5 investigating system requirements
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Transcript of 5 investigating system requirements
Investigating System RequirementsSystems Analysis and Design
The Analysis Phase
Gather Informa
tion
Define System Requirements
Prioritize
system requirements
Prototype for
feasibility and
discovery
Generate and
evaluate
alternatives
Review recommendations and
management
Analysis Phase
Activities Key Questions
Gather information Do we have all the information we need to define what the system would do?
Define system requirements What do we need the system to do?
Prioritize system requirements What are the most important things in the system must do?
Prototype for feasibility and discovery Have we proven that the technology proposed can do what we think we need it to do?Have we built some prototypes to ensure the users fully understand the potential of what the system can do?
Generate and evaluate alternatives What is the best way to create the system
Review recommendations with management
Should we continue with the design and implement the system we propose?
System Requirements
• System Requirements– Specifications that define the functions to be
provided by a system:• Functional requirements• Nonfunctional requirements
– Technical requirements– Performance requirements– Usability requirements– Reliability requirements– Security requirements
System Requirements
• Functional Requirement– A system requirement that describes an activity or
the process that the system must perform– A requirement that is based on the procedures
and rules that the organization uses to run its business
System Requirements
• Nonfunctional Requirement– Characteristics of the system other than the activities it
must perform:• Technical requirements – refers to an organization’s
environment, hardware and software• Performance requirement – refers to workload measure,
throughput and response time• Usability requirement – operational characteristics related to the
user (UI, work procedures, help and documentation)• Reliability requirement – describes the dependability of the
system• Security requirement – describes user access to certain functions
Information Gathering
• Techniques for Information Gathering– Question Themes– Review existing reports, forms and procedure
descriptions– Conduct interviews and discussions with the users– Observe and document business processes– Build prototypes– Distribute and collect questionnaires– Conduct Joint Application Design Sessions
Question Themes
Theme Questions to users
What are the business operations and processes?
What do you do?
How should those operations be performed?
How do you do it?What steps do you follow?
What information is needed to perform those operations?
What information do you use?What forms or reports to you use?
Review Existing Reports, Forms and Procedure Descriptions
• The analyst asks users to provide copies of forms, reports, procedural manuals and work description of the company.
• Forms and reports can serve as visual aids in an interview
• Reviewing documentation of existing procedures helps identify business rules that may not come up during interviews
Conducting Interviews
• BEFORE:– Establish the objective of the interview– Determine the correct users involved– Determine project team members to participate– Build a list of questions to be discussed– Review related documents and materials– Set the time and location– Inform all participants of objective, time and
locations
Conducting Interviews
• DURING– Dress appropriately– Arrive on time– Look for exception and error conditions– Probe for details– Take thorough notes– Identify and document unanswered items or open
questions
Conducting Interviews
• AFTER– Review notes for accuracy, completeness and
understanding– Transfer information to appropriate models and
documents– Identify areas needing further clarifications– Send thank-you notes if appropriate
Observe and Document Business Processes
• Workflow – a sequence of steps to process a business transaction
• Activity Diagram – a type of workflow that describes user activities and their sequential flow
Activity Diagram Symbols
Manager
Review Financials
Prepare report
Swimlane
Starting Activity (pseudo)
ActivityTransaction
arrow
Ending Activity
Activity Diagram Symbols
Synchronization bar (Split)
Synchronization bar (Join)
Decision activity
Yes
No
Example
Customer Salesperson Technical Expert System
Request quote
Develop notes of
requirements
Enter data into
system
Review the quote
Accept the quote as
order
Check requirements
Enter Data into system
Calculate quote
Ask help?
Changes required?
NoYes
No
Yes
Build Prototypes
• Prototype – a preliminary working model of a larger system
• Mock-up – an example of a final product that is for viewing only and not executable
Distribute and Collect Questionnaires
• Questionnaires enable the project team to collect information from a large number of stakeholders.
• Questionnaires are used to obtain preliminary insight on the information needs of various stakeholders.
• Questionnaires can be used to determine users’ opinion on various aspects of the system.
Distribute and Collect Questionnaires
• Questionnaires may include the ff. questions:– Close-ended questions (used to determine
quantitative information)– Opinion questions (respondents are asked
whether they agree or disagree with a statement)– Questions that request explanation
Conduct Joint Application Design Sessions
• JAD – a technique to define requirements or design a system in a single session by having all necessary people participate. People involved are the ff:– JAD Session Leader– Users– Technical Staff– Project Team Members
Validating the Requirements
• Structured walk-through – a review of findings from your investigation and the models built based on those findings.