Costs and schedule pressure mean that this approach became increasingly

Costs and schedule pressure mean that this approach

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Costs and schedule pressure mean that this approach became increasingly unviable , especially for commercial and Internet-based systems. An approach to development based around the reuse of existing software emerged and is now generally used for business and scientific software. 30 Chapter 7 Design and implementation
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12/12/2018 6 7.3.1 Reuse levels The abstraction level At this level, you don t reuse software directly but use knowledge of successful abstractions in the design of your software. The object level At this level, you directly reuse objects from a library rather than writing the code yourself. The component level Components are collections of objects and object classes that you reuse in application systems. The system level At this level, you reuse entire application systems. 31 Chapter 7 Design and implementation 7.3.1 Reuse costs The costs of the time spent in looking for software to reuse and assessing whether or not it meets your needs. Where applicable, the costs of buying the reusable software . For large off-the-shelf systems, these costs can be very high. The costs of adapting and configuring the reusable software components or systems to reflect the requirements of the system that you are developing. The costs of i ntegrating reusable software elements with each other (if you are using software from different sources) and with the new code that you have developed. 32 Chapter 7 Design and implementation 7.3.2 Configuration management Configuration management is the name given to the general process of managing a changing software system. The aim of configuration management is to support the system integration process so that all developers can access the project code and documents in a controlled way , find out what changes have been made, and compile and link components to create a system. See also Chapter 25. 33 Chapter 7 Design and implementation 7.3.2 Configuration management activities Version management, where support is provided to keep track of the different versions of software components. Version management systems include facilities to coordinate development by several programmers. System integration, where support is provided to help developers define what versions of components are used to create each version of a system. This description is then used to build a system automatically by compiling and linking the required components. Problem tracking, where support is provided to allow users to report bugs and other problems, and to allow all developers to see who is working on these problems and when they are fixed. 34 Chapter 7 Design and implementation 7.3.3 Host-target development Most software is developed on one computer (the host), but runs on a separate machine (the target).
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