities emerge as customers and producers seek
frameworks for competition in service niches. However, experience
suggests that over time multiple related standards may begin to
coalesce, as the commercial focus (and margins) move to higher
levels of capability and the differential commercial advantage of
any specific standard diminishes or even evolves into a liability.
Anticipation of the process can yield robust scalable designs for
major applications even when there is volatility in the markets for
the subsystems they depend on.
Competition and layering. With the right approach
to standards and infrastructural subsystems, diverse underlying
technologies can evolve into common, shareable, and reusable
services that can be leveraged across multiple NC applications.
Alternative implementations of a frequently used service, such as
display window management, eventually will lead to the
identification of best practices that can be embodied in a common
services layer—for example, for human interfaces. And robust
designs of the applications layers above will enable this rapid
evolution to be accepted and indeed exploited. (Consider, for
example, the rapid rate of release of new versions of World Wide
Web browsers, and the huge multiplicity of platforms they run on,
and the rapid rate of evolution of the many multimedia (and other)
standards they rely on. The Web itself, however, evolves at a
slower rate and is not invalidated by these changes in particular
niche services. The standards on which the Web is based evolve even
more slowly.) The conclusion we draw is that simultaneous evolution
at multiple layers is not only possible but also needs to be an
explicit architectural goal if ubiquity is to be attained at the
applications level.
Concerning layers. Services depend on other
services for their realization. For example, a protocol for
microtransactions will likely rely on other protocols for
encryption and authentication. This enables a microtransaction
system not only to be designed independently of the particular
encryption and authentication services, but also to sustain later
upgrade of (or recompetition for) those services in a robust
manner. In spite of this dependency, services are not organized
rigidly into layers as is, for example, the seven-layer OSI model.
the term "layering" is instead meant to suggest that services
naturally depend on other services. But the exact interdependency
can change and evolve over time. The commonalities through which
services are delivered thus form a set of multiple bottlenecks in a
complex and undulating hourglass (using the analogy of CSTB,
1994).
Service classification. A consequence of the above
argumentation is that the success of the overall NII does not
depend on achievement of a particular master infrastructural
architecture. But it must be emphasized that it does strongly
depend on emergence of a broad variety of infrastructural service
architectures designed with scale-up, and indeed ubiquity, in mind.
Ubiquity (as suggested in the comments
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above on multiple standards) is in the appearance of
representatives of a set of related commonalities, and not in any
particular protocol or component. This also suggests there is no
ultimately correct layering lurking in the soup of services, but
rather multiple candidates and arrangements. Without commonalities
there is no national information infrastructure, but the particular
need for specific all-encompassing commonalities is mitigated to
the extent that technologies and tools for interoperability are
available. That is, suites of related evolving commonalities can be
supported to the extent that conversion and interoperability tools
are available. The issue devolves into finding the right balance in
this equation.
The government thus can employ a mixed strategy in fostering
national challenge applications through infrastructural
commonalities. It can stimulate development of new services,
creation and evolution of new architectural commonalities, and
development of readily available technologies of interoperability.
Direct research and development is the most effective way to
stimulate new service capabilities and associated commonalities.
The government can also exploit its own market presence (though the
leverage is less), taking an activist role in industry forums for
conventionalization (informal emergent commonalities) and standards
(formalized commonalities).
An illustrative layered model. One possible
service taxonomy, elaborated below, classifies generic services
into categories: human interfaces, applications building blocks,
data and process management, and communications. Human interface
services include window managers (e.g., Motif, NextStep), tools for
speech handling and integration (generation as well as
recognition), handwriting recognition, data visualization packages,
toolkits for audio and video integration, and so on. Applications
building blocks include planning packages, scheduling packages,
data fusion, collaboration support, virtual reality support, and
image processing and analysis. Data and process management services
consist of capabilities for configuration management, shared data
spaces, process flows, data integration, data exchange and
translation, and data search and retrieval. Communications services
include ubiquitous access through various communications mechanisms
(e.g., wireless as well as wired connections into the bitways),
mobility services to support users as they move through the points
of connection into the network, interprocess communications and
remote process call mechanisms to support distributed processing,
and trust mechanisms such as authentication, authorization,
encryption, password, and usage metering.
The service layers themselves evolve as new underlying
technologies appear that provide new functionality or better ways
of doing things. A construction kit can support the assembly and
evolution of applications based on the service suite. Elements of
this kit, also elaborated below, could include software
environments for developing applications, evolution of standard
operational and data exchange protocols, software toolkits and
software generators for building or generating well-defined
portions of applications, and frameworks for integrating tools and
data into coherent, interoperable ensembles.
The value of a common services layer is conceptually indicated
by Figure 2. In Figure 2(a), the lack of a common services
infrastructure leads to stovepipe implementations, with little
commonality among the service capabilities of the various national
challenges. In Figure 2(b), a common set of services is leveraged
among the national challenges, aided by a collection of toolkits,
integration frameworks, and applications generators.
Information Enterprise Elements
Commonalities usually (but not always) emerge in the presence of
a diversity of evolving implementations. A commonality in the form
of a protocol is an abstraction away from the details of
implementation that allows utility or value to be delivered in an
implementation-independent manner to the service client. This
suggests a threefold analysis for service capabilities: utility of
some kind, delivered through a particular commonality such as a
protocol, abstracting away the details of the diversity of
implementations. Of course, the commonalities themselves evolve;
they just evolve more slowly.
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Figure 2
Technical challenges in building a national information
infrastructure.
Figure 3 shows examples of elements for each of the three layers
of the national information infrastructure architecture. In the
figure, the three columns indicate the following:
•
Utility: Each service provides specific
value to users or clients. For example, the bitways are intended to
provide ubiquitous data communications, and in a manner such that
designers of applications need not know whether the communications
links are through fiber, wireless, or some combination of links.
The client needs only an abstract rendering of the characteristics
of the aggregate link.
•
Commonality: A common protocol or API
creates a framework for delivery of utility. Clients engineer to
this framework (and its expected evolution), thereby insulating
themselves from the underlying implementation details.
Diversification of technology occurs behind the protocol, enabling
the technologies to be made accessible to clients with acceptable
risk and cost-effectiveness, and also lowering entry barriers both
for new users of the technologies and for new sources of
capabilities. This is the essence of the principle of open
architecture. For example, transport protocols for bitways provide
users of communications services with a means to access the service
independently of the particular choices of underlying component
technologies.
•
Diversity: These are the areas of
implementation technology where innovation, rapid technological
growth, and diversity of supply are essential to cost-effective
delivery of increasing levels of
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capability. For example, a competitive supply of
fiber optic connectivity is needed to provide ubiquitous access to
high performance bitways. Also, continued improvements in optical
and wireless communication improve affordability of
high-performance mobile communication.
Figure 3 shows examples of these concepts for each of the layers
of the NII conceptual architecture. This organization focuses
attention on two critical issues, alluded to in the foregoing, that
must be addressed in the design of service commonalities:
•
Scalability: Testbeds and other mechanisms
provide means to assess the degree of scalability of new service
concepts and protocols. They also address the extent of
dependencies among services. Scalability, for infrastructure,
necessarily includes potential for pervasive acceptance. Protocols
that are proprietary or encumbered in other ways have a lesser
chance of being accepted, because of the degree of technological
and programmatic risk associated with them. But, as always, there
is commercial advantage to being the first to introduce a
successful open protocol, so the incentive persists for commercial
introduction of commonalities, even when they are fully open.
•
Legacy: There are two aspects of the legacy
issue, a constraint and a goal. The first is the legacy we inherit,
which constrains our architectural design decisions in fundamental
ways. The second is the legacy we bequeath in the form of
commonalities from which later architectures must evolve.
Opportunities for competition are naturally sought by service
clients, and adiversity of implementationsindicates success in this
regard. At the level of bitways, for example, thepace of change is
rapid, and thereare wide-ranging approaches for achieving a given
capability (e.g., physicalmedia may consist of opticalfiber, land
mobile wireless radios, or laser communications). The challengefor
the application developer ishow to exploit the continuing
innovation while remaining insulated fromcontinuous change; the
clientwants to ride the curves of growth while avoiding continual
reengineering.
One conclusion to draw from this analysis is that research must
focus not only on creation and demonstration of new kinds of
service capability, but also on the scientific and technological
aspects of architectural design: designing and evaluating
candidates for protocol and API definitions, looking at both the
supplier and client perspectives.
The Federal HPCC Program and the
NII
Overview
In FY1994, the federal HPCC program was extended with a new
responsibility, to develop Information Infrastructure Technology
and Applications (IITA) to demonstrate prototype solutions to
selected national challenge applications using the full potential
of the rapidly evolving high performance communications and
information processing capabilities. The details of the programs
evolving goals and research plans are in its annual reports to
Congress (FCCSET, 1994; CIC, 1994).
With the incorporation of IITA within its research agenda, the
HPCC program is advancing key NII-enabling technologies, such as
intelligent system interfaces, real environments augmented with
synthetic environments, image understanding, language and speech
understanding, intelligent agents aiding humans in the loop, and
next-generation data and object bases for electronic libraries and
commerce. This is being coupled with a vigorous program of testbed
experimentation that will ensure continued U.S. leadership in
information processing technologies.
IITA efforts are designed to strengthen the HPCC technology
base, broaden the markets for these technologies, and accelerate
industry development of the NII. Federal HPCC agencies are working
closely with industry and academia in pursuit of these objectives.
These objectives are to be accomplished, in part,
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Figure 3
Examples to illustrate the concepts of diversity, commonality, and
utility.
by accelerating the development of readily accessible, widely
used, large-scale applications with significant economic and social
benefit. The HPCC program's original focus of enhancing computing
and communications capabilities is thus extended to address a
broader set of technologies and applications that have an immediate
and direct impact on critical information capabilities affecting
every citizen.
As we have described in the previous section, the development of
such applications is predicated on (1) creating the underlying
scalable computing technologies for advanced communication services
over diverse bitways, effective partitioning of applications across
elements of the infrastructure, and other applications support
services that can adapt to the capabilities of the available
infrastructure; and (2) creating and inserting a richly structured
and intelligent service layer that will significantly broaden the
base of computer information providers, developers, and consumers
while reducing the existing barriers to accessing, developing, and
using advanced computer services and applications. In parallel with
these activities, a more effective software development paradigm
and technology base must also be developed, since full-scale
implementations in support of the national challenges will be among
the largest and most complex applications ever implemented. This
will be founded on the principles of composition and assembly
rather than construction, solid architectures rather than ad hoc
styles, and more direct user involvement in all stages of the
software life cycle. The entire technology base developed in this
program, including services and software, will be leveraged across
the national challenges, leading to significant economies of scale
in the development costs.
The intended technical developments of IITA include the
following:
•
Information Infrastructure Services: These
are the collection of services provided to applications developers
and end users that implement a layered architecture of increasing
levels of intelligence and sophistication on top of the
communications bitways. Services provide a universally available,
network-aware, adaptive interface on which to construct the
national challenge applications, spanning communications-based
services at the low end, to intelligent information processing
services at the high end. These services include network support
for ubiquitous access, resource discovery in a
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complex distributed network environment, and
intelligent support services that can negotiate and adapt to the
service quality needs of the application. Information
infrastructure services also include system software and services
that implement pervasive privacy, security and trust mechanisms for
the information infrastructure, persistent object bases with which
to build large-scale data repositories, reliable computing
technologies to support the mission-critical nature of the
infrastructure, and defensive software organized to protect the
infrastructure from intrusion and attack.
•
Systems Development and Support
Environments: This area consists of the enabling technologies
to develop and support large, complex information systems that
exploit a national-scale information infrastructure. Fundamental to
this activity is the use of that infrastructure in the software
development and support process. Virtual organizations consisting
of end users, contractors, and management will synergistically work
together to develop software systems that are easy to use, that can
be adapted through use to fit human needs and changing
requirements, and that enhance end-user productivity, all despite
the complexity of the underlying infrastructure. To achieve these
goals, the focus is on software architectures, component
prototyping, software composition, libraries of reusable and
reliable software modules, end-user tailoring, intelligent
documentation and online help, machine learning, and scalable
compiler and interpreter technology.
•
Intelligent Interfaces: Many of the
national challenge applications require complex interfacing with
humans or intelligent control systems and sensors. In addition,
these applications must be able to understand their environment and
to react to them. Technology in this area consists of high-level,
network-capable applications building blocks for real-time planning
and control, image processing and understanding, human language
technology, extensive use of intelligent computer-based agents, and
support technologies for more effective human-computer
interaction.
•
National Challenges: The concept of
national challenge applications has already been described above.
It is important to distinguish between the implementation of
operational systems and the use of challenging applications
testbeds to demonstrate the value of high-performance technologies
as well as to drive their continued evolution. The government's
research and development role is to focus on the latter; the
private sector has primary responsibility for the former.
Each of the three technology areas (the first three bullets
above) is discussed in additional detail in the following
subsections, which include a sampling of technical subtopics. The
national challenges have already been summarized in a prior
section.
Information Infrastructure
Services
Services provide the underlying building blocks upon which the
national challenge applications can be constructed. They are
intended to form the basis of a ubiquitous information web usable
by all. A rich array of interdependent services bridge the gap
between the communications bitways and the application-specific
software components that implement the national challenges.
•
Universal Network Services: These are
extensions to the existing Internet technology base to provide more
widespread use by a much larger number of users. These include
techniques for improved ease of use, plug-and-play network
interoperation, remote maintenance, exploitation of new last mile
technologies, management of hybrid/asymmetric network bandwidth,
guaranteed quality of service for continuous media streams, and
scale-up of network capabilities to dramatically larger numbers of
users.
•
Integration and Translation Services: These
services support the migration of existing data files, databases,
libraries, and programs to new, better integrated models of
computing, such as object-oriented systems. They also provide
mechanisms to support continued access to older legacy forms of
data as the models evolve. Included are services for data format
translation and interchange as well as
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tools to translate the access portions of existing
programs. Techniques include wrappers that surround existing
elements with new interfaces; integration frameworks that define
application-specific common interfaces and data formats; and
mediators that extend generic translation capabilities with domain
knowledge-based computations, permitting abstraction and fusion of
data.
•
System Software Services: These include
operating system services to support complex, distributed, and
time- and bandwidth-sensitive applications. The services support
the distribution of processing across processing nodes within the
network, the partitioning of the application logic among
heterogeneous nodes based on their specialized capabilities or
considerations of asymmetric or limited-interconnection bandwidth;
guaranteed real-time response to applications for continuous media
streams; and storage, retrieval, and I/O capabilities suitable for
delivering large volumes of data to great numbers of users.
Techniques include persistent storage, programming language
support, and file systems.
•
Data and Knowledge Management Services:
These services include extensions to existing database management
technology for combining knowledge and expertise with data. These
include methods for tracking the ways in which information has been
transformed. Techniques include distributed databases; mechanisms
for search, discovery, dissemination, and interchange; aggregating
base data and programmed methods into objects; and support for
persistent object stores incorporating data, rules, multimedia, and
computation.
•
Information Security Services: These
services provide support for the protection of the security of
information, enhanced privacy and confidentiality for users of the
infrastructure, protection of intellectual property rights, and
authentication of information sources within the infrastructure.
Techniques include privacy-enhanced mail, methods of encryption and
key-escrow, and digital signatures. Also included are techniques
for protecting the infrastructure (including authorization
mechanisms and firewalls) against intrusion attacks, such as worms,
viruses, and Trojan horses.
•
Reliable Computing and Communications
Services: These include system software services for nonstop,
highly reliable computer and communications systems that can
operate without interruption. The techniques include mechanisms for
fast system restart such as process shadowing, reliable distributed
transaction commit protocols, and event and data redo logging to
keep data consistent and up-to-date in the face of system
failures.
System Development and Support
Environments
These provide the network-based software development tools and
environments needed to build the advanced user interfaces and the
information-intensive NC applications.
•
Rapid System Prototyping: These consist of
the tools and methods that enable the incremental integration and
cost effective evolution of software systems. Technologies include
tools and languages that facilitate end-user specification,
architecture design and analysis, component reuse and prototyping;
testing and online configuration management tools; and tools to
support the integration and interoperation of heterogeneous
software systems.
•
Distributed Simulation and Synthetic
Environments: These software development environments provide
the specialized underlying support mechanisms for the creation of
synthetic worlds, which can integrate real as well as virtual
objects, in terms of both their visual as well as computational
descriptions. Methods include distributed simulation algorithms;
geometric models and data structures; tools for scene description,
creation, and animation; and integration of geometric and
computational models of behavior into an integrated system
description.
•
Problem Solving and System Design
Environments: These environments provide the techniques that
support the software and system design process through the use of
automated tools, with particular emphasis on maintaining
flexibility and tailorability in tool configurations to enable
organizations to tailor
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their support environments to their needs.
Examples include efficient algorithms for searching huge planning
spaces, more powerful and expressive representations of plans,
operators, goals, and constraints, and the incorporation of
efficient methods to facilitate scheduling and resource allocation.
The effects of uncertainty must be taken into account as well as
the effects of goal interactions.
•
Software Libraries and Composition Support:
These software tools and methods support the development of common
architectures and interfaces to increase the potential for
reusability across multiple underlying models of computation, the
diversity of programming languages in use, and the varying degree
of assurance provided by software components. Important elements of
this area include the development of the underlying methodology,
data structures, data distribution concepts, operating system
interfaces, synchronization features, language extensions, and
other technology to enable the construction of scalable library
frameworks.
•
Collaboration and Group Software: These
tools provide support for group cooperative work environments that
span time as well as space. Methods include shared writing surfaces
and live boards, version and configuration management, support for
process and task management, capture of design history and
rationale, electronic multimedia design notebooks, network-based
video conferencing support, document exchange, and agents serving
as intermediaries to repositories of relevant multimedia
information. The technology should be developed to make it possible
to join conferences in progress and to be automatically brought up
to date by assistants (agents) with memory.
Intelligent Interfaces
Advanced user interfaces will bridge the gap between human users
and the emerging national information infrastructure. A wide range
of new technologies that adapt to human senses and abilities must
be developed to provide more effective human-machine
communications. The IITA program must achieve a high level user
interface to satisfy the many different needs and preferences of
vast numbers of citizens who interact with the NII.
•
Human-Computer Interface: This supports
research in a broad range of technologies and their integration to
allow humans and computers to interact effectively, efficiently,
and naturally. Developments in this area include technologies for
speech recognition and generation; graphical user interfaces that
allow rapid browsing of large quantities of data; user-sensitive
interfaces that customize and present information for particular
levels of understanding; language corpora for experimental
research; and human-machine interaction via touch, facial
expression, gesture, and so on. The new IITA emphasis is on
integration, real-time performance, and demonstration of these new
communication modalities in multimedia, multisensory
environments.
•
Heterogeneous Database Interfaces: This
supports development of methodologies to integrate heterogeneously
structured databases composed of multiformatted data. To support
NII information dissemination, a capability is needed for a user to
issue a query which is broadcast to the appropriate databases and a
timely response is returned and translated into the context of the
users query. Multiformatted data may range from ASCII text to
numerical time series, to multidimensional measurements, to time
series of digital imagery, etc. Also of critical importance is the
integration of metadata with the data and its accessibility across
heterogeneous databases.
•
Image Processing and Computer Vision: This
activity supports research in making images, graphics, and other
visual information a more useful modality of human-computer
communication. Research areas include all aspects of theory,
models, algorithms, architectures, and experimental systems from
low-level image processing to high-level computer vision.
Methodologies of pattern recognition will be further developed to
allow automated extraction of information from large databases, in
particular,
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digital image data. The new IITA emphasis is on
integration, scalability, and demonstration of easy access and
usability of visual information in real-world problems.
•
User-centered Design Tools/Systems: This
consists of work in models and methodologies leading to interactive
tools and software systems for design and other user-centered
activities. User-friendly tools that combine data-driven and
knowledge-based capabilities is one of the areas for new research.
The new IITA emphasis is on supporting the development of
ubiquitous, easy-to-use, and highly effective interactive
tools.
•
Virtual Reality and Telepresence: This
consists of research that will provide tools and methods for
creating synthetic (virtual) environments to allow real-time,
interactive human participation in the computing/communication
loop. Such interaction may be through sensors, effectors, and other
computational resources. The IITA focus is creating shared virtual
environments which can be accessed and manipulated by many users at
a distance in support of national challenge application areas.
Summary and Conclusions
Much of the discussion of the national information
infrastructure has been at the applications level or the level of
the bitways. Various groups, including Congress and the Clinton
administration, have identified candidate NC applications on the
one hand, while others have dealt with the issues of making
interoperable the various existing and emerging communications
infrastructures. This discussion suggests a shift in focus to the
services layer. The right collection of capabilities at this level
of the infrastructure will have an extraordinary impact on a wide
range of applications.
We have cataloged many of the key technology areas needed for
the service layer of the NII: information infrastructure services,
systems development and support environments, and intelligent
interfaces. The further development of these technologies and their
integration into coherent and robust service architectures,
incorporating the principles of utility, diversity, and commonality
as described here, will be a major challenge for the information
technology research community in coming years.
Cost-shared sponsorship of pilot demonstrations and testbeds is
a key role for government in accelerating the development of the
NII. In each NC application area, opportunities exist to
demonstrate early solutions, including the potential for scaling
up. We suggest that in the exploration of commonality and
conversion issues, testbeds can also help address the fundamental
issue of ubiquity. The scale of the enterprise, and the fundamental
opportunities being addressed, necessitate cooperation among
industry, government, and academia for success. We have suggested
appropriate roles and approaches to cooperation, with emphasis on
the roles of government and research. This is predicated on the
assumption that government, in addition to sponsoring key basic
research, has a crucial catalytic role in working with all sectors
to address the challenge of the national applications to scaling up
to the point of ubiquity and reliance.
Acknowledgments
The ideas expressed in this paper have been influenced by
discussions with colleagues at DARPA, especially Duane Adams, Steve
Cross, Howard Frank, Paul Mockapetris, Michael St. Johns, John
Toole, Doyle Weishar, and Gio Wiederhold. Our ideas have also
benefited from extensive discussions with participants in the HPCC
program from a diverse collection of federal agencies: Howard Bloom
(NIST), Roger Callahan (NSA), Y.T. Chien (NSF), Mel Ciment (NSF),
Sherri de Coronado (NIH), Ernest Daddio (NOAA), Norm Glick (NSA),
Steve Griffin (NSF), Dan Hitchcock (DOE), Paul Hunter (NASA), Jerry
Linn (NIST), Dan Masys (NIH), Cherie Nichols (NIH), Walter
Shackelford (EPA), and Selden Stewart (NIST).
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