th cases, the overall stages of the lifecycle are not affected; what is affected is the amount of effort required in each stage. As object oriented methods are relatively new, the lifecycle for these methods does not differ from the "standard lifecycle" significantly. 25.4.4 Knowledge based systems lifecycle There are two noticeable changes to the activities carried out in the lifecycle however. These relate to the reuse of components and The lifecycle described below is for KADS as this is the best known to the use of inheritance. emerging method supporting KBS developments. The remaining In order to take advantage of the reuse supported by object text in this section has been reproduced from Hayball with kind orientated methods, a library of standard components must be con- permission from the author. structed. These standard components can then be used not only in KADS (i.e. 'the KADS method') is a set of activities, and defini- the current development, but also, potentially, in future develop- tions of their results, for supporting the Analysis and Design stages ments. of KBS development. KADS covers the following areas: The effort required to create and catalogue these standard compo- nents can be considerable, with the attendant problems that savings 1. Structured activities for Analysis (Product Definition) & De- may only be recouped in future developments. Nevertheless, the sign (High Level Design). reuse of standard components is important to the use of object 2. Framework definitions for the results produced by activities. orientated methods, and this investment should be made. 3. Tools and techniques for activities in KBS development. The second change to the activities in the lifecycle involves the 4. Techniques and check lists for quality assessment and control use of inheritance. Once the objects in the system have been ident- (QAC). 25/10 Software systems in telecommunications 5. Identified prototyping opportunities. it records in a structured manner the requirements for user/sys- tem interaction. 