System Analysis and Design Tutorial in PDF - Learn System Analysis and Design in simple and easy steps starting from basic to advanced concepts with. The primary objective of systems analysis and design is to improve organizational systems. This tutorial provides a basic understanding of system characteristics. Systems Analysis and Design. Michael Brydon. Summer Slide 2. Introduction to the Course. Course structure. Lectures: material from the Dennis text.
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Systems analysis and design /Alan Dennis, Barbara Haley Wixom, business analysis benchmark - full lesforgesdessalles.info; accessed February,. 1. System Analysis and Design. Complete Introductory Tutorial for Software Engineering. Table of contents. Chapter 1: Introduction to Systems. This page is intentionally left blank SYSTEM ANALYSIS AND DESIGN Fifth Edition .. business analysis benchmark - full lesforgesdessalles.info; accessed February,
An association is unidirectional one way or bi- directional two way. Prototyping Key Benefits: Methodology A system development life cycle divides the life of Conversion. How much does she weigh? Airline Reservations Keeping records Keeping records of transactions of Stock. Application logic is placed on its own server Presentation logic and Presentation are placed on the clients.
Do we possess the necessary technical expertise? Can the solution be designed and implemented within an acceptable time period? Whether the solution will pay for itself? How profitable the solution is? Once the specific requirements and solutions have been identified Weight the costs and benefits of each alternative Cost benefit Analysis. Two types of costs, costs associated with Developing the system Can be estimated from the outset of a project Should be refined at the end of each phase One time costs will not recur after the project has been completed Operating a system Can be estimated only after specific computer- based solutions have been defined Recur throughout the lifetime of the system.
System development Cost Categories Personnel costs Computer Usage Training Supply, duplication, and equipment costs Cost of any new computer equipment and software. Benefits increase profit Decrease costs Can be classified as Tangible benefits a benefit that can be easily quantified. Intangible benefits a benefit that is believed to be difficult or impossible to quantify. Compares the annual discounted costs and benefits of alternative solutions Spreadsheets such as Excel, Lotus can be used to calculate all these values.
Communications Template. Used to rank candidate systems Columns represent candidate response Rows correspond to the feasibility criteria Cell contain the feasibility assessment notes for each candidate.
Letter of transmittal Title page Tables of contents List of Figures, illustrations, and tables Abstract or executive summary primary elements are presented in this portion of the report Appendixes. Ambiguous Requirement Statement.
Identify the mode of transportation to transfer a single individual from home to place of work. Therefore, they may not use the system The cost of maintenance may be excessively high The system may be unreliable and prone to errors The reputation of the IT staff on the team will be tarnished.
Consists of Problem discovery and analysis already discussed in Chapter 3 Requirements discovery the process and techniques used by systems analysts to identify or extract system problems and requirements from the user community Documenting and analyzing requirements Requirements management.
Can start to define requirements after understanding the problem Must use effective methods for gathering information Fact Finding After completing the process of fact finding use various tools to document the requirements.
System requirements can be gathered by using discussions with users, about their requirements building systems that satisfy these requirements. Provide direction for the modeling techniques. Decision tables: Help to alleviate the many problems associated with changing requirements Emerging new requirements Changing existing requirements Encompasses Policies Procedures Processes Refer Page Ref1.
Research and site visits Observations of Sampling of the work Existing documents environment. Come across sensitive data e. Leaving sensitive documents in plain view on the desks or publicly discuss sensitive data could cause great harm to the organization Therefore, analysts must take great care to protect security and privacy of any facts.
Thoroughly, research the problem domain. Identify the material that are relevant and reliable. Internet Intranets Reference books Computer trade Journals. Observations of the work environment Systems Analyst participates in or watches a person perform activities to learn about the system Often used when validity of data collected through other methods is in question or the complexity of certain aspects of the system prevents a clear explanation by the end users.
Data gathered by observation can be highly reliable Relatively inexpensive Allows systems analyst to do work measurements Systems analyst is able to see exactly what is being done.
Work being observed may not involve the level of difficulty or volume normally experienced during that time Some tasks may not always be performed in the manner in which they are observed by the system analyst.
Most questionnaires can be answered quickly Allow individuals to maintain anonymity Relatively inexpensive way of gathering data. Responses can be tabulated and analyzed quickly etc. The number of respondents is often low Mostly suited for closed questions No guarantee that an individual will answer or expand on all the questions Good Questionnaires are difficult to prepare No immediate opportunity to clarify a vague or incomplete answer to any question.
A question is asked, and the respondent records the answer in the space provided after the question. Given several answers to select one. Yes, No type 2. Given a statement and asked to use supplied responses to state an opinion. Given several possible answers to be ranked in order of preference or experience Refer Page Ref1. Interviews Most commonly used technique in analysis Collects information from individuals face to face. Must possess good human relations skills for dealing effectively with different type of people - Can be used to achieve any of the following goals: Interviews Advantages Gives the analyst an opportunity to motivate the interviewee to respond freely and openly to questions.
Allow the analyst to look for more feedback from the interviewee. Permit the analyst to ask questions from each individual etc. New ideas may arise.
Very time consuming. Therefore costly approach Success of interviews is highly dependent on the systems analysts human relations skill. Interviews may be impractical due to the location of interviewees etc. Open-ended questions Allows the interviewee to respond in any way that seems appropriate.
Closed-ended questions Restrict answers to either specific choices or short, direct responses. Select Interviewees Interview the end users of the information system you are studying.
A formal organizational chart will help you identify these individuals and their responsibilities. Always make an appointment with the interviewee. Higher the management level of the interviewees, less time should be spent. Prepare for the Interview Prepare an interview guide - checklist of specific questions interviewer will ask the interviewee Avoid the type of questions such as: Loaded questions e. Leading questions e.
You are not going to use this operator code, are you? Biased questions e. How many codes do we need for food classification in the inventory file? I think 20 should cover it?
Prepare for the Interview Interview question guidelines: Use clear and concise language Dont include your opinion as part of a question Avoid long or complex questions Avoid threatening questions verify before you leave The purpose of the interview is to investigate, not to evaluate or criticize.
Conduct the Interview The actual interview consist of three phases: Interview Opening: Intended to influence or motivate the interviewee to participate Interview body: Obtain interviewees response to your list of questions Interview conclusion: Express your appreciation. Important for maintaining good relationship and trust. Building a small working model of the users requirements or a proposed design for an information system.
Can also be used to perform fact-finding requirement analysis discovery prototyping. Allows analyst to quickly create mock forms and tables to simulate the implemented system. May extend the development schedule Increase the development costs. Highly structured group meeting are conducted to analyze problems and define requirements.
Single person in top management who makes the final decision. Facilitator Single individual who plays the role of the leader or facilitator. Someone who has excellent communication skills. Both users and managers are relied on to ensure that their critical success factors are being addressed Scribes Those who are keeping responsible for keeping records pertaining to everything discussed in the meeting.
System analysts frequently play this role. Usually consists of members of the project team. Document Flow Diagrams Used to identify physical movement of documents.
Or de r Purc has e Purch. Supplier Dept. Document Flow Diagrams shows where the document comes from, where it goes to , and what it is called. Pu Dept. Document Flow Diagrams Used to examine the flow of documents within the existing system. Order Purch. Invoice Dept. De liv. Supplier Purch. Document Flow Diagrams Maintenance Example: Purchasing System.
It is a communication tool: Such a repository can prevent unnecessary repetitions when someone leaves the project team. Proper documentation ensures that all the information developed about the system is always available to new people joining the project.
Documentation is also a management tool: It supports management in two ways: Is also a part of the phase output. Also known as requirements statement, requirements specification, and functional specification. Requirement Definition Document Consists of Functions and services the system should provide Nonfunctional requirements systems features, characteristics, and attributes Constraints Information about other systems with which the system must interface No standard format for the document.
Requirement Definition Document Readers of the document System Owners and Users to specify their requirements and any changes that may arise. Developers to understand what is required and to develop tests to validate the system.
Introduction Technique for organizing and documenting the structure and flow of data through a systems process and the logic, policies, and procedures to be implemented by a systems process. Logical Models Physical Models Other names: Other names: Show not only what a system is or does.
But also how the system is physically and technically implemented. Implementation dependent Reflect technology choices and the limitations of those technology choices Used to Depict technical designs. Program Structure Charts Logic Flow Charts Decision Tables, are some examples for various types of process models found in early software engineering methods and programming. Gane and Sarson notation is widely popular. Represented An external agent is an by a square outside person e.
Bank An External that interact with the system. Agent Also called an external entity. An External External Agent external to the system being analyzed or designed. A Data Store is an Data store inventory of data.
That is, stored data A Data Store intended for later use Represented by data at rest. Also the open-end box known as a file or database. These include Persons: Customer, Employee Places: Building, Room, Campus Objects: Book, Machine, Product Events: Invoice, Order, Registration, Renewal Concepts: Course, Fund, Stock. The arrow head indicates Data flow name the direction of data flow.
Label the arrows with the A Data Flow name of the data that moves through it. External External A diagram that shows the Agent Agent system as a black box and its main interfaces with its environment. External Used to document the Agent Process scope of the system Also known as environmental model.
External Agent. Need to identify the data flows and the external agents needed for the context diagram. Add the data flows between each external agent and the process representing the entire system. Order Purchasing Supplier Invoice System. Whenever an account holder wants to withdraw some cash, he presents a cheque or withdrawal slip.
The account is checked for the appropriate balance. If balance exists, the cash is paid and the account is updated. Is the act of breaking a system into its component subsystems , processes and sub processes.
Top level function is then decomposed to its component functions. Wit Ack hdr now awa Account ledg l eme Holder nt. Process 1 8 No data flow should ever go unnamed. Reservation ready notice. Document Flow Diagram Modeling method or technique used to illustrate movements of documents.
What process generates this document flow? What process receives this document? Is the document stored by a process? Where is the document stored? Is the document created from stored data? Stude i ne n e slip. S Library New member details Admin.
DFDs handle transformation from physical document to logical data Advances in technology mean that electronic means are increasingly supplementing the paper based documents. Fi ip Me p mb er c ard Library System Admin. Sl be rc Se. Fi em d. Registration Lib em me m ber y s t New S Details. Member Member Me m. Sl em Lending. Book details m. Boo k deta New member details ils Member member Mem. Registration Book Details Registration details. New member Admin. Users are not overwhelmed by the overall size of the system A powerful communication tool between users and technical professionals.
A language and syntax, based on the relative strengths of structured programming and natural English, for specifying the underlying logic of elementary processes on process models. A tabular form of representation that specifies a set of conditions and their corresponding actions Very useful for specifying complex policies and decision making rules. There exist several notations for an ERD Martin notation is widely used. Entity Relationship Diagrams Shows data in terms of the entities and relationships described by data.
Entities An entity is something about which the business needs to store data. Synonyms entity type and entity class. Entity Instance An entity instance is a single occurrence of an entity. Every entity must have an identifier or key to uniquely identify each instance. Consider Martin notations. The named rounded rectangle represent the entity. A line represent the relationship. Sometimes called as element, property, or field. It is Name sometimes called an identifier.
Address Age. This person can be identified using his ID number. Compound Attribute is one that actually consist of other attributes. Synonyms- composite attribute, concatenated attribute Example: Data type What type of data can be stored in that attribute Number, Date, Text etc.
Domain What values an attribute can legitimately take on. Refer to table in pg Ref1. Default Is the value that will be recorded if not specified by the user. Zero, one or more I may have one, some friends or none.
More than one I am working on many projects. Binary Relationship - When two different entities participates in a relationship. Synchronization is the process of maintaining consistency between the different types of models. Object Modeling techniques prescribe the use of methodologies and diagramming notations that are completely different from the ones used for data modeling and process modeling. Attributes The data that represents characteristics of interest about an object e. Customer Attributes: Customer no, first name, last name, home address, work address, contact no,etc.
Sometimes referred to as an Object. Drawn using a rectangle with the name of the object instance The name consists of the attribute that uniquely identifies it, followed by a colon and then the name of the class in which the object has been categorized.
Customer Also known as a method, operation or service e. Door behavior: Objects encapsulates what they do. When most people watch a television show, - they usually dont know or care about the complex electronics that sit in back of the TV screen - or the operations that are happening.
The TV hides its operations from the person watching it. You interact with a text book by reading it, with a telephone by using it, People interact with each other by communicating with them. An association is unidirectional one way or bi- directional two way.
Conversely, a smaller part class is part of a whole larger class. A club a club is made up of several club members A computer a computer contains a case, CPU, motherboard, power supply etc. If the whole were to die, the part would die with it. A stronger form of aggregation.
The relationship between club and club member would not be composition, because members have a life out-side the club and can, belong to multiple clubs.
Each part can belong to only one whole, therefore, multiplicity needs to be specified only one for the part Components will live and die with the whole object. Close Behavior: Close Slides downwards Swings shut. Both have the common behavior But the way it has been carried Out differs from one another. Produces a design specification for the new system. Also known as physical design.
Design inputs, outputs, files, databases and other computer based components. Systems analysis - emphasize on the business problem Systems design - emphasize on the technical or implementation concerns of the system. Process A11 Process A1 is a process-oriented. Process A technique for breaking up Process A2 Process A12 a large program into a hierarchy of modules Process A3 Process A13 Process A4 result- in a computer program that is easier to synonyms are top-down implement and maintain program design and change.
The software model derived from structured design It is derived by studying the flow of data through the program. Modern Structured Design. Structure Chart Parameter Passing -The calling module passes a set of values to the called module and receives a set of values in return.
These values are passed as parameter values. Structure Chart Execution Sequence By convention, modules are executed from left to right in each level. Module Output Total is the last module to be called. Certain conventions are also used to represent decisions and repetition. Decisions occur whenever a calling module has to decide to call only one of a number of modules.
Repetition occurs when some modules are called repetitively by the calling module. The objective of structured design is to produce a good design. Information Engineering IE. Primary tool of information engineering is a data model diagram ERD.
Involves conducting a business area requirements analysis from which information system applications are carved out and prioritized. The prototyping approach is an iterative process involving a close working relationship between the designer and the users. Prototyping encourages and requires active end- user participation.
Iteration and change are a natural consequence of systems development - that is end-users tend to change their minds.
Prototyping endorses the philosophy that end-users will not know what they want until they see it. Key Benefits: Prototypes are an active, model that end-users can see, touch, feel, and experience. An approved prototype is a working equivalent to a paper design specification, with one exception -- errors can be detected much earlier.
Prototyping can increase creativity because it allows for quicker user feedback, which can lead to better solutions. Prototyping accelerates several phases of the life cycle, possibly bypassing the programmer. Prototyping encourages ill-advised shortcuts through the life cycle.
JAD sessions for systems design, systems designer - role of facilitator for possibly several full-day workshops intended to address different design issues and deliverables. RAD is the merger of various structured techniques especially the data-driven information engineering with prototyping techniques and joint application development techniques to accelerate systems development. RAD calls for the interactive use of structured and prototyping to define the users requirements and design the final system.
The newest design strategy Used to refine the object requirements definitions identified earlier during analysis and to define design-specific objects e. Process Model the technical and human decisions to be ID optional implemented as part of an information system. A physical process is either a processor, such as a computer or person, or a technical implementation of specific work to be performed, such as a computer program or manual process. A physical DFD would model that network structure.
Each logical process must be implemented as one or more physical processes as some logical processes must be split into multiple physical processes. A database command or action create, read, update, or delete Import of data from or the export of data to another information system across a network.
Flow of data between two modules within the same program. External agents were classified during systems analysis as outside the scope of the systems and therefore, not subject to change. Physical Data store MS Access: Databases are a shared resource.
A database should be adaptable to future requirements and expansion. Issues to be addressed during database design include how programs will access the data Programming data structures and their impact on performance and flexibility Internal controls to ensure proper security and disaster recovery technique, in case data is lost or destroyed.
Record size and storage volume requirement. Design the System Database Purpose is to prepare technical design specification for the database. Participants Systems analyst participate in database modeling System designers complete the database design Data administrator recognize that the new system most likely use s some portion of an existing database System builders build a prototype database for the project Inputs: The precise format and layout of the outputs must be specified.
Internal controllers must be specified to ensure that the outputs are not lost, misrouted, misused, or incomplete. Editing controllers must be designed to ensure the accuracy of input data. Design the System Interface. For dialogue design the designer must consider Terminal familiarity Possible errors and misunderstandings that the end user may have or may encounter The need for additional instructions or help at certain points The screen content and layout.
Package all the specifications from the previous design tasks into a set of specifications. Guide the computer programmers activities. The deliverable: Information Technology Architecture System analysts must continuously read popular trade journals to stay abreast of the latest technologies and techniques that will keep their customers and their information systems competitive.
The information system framework provides one suitable framework for understanding IT architecture. Today information systems are no longer monolithic, mainframe computer based systems. Components are distributed across multiple locations and computer networks Processing work load required to support these components are distributed across multiple computers on the net work. Why use distributed systems?
Modern businesses are already distributed Distributed computing moves information and services closer to the customers Consolidates the incredible power More user friendly as they use the PC as the user interface processor PCs and network servers are much less expensive than mainframes Thus, there is a big trend towards distributed systems. Distributed Systems.
Disadvantages Network data traffic can cause congestion that actually slows performance. Higher security risk due to more possible access points for intruders and possible communication with insecure systems. File server Architecture A LAN Local area network based solution LAN is a set of client computers connected over a relatively short distance to one or more servers A server computer hosts only the data layer All other layers are implemented on the client PC.
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