Class Notes (807,515)
Canada (492,691)
York University (33,497)
ITEC 3010 (26)
all (20)

lecture_4 notes.doc

11 Pages
Unlock Document

York University
Information Technology
ITEC 3010

Systems Analysis and Design I ITEC3010 – Fall 2010 – Luiz Cysneiros Lecture 4 – Investigating System Requirements – Oct 5 Analysis Phase Activities - Gather information o Involves gathering lots of information o Can get information from people who will be using the system  By interviewing them  By observing them - Can get other information by reviewing documents and policy statements (e.g. At a bank) - Can involve the analyst actually doing some or part of the task to get a feel for what is done o In order to automate order-entry you may need to become an “expert” on the task (knowing how orders are processed) - Need to understand current and future users, locations, system interfaces, possible solutions, etc. - Define system requirements o Involves modeling  Logical model • Any model that shows what the system is required to do without committing to any one technology – requirements model is logical  Physical model • Any model that shows how the system will actually be implemented  Models are often graphical in nature • Data flow diagrams (dfds) • Entity-relationship diagrams (erds)  Natural language is ambiguous - Prioritize Requirements o Important to establish which functional and technical requirements are most critical o Why? Since resources are always limited and you want to address the most important things o If not addressed can lead to “scope creep”, where the scope of the project just seems to expand over time - Generate and Evaluate Alternatives o Could include considering more than one method to develop system o Could involve in-house development or outsourcing to to a consulting firm o Might be able to use “off the shelf” software package o Each alternative has costs and benefits to be considered o Also must consider technical feasibility - Review Recommendations with Management o Usually done when all the above are completed o Must decide if project should continue at all o Must decide on which alternative is best (if you are going ahead with the project) o NOTE – at this point should include CANCELLATION of project as an option  May have found costs were too high  May have found benefits were lower than thought  Maybe the business environment suddenly changed making the project obsolete o Detailed documentation has been collected  System requirements  Proposed design solution Requirements Specification - Requirement specification results from Analysis phase - What is a requirement? o A feature of the system or description of something the system is capable of doing to fulfill the system’s purpose o It addresses the purpose of the system (i.e. What it is supposed to do) and not how it will be implemented (However, Non-Functional requirements might require the analyst to look closer to how it will be implemented) Functional and Technical Requirements - Functional requirements o A system requirement that describes a function or process that the system must support o E.g. “system will calculate tax amounts, report year-end tax deductions” - Non-functional requirements / technical requirements o A system requirement that describes an operating environment or performance objective. Describe constraints on functional requirements o E.g. Tax amounts should be accurate, calculate tax amount should be easy to use  Security  Safety  Privacy Types of Requirements/Questions Asked - Physical Environment o Where is the equipment to function? o Is there one location or several? o Are there any environmental restrictions such as temperature, humidity or magnetic interference? - Interfaces o Is the input coming from one or more systems? o Is the output going to one or more systems? o Is there a prescribed way in which the data must be formatted? o Is there a prescribed medium that the data must use? - Users and Human Factors o Who will use the system? o Will there be several types of users? o What is the skill level of each type of user? o What kind of training will be required for each type of user? o How easy will it be for a user to understand the system? o How difficult will it be for a user to misuse the system? - Functionality o What will the system do? o When will the system do it? o How and when can the system be changed or enhanced? o Are there constraints on execution speed, response time, or throughput? (Non-Functional Req. frequently associated with FR) - Documentation o How much documentation is required? o To what audience is the documentation addressed? - Data o For both input and output, what should be the format of the data? o How often will it be received or sent? o How accurate must it be? o To what degree of precision must the calculations be made? o How much data flows through the system? o Must the data be retained for any period of time? - Resources o What materials, personnel or other resources are required to build, use and maintain the system? o What hardware is required? o What software is required? (eg. Databases?) o What skills must the developers have? o How much physical space will be taken up by the system? o Is there a prescribed timetable for development? o Is there a limit on the amount of money to be spent on development or on hardware and software? - Security o Must access to the system or to information be controlled? o How will one user’s data be isolated from other’s? o How will user programs be isolated from other programs and from the operating system? o How often will the system be backed up? o Must the backup copies be stored at a different location? o Should precautions be taken against fire or theft? - Quality Assurance o What are the requirements for reliability? o How the characteristics of the system must be demonstrated to others? o Must the system detect and isolate faults? o What is the prescribed mean time between failures? o Is there a maximum time allowed for restarting the system after a failure? o How can the system incorporate changes to the design? o Will maintenance merely correct errors, or will it also include improving the system? o What efficiency measures will apply to resource usage and response time? o How easy should it be to move the system from one location to another or from one type of computer to another? Stakeholders – The Source of System Requirements - Stakeholders: People who have an interest in the success of the new system o The users: who actually use the system o The clients: who pay for and own the system o The technical staff: who ensure the system runs - Must identify stakeholders - Cannot forget an important group – e.g. Users! User Stakeholders - Can identify users horizontally – i.e. Across departments - Can also identify users vertically – i.e. Hierarchy within a department (e.g. lower, middle and upper managers) - Type of users o Business operations users – use the system daily to perform operations (transactions – a piece of work) o Query users – could be business people or customers – request info o Management users – want reports, performance stats, want to know volumes of transactions etc. o Executive users – want information to help with strategic issues, e.g. compare improvements in resource utilization Stakeholders at Rocky Mountain Outfitters - Operational users of the new order system o Inside sales representatives (who take orders) o Clerks (who process order) o Warehouse workers - Each type of user has their own needs and preferences o Need usability testing to get at this! (text doesn’t mention) - Project funded from internal cash flow - Since the system involves new technology (Internet) need involvement from technical staff Identifying System Requirements - Main Objective of Analysis Phase o To understand the business functions and develop system requirements o Question of studying existing systems first or not o Using structured approach, analyst first documents the existing system then extrapolates the requirements of the new system o Approach  Develop current system physical models  Extract the current system logical models  Develop new system logical model  Develop new system physical model - Faster approach o Identify current system procedures immediately (as much as need to, don’t necessarily define specific processes) o Develop requirements and models for new system (ie. develop logical model) - In either approach, need to balance investigation of old procedures with need to focus on requirements of the new system Questions Asked (Overall) - What are the current business processes and operations? o Ask the users, “What do you do ?” o Assess what current functions can remain and which should be eliminated by technology - How should the business processes be performed? o Ask the user “How can it be done?”, “What steps should be followed? (using the new system)”. How else ? - What information is needed? o Specific information requirements, e.g. Databases needed Skills Needed and Methods Used - Understanding of user needs - Ability to analyze and solve business problems o Being able to identify and capture business rules - Methods o Distribute questionnaires to stakeholders o Review existing reports, forms and procedure descriptions o Conduct interviews and discussion with users o Observe business processes and workflows in real life (can video or audio record activities, do usability testing etc.) o Build prototypes o Conduct joint application design (JAD) sessions Distribute and Collect Questionnaires - Allows to collect information from large numbers of users - Can obtain early insight into information needs - Can be useful for collecting demographic or quantitative information o e.g. “how many orders do you enter a day?” “What is your educational background?” - Can collect information using scales, e.g. “On a scale of 1 to 7 how important is system speed?” – closed-ended questions which do not invite discussion - Less useful for collecting other types of qualitative information (e.g. system usability, user-interface ne
More Less

Related notes for ITEC 3010

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.