Carlos G. Borgialli,
DECtp Software Engineering
Transaction processing is one of the largest, most rapidly growing segments of the computer industry.
Digital's strategy is to be a leader in transaction processing, and toward that we are making
many technological advances and delivering products that meet the evolving needs of businesses
that rely on transaction processing systems.
Because of the speed and reliability with which transaction processing systems capture and display
up-to-date information, they enable businesses they enable businesses to make well-informed,
timely decisions. Industries for which transaction processing systems are a significant asset
include banking, laboratory automation, manufacturing, government, and insurance. For these
industries and others, transaction processing is and information lifeline that supports the
achievement of daily business objectives and in many instances provides a competitive advantage.
Many older transaction processing systems on which businesses rely are centralized and tied to
a particular vendor. A great deal of money and time has been invested in these systems to keep
pace with business expansion. As expansion continues beyond geographic boundaries, however, the
centralized, single-vendor transaction processing systems are less and less likely to offer the
flexibility needed for round-the-clock, reliable, business operations conducted worldwide. Transaction
processing technology therefore must evolve to respond to the new business environment and at the
same time protect the investment made in existing systems.
Our research efforts and innovative products provide the transaction processing systems that
businesses need today. The demands for distributed rather than centralized systems has focused
attention on system management. Queuing services, highly available systems, heterogeneous environments,
security services, and computer-aided software engineering (CASE) are a few examples of areas in
which research and advanced development efforts have had and will continue to have a major impact
on the capabilities of transaction processing systems.
Transaction processing solutions require the application of a wide range of technology and the
integration of multiple software and hardware products; from desktop to mainframe; from presentation
services and user interfaces to TP monitors. database systems, and computer-aided software
engineering tools; from optimization of system performance to optimization of availability.
Making all of this technology work well together is a great challenge, but a challenge Digital is
uniquely positioned to meet.
Digital ensures broad applications of its transaction processing technology by defining an
architecture, the Digital Distributed Transaction Architecture (DECData). DECData, about which
you will read in this issue, defines the major components of a Digital TP system and the way those
components can form an integrated transaction processing system. The DECData architecture
describes how data and processing are easily distributed among multiple VAX processors, as well
as how the components can inter operate in a heterogeneous environment. The DECData architecture
is based on the client/server computing model, which allows Digital to apply its traditional
strengths in networking and expendability to transaction processing system solutions. In the DECData
client/server computing model, the client portion interacts with the user to create processing
requests, and the server portion performs the data manipulation and computation to execute the
processing request. This computing model facilitates the division of a TP system into small
components in three ways. It allows for distribution of functions among VAX processors; it
partitions the work performed by one or more of the components to allow for parallel processing;
or it replicates functions to achieve higher availability goals. These options permit the customer
to purchase the configuration that meets present needs, confident that the system will allow
smooth expansion in the future.
Further, the DECData architecture sets a direction for its evolution through different products
in a coordinated manner. It provides for the cooperation and inter operation of components
implemented on different platforms, and it supports the expansion of customer applications to
meet growth requirements. The DECData architecture is designed to work with other Digital
architectures such as the Digital Network Architecture (DNA), the network application services (NAS),
and the digital database architecture (DDA). Moreover, the DECData architecture supports industry
standards that enable portability of applications and their inter operation in a multi vendor,
heterogeneous environment are being developed by the International Standards Organization as part
of the Open Systems Interconnection activities.
Among the products Digital has developed specifically for TP systems are the TP monitors. These
monitors provide the system integration "glue," if you will. Rather than act as their own systems
integrators, customers who use the Digital TP monitors are able to spend more time on solving
business problems, such as how to make forms and database products work together smoothly.
Digital's TP monitors run on all types of hardware configurations, including local area networks
(LANs), wide area networks (WANs), and VAXcluster systems. The DECData client/server computing model
provides the necessary flexibility to change hardware configurations, thus allowing reconfiguration
without the need for any source code changes. The two TP monitors, DECintact and VAZ ACMS, integrate
vital Digital technologies such as the Digital Distributed Transactio Manager (DECdtm) and products
such as Digital's form systems (DECforms) and our Rdb/VMS or VAX DBMS database products. DECdtm
uses the two-phase commit protocol to solve the complex problem of coordinating updates to multiple
data resources or databases.
Major developments in Digital's database products have enhanced the strengths of its overall
product offerings. The two mainstream database products noted above, Rdb/VMS and VAZ DBMS, layer
on top of a database kernel called KODA, thus providing data access independent of any data model.
The services made available by KODA, besides its high performance, allow Digital's database products
to efficiently support TP applications as well as to provide rich functionality for general-purpose
For those TP systems that require user interfaces, DECforms provides a device-independent, easy-to-use
human interface and permits the support of multiple devices and users within a single application.
TP systems that require high availability or continuous operations are supported by the VAX family
of hardware and software. The introduction of the fault tolerant VAXft 3000 system, added to the
successful VAXcluster system, allows for a high level of system availability. Performance needs
also are being met by a combination of hardware resources, including the VAX 9000 systems.
This combination of architecture, software, and hardware technology, and support for emerging industry
standards places Digital in an excellent position to become the industry leader for distributed,
portable transaction processing systems. The papers in this issue of the Journal provide a view of
the key elements of Digital's distributed transaction processing technologies.
Many individuals, teams, organizations, and business partners are responsible for bringing Digital's TP
vision to fruition. Their dedication, hard work, and creativity will continue to drive the
development of new technologies that enhance our family of products and services.