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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
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