【正文】 ounting fraud may be more plex and require a great deal of time to find. – Carry out the plan ? …… ? Code generation – Examine the result for accuracy ? Testing and quality assurance 2 軟件工程 ? Why到 How（工程） – To develop high quality software systems that satisfy the customers requirements in the control of schedules and costs ? To estimate costs， ? To control progress， ? To guarantee quality – to overe plexity 2 軟件工程 ? 軟件工程的國際標(biāo)準(zhǔn) – ISO90001,9001,12207 – IEEE – SWCMM(SEI) 國內(nèi)企業(yè)開始用 – ITU ? 國標(biāo)，滯后！ ? 國內(nèi)軟件業(yè)的軟肋 – 實(shí)踐中，沒有標(biāo)準(zhǔn)可遵行 2 軟件工程的本質(zhì) ? SE面臨的主要挑戰(zhàn) – 要迎合軟件的多樣性 ? 技術(shù)，運(yùn)行平臺(tái) – 急速的上市時(shí)間 – 有價(jià)值的軟件 ? SE的總體目標(biāo) – 降低成本、提高速度和質(zhì)量、可用，可維護(hù)，可重用 3 軟件工程的目標(biāo)與原則 ? 隨著技術(shù)進(jìn)步，人們對(duì)軟件及其運(yùn)行環(huán)境的要求越來越高 ? 軟件工程的目標(biāo)是： ?在給定成本、進(jìn)度前提下，開發(fā)出具有可修改性、有效性、可靠性、可理解性、可維護(hù)性、可重用性、可適應(yīng)性、可移植性、可追蹤性和可互操作性并且滿足用戶需求的軟件產(chǎn)品。 2 軟件工程 ? The IEEE standard:Software Engineering: (1) The application of a systematic, disciplined, quantifiable approach to the development, operation and maintenance of software, that is, the application of engineering to software. (2) The study of approaches as in (1). ? 過度定義，無所適從？ – software engineering is the study of the processes, methods, tools and techniques for achieving such control over the quality and outes in software development. – Software engineering is the establishment and use of sound engineering principles in order to obtain economically, software that is reliable and works efficiently on real machines. ? 哪些原理？ 2 軟件工程 ? The control over the quality and the outes of the project in the definition above means that software developers are able to: – repeatedly determine and achieve the desired level of quality for their products。 – 軟件工程借鑒傳統(tǒng)工程的原則、方法，以提高質(zhì)量、降低成本： ? 計(jì)算機(jī)科學(xué)、數(shù)學(xué)用于構(gòu)建模型與算法， ? 工程科學(xué)用于制定規(guī)范、設(shè)計(jì)范型 (paradigm)、評(píng)估成本及確定權(quán)衡， ? 管理科學(xué)用于計(jì)劃、資源、質(zhì)量、成本等管理。 ? 而美國梅隆卡耐基大學(xué)軟件工程研究所（ SEI）：以工程形式應(yīng)用計(jì)算機(jī)科學(xué)和數(shù)學(xué)原理，從而經(jīng)濟(jì)有效地解決軟件問題。 – Software engineering (SE) is a profession dedicated to designing, implementing, and modifying software so that it is of higher quality, more affordable, maintainable, and faster to build. – IEEE defines SE as the application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software, and the study of these approaches。萬物皆模型 2 軟件工程 ? 定義繁多而不一，涉及面廣，側(cè)重點(diǎn)不同，因?qū)W科發(fā)展程度而異（過度定義?。? – Fritz Bauer在 NATO會(huì)議上給出的定義： ? 建立并使用完善的工程化原則，以較經(jīng)濟(jì)手段獲得能在實(shí)際機(jī)器上有效運(yùn)行的可靠軟件的一系列方法。硬件已向巨型化、微型化、網(wǎng)絡(luò)化和智能化四個(gè)方向發(fā)展，數(shù)據(jù)庫技術(shù)已成熟并廣泛應(yīng)用，第三代、第四代語言出現(xiàn)； ? 第一代軟件技術(shù)：結(jié)構(gòu)化程序設(shè)計(jì)在數(shù)值計(jì)算領(lǐng)域取得優(yōu)異成績；（軟件方法學(xué)問世） ? 第二代軟件技術(shù)：軟件測(cè)試技術(shù)、方法、原理用于軟件生產(chǎn)過程；（軟件測(cè)試） ? 第三代軟件技術(shù)：處理需求定義技術(shù)用于軟件需求分析和描述。 ? 但軟件開發(fā)技術(shù)沒有重大突破，軟件產(chǎn)品的質(zhì)量不高，生產(chǎn)效率底下，從而導(dǎo)致了“軟件危機(jī)”的產(chǎn)生。開始廣泛使用產(chǎn)品軟件（可購買），建立了軟件的概念。 – 軟件設(shè)計(jì)階段（ 1956～ 1970）。 – it helps busy practitioners decide how to respond to unexpected situations. – it is seen that much of engineering in the general belongs in the category of resourcelimited, cooperative games. 2 軟件工程 ? Contemporary system developers have some serious problems to cope with. The systems they develop are being increasingly plex as customers demand richer functionality delivered in ever shorter timescales. ? They are exposed to a huge diversity of implementation technologies, design techniques and development processes, particularly the latest ’silver bullet’ design abstraction Model Driven Software Development. 2 軟件工程 ? 起源：國際學(xué)術(shù)會(huì)議：軟件工程問世 – 1968 NATO (Military alliance of democratic states in Europe and North America) Software Engineering Conferences, Garmisch, Germany ? Aim: To solve the software crisis – 應(yīng)用工程學(xué)原理、技術(shù)和方法，科學(xué)地組織、管理軟件生產(chǎn)和運(yùn)行 – 軟件危機(jī)表象：低質(zhì)量、超期、超支 – 2021年，第 35屆會(huì)議持續(xù) 9天，舊金山 2 軟件工程 ? 發(fā)展過程 – 程序設(shè)計(jì)階段（ 1946～ 1955）。缺乏應(yīng)對(duì)復(fù)雜性的、支持開發(fā)過程的方法、技術(shù)、工具、質(zhì)量控制機(jī)制等 ? How to guarantee the quality of the software systems? ? How to develop such software systems? – Problems? Skills? Approaches? Technologies? Steps and processes? 軟件開發(fā)：軟件危機(jī)解決方案 ? 兩種解決方案 – 軟件工程 ? Software engineering (SE) is an attempt to solve these problems. ? 開發(fā)不僅僅是編程，按項(xiàng)目來實(shí)施 – 形式化方法 ? 可信軟件 ? 用數(shù)學(xué)語言描述軟件過程 Formal methods ? Formal methods are mathematical approaches to solving software (and hardware) problems at the requirements, specification, and design levels. Formal methods are most likely to be applied to safetycritical or securitycritical software and systems, such as avionics software. Software safety assurance standards, such as DO178B, DO178C, and Common Criteria demand formal methods at the highest levels of categorization. – For sequential software, examples of formal methods include the BMethod, the specification languages used in automated theorem proving, RAISE, and the Z notation. – Formalization of software development is creeping in, in other places, with the application of Object Constraint