Hewlett-Packard Laboratories

In this column, I delve into how a reuse program integrated with an SEI program can take advantage of the Personal Software Process (PSP) ^SM, the Team Software Process (TSP)^SM and the reuse-oriented aspects of the CMM Key Process Areas (KPAs).

Most reuse programs go through stages of increasing formality and organizational ability to create, manage and reuse carefully designed reusable assets. These stages, driven by increasing experience and business need, are summarized in the six levels of the simple Reuse Maturity Model (RMM) described in more detail in the March column[1]:

The SEI CMM is a framework for staged process improvement that prescribes the kinds and quality of a group of processes that should be used at each level. The five levels of the Capability Maturity Model and corresponding Key Process Areas (KPAs) are[2]:

In the decade since 1987, an increasing number of organizations used the CMM to guide their process improvements. In 1987, only a few dozen organizations were assessed, and the vast majority were at level 1. Ten years later, more than 600 organizations have reported CMM results. A significantly greater proportion are now operating at levels 2 and 3. After several years spent on process improvement, they see an average 35% productivity improvement per year, 19% reduction in time to market and 39% improvement in quality[2].

As described in the March column, the CMM is a reuse-friendly process improvement framework. While it does not prescribe the processes in detail, there are specific reuse-oriented choices projects and the organization can make as it designs these processes.

The CMM enables and facilitates good work and reuse, but does not guarantee it. Engineers must use effective personal and team practices. A specific process improvement plan must describe standard processes, metrics and training, that match the specific business and software development needs of the organization.

The Personal Software Process (PSP)[3, 4, 5] (PSP) provides a detailed, bottom-up approach to process improvement. PSP brings discipline to the practices of individual software engineers, dramatically improving quality, predictability and cycle time. The PSP guides engineers in measuring, evaluating and improving the way they do their software engineering tasks. They set personal goals, measure and analyze their work, and adjust their processes to meet their goals. Individuals develop new habits so that they become aware of their processes and how those processes perform. Continuing management attention helps engineers use and maintain these new habits. A related Team Software Process (TSP), still under development, offers promise in describing how teams should operate in accord with the PSP.

The PSP is best introduced by a rigorous training program, offered to new programmers or to all members of a project team. PSP is introduced incrementally, using lectures, exercises, reports, personal logs and templates. Completion of PSP training results in a personal process with significant reuse, and improved skills and discipline in:

• Personal measurement: Dealing with basic measurement, assessment of current process, coding standards, size measurement and measurement-based process improvement.
• Personal planning: Involving size estimating, test and defect reporting, task and schedule planning
• Personal quality: Code and design reviews, and design templates
• Cyclic development: Incremental, iterative process

In a typical PSP class, students reduced defects by a factor of 5, and improved their ability to estimate project time by a factor of 2. In some cases, they improved productivity by 20-30%, while greatly increasing the proportion of time spent on design as compared to coding or testing. In industrial use, similar results are obtained – project schedule estimation errors drop significantly, defects are reduced, and test time radically reduced[5].

The Team Software Process (TSP)[6] is still under development. It refines and extends both CMM and PSP to guide engineers to work effectively in development and maintenance teams. The current TSP uses 23 scripts and 14 templates and 3 standards. TSP provides standard, proven answers to the many questions about schedule management, project tracking and other software development strategies that plague teams when planning a project and moving from phase to phase. Early results with TSP show that it helps teams identify and remove close to 99% of defects before test. TSP also helps teams gather the data needed to quickly assess component quality before integration and test. A novel "component quality profile" is used to quickly judge five quality parameters. High quality components are key to successful organizational reuse.

To get increasingly systematic reuse, certain processes and skills have to be defined with increasing rigor, and followed with increasing precision. Several of the CMM KPAs are essential parts of the reuse process. The PSP methods explicitly address reuse, specifically during design and project estimation.

Watts Humphrey asserts that "Reuse is important for the PSP both because it can substantially improve your productivity and because it demands extraordinarily high-quality software. One PSP objective is to develop the personal process disciplines needed to produce reuse-quality software."[3]. PSP provides several reuse-oriented planning, measurement, component creation and organization guidelines.

PSP discusses reuse standards, and how reuse must be addressed during estimation, design and reviews. Reuse-quality software is produced by following a process that utilizes good design standards and effective design verification methods. Reuse standards ensure that standard components are used correctly, and that a programmer has taken maximum advantage of available reusable components. Consistent design standards, such as calling and naming conventions, header standards, test standards and documentation provide a basis for effective sharing within a team. Reusable parts must be precisely specified, and properly supported.

PSP’s PROxy-Based Estimation (PROBE) method specifically describes the need to identify reused objects that will become part of the design, as well "new reused" objects that are sufficiently general to be put in the reuse library. It requires different size estimates for new code, reused code and new reused code. There is extensive discussion on how to measure and estimate amounts of reuse, and how these measures are to be used to motivate engineers to do the right kind of reuse.

An effective reuse program will require effective (multi-project) project management, requirements management and quality control, supported by careful configuration management. Most of the CMM Level 2 KPA's are needed for almost any form of reuse:

• Requirements management is an important part of domain engineering. Careful analysis of commonality and variability in requirements, keeping track of changes, and keeping track of which requirements are met by which components.
• Software project planning and Software project tracking and oversight increase confidence in reuse processes by keeping multi-team project efforts on schedule, managing risks to the program through corrective action process and keeping all parties aware of changes in plans or commitments. RMM 3 is enhanced by deliberate use of resources to create reusable components or apply them in application building. RMM 4-6 are enabled through coordinated project plans, good estimating methods, effective use of resources across teams, and good processes for achieving commitments from infrastructure teams.
• The relationship between reuse Creator projects and reuse Reusers can be thought of as a form of Software subcontract management. The projects need to ensure that key agreements relating to quality, features and deliverable schedule are as explicit as if an external supplier was being used.
• Software quality assurance can have significant impact in allowing salvaging (RMM 1 ) and black box reuse (RMM 2) to be cost effective, especially if specific code areas are targeted for systematic defect removal. An important part of the reuse library process are certification and acceptance standards, which become increasingly rigorous at higher levels of RMM. RMM 4-6 are difficult to achieve if quality assurance is not integral to the development process, if design, coding and test standards are not applied effectively, and if compliance to architecture, workproduct and coding standards is not enforced.
• A well functioning Software configuration management process is needed to ensure that projects know which versions of components are available and which they are using in any application. RMM-2 salvaging operations are more effective when source is in a "known state". Versioning and change control are very important for multi-project black-box reuse (RMM 3). . Communication of changes to reusable components is critical to engineers using the components. RMM 4-6 is virtually impossible to achieve without a multi-project version and configuration management process well integrated into the library management systems and creator and reuser processes.

Managed workproduct reuse (RMM 4) requires even more organizational process support. Decisions impacting many teams are made on a regular basis, such as which components are being produced or supported. Many CMM 3 KPAs support, or should be adapted to, the reuse process:

• Organization process definition, implies the use of standard process templates, and guidelines which enable effective management of workproduct reuse at RMM 3. These are essential for highly effective work by Creators and Reusers in RMM-4 and above. At HP, we developed a set of reuse process elements as a set of WWW pages. Our reuse process elements consist of templates, steps and guidelines for each of the distinct Manage, Create, Support and Reuse processes. They also describe how a reuse library should be structured and guidelines for certification and classification of components.
• An effective Training program for developers and project managers could have significant impact on benefits of salvaging (RMM 2) and planned black box reuse (RMM 3), especially if it includes process standards and introduction to the components. Formal training steps are increasingly critical at RMM 5 and higher for effective operation of processes at these levels, especially for critical skill areas in design, architecture, domain engineering and reuse support.
• Intergroup communication is key to establishing an effective reuse process across creators and reusers and ensuring that the groups coordinate efforts, and use components.
• Peer reviews ensure the quality of the components, and discover opportunities for increased reuse.

Architected reuse (RMM 5) requires most of the discipline and well-defined processes characteristic of CMM 3. Installing systematic reuse can help focus on these well-defined processes. The domain engineering and architecting processes that discover the commonality and variability need to be well-defined, need to link the needs of multiple projects, and control how they develop applications to conform to this architectures. Finally, well-managed, cost-effective pervasive domain-specific reuse (RMM 6) requires the measurement-driven process and product improvement characteristic of CMM 4 and 5.

The SEI is revising the current CMM Version 1. In the most recent draft of CMM Version 2, several KPAs have been renamed or refined. Restructuring will continue as several CMM models are integrated into a common maturity model framework. A new Level 4 KPA, Organization Software Asset Commonality, captures the concept of common software assets. It deals with management guidelines, software and organization processes, and metrics needed to effectively handle common assets. It mentions opportunistic reuse and reengineering, as well as business-driven domain engineering and product line reuse, involving common assets and variants across domains or product families. Senior management has a key role in organizing and driving "domain specific" and "product line" reuse. The management of a reuse library and reuse metrics is also key.

In our experience, several of these activities can be started and yield beneficial results much earlier than CMM 4. Simple domain engineering techniques can be applied as early as the CMM 2 repeatable phase, with most benefit at RMM 3 Black Box reuse. Widespread domain engineering is most cost effective for architected reuse (RMM 5) practiced systematically and formally across the organization at CMM 3.

Integrating the reuse program with the SEI program allows one to pay attention to the reuse process content of each of the key process areas and helps address some key resource allocation questions.. Many of the CMM process KPAs, as well as process elements from PSP and TSP can be directly oriented towards improving the production, handing and use of various reusable artifacts. As more organizations achieve levels CMM 2 and 3, or higher, the opportunities for simultaneously improving reuse will increase.