INF3705_Exam_Summary

INF3705 Activity 1.3 As an information system developer, explain the following process activities to your co-workers: specification, development, validation and evolution Specification: Software specification or requirements engineering is the process of understanding and defining what services are required from the system and identifying the constraints on the system’s operation and development. Development: The implementation stage of software development is the process of converting a system specification into an executable system. Validation: Verification and validation (V&V) is intended to show that a system both conforms to its specification and that it meets the expectations of the system customer. Evolution: Software is inherently flexible and can change. As requirements change through changing business circumstances, the software that supports the business must also evolve and change. The principles of agile methods include the following: Principle Customer involvement. Incremental delivery. People not process. Maintain simplicity. 2.2.2 What are the differences between functional and non-functional software requirements?  Functional requirements – Statements of services the system should provide, how the system should react to particular inputs and how the system should behave in particular situations – May state what the system should not do  Non-functional requirements – Constraints on the services or functions offered by the system such as timing constraints, constraints on the development process, standards, and so forth – Often apply to the system as a whole rather than individual features or services  Domain requirements – Constraints on the system from the domain of operation Example of Functional requirements for the MHc-PMS  A user shall be able to search the appointment lists for all clinics.  The system shall generate each day, for each clinic, a list of patients who are expected to attend appointments on the specific day.  Each staff member using the system shall be uniquely identified by his or her 8-digit employee number. Page 1 of 45 Metrics for specifying non-functional requirements Property Measure Speed Processed transactions/second User/event response time Screen refresh time Size Mbytes Number of ROM chips Ease of use Training time Number of help frames Reliability Mean time to failure Probability of unavailability Rate of failure occurrence Availability Robustness Time to restart after failure Percentage of events causing failure Probability of data corruption on failure Portability Percentage of target dependent statements Number of target systems Development testing Development testing includes all testing activities that are carried out by the team developing the system.  Unit testing– where individual program units or object classes are tested. Unit testing should focus on testing the functionality of objects or methods.  Component testing – where several individual units are integrated to create composite components. Component testing should focus on testing component interfaces.  System testing – where some or all of the components in a system are integrated and the system is tested as a whole. System testing should focus on testing component interactions. Importance of dependability  System failures may have widespread effects with large numbers of people affected by the failure.  Systems that are not dependable and are unreliable, unsafe or insecure may be rejected by their users.  The costs of system failure may be very high if the failure leads to economic losses or physical damage.  Undependable systems may