Systems analysis and design /Alan Dennis, Barbara Haley Wixom, Roberta . need for new or revised information systems to support business processes. .. business analysis benchmark - full kipentoriber.tk; accessed February. Arthur M. Langer. Analysis and Design of Information. Systems. Third Edition information contained in this book and cannot accept any legal responsibility or. Types of Information System. Brief Introduction to System Analysis and Design . . Case Study: Library Management System(Preliminary analysis).
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All information systems projects move through the four phases of planning, analysis, design, and imple- mentation; all projects require analysts to gather. The primary objective of systems analysis and design is to improve organizational systems. This tutorial provides a basic .. Information Gathering Techniques. In any software design project, the analysis stage – documenting and ISBN ; Digitally watermarked, DRM-free; Included format: PDF This third edition of the successful Analysis and Design of Information Systems.
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.
Disadvantages Large amount of unnecessary data must be moved between the client and the server Reduce network and application performance The client PC must be robust. Client Server Architecture The presentation, presentation logic, application logic, data manipulation and data layers are distributed between client PCs and one or more servers.
Client Computers: A personal that does a personal computer, not have to be very notebook computer, or powerful acts as a work station that is terminal typically powerful e.
Remote desktop e. Database Server: A server that hosts one or more databases. Transaction Server: Application Server: A server that hosts application logic and services for an information system Messaging or Groupware Server: A server that hosts services for groupware.
Web Server: Application logic is placed on its own server Presentation logic and Presentation are placed on the clients. Stores data in a tabular form Each file is implemented as a table Each field is a column in the table Each record is a row in the table Related records between two tables e.
The software required to implement distributed relational databases Controls access to and maintenance of the stored data in the relational format Provides back-ups, recovery and security Also called as client-server database management systems e. Supports two types of data Data partitioning: Data Architectures.
For a given information system application the data architecture must specify the RDBMS technology and the degree to which data will be partitioned or replicated. Batch inputs or Outputs Transactions are accumulated into batches for periodic processing Batch inputs e. Online inputs or Outputs Provide for a more conversational dialogue between the user and the computer applications. Provide immediate feedback in response to transactions, problems, and inquiries.
Remote batch Combines the best aspects of batch and online inputs and outputs. In batch systems, keying errors can be eliminated through optical character reading OCR and optical mark reading OMR technology The real advance in keyless data entry are coming for online systems in the form of auto-identification systems.
Pen input A pen-based operating system become more widely available and used e. Imaging and Document Interchange The actual images of the forms and data are transmitted and received. Demand for Project managers in the Information system community is strong. Information system project managers come from the ranks of experienced IS developers such as systems analysts Systems Analysts should be aware of Project management processes, tools and techniques.
Project Management Project manager The person responsible for supervising a systems project from initiation to conclusion. Should possess a wide range of technical, management, leadership and communication Project skills. It is the process of Scoping Planning Staffing.
Directing Organizing Controlling. Necessary to ensure that the project. PM is a cross life cycle activity because it overlaps all phases of any systems development methodology. A project is successful if The resulting Information system is acceptable to the customer The system is delivered on time The system is delivered within budget The system development process had a minimal impact on ongoing business operations.
Causes of failed projects Over optimism The mythical man-month Inadequate people management skills Failure to adapt to business change Insufficient resources Failure to manage to the plan.
Major cause of project failure is that most project managers were not educated or trained to be project managers. Project Manager Competencies. Good project managers possess a core set of competencies. Some of these can be taught in courses, books and workshops Some come only with professional experience in the field basic premises of project management competencies: Project Manager Competencies Influence Competencies.
Project management functions Scoping: A project manager must scope project expectations and constraints in order to plan activities, estimate costs, and manage expectations. What skills will be needed? How much will it cost? Can some of the tasks overlap?
Project management functions Scheduling: Project management functions Controlling: They learn from mistakes and plan for continuous improvement of the systems development process. All these functions depend on ongoing interpersonal communication among the project manager.
The team, and other managers. Project Management Tools and Techniques. Project Management Tools and Techniques A PERT chart is a graphical network model that depicts a projects tasks and the relationships between those tasks.
Boxes represent project tasks Content of the boxes can be adjusted to show various project attributes such as schedule and actual start and finished times. Arrow indicates that one task is dependent on the start or completion of another task. Project Management Tools and Techniques Gantt Chart The most commonly used project scheduling and progress evaluation tool a simple horizontal bar chart that depicts project tasks against a calendar. Each bar represents a named project task.
The tasks are listed vertically in the left-hand column. Project Management Tools and Techniques e. Gantt Chart. For more details: Project Management Tools and Techniques Gantt Chart Advantages Clearly show overlapping tasks Tasks that can be performed at the same time the bars can be shaded to clearly indicate percentage completion and project progress Shows which phases are ahead of and behind schedule at a glance. Gantt Vs. Gantt charts are more effective when seeking to communicate schedule PERT charts are more effective when you want to study the relationships between tasks.
Project Management Tools and Techniques Used to help project managers plan projects, develop schedules, develop budgets, monitor progress and costs, generate reports, and effective change. Automated project management tools: In the not too distant past the principle tools of the systems analyst were paper, pencil, and flowchart template. There are three classes of automated tools for developers.
Some CASE tools also provide prototyping and code generation capabilities. It is the application of information technology to system development activities, technique and methodologies. Case tools are programs that automate or support phases of a system development life cycle. CASE Repositories A system developers database where developers can store system models, detailed descriptions and specifications, and other products of system development.
Forward and Reverse Engineering Two distinct ways to develop system models. Forward Engineering: Systems designed to automate the stages of Systems Development. Capable of bringing clear benefits to Systems Development. Skills and Capabilities of the Systems Analysts. An integrated software development tool Provides all the facilities necessary to develop new application software with maximum speed and quality.
Also known as integrated development environment IDE e. Provide a number of productivity and quality management facilities cont. Testing tools: Help authoring tools: Repository links: Process and Project Management Tools CASE tools and ADEs support analysis, design and construction of new information systems and software Process manager and project manager application tools are intended to support cross life-cycle activities.
Process manager application An automated tool Helps to document and manage a methodology and routes, its deliverables, and quality management standards. Project manager application An automated tool Helps to plan system development activities, estimate and assign resources, schedule activities and resources, monitor progress against schedule and budget, control and modify schedule and resources, and report project progress. System Analysis and Design Uploaded by erangirifad.
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Jump to Page. Search inside document. Studies the problems and needs of an organization Determine how people, data, processes, and information technology can best accomplish improvements for the business Bridge the communication gap that exists between non Systems Analysts technical and technical people involved with building systems.
Y2K problem Many computers and applications stored date with only 2 digits. Supports the planning and assessment needs of executive managers. Accounts Sales Client Computers: Clients may be thin or flat Almost all PCs Acts only as a terminal e. Batch Processing Data about many transactions is collected as a single file which is then processed The data entered is collected into files called batches. Each file is processed as a batch of many transactions. Online Processing The data about a single transaction is processed immediately.
Progress is more difficult to track. Study and understand the problem and its context Define the requirement of a suitable solution. Observe and evaluate the solutions impact, and refine the solution accordingly. Document through out Development An ongoing activity of recording facts and specifications for a system for current and future reference Documentation enhances communications and acceptance Stimulates user involvement and reassures management about progress Reveals strengths and weaknesses of the system to multiple stakeholders.
Project Management Process of Scoping Planning Staffing Organizing Directing Controlling a project ensures that an information system is developed at minimum cost, within a specified time frame and with acceptable quality. Cancel the project if it is no Cancel longer feasible If project scope is to be increased, reevaluate and adjust the cost and schedule If the project budget and schedule are frozen and not sufficient to cover all project objectives, reduce the scope. Methodology The system development methodology consists of several well-defined steps.
Increase the quality of software Tools will support methodologies but will not replace system analysts. A measure of the Practicality of a technical solution Availability of technical recourses and expertise Addresses three major issues Is the proposed technology or solution practical? Once the specific requirements and solutions have been identified Weight the costs and benefits of each alternative Cost benefit Analysis e. Problems at the end of Chapter 11 in Ref. Single person in top management who makes the final decision Facilitator Single individual who plays the role of the leader or facilitator.
De liv Supplier er y e no t no te ry Example: downloading System Order Supplier Purch. Consists of various types of process models. Data Flow Diagram: Popular System Analysis Process Model.
Refer to table in pg Ref1 3. Book There are two basic types of questions: open ended and closed ended. Open-ended questions are neutral and non-restrictive. They allow interviewees to answer questions in any way they wish, and they encourage them to reveal information. Open-ended questions can sometimes result in the disclosure of irrelevant information.
Closed-ended questions are specific and provide the interviewer with greater control over the interview. However, they achieve only what they ask and discourage interviewees from opening up and revealing relevant information which the interviewer did not anticipate.
Questions can be sub-divided into two categories: primary and secondary; both can be open or closed-ended.
Primary Questions address a specific topic. Secondary Questions are follow-up questions designed to obtain more information than was given in response to a Primary question. Questionnaires Questionnaires allow the analyst to collect information from a large number of people, possibly spread over several sites. Standardised question formats can yield more reliable data than other fact-finding techniques, and wide distribution ensures that respondents remain anonymous. This can lead to more honest responses.
However, questionnaires don't let the analyst see the expressions or reactions of respondents. Respondents may not complete questionnaires as a high-priority task.
If everyone doesn't reply, the respondents can become a self-selected group, which can lead to problems with data reliability.
Open-ended questionnaires allow people to express their feelings, opinions and experiences or explore a problem. Closed-ended questionnaires provide greater control by presenting respondents with specific responses to choose from. This format is excellent for obtaining factual information.
Questionnaires are expensive to develop and distribute. Analysts must consider the objectives of the questionnaire and determine what structure will be most useful and easiest to understand. Questionnaires should be tested before being printed and distributed. Questionnaire recipients should be selected for the information they can provide.
The analyst should make sure that they have the background and experience to enable them to answer the questions. Observation Observation is another technique used to gather information by observing people performing various aspects of their jobs. It allows the analyst to determine what is being done, how it is being done, who does it, when it is done, how long it takes, where it is done and why it is done.
Information Systems: Systems Analysis and Design AH 18 Also, observation lets the analyst take part in procedures being performed by employees. With this hands-on approach, the analyst may find out that forms are poorly designed or that insufficient time is allocated to a particular procedure. In addition, the analyst may uncover better and quicker ways to carry out a procedure.
Consistency Checking The analyst must check that information obtained from different sources is consistent. In general, information should be obtained from at least two sources to allow consistency checks to be carried out. Any inconsistencies must be investigated. It is unlikely although not unknown that anyone will deliberately supply an analyst with wrong information.
However, different people do have different knowledge and different memories of events, so inconsistencies often occur. The analyst will have to identify all the major components of the existing system, i.
These will be recorded using one or more data flow diagrams. Data flow diagrams are described briefly below.
Several examples of their use are given in the Case Study which forms the next two sections of these notes. The analyst will also have to describe the processes involved in the current system.
System Analysis and Design
One way of doing this is by a simple narrative, i. Other methods include the use of Structure Diagrams, a graphical technique derived from structured programming, or Structured English, a more rigorous form of English, which is written in a similar manner to a programming language.
Both of these techniques are described in more detail in the next section. In general the new system will be required to that the new system should be able to carry out the same tasks as the existing system, but with improved efficiency. This is described in greater detail in the next section. A variety of different notations are used, but they all serve the same basic purpose.
Templates of the symbols are readily available. This section introduces the basic concepts of DFDs. More detailed examples of their use are given in subsequent sections.
DFDs show the movement of data or goods through a system. They make use of five basic symbols: Data Flows A data flow is a route that allows data to travel from one location to another.
It is represented by a line, with an arrowhead showing the direction of flow. Data can flow from a source to a process, from one process to another, or from a process to a data store or destination.
Each data flow should be given a unique descriptive title. Physical Flows A physical flow is a route which allows goods or materials to travel from one location to another. It is represented by a heavier line or sometimes a double line with an arrowhead showing the direction of flow. Goods can flow from a source to a process, from one process to another, or from a process to a destination.
Each physical flow should be given a unique descriptive title. Processes Processes show actions or transformations carried out on data. They are represented by a rectangle and should have an incoming data flow and an outgoing data flow.
Processes should also be given descriptive names, ideally in the form of a verb followed by an object, e. They are often numbered to aid identification.
They are represented by a narrow rectangle with one end left open. They should be given simple, descriptive names. The same data store may appear more than once on a DFD to simplify the diagram and avoid crossing data flows. External Entities External entities include sources and destinations.
Sources are the origins of data or goods and destinations their ultimate end point. They are represented by an oval or lozenge shape and should be given simple, meaningful names. Sources and destinations are outwith the boundaries of the system. They show how data and goods initially enter the system and how they leave the system.
A source or destination may appear more than once on a DFD to simplify the diagram and avoid crossing data flows. Different levels of DFD can be used in discussing the system with different grades of staff, e. Level 0 diagrams are sometimes known as context diagrams.
Numbering must be kept consistent in the different levels of diagram, e. Process 2. It is essential to ensure that all the flows and stores connected to a process in a higher level diagram also appear in the lower-level DFDs. Similarly, no new flows or stores should be introduced in the lower-level DFDs. If these turn out to be necessary, the higher level DFDs must be amended to include them.
These will indicate the boundaries of the system and provide an initial set of data flows - those which bring data into the system and those which take data out of it. Choose an input from a source or an output to a sink and insert a box where a process is required to transform data in some manner.
Check whether all the required data is flowing into the process to carry out the desired transformation and produce the required output - if not, you may have to add additional input data flows. DFDs can be useful in identifying the need for additional data items that were not obvious from a verbal description. Do your initial drafts freehand with a pencil. Your first draft will probably be wrong and end up as a hopelessly tangled scribble.
It normally takes at least three drafts before a DFD starts to make sense. Most processes should access a store of some kind - if this is not the case, check carefully for mistakes or omissions. DFDs are a useful modelling tool, which provides a clear indication of how data makes its way through the system. However they lack the detail about data which is required at the Systems Design stage. This detail is provided by the Data Dictionary, which we will look at next.
These follow the same conventions as the data flow diagrams we used earlier. Logical DFDs can have two types of data stores, manual data stores and computerised data stores. Manual data stores will contain physical objects such as stock, money or paperwork, whereas the computerised data stores will contain the customer databases, stock records etc.
The functions shown in the logical data flow diagrams will reflect the procedures which are carried out by the new system.
Function boxes represent the main functions carried out by the new system. It should include the paperwork which is to be completed and filed, the computer files and programs which are to be used, and the information which will be passed between departments and to-from external entities. Each item of data should be uniquely identified and defined. Information about data items can usefully be collected together into a data dictionary.
No analyst can carry all the details of a system in his head, so records are vital. The data dictionary is an essential component of the analyst's record. The most important features of a data dictionary are completeness and consistency. Partno, Price, StockQuant etc. A description should be given for each of data flow in the required logical level 1 DFD which flow to or from an external entity.
For each flow you should state: Name of the flow Type of flow, eg: physical flow stock, money, people computer printout screen information manual document Data Contents, i. Any files should have the fieldname, the length of the field to hold the longest entry, and the type of the field entry e. A typical layout for a database file structure could be: Customer Database Field Name Type Length cust-no n 6 surname c 20 forename c 15 street a 25 town c 15 county c 20 postcode a 12 the files should be drawn with the headings and column details.
A short description of the purpose and use of each file should also be included.
The Systems Implementation Plan gives a detailed description of how implementation will be achieved. It is usually prepared several weeks or even months in advance, depending on the complexity of the project. Implementation involves co-ordination and scheduling of a number of activities and tasks performed by an implementation team which might include: systems analysts, departmental managers, vendor representatives, users, programmers and technicians.
At this stage, the hardware for the system should have been selected and site preparation commenced.
When the equipment arrives everything should be ready for installation. A programming team should be formed and should start by reviewing the design specifications to ensure clear understanding before coding and testing start. Training of users and other relevant personnel should begin. Preparing the Site If the hardware is PC based, only minimal site preparation should be required.
Adequate space should be provided for equipment and furniture. Appropriate wiring, lighting, and air conditioning should be installed to ensure a clean, workable environment. Staff may require acoustic privacy panels, printer enclosures and ergonomically designed furniture and workstations.
Training Personnel No system can function effectively unless all users are properly trained. Training increases staff expertise and facilitates acceptance of the new system - an important factor in a system's ultimate success.
Training should begin early enough to be completed around the same time as the system becomes operational. Training increases user confidence and minimises disruption during early stages of systems operation. Training ranges from a brief tutorial showing one user how to perform a simple task to training most of the users throughout the organisation for a major new system.
A training schedule must be drawn up to make efficient use of resources. Training may be provided in-house or bought in from vendors or other outside suppliers. It includes descriptions of how software operates and the procedures users follow.
Everyone agrees about the need for good system documentation, but it is often neglected by those who ought to provide it. This may be on-line or contained in a procedures manual. Documentation also tells users how to complete source documents and data entry screens, generate reports, and check the validity of output.
It is a valuable resource and guide for all information systems students, as well as practitioners and professionals who need an in-depth understanding of the principles of the analysis and design process.
Computer Science Theoretical Computer Science. Free Preview. Revised, third edition provides a thorough introduction to all aspects of business transformation and analysis Brand new case studies give readers a deeper understanding of the practicalities of the analysis and design process Additional chapters on Web interface tools, security and change control, and data warehouse system design Presents a set of good practices that allows professionals to adjust to the needs of any business without adhering to any particular methodology of systems design A valuable and user-friendly resource, for both information systems students and professionals see more benefits.Most books on Systems Analysis and Design relate to specific methodologies and contain significantly more detail than required for this unit.
It contains key information and diagrams about the operational aspects of the system. Both of these techniques are described in more detail in the next section. Basically, the modified waterfall model is a more efficient model to use. Arrow indicates that one task is dependent on the start or completion of another task.
In this case there is only one sources, the Customers who order books. The named rounded rectangle represent the entity. Decision tables:
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