CS 1 System Fundamentals PDF

CS 1 System Fundamentals System Life Cycle TELOS (technical, economic, legal, operational, schedule) Change management: Planning, analysis, design, implementation, maintenance Legacy system: Continued to be use, poor competitiveness, compatibility with mo...

CS 1 System Fundamentals System Life Cycle TELOS (technical, economic, legal, operational, schedule) Change management: Planning, analysis, design, implementation, maintenance Legacy system: Continued to be use, poor competitiveness, compatibility with modern equivalents Cost of replacing, large monolithic, difficult to modify Business mergers: Data migration: transfer of data from one system to another Compatibility: different file formats, languages, conventions in representing various data, incompatible software/hardware Time + money spent, data redundancy Retraining staff, purchasing new hardware/software Cloud service: services made available to users on demand via the Internet from a cloud computing provider’s servers Convenience, security (professional, big company in charge), backup, collaboration, environmentally friendly, cheap (no need for hardware), slow, storage & feature limits, data could be intercepted in transmission Implementation: Direct: old system is completely replaced in one move by the new system; new system immediately available, if fail, no backup, no compatibility issue within organisation Parallel: old system running alongside; backup O, comparison available, costly + time Pilot: trailed in small part; if fail, only small part suffer, no backup, can be fully trailed Phased: gradually replaced from one section of system, replaced if satisfactorily working; if fail, no backup, people get used to system Testing: (feedback to developers; product improved; before final release) User Acceptance Testing: in ‘real world’ by intended users, well-trained users, eliminates communication gaps, users assess capabilities Alpha Testing: done in house by developers, uncover bugs not found during previous testing, not all functionality expected to be tested Beta Testing: done by end users, real user’s perspective, feedback help improving product, increase satisfaction of customers, quality not assured Not involving end-users in development: Software may not meet user requirements/expectations, missing some key features, not user friendly User Focus User Documentation: User-friendliness, accessibility, quick updatability, amount of information Manual: online or offline, PDF files Email Support: contact support team, problems resolved by technicians Embedded Assistance: e.g. tooltips, dynamic page contents FAQ: online or offline, common set of problems Live chat sessions: real-time support Online portals: e.g. PDF files Remote desktop connections: technician connected and control user’s computer to resolve User Training: Self-instruction: cheap, own pace, anytime, more time, unable to ask very specific questions, minimal external guidance Formal classes: open exchange of ideas in real-time, no barriers to communication, shy member disadvantaged Remote/online training: any time, delivered globally, flexibility, access to technology, sometimes face to face approach necessary System Backup Data loss: human error - accidental deletion, overwriting of files; computer virus/malware infiltrates and damage the data; natural disaster causing system to crash and destroy data; malicious activities - unauthorised user gaining access to data and deleting/altering it Data loss prevention: Failover system: redundant system which seamlessly/automatically takes over if the primary system suddenly becomes unavailable - reduce the impact on users Security: physical security (prevented access to room), encryption Copies of backup kept off-site: unlikely that the other site offed by natural disaster Redundancy, removal media (multiple HDDs) Regularly backup data that has changed: requires less storage capacity Printed copies of data Release: Pre-alpha —> Alpha —> Beta —> Release candidate Update: Automatic: systems checks for updates over internet, downloaded and installed automatically, easier for inexperienced users, miss updates if not connected to internet, major change not informed Manual: manufacturer contacts every user and supplies installation package, users have control, aware of major changes, users might not know how to install the update, may harm system by wrongly installing Components of Computer System Components: Hardware: anything within a computer you can physically touch Software: the collection of programs and instructions that control the computer Peripheral: a hardware that is externally/remotely connected to the computer system Network: group of computers connected together in some way to share resources/data Human resources: humans operating the computers Different roles: Client: a computer accessing resources hosted by server computer Server: a host computer that awaits and fulfils requests from client programs Social & ethical issues associated with networked world: Digital divide, loss of jobs, social media replacing face-to-face interaction Security, privacy e.g. GPS System Design Analysis Stakeholder: a person with an interest or concern in something (end-user, system analyst, client company, software manufacturer) Obtaining requirements: Surveys: general questions distributed to many stakeholders as a written or online document; large data can be collected, simple, less time, many not be taken seriously, information gathered limited by questionnaires Interviews: specific questions asked to nominated stakeholders in an individual setting; detailed information can be gathered, takes time Direct observation: observer watches stakeholders performing their current tasks; unbiased information, in natural setting, users may act differently if aware of observation, time consuming, observer bias Collecting documents: detailed information, time-consuming System Flowchart:  Data Flow Diagram: Prototypes: abstract representation of the system, often focusing on only one or two key aspects of the system Allows stakeholders to gain an idea of how the system would be work Gives opportunity to demonstrate potential buyers, get feedbacks to improve product Usability: the property of a system that determines how easy and self-explanatory use of the system is for inexperienced end-users, ergonomics + accessibility Accessibility: refers to the design of products for people with disabilities or specific needs improved by touch screens, voice recognition, text-to-speech, braille keyboards Consistency of user interface, conventions Controls in logical way, visible, labelled, similar functions in group User documentation e.g. Mobile phone: iOS and Android completely different platform, battery life, touch recognition ability decreases, small buttons - mistouch, frequent update with less approachable user documents