The phenomenal growth and complexity of computer networks has created a
wealth of opportunities for communication and resource sharing and a multitude
of concerns about privacy and security. The Open Software Foundation's Distributed
Computing Environment (DCE) was developed to fill the need for a standardized
approach to creating and executing secure client/server applications in complex,
highly networked environments. Applications developed using the DCE software
system are portable and interoperable over a wide range of computers and networks.
Applications running in DCE are also able to share data and services efficiently
and securely regardless of the number of computers used or where they are located.
HP, like some other companies in the computer industry, has contributed technologies
to DCE and released several versions of DCE as a product for the HP-UX* operating
system. The first eight articles in this issue describe the fundamental elements
of DCE and the enhancements made to DCE by HP in the areas of application development
DCE is based on the client/server model in which an application's functionality
is divided between clients, which represent users, and servers, which provide
the services requested by users. In a DCE environment, there might be several
thousand host systems, some of which might be from different vendors, and many
different categories of users and applications. To deal with this heterogeneous
and diverse environment, DCE defines a basic unit of operation and administration
called a cell, which allows users, systems, and resources to be grouped together
according to their needs and common interests. The client/server paradigm and
the concept of cells are introduced in the article on page 6 .
This article also introduces features in DCE that facilitate concurrent programming,
DCE client/server remote communication, time synchronization between distributed
hosts, and handling a distributed file system.
Encouraging others to adopt a new technology is made a lot easier if you have
examples of its use. HP's information technology group has adopted DCE and
has begun to move HP's legacy information technology system to the DCE architecture.
The article on page 16
describes the issues and rationale that led HP to adopt DCE for information
technology, and the administration and planning issues associated with this
A typical DCE cell can span several systems and networks. To find users, files,
devices, and resources inside and outside these cells requires a naming system
that allows each cell and the objects contained inside it to have unique names,
and a directory service that can cope with different naming systems. The article
on page 23 describes
the DCE directory services and the article on page
describes the X/Open) Federated Naming specification, which defines a uniform
naming interface for accessing a variety of naming systems.
One of the biggest issues surrounding networked systems today is security.
How do we protect an open, distributed system from unauthorized access and
abuse? DCE provides a collection of services for developing security mechanisms
to protect against unauthorized access. The user's password is the primary
key for getting into a system, and in some situations users may be required
to enter several passwords during a session to gain access to different applications
or other parts of the system. Each time the user is required to enter another
password, the system is made vulnerable to an opportunity for hostile invasion.
The article on page 34
describes the HP Integrated Login product, which is a single-step login facility
in which the user enters a password once at login time, and this password is
used to grant access to the HP-UX machine as well to verify access to other
secured parts of the system. The security protocol that takes over after the
password is entered is described in the DCE security service article on page
41. The DCE security
service authenticates a legitimate user and then checks to make sure that the
user is authorized to have access to the requested services. The article on
page 49 describes one
of these authorization mechanisms called access control lists (ACLs). ACLs
are lists of permissions that belong to certain users or groups of users.
DCE provides several very powerful facilities for creating DCE client/server
applications. However, the interfaces to some of these facilities are quite
complex. The article on page 55
describes the HP Object-Oriented DCE (OODCE) product, which is an object-oriented
library of C++ classes that hide the programmatic complexity of DCE from developers
to ease the development of distributed applications.
Transaction processing systems are used in large enterprises to store, retrieve,
and manipulate data reliably in the face of concurrent access. The HP Encina/9000
transaction processing monitor described on page 61
provides an environment for developing distributed OLTP (online transaction
processing) applications. Encina/9000 uses many of the features of DCE to create
its distributed, client/server capabilities.
One of the biggest challenges in software development is still testing the
product. This challenge is even more daunting in distributed client/server
environments. In the article on page 75
the authors describe how the testing environment for nondistributed, procedural
software is not applicable to a distributed environment. The article describes
the evolution of a reusable, object-oriented testing environment called the
object testing framework (OTF). Although OTF was designed for a non-DCE-based
product, the concepts and tools developed for OTF are applicable to products
that might be based on DCE.
Bar code readers and magnetic strips are so commonplace today that their usefulness
in areas such as banking, manufacturing, and retail is taken for granted. However,
these technologies do have their limitations in that they require a direct
line of sight and a relatively clean, benign environment. Another technology
called RF/ID (radio frequency identification), which is a combination of two
components-a transmitter and a receiver-overcomes the limitations of these
other technologies. The article on page 94 describes the HP HSMS-285x silicon
detector diodes designed for use in RF/ID applications.
In today's modern hospitals patients who have to be monitored are connected
to an array of high-tech patient monitoring equipment. Aware of the intimidating
look of all this equipment, many hospitals are trying to create a more friendly
environment in their labor and delivery departments by reducing the amount
of technology at the patient's bedside. The HP Series 50 T fetal telemetry
system, which is described in the article on page 82
is a step in this direction. The HP Series 50 T combines external and internal
fetal monitoring in a lightweight, portable transmitter.