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.