As well as testing that a component for reuse does

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As well as testing that a component for reuse does what you require, you may also have to check that the component does not include any malicious code or functionality that you don t need. Chapter 17 Software reuse 37 Ariane launcher failure validation failure? In 1996, the 1st test flight of the Ariane 5 rocket ended in disaster when the launcher went out of control 37 seconds after take off. The problem was due to a reused component from a previous version of the launcher (the Inertial Navigation System) that failed because assumptions made when that component was developed did not hold for Ariane 5. The functionality that failed in this component was not required in Ariane 5. 38 Chapter 17 Software reuse Component composition The process of assembling components to create a system. Composition involves integrating components with each other and with the component infrastructure. Normally you have to write glue code to integrate components. 39 Chapter 17 Software reuse Types of composition Sequential composition where the composed components are executed in sequence. This involves composing the provides interfaces of each component. Hierarchical composition where one component calls on the services of another. The provides interface of one component is composed with the requires interface of another. Additive composition where the interfaces of two components are put together to create a new component. Provides and requires interfaces of integrated component is a combination of interfaces of constituent components. 40 Chapter 17 Software reuse Types of component composition 41 Chapter 17 Software reuse Interface incompatibility Parameter incompatibility where operations have the same name but are of different types. Operation incompatibility where the names of operations in the composed interfaces are different. Operation incompleteness where the provides interface of one component is a subset of the requires interface of another. 42 Chapter 17 Software reuse
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