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Managing Multivendor Networks
  
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Hewlett-Packard
Company Background
rom a modest start in 1939, Bill Hewlett and Dave Packard developed HP into a
company that specialized in instruments and instrument control, marketing their products
through independent sales organizations. Ten years later, in 1949, HP had sales in
excess of $2 million and more than 100 employees. Throughout the 1950s and into the
1960s, HP continued to grow conservatively. In 1966, Hewlett-Packard released the
first product that could be legitimately called a computer, the HP2116A. The HP2116A
did not, however, mark the beginning of explosive growth in computer manufacturing--it
merely signaled the start of HP's computer-line development.
In 1971, HP released its first hand-held scientific calculator. Unexpectedly,
this product caused a tidal wave of demand that led HP to expand and refine its calculator
products into a variety of specialized markets. The 1970s also saw HP define and
refine its computer product line. Between the mid-70s and mid-80s, its computer offerings
evolved into three basic lines: the HP 1000 real-time technical computer, the HP
3000 general business computer, and the HP 9000 engineering workstation.
Yet, HP was not widely regarded as a leading edge technology company. To be sure,
HP had an excellent reputation for innovation in instrumentation, but this innovation
was never seen in its computer line. In the late 1980s, however, HP gambled--and
gambled big--by introducing a reduced instruction set computer (RISC) design in the
HP 3000, its general business computer. HP stayed in the spotlight with the acquisition
of Apollo Computer in 1989. A seemingly dramatic departure from HP's normally conservative
management style, this acquisition strengthened HP's overall position in the engineering
workstation and workstation server market.
Product Line Overview
As a full-line manufacturer, Hewlett-Packard produces a range of products, from
basic terminals to the high end of the midrange market. Although HP often positions
itself against the low end of the IBM-based mainframe market, it does so more because
of overlaps between IBM's own product lines than true mainframe-class power and performance
in an HP computer.
The latest member of the PA-RISC processor family, the PA-7200, extends the previous
single chip superscalar PA-7100 design with a number of design improvements. The
PA-7200 permits higher clock frequencies and has an on-chip assist cache that combines
with a hardware prefetch mechanism, which can significantly speed up many analytic
and high-end applications. The prefetch algorithm permits instructions to be prefetched
from memory on cache misses, and can offer significant performance improvements in
a transaction processing environment.
HP Terminals
HP terminals are unique in that they can operate in several different modes, and
actually switch in and out of these modes as directed by applications. From a data
communications point of view, this approach offers efficiency--the application minimizes
transmission between the terminal and itself without sacrificing ease of data entry.
On the other hand, first-time HP programmers are often confused by this multipersonality
technology.
In many ways, the HP terminal represents the crossbreeding of the character-oriented
DEC VT terminal with the block orientation of the IBM 3270 and 5250 terminal families.
Some of the terminal's more familiar, character-oriented operations include the following:
- Character mode. In this mode, individual characters are transmitted to
the host as they are typed at the keyboard. This mode is similar to the way that
DEC terminals operate normally.
- Character/forms mode. In this mode, specific areas of the screen are designated
for data entry (termed unprotected fields) and the rest of the display is protected
from alteration.
When an HP terminal is in character mode, the end of transmission is normally
signaled when the operator presses the Return key. In block-mode operation, the operator
must trigger transmission by hitting a separate Enter key.
Furthermore, HP terminals make a critical distinction between block mode and forms
mode (HP actually refers to the latter as format mode). In block-mode operations,
the terminal enters data locally; therefore, the user may edit data before pressing
the Enter key to transmit the data. Forms mode, on the other hand, defines the rules
for establishing protected, unprotected, and transmit-only fields on the terminal
screen.
Forms mode does not require block mode, nor does block mode require forms mode.
These modes are further complicated by a line setting that defines the size of the
transmission. The functional capabilities that result from these seemingly unholy
marriages include the following:
- Block/line mode. When the Enter key is pressed, the current line is transmitted
to the host computer.
- Block/line/forms mode. This causes transmission of multiple fields on
a single line.
- Block/page mode. This is the opposite of block/line mode. In this setting,
the screen (or page) is transmitted when the Enter key is pressed.
- Block/page/forms mode. This mode is similar to the way 3270 -type
terminals operate in that all fields on the screen (or page) are transmitted to the
host computer when the Enter key is pressed.
HP's X terminals are designed to accommodate the desktop computer's increasing
role in corporate computing. HP's X terminal product line provides high-performance
graphics and maximizes access to information and multivendor resources across the
enterprise. HP has two lines of RISC-based X terminals--the low-end Entria Plus and
the higher-end Envizex. Both run the Intel i960 RISC processor.
HP's Envizex color X station appears to the end user as a full-fledged workstation.
The terminal's superb multimedia support provides full-motion MPEG video. The machine
is the only X terminal to provide access to high-speed networks through 100VG-AnyLAN
networking, and is also one of the only X terminals to include an optional internal
floppy drive. The Envizex also builds in ThickLAN, ThinLAN, and standard twisted-pair
network connectors, as well as optional Token Ring support.
The lower-end Entria X terminal is an excellent choice to upgrade from character-based
ASCII or 3270 terminals. Mainframe access can be achieved through a transparent terminal
emulation program and you will enjoy a color GUI-based X station, which can function
as a plug-and-play HP 9000 server console. You can easily switch between console
operations and system management applications on the same desktop. The Entria includes
built-in support for ThinLAN and 10BaseT networking.
The HP Entria Plus line provides access to UNIX, Windows, Internet, and legacy
applications--all from a single X station. The Entria and Envizex are referred to
as thin clients, which make use of the network's infrastructure and devices
as opposed to providing processing and storage for each desktop. HP's approach to
X terminals provides a number of advantages, including auto-configuration and centralized
maintenance of TCP/IP environments through Dynamic Host Configuration Protocol (DHCP).
All of HP's X stations are also tightly integrated with HP's OpenView systems management
software, which permits all of an enterprise's X stations to be centrally managed.
OpenView offers a broad range of management features and is capable of managing any
SNMP-compliant device.
The Entria Plus can function as an HP 9000 graphics server console, eliminating
the need for multiple desktops. Both Entria Plus and Envizex come with HP's line
of software, which includes the following:
- HP Enware X Station Software. One site copy is required to run HP X stations.
- HP Enware X Terminal Manager. Simplifies the administration of large groups
of X terminals and permits an IP address to be assigned automatically through DHCP.
- HP Enware CDE. Provides a standard GUI for UNIX users.
- HP Enware 3270. A motif-based 3270 emulator for legacy mainframe or SNA
connectivity.
In terms of network connectivity, both models can run on a standard Ethernet network;
the Envizex can also be connected to a Token Ring or 100VG-AnyLAN infrastructure.
Both models use standard 10Base-T and ThinLAN connectors. The included SharedX and
SharedWhiteboard features permit multiple users linked with any X Window system and
standard phone line to work cooperatively on a document.
PCs
Until the late 1980s, HP chose to follow the de facto standards set by the original
IBM PC. The early machines were, in fact, Intel processors running MS-DOS software,
but HP added its own enhancements to the product.
In an effort to overcome the cumbersome interface offered by standard MS-DOS (or
PC-DOS), HP developed an alternative command processor that could be used in place
of the standard COMMAND.COM processor. Good intentions notwithstanding, HP called
this interface the Personal Applications Menu (PAM).
The PAM approach gave the end user an applications menu for selecting and running
applications in a point-and-shoot fashion. It also provided a front-end to some of
the more unfriendly DOS processes, such as formatting diskettes. However, PAM was
not performance-oriented, so many veteran users simply abandoned PAM in favor of
the standard command processor.
While it is neither important (nor fair) to review the entire history of HP's
PC products, some of the more interesting innovations included the HP 125 dual terminal/computer,
the HP 150 touchscreen terminal/computer and the HP Portable and Portable Plus. The
HP 125 and HP 150 systems' built-in terminal functions made them popular alternatives
to dedicated terminals. The HP Portable and Portable Plus were among the first of
the MS-DOS transportable, quasi-laptop computers.
With the introduction of the HP Vectra in the mid-1980s, however, HP became a
serious manufacturer of high-performance, IBM-compatible PCs. The Vectra is one of
the original high-performance clones produced by a reputable manufacturer and offering
performance in excess of the equivalent IBM models. Furthermore, in 1989 the 486
Vectra became the first PC on the market to offer the Extended Industry Standard
Architecture (EISA) bus, an alternative to IBM's closed Micro Channel Architecture
(MCA) for its PS/2 line.
Since the introduction of the Vectra line, HP has demonstrated a strong commitment
to releasing network-ready PCs. A network-ready PC, as opposed to a PC designed for
freestanding use, focuses on easy integration into an existing networking environment.
HP addresses the issue of networkability in the Vectra line in several ways. The
Vectra line supports several networking environments, industry-standard management
is included, and the PCs offer remotely manageable security features. In addition,
the higher-end Vectras are ready to attach to the network "out of the box."
The Vectra includes several technologies to maximize LAN performance, including
an integrated PCI LAN adapter, PCI bus mastering, and parallel transfer technology.
The presence of an integrated LAN adapter minimizes CPU usage, as compared to the
alternative of placing a 16-bit ISA LAN adapter in a non-network-ready PC.
In addition, the HP Vectra XM Series 3 uses a parallel transferring driver. Typically,
a LAN adapter is unable to transfer a frame to the CPU before the frame has been
completely received from the network. The parallel transferring driver permits the
transfer to the CPU to start in a parallel fashion, instead of sequentially. This
model significantly improves throughput performance of the LAN interface.
The Vectra PCs are Desktop Management Interface (DMI)-enabled and include client-side
DMI software. The DMI is a product of the Desktop Management Task Force (DMTF), of
which HP is a founding member. DMI is a vendor-independent system that provides management
information about the PC. Interestingly, the Vectra is one of the most network-ready
PCs on the market. It can be turned on remotely from anywhere on an Ethernet LAN,
and includes both local and remote support for HP's OpenView management platform.
The PC's Medium Access Control (MAC) address, which is accessible through remote
DMI or the PC Setup program, is a unique address required to identify each Ethernet
LAN adapter on a network. The availability of the MAC address through remote DMI
eliminates both the need to physically discover the address by removing the case
and the need to use a separate operating system utility.
HP is a leader in multiprocessing technology, first implementing the technology
in its minicomputers and workstations in the 1980s. Multiprocessing at the PC level,
however, is very new, and HP is one of the first vendors to implement Intel's Multiprocessor
Specification (MPS) for dual processing on desktop PCs.
Engineering Workstations
Until the acquisition of Apollo Computer in 1989, the HP 9000 line of technical
computers was HP's entry into this computation- and graphics-intensive, UNIX-hungry
market. Designed to compete head-to-head in the engineering workstation market with
Sun, DEC, IBM and others, the HP 9000 is now divided into the C Class and J Class
categories. HP's workstation product line is largely based on the PA-7200 processor
and provides a migration path to the innovative next-generation PA-8000 microprocessor.
The workstations run the HP-UX UNIX operating system and sport the HP VUE user interface.
Before the C Class and J Class machines, HP's workstations were divided into three
basic categories: the 700/800 (RISC) Series; its predecessors, the 200/300/500 Series;
and the HP Apollo 9000 Series 400, the first collaboration of the combined HP and
Apollo divisions.
The HP 9000 Series 200, 300, and 500 computers were based on the Motorola MC68000
line of CPUs, although some configurations did include an Intel processor. These
low-end units could optionally run one of three operating systems: BASIC, Pascal
and HP-UX. While the BASIC and Pascal operating systems are HP proprietary (although
somewhat portable because they are based on the programming languages of the same
name), the HP-UX operating system is Hewlett-Packard's implementation of AT&T's
UNIX.
On the high end, the HP 9000 Series 800 was HP's first technical venture into
RISC architecture. RISC stands for Reduced Instruction Set Computer and is an alternative
architecture to the standard Complex (or Complete) Instruction Set Computing (CISC).
Under RISC architecture, computer hardware is optimized for absolute maximum performance
and is streamlined so the software at some level (typically the compiler) has to
handle the translation of complex activities into simple, high-speed hardware operations.
In contrast, the CISC architecture uses specialized hardware and firmware to handle
complex activities. Here, the software is streamlined, so the hardware has to compensate.
The demands for engineering workstation functions lie heavily in the areas of
hardware performance. Real-time graphics displays (of extremely high resolution)
driven by computation-intensive modeling programs are not trivial to produce. HP
accommodates the need for real-time graphics with the inclusion of its VISUALIZE
graphics accelerator in all of its work-station products. VISUALIZE combines the
fast, RISC-based CPUs with an on-board RISC-based geometry accelerator.
Some of the newer designs also seek to optimize performance by having concurrent
tasks han-dled by multiple CPUs. Under this multiprocessing model, a sophisticated
CPU--independent of the main CPU--can handle the display.
Like its predecessors, the HP 9000 Series 800 runs the HP-UX operating system.
But here, there are no esoteric options to run the BASIC or Pascal operating systems.
HP's positioning of the Series 800 in the strict UNIX market, however, was very much
in line with the market, which was moving away from proprietary (closed) operating
systems to UNIX and its many derivatives. This position was further fortified by
the introduction of the HP 9000 Series 700 in 1991. Hailed as the highest-performance
workstation at the time of its introduction, the HP 9000 Series 700 also uses RISC
technology to sponsor the HP-UX operating system.
HP's acquisition of Apollo in 1989 greatly changed the complexion of its engineering
workstation offerings and also enhanced its overall position in that market. Although
the Apollo line was also based on the Motorola MC68000 series of processors, it offered
more synergy than compatibility when combined with the HP line. In many respects,
this was the desired result.
Originally established in 1980 by former employees of DEC and Prime, Apollo had
been a small but successful player in the workstation market, like its primary competitor,
Sun Microsystems. Apollo offered a range of workstations that ran Apollo's proprietary
Domain operating system. But it was in the area of networking that Apollo earned
a great deal of attention.
Apollo adopted the philosophy that programmatic network access should be an integral
but open part of the operating system. Toward this goal, Apollo introduced the Network
Computer System (NCS), a methodology for allowing applications to exchange information
with one another as well as access shared network resources. NCS has since become
a standard of such interest that it has been licensed by other major manufacturers.
The fusion of Apollo's NCS with the HP approach to networking, as well as the
fit of the Apollo product line with the HP 9000 line, have made the joining of Apollo
with HP a very noteworthy union. The first offspring of this union was the HP Apollo
Series 400 line. Like the Series 300, the Series 400 was based on the Motorola MC68000
line of microprocessors. Capable of running either the HP-UX or Apollo Domain operating
system, the Series 400 was the first tangible result of HP's long-term plan to integrate
the HP and Apollo workstation lines.
The C - class workstation family is well-suited to graphical applications
such as electronic design automation (EDA), computational analysis, and other compute-intensive
processing applications. The C class is available in two configurations: the C100,
running a 100 MHz PA-7200 CPU, and the C120, running at 120 MHz. The C - class
supports IEEE 802.3/Ethernet networking connections.
The high-performance HP 9000 J- class Workstations (see Figure 3.1) are available
in two configurations, the J200 and J210. The workstations use HP's 2-D and 3-D graphics,
and are appropriate for computational analysis, CAD, and 3-D design work. Like the
C - class, the J- class workstations run the PA7200 processor and
are upgradable to the PA8000. A second CPU module can be added to increase performance.
Like the C - class, the J- class also supports IEEE 802.3/Ethernet
network connections.
Midrange Offerings
The HP 1000 midrange line was quite popular, and enjoyed a long and successful
life. However, it has largely been replaced with the HP 9000. The HP 1000 was found
mainly in technical environments--on the shop floor or in medical labs controlling
sophisticated instruments. A backplane-oriented, interrupt-driven machine that is
vaguely reminiscent of 1960s technology, the HP 1000 was a real-time machine with
interfaces to a variety of instruments. The machine was highly reliable and had a
published mean time between failure (MTBF) of nine years. HP has since positioned
the HP 9000 Series 700/800 computers as a replacement for the HP 1000 line.
The operating system for the HP 1000, Real Time Executive (RTE), is ideal for
handling real-time operations. But, from a human interface perspective, it is appealing
only to those who have long memories for short and cryptic commands.
The HP 3000, on the other hand, is a general business computer that marked HP's
entry into the midrange market. In discussing the HP 3000 line, however, it is important
to distinguish the old technology models from the new ones.
The first HP 3000 was introduced in 1972 as a general-purpose, 16 -bit business
minicomputer. This represented a significant departure for HP, which had previously
stayed in more specialized markets. The operating system for the HP 3000 was termed
MultiProgramming Executive (MPE). MPE was created by a group of engineers who had
previously designed the Burroughs Corporation Master Control Program (MCP) operating
system. A head-to-head comparison of MPE to MCP, however, would reveal far more differences
than similarities.
FIG. 3.1 HP 9000 J-Class Workstation
Unlike its relatives, the HP 9000 and the HP 1000, the HP 3000 was not designed
to run special interfaces or highly complex, concurrent hardware activities. The
HP 3000 is a general-purpose business machine designed to accommodate concurrent
users working at administrative and business applications. Each user has a session
environment from which he or she works independently of other users.
Taking a RISC
The introduction of RISC architecture really shook up the HP 3000 product line and
its market. Inside HP, this project was known as "Spectrum." As previously
discussed, HP had incorporated the RISC architecture into the HP 9000 earlier in
the 1980s under the terminology HP Precision Architecture (HP-PA). Introducing RISC
to the HP 9000 line, however, was not a great risk (no pun intended) because of the
specialized hardware used in engineering workstations. After all, the more unique
a workstation's hardware, the more likely the technical market will notice and accept
it.
This same philosophy of "newer is better," however, is not prevalent
in the general business computer market. End users are not interested in the possibilities
of running the financial affairs of their companies on some new and not widely accepted
computer architecture. Thus, crossing RISC into the HP 3000 was risky. Certainly,
it did not require a massive hardware reengineering effort (the HP 9000 and HP 3000
RISC machines are built from the same base hardware components). HP was taking chances
in two areas: customer acceptance of the new design, and reengineering MPE to function
on a new hardware platform dramatically different from the old HP 3000 models.
When the HP 3000 RISC machines were introduced as the 900 Series, they were released
with MPE-XL. This RISC-specific version of the operating system is capable of running
in MPE compatibility mode to provide migration. Programs running in this compatibility
mode do not achieve the same performance benefits as those programs running in native
mode MPE, but portability was critical to the success of the product.
The release of the 900 Series did not bury the older, 16-bit CISC models of the
HP 3000. In fact, HP continued to offer a low-end line (the MICRO 3000LX, 3000GX
and 3000XE) as well as the midrange HP 3000 Series 70. These machines, renamed the
Classic 3000 line, were released with support for the then current MPE-V operating
system.
The HP 3000 continues to be widely respected as a strong and reliable general-purpose
midrange system. However, there are very few new sales of the HP 3000 line, as new
projects are more often based on UNIX Relational Database Management Systems (RDBMS)
and applications. However, HP continues to support existing HP 3000 customers, the
majority of whom plan to continue using their HP 3000s for many years. Although there
are few new sales of HP 3000s, the existing customer base remains loyal. HP plans
to continue offering enhancements to the HP 3000's integrated systems software, operating
environment, and network database. For those HP 3000 users that require connectivity
to UNIX-based RDBMS products, HP provides the means to interoperability.
The HP 3000 was never intended to be a platform for portable, third-party RDBMS
products. The HP 9000, on the other hand, is HP's leading product for running RDBMS
products from companies such as Oracle, Informix and Sybase. The hardware is basically
the same in the HP 3000 and HP 9000; the different operating systems provide different
personalities for the two environments. The HP 3000 offers tight integration between
its MPE/iX operating system and the IMAGE/SQL network database, ALLBASE/SQL relational
database, and other software components. In addition, HP has added POSIX APIs to
MPE/iX and SQL access to IMAGE/SQL, which makes it easier for independent software
vendors to port their applications to the HP 3000 platform.
The HP 9000 K-Class Symmetric Multiprocessing Server is a powerful midrange performer,
based on the PA-7200 RISC processor and featuring a 64-bit design. The K- class
is designed for high-speed networking, and includes optional high-speed FDDI, ATM
and Fibre Channel networking capabilities, in addition to standard IEEE 802.3. The
K- class expands up to four-way symmetric multiprocessing and supports the HP-UX
UNIX operating system.
Top-end Offerings
HP's latest plan involves moving its largest customers to parallel processing.
The HP 9000 EPS20 Enterprise Parallel Server (see Figure 3.2) is suitable for data
warehousing and online transaction processing applications, or compute-intensive
applications such as simulation or scientific visualization. HP offers two migration
paths. The first combines multiple existing HP 9000 SMP servers into parallel clusters
and the other solution deploys multiple HP 9000 T-class or K-class SMP servers as
nodes, connected with a Fibre Channel link. Because this design allows sites to use
their existing systems, moving to parallel clustering is fairly straightforward.
Clusters can be created without new hardware, unlike massively parallel processing
(MPP) systems, which require new hardware to be purchased.
FIG. 3.2 HP 9000 Model EPS20
The HP 9000 EPS20's parallel architecture differs from traditional parallel architectures,
which often use loosely coupled uniprocessor nodes. By tightly coupling CPUs in an
SMP infrastructure, a higher level of performance can be achieved. Additional SMP
modules can be added as needed, and scaling is almost linear in most cases. The EPS
can be seamlessly integrated into an existing multivendor environment and runs HP-UX,
enabling it to support the thousands of existing commercial applications available
for that platform.
Bundled with the EPS is HP's MC/System Environment (MCSE) administration software,
which includes several system management tools and provides a centralized point of
control for a variety of administrative tasks. MCSE includes the following:
- HP TaskBroker. An X/Motif job scheduler and load balancer for distributed
batch processing.
- Parallel Virtual Machine (PVM). A library of parallel development tools
for developing parallel applications.
- System Monitor Station. An X/Motif interface application for system monitoring
tasks.
- System Instant Ignition. Used for automating system configuration, network
integration, boot-up, and shut-down.
- HP-UX System Administration Manager Utility. An enhancement for performing
administrative tasks on a multi-computer EPS server.
The 64-bit EPS has a maximum external storage capacity of 8.3 terabytes. It has
a maximum of four processors per node, up to eight modules, for a total of 32 120 -MHz
PA-7200 processors. The board can be upgraded to the PA-8000. The PA8000 design will
offer nearly double the performance of a PA-7200 machine, going from 240 Peak MFLOPS
(Millions of Floating Point Operations per Second) with the PA-7200 to 700 Peak MFLOPS
(with the PA-8000).
HP's 64-bit, PA-8000 microprocessor uses a four-way superscalar design. The chip
was designed for commercial data processing and compute-intensive applications, where
data sets would otherwise be too large to fit into an on-chip cache. HP's design
is unique in that it leaves primary instruction and data caches off-chip, thereby
permitting them to be quite large.
Strategy for Connectivity
Hewlett-Packard's transition from CISC to RISC pales in comparison to the changes
it has made in its overall network architecture. Specifically, HP entered into the
1980s with a simple strategy for the attachment of devices to host computers, with
the most technically interesting interface at that time being HP-IB--HP's implementation
of the IEEE-488 general-purpose interface for high-speed devices (disks, tapes, and
so forth). By the end of the 1980s, however, HP had laid the groundwork for a comprehensive
networking architecture that included LANs, WANs, and sophisticated graphics-based
user interfaces.
HP chose to base its networking products on the IEEE 802.3 standard. The 802.3
implementation closely resembles the Ethernet II implementation used by DEC and others.
In fact, they are so close that both types of networks can coexist on the same physical
network (although they cannot communicate). For HP, the 802.3 implementation enables
many prospective customers to plug HP gear into their existing Digital Ethernet networks.
With the issue of the physical topology of the network resolved, HP then went
on to define the networking services (and software) that it would implement on its
network. HP will unofficially acknowledge (and officially too, under the right circumstances)
that it based its networking services design on the TCP/IP model.
However, in creating its Networking Services (NS) product line, HP sufficiently
deviated from the TCP/IP standard to introduce levels of incompatibility with existing,
competitive TCP/IP products.
Application/User Relationship
HP's approach to interfacing the human with the program uses a session philosophy
in the multi-user environment. Specifically, the user logs on to the system, providing
a proper user name and optional password, and can then access files or run programs
that he or she has been given authority to read, write, or execute. This approach
holds for the MPE (HP 3000), RTE (HP 1000), and the HP-UX (HP 9000) operating systems.
In this session environment, as far as the user can easily tell, he or she is
the only person accessing that particular program at that time. The interaction between
the user and the program can take on any of the terminal's characteristics (as discussed
earlier in the section "HP Terminals"): the interaction can be free-form
conversational entry, rigid and unforgiving template-based data entry, or virtually
any structure in between. Again, this is one of the difficulties in learning HP--the
wide range of choices can leave you hungering for rigid standards.
From the application's perspective, the program also recognizes only one user
when it is running. In the simplest of applications, each user might have a copy
of the program running out of the user's portion of the system's memory. From a programmer's
perspective, this can ease the pain of program development because there is no need
to take into consideration the complications caused by multi-user, multithreaded
access (multiple users accessing the same program at the same time but at a different
logical point in the program).
But reality dictates that large multi-user computers cannot truly give each user
program and memory space. At a minimum, there must be a standard or interface that
allows multiple programs to share data in a file. (After all, if everyone lived in
their own little world and never needed to share or integrate information, they might
as well each have stand-alone PCs and throw away the minicomputers and mainframes.)
To address these real-world, multi-user interfaces, HP uses layers of programs
and provides central, shared resources to back them up. For example, while each user
might have a copy of the portion of the program that is processing the screen, each
copy of this program might in turn pass the data to another common program that coordinates
all the input and output from all of the user programs. This arrangement ensures
that Person A does not obliterate the information Person B is working on.
While it is probably unreasonable to go into further detail regarding how application
programs are layered within the system, the availability and function of the central
application resources are noteworthy. One of the key functions of any computer system
is the database. To address this key area, HP provides a product called TurboIMAGE--a
proprietary database package for its entire computer line (HP 1000, 3000, and 9000).
TurboIMAGE enables multiple programs to access and retrieve information based
on a wide variety of selection criteria. It supports its own interface with programs
and the Structured Query Language (SQL) interface. But TurboIMAGE is unique because
it is one of the few databases developed by a computer manufacturer. Although end
users do not see TurboIMAGE directly, the way that TurboIMAGE stores and retrieves
information significantly controls what the users do see.
In contrast to TurboIMAGE's transparency is the physical appearance of the operating
system. Until the late 1980s and early 1990s, the user saw a character-based (nongraphical)
interface that prompted for action and then read back the typed response. In the
late 1980s, HP adopted a graphics-based interface it termed NewWave. Although initially
implemented on PCs with Microsoft Windows, NewWave was intended to also serve as
an interface for graphics-based terminals. Furthermore, HP's experience developing
NewWave greatly influenced its role in the development of the OSF/Motif graphic interface.
Following NewWave was HP-VUE, which ultimately formed the basis of the Common
Desktop Environment (CDE), a standard GUI for all UNIX and X-based systems. CDE,
a joint project led by HP and other prominent vendors, establishes a common look
and feel for all UNIX systems, including workstations, X terminals and PCs, and provides
for easier portability between UNIX-based operating systems. CDE does not actually
represent any new technology, but instead incorporates existing technology from several
vendors into a single, common standard. CDE includes HP's Visual User Environment
(VUE), and is available on HP-UX and several other UNIX operating systems. Besides
HP-VUE, CDE also includes elements of IBM's Common User Access Model.
In many respects, HP's approach to the user/application interface combines the
best of both worlds. The user and the program appear to have a relatively simple
one-to-one relationship while, in reality, these seemingly separate tasks are being
centrally coordinated. The downside of this approach is the overhead and resources
used to maintain the separate user identities and work areas.
Terminal Attachment Philosophy
Before HP's pervasive changes in its networking strategy, the relationship between
an HP terminal and a computer was so straightforward that it bordered on boring.
In the majority of installations, HP terminals were directly attached to the main
computer via simple asynchronous connections. One terminal was attached to one port
on the computer using one line.
These attachments generally used standard RS-232C connections (although options
for RS-422 were also supported). Of the 25 supported RS-232C leads, direct-connected
terminals can be configured to only three required lines: reference ground (7), transmit
(2), and receive (3). An optional fourth line for frame ground (1) was more often
ignored than used. Remote (modem) connections followed the more-or-less standard
RS-232C asynchronous signals (pins 2-7, 20, and 22).
With this limited number of signals, the flow of data between the terminal and
the computer is controlled through software--specifically, HP's proprietary, point-to-point
terminal control protocol. Like the HP terminals and their multifaceted capabilities,
the terminal protocol is also multilayered. Essentially, the flow control options
can be lumped into the following groups:
- DC1 handshaking. This option, which regulates when the terminal can transmit
data to the computer, has two different (and mutually exclusive) implementations.
DC1 trigger is the simpler option; it specifies that the terminal can transmit after
receipt of a DC1 control character. With the other option, DC1/DC2 handshake, the
computer sends a DC1 character, the terminal responds with a DC2 acknowledgment,
the computer sends a second DC1, and then the terminal can transmit.
- ENQ/ACK pacing. This option ensures that the data is received correctly
by the terminal and gives the terminal sufficient time to keep up with the computer.
When ENQ/ACK is enabled, the computer breaks up a large transmission into small groups
and terminates each group with the ENQ control character. When the terminal sees
the ENQ, it responds to the computer with an ACK, thereby indicating it is ready
for the next block of data.
- XON/XOFF pacing. XON/XOFF pacing also ensures that the side receiving
the data is keeping up with the side transmitting the data. The XON and XOFF signals
are the DC1 and DC3 control characters. XON/XOFF pacing has two implementations:
- XOFF transmitted by the terminal. This implementation enables the terminal
to terminate transmission, giving it time to process the data in its local buffer.
When the terminal has caught up with the computer, it sends an XON, signal- ing the
computer to resume transmission. (Also note that the user can perform this function
by pressing Ctrl+S for XOFF and Ctrl+Q for XON, providing an opportunity to pause
and review lengthy displays.)
- XOFF transmitted by the computer. Here the perspective is reversed. The
computer sends an XOFF to pause a transmission from the terminal and then sends an
XON to resume it. Because the XON and XOFF characters are DC1 and DC3, this op- tion
cannot be used if either of the DC1 handshakes is enabled.
Of course, to make life complicated, any of these options can be used alone or,
more likely, in a combination. Like the functional capabilities of the terminals,
the flexibility of the data communications options can be overwhelming.
Even when HP made a major commitment to redevelop its LAN architecture along the
lines of IEEE 802.3, terminal computer communications were not affected. Not until
the introduction of the RISC-based HP 3000 Series 900 did HP change the way that
terminals connected to computers; and even then, HP's changes affected only the HP
3000 RISC machines.
Given the general nature of IEEE 802.3 as a relatively high-speed (10 Mbps) coaxial-type
of LAN, HP borrowed a page from the book of Digital Equipment and developed its own
type of terminal servers, Distributed Terminal Controllers (DTCs). These DTCs took
the place of asynchronous ports; in fact, each DTC interfaced up to 48 lines (terminals)
to the IEEE 802.3 network, and consequently into the computer (see Figure 3.3).
FIG. 3.3 HP 3000 Series 900 Attachments
While the DTCs introduced some new functions to HP's networking architecture (such
as the ability for one terminal to connect to different hosts--a tough trick when
they are hard-wired), the basic data communications flow between the terminal and
the computer remained (for the most part) unchanged.
Peer-to-Peer Relationships
In HP's pre-NS days, establishing communications paths between programs (or even
systems) was not a pretty sight. Within a machine, HP offered memory- and disk-based
mailboxes to facilitate interprocess communications. This technique, however, required
a great deal of standardization and cooperation from the programmers developing such
applications.
On a larger scale, the Data Services (DS) family of products provided system-to-system
communications. The physical communications between systems was typically HP's imple-mentation
of a High-Level Data Link Control (HDLC) protocol, although support for X.25 connectivity
was also permitted. Essentially, DS allowed terminals on one system to log onto other
systems, files to be exchanged, and programs to open and access remote databases.
But in comparison to NS, DS was a dinosaur waiting for a comet.
Because NS was modeled in many ways after the TCP/IP standard, its interprocess
commun-ications (IPC) methodology also follows the TCP/IP IPC standards. Much like
Digital's task-to-task programmatic access, HP's NetIPC interface allows programs
on the HP NS system to exchange information without requiring the programming gyrations
necessary under the mailbox approach.
Furthermore, HP's acquisition of Apollo greatly enhanced its offering in this
area. Apollo's own implementation of program-to-program communications--here, Apollo
used the term remote procedure calls (RPCs)--was part of its overall Network Computing
System (NCS). Apollo's approach to the matter became a subject of great interest
to the computer industry as a whole, and the marriage of the two represented a new
and significant standard to peer- to-peer processing.
PC Integration Strategy
Having chosen the IEEE 802.3 standard to implement its systemwide communications,
HP borrowed its PC networking strategy from AT&T's StarLAN network. Integration
of this separate network strategy with the backbone 802.3 computer system is handled
through the use of a bridge.
With HP StarLAN, each PC is connected to a central hub using 1 Mbps thin wire
(or optional twisted pair) cables (see Figure 3.4). Such systems as the HP 3000 can
be connected directly to the same hub, or a node on the hub can be connected to an
HP bridge that connects that hub to the backbone of the main 802.3 network.
A high-performance version of this basic network architecture is also available
in the form of HP's StarLAN-10. StarLAN-10 differs from the original StarLAN in that
it is based on a 10 Mbps coaxial medium and does not require a bridge to link with
the main backbone (see Figure 3.5). Also note that either HP StarLAN or StarLAN-10
can be implemented as a stand-alone PC network--larger systems (HP 3000) need not
be connected.
FIG. 3.4 HP StarLAN Network
Although this PC networking strategy might seem somewhat less than awe inspiring,
HP's advances in the area of user interfaces are noteworthy. Specifically, HP's NewWave,
a graphical user interface for the PC environment, and the subsequent HP-VUE interface,
provide an alternative to the IBM Presentation Manager (note that the release of
NewWave preceded the final release of Presentation Manager).
NewWave, working with Microsoft Windows, provided a graphical interface that enables
the user to select from programs and applications, regardless of where the applications
reside or the information is located. VUE continued this functionality, and with
the establishment of CDE, provided a single set of interfaces for HP-UX, IBM AIX,
Solaris, UnixWare, and other UNIX platforms. This enabled users to access data and
applications from anywhere in the network, regardless of physical location or hardware
platform.
FIG. 3.5 HP StarLAN-10 Architecture
NewWave, although it was a significant development, was also important in that
it paved the road for other developments, including VUE and CDE. Within a year of
NewWave's formal release, HP released NewWave Office. Whereas NewWave focused on
bringing a better, graphical interface to the PC, NewWave Office is the first application
implemented under the NewWave architecture. Under NewWave Office, the PC user selects
an application whose core service (HP DeskManager) resides on an HP 3000 under the
MPE operating system.
The HP implementation of CDE supports a variety of capabilities, including session
management, window management, object/folder management, a full set of productivity
tools and network services, and a set of GUI toolkits. CDE provides a set of policies
and protocols for exchanging data between applications, and a file manager for manipulating
objects.
Beyond improving the basic PC interface, HP's VUE pushes into the more traditional
area of terminal interfaces. Here, by combining the graphical capabilities of X Terminals
with its own implementation of X Window, VUE lays the foundation for a distributed
computing environment that supports multiple systems and graphics terminals. Therefore,
given the graphical, client/server foundation of VUE, HP's PC integration approach
moves from a novel PC integration strategy to a networkwide standard for user/application
interfaces.
Office Automation
The core product in HP's office automation package is HP Open DeskManager, which
resides on an HP 3000 and uses HP's TurboIMAGE database system to maintain its structure
and information. HP Open DeskManager provides office automation functions over a
wide area encompassing different processing nodes (systems) and nonlocal users. HP
Open DeskManager offers these features:
- Electronic mail. HP Open DeskManager provides a strong client/server-based
electronic messaging system that integrates several commonly-used clients (such as
Microsoft Mail and Lotus cc:Mail) into an HP 3000 messaging backbone. The system
includes its own text editor, supports the native HP 3000 line editor, and can import
or export files created by HP Word or any other program that can process standard
text files.
- Calendar/scheduling. HP Open DeskManager provides an electronic calendar
that includes to-do list processing and schedules meetings with other users. (This
scheduling capability also includes finding common free times for all target participants).
Users can also choose to deploy Microsoft's Schedule+ calendaring package as a front
end.
- Filing. HP Open DeskManager can organize files or documents into folders
that are placed in filing cabinets. This capability accommodates a range of functions,
such as setting up an information database or simply filing inbound and outbound
mail in a highly organized fashion.
HP Open DeskManager's unique interpretive language, combined with its capability
of altering screen contents, enables customization of the product at almost any level.
New commands and functions can be implemented to expand (or redefine) the role of
the product.
Although HP Open DeskManager is a stand-alone product, it is also part of HP's
NewWave Office strategy. As part of the bigger picture, Open DeskManager provides
a core set of services on an HP 3000 computer that can be joined by other services
such as HP Resource Sharing and HP Networked PC Management.
HP Open DeskManager can be used to provide electronic mail services to terminal
users, while still allowing for future growth to PC clients and an electronic mail
server backbone. The HP 3000-based messaging backbone is often more robust and easier
to manage than PC-LAN- based e-mail systems, especially in a larger environment.
Open DeskManager can be used to migrate to this enterprise messaging environment,
while retaining an existing investment in PC messaging applications. The latest release
can support both HP and non-HP user interfaces. Clients supported include Lotus cc:Mail,
Microsoft Mail, HP NewWave Mail, and HP Advance Mail; these clients are all included
in the basic package. HP is also planning to add support for additional Windows and
Macintosh clients. Connectivity with other e-mail systems, including X.400, the Internet,
EDI network, and products such as Digital's ALL-IN-ONE and IBM's PROFS, is provided
through available gateways. PC users access the system through either terminal emulation
or one of the aforementioned front-end clients.
Network Architecture
Because the HP line of computers does not yet share a common set of connectivity
guidelines, the networking architecture of HP machines is quite diverse. This is
not to say that the computers have no common ground for connectivity (in fact, they
have several); rather, each line must be analyzed for its own relative merits. HP
calls its network architecture AdvanceNet (see Figure 3.6).
FIG. 3.6 Sample HP AdvanceNet Network
For example, while the HP 3000 Series 900 requires an IEEE 802.3 (or Ethernet)
LAN, the HP 1000, HP 9000, and HP 3000 CISC computers support the IEEE 802.3 LAN
as an option. In supporting the IEEE 802.3 standard, HP can use a ThickLAN backbone
(conforming to the IEEE 10BASE5 standard) while also supporting ThinLAN (IEEE 10BASE2)
coaxial segments. This implementation is compatible with Digital's Ethernet backbone
and ThinWire coaxial segments. In HP terminology, however, attachments to the LAN
are made via Medium Attachment Units (MAUs) instead of transceivers.
When all of the various models are connected to a common LAN, they can communicate
with one another using either HP's Networking Services products (NS/1000, NS/3000,
or NS/9000) or via TCP/IP (TCP/IP products are available from HP and from third-party
companies).
Although the IEEE 802.3 LAN is the preferred methodology for system-to-system
network- ing (with or without the use of third-party bridges to address WANs), an
older product-- Distributed Services (DS)--is often used with HP 1000
computers. In a nutshell, DS provides HDLC-type point-to-point links between HP 3000
and the older HP 1000 systems. Although DS is no longer an option for the HP 3000s,
it remains available on HP 1000s.
To integrate PCs into the mainstream LAN, HP provides several different PC strategies:
- HP StarLAN. This is the traditional 1-Mbps star-topology LAN. In this
case, a bridge interfaces the star's hub with the ThickLAN (via a MAU).
- HP StarLAN-10. An improved and faster (10 Mbps) version of the StarLAN.
In this implementation, the star's hub can attach directly to the ThickLAN (via a
MAU).
- ThinLAN hub. A similar product to Digital's ThinWire repeaters. The ThinLAN
hub attaches to the ThickLAN (via a MAU) and provides multiple ThinWire segments.
HP uses two solutions to provide connectivity to IBM and Digital. For IBM connectivity,
HP provides combined hardware/software products for its computer lines to implement
bisynchronous and SNA SDLC links to IBM systems. For Digital Equipment connectivity,
HP provides DEC-resident software that implements HP's NS within a VAX. In this scenario,
the HP equipment and Digital equipment must reside on the same physical LAN.
HP also produces a variety of X.25 interface devices. The majority of these devices
implement bridges between asynchronous connections (to computers or terminals) and
the X.25 network.
To connect terminals to the system, HP employs several approaches (see Figure
3.7).
FIG. 3.7 HP Terminal Server Connections
Terminals attach directly to HP 1000, HP 9000 and HP 3000 CISC machines via asynchronous
serial links to ports (of varying levels of intelligence) integrated into the main
system hardware.
For the HP 3000 Series 900, terminals connect to DTCs via asynchronous serial
links, and the DTC, in turn, connects to the IEEE 802.3 LAN. Each DTC can support
up to 48 direct-connect lines. This approach is remarkably similar to Digital's terminal
server approach, with these exceptions:
- A DTC provides access to the HP 3000 Series 900 only. If a DTC-attached terminal
must access a different type of HP computer, it must use some form of networking
service or be used with a TS8 (as explained later).
- For a DTC to be fully functional (for example, for one terminal be able to access
multiple Series 900s), it must be controlled by an OpenView DTC Manager (a PC attached
to the LAN and running the HP management software).
The TS8 terminal server is used for terminal access to LAN-based HP computers.
The TS8 provides asynchronous attachment for up to eight terminals (or printers)
using the TCP/IP TELNET protocol. The value of a TS8 is directly related to the types
of hosts in the network and the networking services that are available:
- For the HP 9000 running TCP/IP, terminals attached to the TS8 can directly access
that computer.
- For the HP 3000 Series 900, an additional TS8 (or multiple TS8s) must be attached
to DTCs. The terminal attached to the first TS8 is routed through the second TS8
into the DTC and then into the Series 900 host.
- For all other cases, the HP host must also have one or more TS8s attached directly
to its asynchronous ports. A terminal directly attached to a TS8 then is routed to
a host-based TS8 that converts the traffic back to an asynchronous serial connection.
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