Systems Analysis Recapitulation The techniques and aids used

Systems Analysis - Recapitulation The techniques and aids used during systems analysis, to develop a detailed model of the existing system include: · · · Fact-finding techniques - to gather user requirements. Process Modelling: DFDs. Data Modelling: ERDs and Normalisation. Event or Change Modelling: ELHs. Data Dictionary (i. e. info on data used by the models). Structured Walkthrough (i. e. reviews that detect errors in a product such as a DFD, etc. ).

Systems Analysis - Recapitulation Modelling techniques : • Used to develop models of the existing and new system. • Produce graphical documentation about system which facilitates communication between users, managers, programmers, and the analyst. • Models produced in analysis phase are independent of physical commitments (i. e. they do not show the system will work, only what the system does/will do).

Systems Analysis - Recapitulation Modelling what the existing system does (if there is one), and modelling what we think the new system will do, provides different views of the system that help us describe and understand it. This greater understanding of the system is a big help in defining the requirements for the new system and also in creating a design for how the system will be implemented.

Systems Analysis - Recapitulation Process modelling concentrates on modelling processes (major activities) within the existing and new system. Data and event modelling model the data - processes share same data so it is important to understand it. Data, process, and event modelling complement each other, and provide the analyst with different views of the system. Different views are needed so that the different aspects of a system are modelled and understood.

Entity Process DFD Data Store ER Entity ELH Entity Event

Systems Analysis - Recapitulation When analysis is complete, its outputs are passed on to the design phase. The outputs from the analysis phase include the following: • Models of the system, such as DFDs, ERDs, ELHs, normalised data. • A requirements specification: document which specifies what is required by the users of the new system. The spec. includes a list of requirements for the new system, along with any models that have been created – the models help in communicating and understanding the requirements.