2- THE CHANGING NATURE OF SOFTWARE.pdf
- 1. THE CHANGING NATURE OF SOFTWARE The 7 broad categories of computer software present continuing challenges for software engineers: 1) System software 2) Application software 3) Engineering/scientific software 4) Embedded software 5) Product-line software 6) Web-applications 7) Artificial intelligence software. System software: System software is a collection of programs written to service other programs. The systems software is characterized by - heavy interaction with computer hardware - heavy usage by multiple users - concurrent operation that requires scheduling, resource sharing, and sophisticated process management - complex data structures - multiple external interfaces E.g. compilers, editors and file management utilities. Application software: - Application software consists of standalone programs that solve a specific business need. - It facilitates business operations or management/technical decision making. - It is used to control business functions in real-time E.g. point-of-sale transaction processing, real-time manufacturing process control. Engineering/Scientific software: Engineering and scientific applications range - from astronomy to volcanology - from automotive stress analysis to space shuttle orbital dynamics - from molecular biology to automated manufacturing
- 2. E.g. computer aided design, system simulation and other interactive applications. Embedded software: - Embedded software resides within a product or system and is used to implement and control features and functions for the end-user and for the system itself. - It can perform limited and esoteric functions or provide significant function and control capability. E.g. Digital functions in automobile, dashboard displays, braking systems etc. Product-line software: Designed to provide a specific capability for use by many different customers, product-line software can focus on a limited and esoteric market place or address mass consumer markets E.g. Word processing, spreadsheets, computer graphics, multimedia, entertainment, database management, personal and business financial applications Web-applications: WebApps are evolving into sophisticated computing environments that not only provide standalone features, computing functions, and content to the end user, but also are integrated with corporate databases and business applications. Artificial intelligence software: AI software makes use of nonnumerical algorithms to solve complex problems that are not amenable to computation or straightforward analysis. Application within this area includes robotics, expert systems, pattern recognition, artificial neural networks, theorem proving, and game playing. The following are the new challenges on the horizon: Ubiquitous computing Netsourcing Open source The “new economy” Ubiquitous computing: The challenge for software engineers will be to develop systems and application software that will allow small devices, personal computers and enterprise system to communicate across vast networks.
- 3. Net sourcing: The challenge for software engineers is to architect simple and sophisticated applications that provide benefit to targeted end-user market worldwide. Open Source: The challenge for software engineers is to build source that is self descriptive but more importantly to develop techniques that will enable both customers and developers to know what changes have been made and how those changes manifest themselves within the software. The “new economy”: The challenge for software engineers is to build applications that will facilitate mass communication and mass product distribution. -----------***********************---------------------***************----------------------***************** SOFTWARE ENGINEERING - A LAYERED TECHNOLOGY Software Engineering: A layered technology Software engineering is a layered technology as referred in fig shown below. It consists of four layers as A quality focus Process Methods
- 4. Tools A quality Focus The bedrock that supports software engineering is a quality focus. Software engineering approach must rest on the organizational commitment to quality. Total Quality Management (TQM) philosophies that support continuous improvement culture leads to the development of increasingly more approaches to software engineering. Process Layer It is the foundation of software engineering that defines a framework for a set of KPA (key process areas) that must be established for effective delivery of software engineering technology. The KPA form the basis for management control of software projects and establish the context in which technical methods are applied, work products (models, documents, data, reports, forms etc) are produced, milestones are established, quality is ensured, and change is properly managed. Methods It provides technical how-to's for building software. Methods encompass a broad array of tasks that include requirements analysis, design, program construction, testing, and support. Methods rely on a set of basic principles that govern each area of the technology and include modeling activities and other descriptive techniques. Tools It provide automated or semi-automated support for the process and methods. Integrated tools establish computer-aided software engineering (CASE). CASE combines software, hardware and software engineering database to create a software engineering environment analogous to CAD/CAE (computer aided design/engineering) for hardware. -------*********-----------------*************----------------****************----------------************---------- A PROCESS FRAMEWORK: Software process must be established for effective delivery of software engineering technology. A process framework establishes the foundation for a complete software process by identifying a small number of framework activities that are applicable to all software projects, regardless of their size or complexity. The process framework encompasses a set of umbrella activities that are applicable across the entire software process.
- 5. Each framework activity is populated by a set of software engineering actions Each software engineering action is represented by a number of different task sets- each a collection of software engineering work tasks, related work products, quality assurance points, and project milestones. In brief "A process defines who is doing what, when, and how to reach a certain goal." A Process Framework - establishes the foundation for a complete software process - identifies a small number of framework activities - applies to all s/w projects, regardless of size/complexity. - also, set of umbrella activities - applicable across entire s/w process. - Each framework activity has - set of s/w engineering actions. - Each s/w engineering action (e.g., design) has - collection of related tasks (called task sets): work tasks work products (deliverables) quality assurance points project milestones. Software process
- 6. Generic Process Framework: It is applicable to the vast majority of software projects - Communication activity - Planning activity - Modelling activity - analysis action - requirements gathering work task - elaboration work task - negotiation work task - specification work task - validation work task - design action - data design work task - architectural design work task - interface design work task - component-level design work task - Construction activity - Deployment activity 1) Communication: This framework activity involves heavy communication and collaboration with the customer and encompasses requirements gathering and other related activities. 2) Planning: This activity establishes a plan for the software engineering work that follows. It describes the technical tasks to be conducted, the risks that are likely, the resources that will be required, the work products to be produced, and a work schedule.
- 7. 3) Modelling: This activity encompasses the creation of models that allow the developer and customer to better understand software requirements and the design that will achieve those requirements. The modelling activity is composed of 2 software engineering actions- analysis and design. Analysis encompasses a set of work tasks. Design encompasses work tasks that create a design model. 4) Construction: This activity combines core generation and the testing that is required to uncover the errors in the code. 5) Deployment: The software is delivered to the customer who evaluates the delivered product and provides feedback based on the evolution. These 5 generic framework activities can be used during the development of small programs, the creation of large web applications, and for the engineering of large, complex computer-based systems. The following are the set of Umbrella Activities. 1) Software project tracking and control – allows the software team to assess progress against the project plan and take necessary action to maintain schedule. 2) Risk Management - assesses risks that may effect the outcome of the project or the quality of the product. 3) Software Quality Assurance - defines and conducts the activities required to ensure software quality. 4) Formal Technical Reviews - assesses software engineering work products in an effort to uncover and remove errors before they are propagated to the next action or activity. 5) Measurement - define and collects process, project and product measures that assist the team in delivering software that needs customer’s needs, can be used in conjunction with all other framework and umbrella activities. 6) Software configuration management - manages the effects of change throughout the software process. 7) Reusability management - defines criteria for work product reuse and establishes mechanisms to achieve reusable components. 8) Work Product preparation and production - encompasses the activities required to create work products such as models, document, logs, forms and lists.
- 8. Intelligent application of any software process model must recognize that adaption is essential for success but process models do differ fundamentally in: The overall flow of activities and tasks and the interdependencies among activities and tasks. The degree through which work tasks are defined within each frame work activity. The degree through which work products are identified and required. The manner which quality assurance activities are applied. The manner in which project tracking and control activities are applied. The overall degree of the detailed and rigor with which the process is described. The degree through which the customer and other stakeholders are involved with the project. The level of autonomy given to the software project team. The degree to which team organization and roles are prescribed.