the system life cycle

• analysis - of the current system

  • conducting interviews
  • completing observations
  • distributing questionaires
  • reviewng existing documentation
• analysis - conducting interviews - pros

  • Interview questions can be adjusted throughout the interview and tailored to the interviewee. This allows the analyst to obtain more feedback.
  • The interviewer can also gauge body language and expressions.
  • The person interviewed may give more open and candid responses.
  • Interviews may be conducted remotely using video conferencing techniques.
• analysis - conducting interviews - cons

  • The interviewee may provide responses that they think the interviewer would want to hear.
  • Interviewing individual people can be costly and time-consuming.
  • The interviewee cannot be anonymous, so may hide information or not give truthful answers.
  • Interviewees may not be available at convenient times to attend an interview.
• analysis - completing observations - pros

  • Observing systems being used provides a better understanding of logical and physical processes.
  • All the input and output data and methods can be observed.
  • The data is gained from first-hand experience so will be more reliable.
  • Less expensive than other methods, such as interviews, as observation can be undertaken by a single systems analyst.
• analysis - completing observations - cons

  • The person being observed may take a negative view of being watched and may not follow usual procedures.
  • The person being observed may not show any shortcuts while being observed.
• analysis - distributing questionares - pros

  • Quick and inexpensive to produce and distribute.
  • Can be created and sent out electronically
  • Questions can be answered quickly and in the recipient’s own time.
  • Data can easily be analysed, particularly if using electronic questionnaires.
  • Allows large numbers of people to be surveyed.
  • May be answered anonymously, which can lead to more honest responses.
• analysis - distributing questionares - cons

  • Questions are usually generic and cannot be tailored to an individual person.
  • Poorly constructed questionnaires may result in a low response rate.
  • Recipients may not take them seriously and could give silly responses if they are anonymous.
• analysis - reviewing existing documentation - pros

  • Systems analyst can gain an in-depth understanding of how the existing system operates.
  • Information gleaned from existing documentation may not be found by using other data gathering techniques.
• analysis - reviewing existing documentation - cons

  • Searching through large quantities of documentation may be costly and time-consuming.
  • Documentation does not necessarily show the daily reality of working with a system.
• analysis - user requirements

  • written for customers
  • often in natural language, no technical details
• analysis - system requirements

  • written for developers
  • detailed functional and non-functional requirements
  • clearly and more rigourously specified
• analysis - user requirements definition

  • the software must provide a means of representing and accessing external files created by other tools
• analysis - system requirements defintion

  • the user shoukd be provided with facilities to define the type of external files
  • each external file type may have an associated tool which may be applied to the file
  • each external file type may be represented as a specification from the user's display
  • the facilities should be provided for the icon representing an external file type to be defined by the user
• analysis - hardware specification - Computer architecture – the overall technology required, e.g. PC, Mac

  • The architecture will often be dependent upon your choice of software e.g. some systems may only run on a PC
• analysis - hardware specification - Processor – generally, the higher the specification the faster the performance

  • Dependent upon the demands of the software to be used.
• analyss - hardware specification - Memory (RAM)

  • Some software has minimum specifications for recommended RAM size.
• analysis - hardware specification - Storage devices – HDD, SSD etc.

  • Again, dependent upon the size of software application and the amount and type of data to be stored, e.g. if the system needs to store video or photos then storage requirements will be higher.
• analysis - hardware specification - LAN, Wi-Fi, USB, Bluetooth connections

  • Connectivity – what is required for system connectivity and communication?
• analysis - hardware specification - Specialist input devices, such as scanners, barcode scanners, POS terminals, touch screens etc.

  • These devices allow fast and efficient input of data into the system. For example, touch screens may be used when taking a food order in a restaurant.
• analysis - hardware specification - Specialist output devices, such as 3D printers, plotters, larger screens, speakers etc.

  • These devices may be needed but are dependent upon the type of output required from the system.
• analysis - hardware specification - Specialist hardware for accessibility, such as special keyboards, voice input etc.

  • These devices may be required depending upon the people using the system.
• analysis - software specification - Operating system (OS), e.g. Windows, Mac OSX, Linux etc.

  • The OS will often be dependent upon your choice of software, e.g. some systems may only run on Windows.
• analysis - software specification - Off-the-shelf software, e.g. Office software

  • Saves on cost and time. Well tested with a large user community. Familiar to most people so minimal user training required.
• analysis - software specification - Bespoke software, specially created for the business or organisation

  • Requires greater investment to develop and implement in terms of time and cost.

  However, it is more likely to meet the exact requirements and specifications of the organisation. More difficult to implement with special user training needed.
• design - file structures 1

  • The header row shows the field names, e.g. Model, Year etc.
  • Each row shows the data for one motorcycle. This is called a record.The record for the Royal Enfield Interceptor is highlighted in blue.
  • Each column shows an attribute for each motorcycle. This is called a field. The fields ‘Manufacturer’ and ‘Class’ are highlighted in orange
• design - file structures 2

  • One field for a particular record contains specific data, such as ‘Triumph’ highlighted in yellow.
  • To identify each record one field must be unique. In this case, the ID-Code field for each record is unique. This is called the key field. The key field ‘D-001’ is highlighted in pink.
• data types - Alphanumeric, Text or String - This type of data stores letters or text and numbers, but does not contain numeric values
• design - data types - Char or Character - This is just a single character – a letter, number or symbol
• design - data types - Boolean, True or False, Y or N - This data type stores logical Y/N or True/False options
• design - data type - Numeric: Integer - This stores whole numbers
• design - data type - Numeric: Real or Decimal - This stores non-integer or decimal values
• design - data type - Numeric: Date/Time - This stores numbers in the format of a date or time
• design - data type - Numeric: Currency - This stores numbers as a currency, £, $ etc.
• design - data validation checks - Presence - Checks that some data has been entered into the field.
• design - data vallidation checks - Range - Usually used for numeric data. Checks that data lies within a specified range.
• design - data validation checks - Length - Checks that data entered does not exceed the correct length.
• design - data validation checks - Character/type - Checks that data of the correct character is entered.
• design - data validation checks - Format - Checks that the input data is in the correct format, if required
• design - data validation checks - Check digit - Checks that a series of numbers has been entered correctly. There are many different ways to produce check digits.
• design - paper-based

  • a printed copy that is completed with a pen or pencil and then entered on the computer later