第9章ソフトウェア工学

By the end of this section, you will be able to:

• Describe the intent of software engineering and how it relates to computer science

• Recognize various categories of software

• Identify the skills that are required for a software engineer

This section introduces software engineering along with the challenges associated with the creation and evolution of software. The various fundamental facets of software engineering are presented including the skills required to properly engineer software and the role that a software engineer is expected to play within a software team.

The IEEE¹ defines software engineering as the application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software; that is, the application of engineering to software. It is important to understand how software engineering fits into the larger context of computer science. It is also important to understand the role of a software engineer and how it fits within an organization.

The reference to “a systematic, disciplined, quantifiable approach” does not mean a bureaucratic, document-laden approach. Software engineering relies on various methodologies/processes, methods and tools that may be used to professionally develop and maintain quality software while optimizing the use of resources such as time and cost. Selecting the right processes and methods for a project and using tools to accelerate the ongoing development of a solution is challenging especially when requirements are changing and many software developers are working together to tackle a large project. Part of the issue is that software engineering as a process cannot (in general) be fully automated and therefore it is difficult to keep all the activities aligned with the end goal of delivering a solution on time and within budget.

Selecting and tailoring software engineering processes and methods as well as using the right tools in the right fashion to meet this end goal, which in essence defines a majority of what a software engineer does, is covered in detail as part of this chapter.

Software is everywhere, and most of us interact with a software system on a daily basis. Yet the importance of software is expected to grow even greater in the coming decades. Although most software revenue comes from a generic software, software systems tailored to specific needs can be found everywhere, from our cars to our smartwatches. Thus, quite a few of us can expect that we will be involved as customers in some software engineering process during our professional lives. People who are familiar with concepts of software engineering can better oversee the projects they are working on by interacting with customers so their needs are clearly specified and by working with developers to smooth out the development process and ensure the final product meets customers’ expectations.

In most organizations, software is developed by a team of software engineers, as well as other people with different backgrounds and skills. To be effective, the project team must be organized in a way that maximizes the use of each person’s skills and abilities and emphasizes the importance of teamwork to address all the aspects of the projects. This is especially true for complex projects. Effective project managers focus on problem-solving and end-product quality, and thus they may organize software teams in a variety of ways. The key factors considered when selecting a team organizational model are as follows:

• difficulty of the problem to be solved

• degree to which the problem can be modularized

1 While IEEE is an acronym for the Institute of Electrical and Electronics Engineers, the organization has expanded to include all technology professionals. This worldwide organization is “dedicated to advancing technology for the benefit of humanity.” Examples of the work it does is publishing journals to disseminate the latest research, creating model curricula that help universities provide up-to-date degree programs, and defining standards that ensure electronic devices are interoperable. You can find more about the IEEE at www.ieee.org.

• required quality, reliability, and other nonfunctional requirements of the system to be built

• delivery date

• budget limitations

• team lifetime (i.e., overall period of time during which the team members will work together)

During the creation of a software solution, software engineer team members may take on various roles, such as:

• project manager, who is responsible for making sure that the project gets completed on time and on budget

• enterprise or solution portfolio architect, who makes high-level design decisions on high-level modeling or solution design building blocks and their interconnections to best address functional requirements as well an nonfunctional ones such as performance and usability

• user experience (UX) designer, who plans how users will interact with the software system; this involves tasks like designing the user interface (UI), making wireframes and prototypes, and conducting user testing to ensure the software is user-friendly and meets user needs

• software developer, who analyzes requirements, refines the design, writes and tests code, and collaborates with the operations team to deploy the software into testing and production environments

• quality assurance tester, who checks for bugs and validates that the system meets the requirements

It is common for one team member to act in several roles (for example, a solution architect might also be a software developer), and some roles may be filled by multiple team members (for example, there are typically multiple software developers on a project). Additionally, a software engineer may work directly with other people, including:

• product owners, who are generally project sponsors and provide the requirements and overall guidance on what is expected from the solution

• subject matter experts (SMEs), who are specialists in areas such as business, technology, products, or other topics as needed

• database administrators, who focus on areas such as data storage, organization, and access associated with a software solution

• operations specialists, who are IT and/or DevOps professionals with a focus on computer hardware and software operations

Because projects can involve a large number of people working in many different roles, communication and interaction among team members is critical for a project to succeed. To keep the team running smoothly, projects are ideally structured so they include the following:

• deadlines that provide sufficient time for team members to fully complete their tasks and ensure results that match the requirements

• standards for how business and technology decisions are made to avoid business or technology-related disagreements

• processes and procedures that make it easy for team members to coordinate their activities

• clear definitions of each team members’ role and authority so that everyone knows who is accountable for each task and where questions should be directed