Modernizing Legacy Systems - Software Technologies, Engineering Processes, and Business Practices
Modernizing Legacy Systems - Software Technologies, Engineering Processes, and Business Practices
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发表时间：
2003-02
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通讯作者：
R. Seacord;Daniel Plakosh;G. Lewis
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作者：
R. Seacord;Daniel Plakosh;G. Lewis
从本书开始：软件系统开始抗拒修改和演变时成为旧系统。但是，在旧系统中体现的知识构成了重要的公司资产。假设这些系统仍然具有巨大的业务价值，则必须进行现代化或更换它们。本书描述了一种风险管理的传统系统现代化方法，该方法应用了软件技术的知识以及对业务环境中工程流程的了解。审计化现代化的遗产系统：软件技术，工程流程和业务实践都应对参与的任何人都有用现代化遗产系统。作为软件工程师，它应该帮助您了解一些推动现代化工作的较大业务问题。作为软件设计师，本书应帮助您了解旧版代码的影响，再加上增量开发和部署实践对设计活动的影响。作为系统架构师，本书解释了在实践中失败或成功的过程和技术。它还应该提供有关如何重复这些成功并避免失败的洞察力。作为IT经理，本书解释了技术和业务目标如何影响软件现代化流程。特别是，它应该帮助您回答以下问题：何时以及如何确定现代化或替代工作是否合理？我如何发展对传统系统的理解？我如何了解并评估可以在我的系统现代化中使用的Infsystem Technologies的适用性？我什么时候参与利益相关者，如何调和他们的冲突需求？建筑在旧系统现代化中起什么作用？我如何估计旧系统现代化的成本？我如何评估和选择现代化策略？如何制定详细的现代化计划？组织和内容现代化的旧系统：软件技术，工程流程和业务实践显示了如何逐步现代化旧系统。它使用并扩展了从商业组件Wallnau（2001年）在建筑系统中描述的方法和技术，以在概念阶段早期借鉴工程专业知识，以确保现实和全面的计划。这本书以广泛的案例研究为特色，涉及重大的现代化工作。在这种情况下，遗产系统包括近200万行COBOL代码在30年内开发的近200万行。该系统将被基于Java 2 Enterprise Edition（J2EE）体系结构的现代系统替换。其他挑战包括逐步开发和部署系统的要求。我们研究用于现代化系统的策略；使用企业Javabean，面向消息的中间件，Java和其他J2EE技术来生产现代系统；支持软件工程过程和技术；以及最终的系统。本书的第1章介绍了软件演化的挑战和实践，第2章介绍了BO中的主要案例研究介绍了风险管理的现代化（RMM）方法，该方法在第4至第17章中详细阐述了，并由案件进行了说明，并由案件进行了说明。学习。在第4至17章中，我们提供了RMM的活动图作为每章的路线图。第18章提供了一些建议，以帮助指导您的现代化工作（尽管如果不阅读本书的主体，这些建议将无法完全理解）。本书，我们使用统一的建模语言（UML）来表示建筑图纸和设计模式。第6章提供了对UML的简要介绍。
From the Book: Software systems become legacy systems when they begin to resist modification and evolution. However, the knowledge embodied in legacy systems constitutes significant corporate assets. Assuming these system still provide significant business value, they must then be modernized or replaced. This book describes a risk-managed approach to legacy system modernization that applies a knowledge of software technologies and an understanding of engineering processes within a business context.Audience Modernizing Legacy Systems: Software Technologies, Engineering Processes and Business Practices should be useful to anyone involved in modernizing a legacy system. As a software engineer, it should help you understand some of the larger business concerns that drive a modernization effort. As a software designer, this book should help you understand the impact of legacy code, coupled with incremental development and deployment practices, on design activities. As a system architect, this book explains the processes and techniques that have failed or succeeded in practice. It should also provide insight into how you can repeat these successes and avoid the failures. As an IT manager, this book explains how technology and business objectives influence the software modernization processes. In particular, it should help you answer the following questions: When and how do I decide if a modernization or replacement effort is justified? How do I develop an understanding of the legacy system? How do I gain an understanding of, and evaluate the applicability of, infsystem technologies that can be used in the modernization of my system? When do I involve the stakeholders and how can I reconcile their conflicting needs? What role does architecture play in legacy system modernization? How can I estimate the cost of a legacy system modernization? How can I evaluate and select a modernization strategy? How can I develop a detailed modernization plan? Organization and Content Modernizing Legacy Systems: Software Technologies, Engineering Processes and Business Practices shows how legacy systems can be incrementally modernized. It uses and extends the methods and techniques described in Building Systems from Commercial Components Wallnau, 2001 to draw upon engineering expertise early in the conceptual phase to ensure realistic and comprehensive planning. This book features an extensive case study involving a major modernization effort. The legacy system in this case study consists of nearly 2 million lines of COBOL code developed over 30 years. The system is being replaced with a modern system based on the Java 2 Enterprise Edition (J2EE) architecture. Additional challenges include a requirement to incrementally develop and deploy the system. We look at the strategy used to modernize the system; the use of Enterprise JavaBeans, message-oriented middleware, Java, and other J2EE technologies to produce the modern system; the supporting software engineering processes and techniques; and the resulting system. Chapters 1 of this book provides an introduction to the challenges and practices of software evolution and Chapter 2 introduces the major case study in the bo introduces the Risk-Managed Modernization (RMM) approach which is elaborated in Chapters 4 through 17 and illustrated by the case study. Throughout Chapters 4 through 17 we provide an activity diagram of RMM as a road map to each chapter. Chapter 18 provides some recommendations to help guide your modernization efforts (although these recommendations cannot be fully appreciated without reading the main body of the book).Throughout this book we use the Unified Modelling Language (UML) to represent architecture drawings and design patterns. A brief introduction to UML is provided in Chapter 6.