Carlos G. Borgialli,
Senior Manager,
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 database applications.

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.