Chapter 1<P> Introduction
Introduction
The SCO® Embedded Configuration Toolkit (formerly known as the
``SCO POS Configuration Toolkit'') provides a mechanism
for configuring SCO OpenServer™ for embedded systems. The operating
systems generated by the toolkit are designed to operate in the
minimum amount of RAM whilst still providing facilities
associated with traditional UNIX operating systems. Some of the
key features of the environment generated by the toolkit are:
a 32-bit multitasking operating environment
a high-performance architecture that includes development features
to enhance the performance of application software
hardware and software portability
an optimized UNIX® kernel that provides only the functionality
required by the embedded application
a common environment for back-end and front-end processors
full networking support
The SCO Embedded Configuration Toolkit (also referred to as
``the toolkit'' in this document) still supports all the POS
related devices supported by its predecessor, the ``POS
Configuration Toolkit''. However, the new toolkit has additional
features that enable you to configure UNIX operating environments
for a variety of embedded systems such as POS applications,
Network Computers, client-server applications and so on.
Traditionally, UNIX systems were used as back office systems
because they had a mature, standards-conformant open architecture
that provided a high degree of inter-system connectivity.
It was not so common to see such
systems utilized as front-end or desktop machines because
of the large amount of hardware resources they
required.
The toolkit addresses this problem by generating a customized UNIX
operating system that can run in the more confined
hardware environment of a desktop machine. Some of the
advantages of bringing UNIX to the desktop as well
as to the back office include:
operating systems that conform to industry standards
a stable environment on which to develop, test and run embedded applications
an open system architecture
an optimized UNIX kernel providing a 32-bit multitasking environment
support for diskless configurations and client controllers
integral network and remote filesystem support
high performance
remote client administration
X windows, a powerful networked windowing system
protection from power failure
You can use the toolkit's advanced graphical user interface to
help you customize the operating system environment for your
embedded systems. The toolkit also enables you to specify
a path to your embedded application. It can then
build a software profile of the operating system and
the embedded application. Once the software profile has been
built, it can be deployed to target machines in
a variety of ways. These deployment methods are described
in
``Deployment''.
This document provides an introduction to the many features of the
toolkit and some of the possible environments in which
it can be used. It does not describe the
user interface of the toolkit: this is done in
the SCO Embedded Configuration Toolkit Developer's Handbook.
The following special terms are used in this document.
Build machine
An SCO OpenServer Release 5.0 system used in the development environment
to run the Embedded Configuration Toolkit. The build machine
is used to configure the various systems in an
embedded application environment and to build and cut the
installation medium used to transfer the resulting software to
the installation
server.
Installation servers
An SCO OpenServer Release 5.0 system used to install disk target
systems via a LAN connection. The software to install
originates from the build machine. The installation server also
generates any installation boot disks that are required. The
purpose of the boot disks is described in
``Deployment''.
NOTE:
If required, the build machine can also act as the installation server.
Boot servers
Any server that supports BOOTP and TFTP. The purpose of
the boot server is to download, via a LAN
connection the operating system and application environment used by
diskless clients.
Application servers
Any server that can support TCP/IP and runs the server component of a
client-server embedded application.
Administration servers
An SCO OpenServer Release 5.0 system that has administrative tools that
can be used to perform certain tasks on disk based systems and
diskless clients. Some of these tools are provided as
part of the OpenServer package and others are supplied
as part of the SCO Embedded Application Toolkit.
Disk based systems
A general term that is used when referring to clients
with hard disks, client controllers, stand-alone systems and simple
networked systems.
Disk based clients
A desktop or front-end system used to run an embedded
application. Such systems always have an Intel processor (386,
486 or Pentium), at least 4MB of RAM, a
LAN connection and a hard disk. Disk based systems
are installed by booting them from boot disks generated
on the installation server. The boot procedure takes care
of configuring and then downloading the software from the
installation server to the client. Once installed, disk based
clients can boot from the local hard disks rather
than from the boot diskette.
Diskless clients
A desktop or front-end system used to run an embedded
application. Such systems always have an Intel processor (386,
486 or Pentium), at least 4MB of RAM, a
LAN connection but no hard disk. Diskless systems are
installed by booting from boot servers or from internal ROM
or EPROM. The boot procedure takes care of creating an
in-memory filesystem and then
copying the operating system and application from the boot
server or ROM/EPROM to the in-memory
filesystem. Instead of booting from a boot
track on a disk, diskless clients use boot PROMs
to initiate the boot procedure described above.
Client controllers
Client controllers are typically located between the clients and the
server, and have the task of regulating traffic over
the network and controlling operation of the client systems. They
can do this by acting as
a gateway between sub-networks connecting locally grouped client machines.
This prevents the network from becoming overloaded at times
of high system load, at the same time protecting
the server from being overloaded by client requests. Typically,
a client controller will also take over the server's diskless
client boot responsibilities. In a POS environment a client controller
will typically also act as a central data repository for client systems and
hold information such as pricing tables, transaction summaries, statistics
and so on.
Simple networked systems
Simple network systems are systems that can function independently of
other computers but can also utilize their network connections
to access information and resources if required. A typical
example of a simple networked system is a Network Computer.
Stand-alone systems
Stand-alone systems are systems that function independently of other systems
and do not require any form of network or
media transfer to perform their functions. These functions are
usually simple repetitive actions based on static information that
is not prone to frequent changes. An example of
a stand-alone system might be an environmental control system
for a building's sun blinds or air conditioning.
Embedded application
The application that runs on the target system(s). The application
can be a client-server server application using an application
server and one or more clients, or a stand-alone
application that runs independently of any server. Some examples
of embedded applications could be the controlling software for
a cash till or an application controlling external devices
such as actuators for window
blinds.
In-memory filesystem
A filesystem that only exists in its runtime form in
the RAM of a system, typically a diskless client.
In the environments discussed in this document, such filesystems
are stored as images on the hard disk of a boot server.
When required, the boot server downloads the image to the diskless
client's RAM. The in-memory filesystem then has the same appearance
as a filesystem on a hard disk.
When an executable is invoked from an in-memory filesystem, it
is invoked in-place, that is, the executable's image is
not copied to another part of memory. This is
a key feature of in-memory filesystems generated by the toolkit.
Any changes made to an in-memory filesystem are lost
as soon as the system is switched off, any
permanent changes to an in-memory filesystem must be made
to the image stored on the boot server.