Diesel engine software product line, Cummins, Inc.
Cummins, Inc., is the world’s largest manufacturer of large diesel engines. Modern engines can contain over 100KSLOC of software to micro-control ignition to produce an optimum mix of power, economy, and emissions. In 1993, faced with the need to produce almost 20 new systems but with staff and resources available only for six, Cummins changed the way they developed software and embraced the product line approach. Their product line is a story of extensive use of legacy software, strong processes, and a culture of intra-organizational cooperation.

Today the Cummins software product line covers 9 basic engine types ranging over 4-18 cylinders and 4-164 liters of displacement, with 12 kinds of electronic control modules, 5 kinds of processors, and 10 kinds of fuel systems. To date, 20 basic software builds have been parlayed into well over 1000 separate products. Cycle time has been reduced from around 250 person months to a few person months. Quality and customer satisfaction are both up, and 15 of 15 projects are on track. Cummins estimates a productivity improvement of 3.6, and an ROI of 10:1, from the product line approach. It has also enabled them to quickly enter and become successful in a related market area -- namely, industrial diesel engines that power a variety of applications from rock crushers to ski lifts.

• P. Clements and L. Northrop, Software Product Lines: Practices and Patterns, Addison Wesley, 2001.

  Telecommunication Switching System, Philips
The PKI tss (Telecommunications Switching System) is a product family (product line) originating from the middle of the 1980s. PKI was a small player in the telecommunications world, and had to survive by addressing a niche market. In particular, the tss family had to serve a large variety of clients and regulations. The approach emphasized a component-based architecture; components were called "Building Blocks." The architecture consisted of a component based framework where plug-ins are available to tailor the system to the actual requirements. Moreover, aspects were defined for meeting quality requirements. For many aspects automatic code generation was available. For other aspects code guidelines were available, easing the burden of implementation.

The architecture of the system ensured that it could be built and tested incrementally. The family was very successful in having a fast time-to-market, and high reuse.

In 1994 PKI was sold to Lucent, which did not continue the tss family. The knowledge about the tss system stayed within Philips, however, and the majority of the present day product family developments within Philips are still influenced by the tss experiences.

• Frank van der Linden and Jürgen K. Müller: “Creating Architectures with Building Blocks,” IEEE Software, Nov. 1995.

• Frank van der Linden, Jürgen K. Müller: Composing Product Families from Reusable Components, Bonnie Melhart, Jerzy Rozenblit (eds.), Proceedings 1995 International Symposium and Workshop on Systems Engineering of Computer Based Systems, IEEE, pp. 35 - 40 (1995).

• Jürgen K. Müller: “Integrating Architectural Design Into The Development Process,” Bonnie Melhart and Jerzy Rozenblit (eds.), Proceedings 1995 International Symposium and Workshop on Systems Engineering of Computer Based Systems, IEEE, pp. 114 - 121 (1995).

• Jürgen K. Müller: “Feature-Oriented Software Structuring,” Proceedings CompSAC'97, pp. 552-555, (1997).

• Jan Gerben Wijnstra: Critical Factors for a successful Platform-based Product Family Approach, Gary J. Chastek (ed.) Proceedings SPLC2, Springer LNCS 2379, (2002).

  5ESS telecommunications switch, Bell Labs / AT&T / Lucent
The 5ESS^tm product-line is a family of telephone switches that has an unparalleled reputation for reliability, quality, and performance. The switch was originally developed by AT&T Bell Labs and was first put into commercial use in 1982. It is currently made by Lucent Technologies. The majority of local telephone switches in the U.S. today are still 5ESS switches. If you live in the U.S. most likely when you pick up the handset on your telephone you are connected to a 5ESS switch.

Any particular switch in the product line is operated by approximately 10MLOC. The software architecture reflected in that code has remained relatively stable at the subsystem level over a period of 20 years, and was designed to accommodate a set of variabilities that can still be discerned by examining the architecture. In the early 1990s some of the first applications of domain engineering to a large, complex system were successfully accomplished in the 5ESS software and documented in the software engineering literature. Domains such as switch maintenance, signalling, and traffic management showed productivity improvements of factors of 3 to 5 as a result.

• W. Howard, editor, “The 5ESS Switching System,” vol. 64, AT&T Technical Journal, July-August, 1985, Special Issue on the 5ESS Switch.

  Bold Stroke avionics software family, Boeing
The Bold Stroke Software Product Line is comprised of a wide range of artifacts required to create Operational Flight Programs for a variety of Boeing military fighters, including a highly configurable architecture, application components, middleware framework, and development processes and tools. Operational Flight Programs are mission critical distributed real-time embedded applications supporting the avionics and cockpit functions for the pilot. A well-defined software architecture and carefully designed approaches to handle commonality and variability were crucial to the success of this product line. The architecture is heavily based on and expressed via object-oriented patterns. These patterns were leveraged to convey both the architecture and its rationale to a large community of software engineers previously experienced primarily with military standard assembly language systems. The product line exploits commercial standards, technologies, and products as much as possible, using an open source real-time Object Request Broker - The ACE ORB-developed in partnership with Washington University in St. Louis and a commercial real-time operating system. The Bold Stroke Software Product Line is the foundation for an increasing number of production and research programs including several funded by the Air Force Research Laboratory and the Defense Advanced Research Projects Agency.

• Sharp, David C., "Reducing Avionics Software Cost Through Component Based Product Line Development", Patrick Donohoe (ed.) Proceedings SPLC1, Kluwer Academic Publishers, 2000.

• Doerr, Bryan S., and Sharp, David C., "Freeing Product Line Architectures from Execution Dependencies", Patrick Donohoe (ed.) Proceedings SPLC1, Kluwer Academic Publishers, 2000.

• Popp, Timothy J., "Software Architecture Development for Product Line Software", AIAA/IEEE Digital Avionics Systems Conference, October 1999.

 The MERGER Software Product Line (MARKET MAKER Software AG)
MARKET MAKER Software AG, Kaiserslautern, Germany, provides Europe’s most popular stock market software. Since 1989, its products have allowed the stock market to be tracked and analyzed. In 1999, MARKET MAKER decided to launch an internet-based version of its product, using the functionality of their desktop products as the engine to power other companies’ financial web sites. This kind of system has to integrate with the customers’ databases and other content-producing software, run on who-knows-what kind of computing platforms and servers, satisfy human-user performance requirements, and be tailored to show exactly the kind of data, in exactly the kind of charts, in exactly the kind of form required by each particular customer’s web site. That is, the product must be flexible, widely tailorable, deliverable in a very short amount of time, and producible by a very small development staff.

For these reasons, MARKET MAKER decided to plan the internet versions right from the beginning as a software product line, which they called MERGER. The result is a 520 KSLOC system that meets all of those requirements and more. Six people (two of whom were part-time) worked for about a year to produce the core system, from which instantiated products are turned out. Each product in the family must be built to the client's specifications and installed and tested on the client's own platform. Because of their systematic product line approach, MARKET MAKER is able to set up such systems in a few days. In the early days of the product line, this short time-to-market was the major advantage of MARKET MAKER over its competitors. In the current bad economic times, MARKET MAKER can survive because of their small, efficient team required for maintaining the running systems.

• P. Clements and L. Northrop, Software Product Lines: Practices and Patterns, Addison Wesley, 2001.

• C. Gacek, P. Knauber, K. Schmid, and P. Clements. Successful Software Product Line Development in a Small Organization. A Case Study, Technical Report, Fraunhofer Institute for Experimental Software Engineering (IESE), 013.01/E, 2001.

  A-7E Operational Flight Program, U.S. Naval Research Laboratory
The A-7E operational flight program (OFP) is the software that assists the pilot of the Navy's A-7E aircraft to operate the airplane. The OFP was redesigned by the Software Cost Reduction project at the Naval Research Laboratory to show how to apply family-based software development principles in the development of a hard real-time system. Commonalities and variabilities were explicitly identified starting in the requirements specification for the family, and were a strong driving factor in the modular design of the OFP. The OFP design, including a modular structure, a process structure, and a uses relation, was explicitly created and documented to be an engineering model that others could follow. It has had a strong influence on the field of both software engineering and of product line engineering.

  ShipSystem 2000, CelsiusTech Systems AB
ShipSystem 2000 is a family of naval shipboard comment and control systems produced by CelsiusTech Systems AB of Sweden since the late 1980s. Begun in 1985 as a business and technical response to two large contracts awarded simultaneously, ShipSystem 2000 is based upon a robust architecture that was designed to handle both of those initial systems as well as the more than fifty variants that followed. Family members include systems for ships from coastal corvettes to cruisers to submarines, for navies all over the world. These systems comprise 1-1.5 million SLOC of Ada code, are hard-real-time, embedded, and safety-critical. CelsiusTech has been able to slash production time, build more systems with fewer people, and increase quality. The story of ShipSystem 2000 was one of the first and most important case studies in successful software product line engineering.

  Mobile phones, Nokia
Nokia Mobile Phones produces a wide range of mobile phones. Currently 32 different phones are manufactured covering six different protocol standards, a wide variety of functional features and capabilities, different user interface designs, and many platforms and environments. The initial software architecture for this product line addressed variations in hardware, communication standards, and user interfaces; the product line was selected "The Product of the Year" by Business Week and Connect magazines. The current architecture is component based in the client-server style. It allows separate service providers to be plugged in or taken out without restarting the system. This architecture supports both local and remote message passing and component management, task scheduling and event control. Nokia Mobile Phones is the world's largest mobile phone manufacturer, and they believe that software product line engineering has helped it to reach that position.

  Owen Firmware Cooperative, Hewlett Packard
Owen is a community of firmware development teams from HP product divisions in two states in the USA; they produce firmware for a number of printers and printer/copier/scanner/fax devices. Participating teams contribute to the cooperative by producing assets conformant to the Owen architecture, and benefit from other teams' contributions. Owen is unique because of its strong cultural aspects. A steering team, firmware architect, firmware asset lead, and "cooperative steward" roles provide the overall direction. There are cooperative operating principles, and members (while first and foremost turning out their own products) have explicit responsibilities to the coop. Owen products have been produced using 1/4 of the staff, in 1/3 of the time, and with 1/25 the number of bugs of earlier products.