Flashcards for the Main Parts of the SDLC (Topic 9)

What is a System?

- A system is a complex whole, the component parts of which are arranged for a common purpose

What is the System Development Life Cycle?

- A sequence of activities which are performed when a system is analysed, designed and implemented

- It is cyclic because once a system has been built then it will be regularly looked at to see if any improvements need to be made

What are the Main Tasks Involved in System Investigation?

- Interviews -> Shows how a particular department works and the issues that it is having with the current system but is time consuming

- Observations -> Sit with someone and observe what they do to understand the information flows and processes

- Inspection of Records -> Can understand what information there is and the way it is communicated among departments or among the organisation and suppliers and customers

- Questionnaires -> Collect information about an organisation by sticking to the important points

What are the Advantages and Disadvantages to each of the Previous Tasks?

- Interviews -> Time consuming

- Observations -> Good way of learning what to do however things could be easily forgotten

- Inspection of Records -> Good for finding out how information is held and how it is communicated

- Questionnaires -> Good for collecting information from a huge group of people (take up less staff time) however people forget to fill them in, and those who do may not fully understand all of the questions

What Should be Considered when Creating Questionnaires?

- Precisely worded questions

- Make sure that they don't have to put their names on the questionnaires because otherwise they may not give their honest opinion

- General questions to start with and then go onto more detailed questions

- Try not to include leading questions and add the question 'Is there anything I have missed that you think I ought to know about?' at the end

What is Meant by the terms Feasibility and Feasibility Report?

- Feasibility -> Initial investigation to look at the probability of being able to create a new system with aims and objectives at reasonable cost (involves a fact find, implication research, cost v benefits, etc.)

- Feasibility Report -> Where the results are summarised and the senior managers assess the project's feasibility based on this report

What Should be Included in a Feasibility Report?

- User Requirements

- Details of existing hardware and software

- Scope of the current system

- Data processing functions and processes

- List of problems with the current system

- Cost v Benefit analysis of the new system

What does Analysis Normally Involve?

- Understanding the current system

- Understanding the new system

- Analysing lots of different user requirements

- Using tools and techniques to show the solution in a logical way

- Creating a specification

What are the Tools and Techniques Used to Understand a System?

Data Flow Diagrams - Describe a system and focus on inputs, processes and outputs (examples of uses: during system investigation to record findings, during system design to show how the new system would work and during the outline of the specifications

Decision Tables - Shows actions to be undertaken when specific conditions occur -> Advantages: Easy to understand, standard layout, show cause and effect

Systems Diagrams - Show how a system works (inputs processes and outputs) through pictures

Entity Relationship Models - Describes a system as a set of data entities with relationships between them

Entity Relationship Diagrams - They focus on the important components of the system and the relationships of these components

Data dictionaries - A centralised collection of information about data such as meaning, relationships to other data, origin, usage, etc., used mainly in database design to ensure consistency

What does System Design Usually Involve?

- Production of the specification for the hardware and software

- Design of data and file structures

- Design of input and output procedures

- Design of information systems

- Design of networks and transmission problems

- Personnel issues

- Design of security processes and procedures

What will Implementation Usually Involve?

- Obtaining and installing hardware and software and software training

- Altering the current software

- Creating programming code

- Installing software on operational hardware

- Creating framework for databases

- Training the users

What does Testing Usually Involve?

- Testing at very detailed levels

- Testing at a higher level

- Testing at a systems level

- Testing every field

- Testing the system with real-life data

What are the Different Types of Changeover Strategies?

Direct Changeover - Stop using the old system one day and start using the new one another day (risky but needs fewer resources)

Parallel Changeovers - Old system is run alongside the new system (reduces the risk however it wastes time and adds to planning needed)

Phased Conversion - Module by module is converted (can deal with issues before going onto the next module however it only suits systems which have separate modules)

Pilot Conversion - Where system is used in a branch at a time and then transferred to others (manageable but takes longer to enrol)

What Factors are Considered when Choosing a Changeover Method?

- Whether there actually is a current system (e.g. if there isn't then a parallel changeover cannot be used)

- Whether the system is cutting edge (parallel changeover or pilot conversion would minimise the problems)

- Whether the system would be enrolled in many locations (pilot conversion)

What does System Maintenance Involve?

- Training all of the potential users

- Creating technical and user documentations

- Establishing help-desk facilities to help the users

- Changing current programs or creating further ones

- Operational issues e.g. poor performance being corrected

- Investigation of system crashes

- Managing interfaces with other systems e.g. Internet and email

What are the Three Types of System Maintenance?(Give Description of each)

Perfective - Improves the performance of the ICT system by adding features to speed up the system

Adaptive - This is when things change in a business e.g. new laws would require the system to be changed

Corrective - Correcting faults or bugs which didn't appear during the testing stage

What are Some of the Maintenance Issues?

- Identification of errors

- Security problems

- Changes in the business environment

- Dissatisfaction with hardware and software

- Updating system

What is Included in a User Documentation and a Technical Documentation?

User Documentation -> Minimum hardware and software requirements, how to load software, how to do certain functions, how to save and print, FAQs, how to cope with error messages and troubleshooting and how to perform back ups

Technical Documentation -> Copy of the spec, all diagrams used to show the system, data dictionary, macro designs, spreadsheet formulae or program listings, screen layout designs, UI designs and a test plan

What does the Evaluation and Review Usually Involve?

- Ensuring that the new system fully meets the user requirements

- Assessing how happy the clients are

- Establishing a review cycle

What are Tools for Gathering Information for the Evaluation Report?

Quantitative Test - e.g. satisfaction on a scale of 1-10 and then you can work out the average, etc.

Error Logging Interviews - All calls to the help-desks are logged

Questionnaires - Give honest opinions if they are allowed to be anonymous

What Procedures can be undertaken to Reduce the Post-implementation Cost?

Training Costs -> Can't really reduce this cost

Modification Costs -> Improved identification of user requirements

Help-desk and Other Support Costs -> Complete training and easy to use software

Need to Purchase Additional Hardware -> Systems should be created with additional capacity

Correction of Bugs -> Thorough testing

Key Word: What is the Definition of Fact Finding?

Key Word: What is the Definition of Feasibility Study?

Key Word: What is the Definition of a Context Diagram?

Key Word: What is the Definition of a Data Flow Diagram?

Fact Finding -> Initial investigation of a system before a feasibility study is carried out

Feasibility Study -> A study carried out before a new ICT system is developed to see whether a new system can be developed at an acceptable cost to realise user benefits

Context Diagram -> Diagram which represents a system as a single DFD process

Data Flow Diagram -> Shows the flow, storage and processing of data in a system

Key Word: What is the Definition of an Entity?

Key Word: What is the Definition of an Attribute?

Key Word: What is the Definition of a Data Dictionary?

Entity -> An object of the real world that is relevant to an ICT system, e.g. a place, object, person, customer, invoice, product, course, etc.

Attribute -> A single item of data which represents a fact about an entity. An attribute can be thought of as something which adds further detail/information to the entity.

Data Dictionary -> A centralised collection of information about data such as meaning, relationships to other data, origin, usage, etc., used mainly in database design to ensure consistency