What are some reasons to create ormodify an information system? To correct problem To improve in existing system existing system Competition can Outside group may lead to change mandate change
System Development Systems development is the process of defining, designing, testing, and implementing a new software application or program. It could include the internal development of customized systems, the creation of database systems, or the acquisition of third party developed software.
System DevelopmentLife Cycle (SDLC) Six Phases of the System Development Life Cycle Preliminary Investigation ◦ Assesses feasibility and practicality of system System Analysis ◦ Study old system and identify new requirements ◦ Defines system from users view System Design ◦ Design new/alternative system ◦ Defines system from technical view
System Development ◦ New hardware and software is acquired, developed, and tested System Implementation ◦ System installation and training System Operation & Maintenance ◦ Daily operation ◦ Periodic evaluation and updating
Preliminary Investigation SystemSystem Operation Analysis& MaintenanceSystem SystemImplementation n Design System Development
Who is a systems analyst? Responsible for designing and developing informationsystem Liaison between users and IT professionals
What is the project team? Formed to work on project from beginning to end Consists of users, systems analyst, and other IT professionals Project leader—one member of the team who manages and controls project budget and schedule
What is feasibility? Schedule feasibility Measure of how suitable Four feasibility system tests: development Operational will be to the feasibility company Economic feasibility (also called cost/benefit feasibility)
Approaches to SystemsDevelopment Process-Oriented Approach ◦ Focus is on flow, use and transformation of data in an information system ◦ Involves creating graphical representations such as data flow diagrams and charts ◦ Data are tracked from sources, through intermediate steps and to final destinations
Approaches to SystemsDevelopment Data-Oriented Approach ◦ Depicts ideal organization of data, independent of where and how data are used ◦ Data model describes kinds of data and business relationships among the data ◦ Business rules depict how organization captures and processes the data
AlternativeApproachesPrototypingApproach The prototyping approach is used in the requirement gathering and in the analysis phase to capture the exact requirement of the proposed system. After the requirements are frozen, the remaining phases of the development process needs to be executed to complete the development of the software system. An e-commerce website, such as shopping site is an example where you can implement the prototyping approach. You can develop the prototype of the various web pages of the shopping site such as catalogue page, product order page etc., and present it to the customer for approval. If the customer approves the prototype of the site, requirements are states again and the design of the web site is initiated.
The prototype is a working system developed to test the behaviour of new system.The prototype generates output from input of data fed to it and this output is evaluated to know knoe possible enhancements to the prototype. Its required while: Building an experimental system quickly and cheaply Unclear user requirements 1.User involvement 2.Fast 1.Poor system quality 2.Lack of standard
Need for prototyping Enables us to explore the problem space with the stakeholders. A vehicle for you to communicate the possible UI design(s) of your system. A potential foundation from which to continue developing the system
Advantages: * This type of approach of developing the software is used for non-IT-literate people. They usually are not good at specifying their requirements, nor can tell properly about what they expect from the software. * It reduces risk of failure, as potential risks can be identified early and mitigation steps can be taken. * Iteration between development team and client provides a very good and conductive environment during project.
Disadvantages of PrototypingModel: Prototyping is usually done at the cost of the developer. So it should be done using minimal resources. * It is a slow process. *Too much involvement of client, is not always preferred by the developer. *Too many changes can disturb the rhythm of the development team.
Application Software Packages Prewritten, pre-coded application software, commercially available for sale or lease Geared to common requirements (sig nificant few; Canned functions) Accounts receivable; Bond & stock management; Computer-aided design (CAD) ; document imaging; E- mail; Enterprise.Resource planning (ERP); Groupware; Health care; Hotel.Management; Internet telephone; Inventory control; Job costing.
Enduser development Building the system by end-users with little or no formal technical assistance When? ForPersonal & small applications WHY? 1.No misunderstanding 2.Fast
End-users develop information system themselves, with little help from technical specialists; Using 4th generation toolsStrengths: Improved requirements determination Increased user involvement & satisfaction
ADVANTAGESA waterfall model helps findproblems earlier on which cancost a business less than if itwas found later on.Requirements will be set andthese wouldnt be changed. As everything is documented anew team member can easilyunderstand whats to be done.Implementers have to followthe design accurately
DISADVANTAGES If requirements may change the Waterfall model may not work. Many believe it is impossible to make one stage of the projects life cycle perfect. Difficult to estimate time and cost for each stage of the development process. Constant testing of the design is needed.
System analysis Systems ◦ System is an interrelated set of components, with identifiable boundary, working together for some purpose A system has nine characteristics: ◦ Components----------------------Subsystems ◦ Interrelated components ◦ A boundary ◦ A purpose ◦ An environment ◦ Interfaces ◦ Input ◦ Output ◦ Constraints
System Analysis Systems analysis is a process of collecting factual data, understand the processes involved, identifying problems and recommending feasible suggestions for improving the system functioning. This involves studying the business processes, gathering operational data, understand the information flow, finding out bottlenecks and evolving solutions for overcoming the weaknesses of the system so as toachieve the organizational goals.
OBJECTIVES The major objectives of systems analysis are to find answers for each business process: What is being done, How is it being done, Who is doing it, When is he doing it, Why is it being done and How can it be improved?
System Design Based on the user requirements and the detailed analysis of the existing system, the new system must be designed. This is the phase of system designing. It is the most crucial phase in the developments of a system. The logical system design arrived at as a result of systems analysis is converted into physical system design. Normally, the design proceeds in two stages: Preliminary or General Design Structured or Detailed Design
Preliminary or General Design: In the preliminary or general design, the features of the new system are specified. The costs of implementing these features and the benefits to be derived are estimated. If the project is still considered to be feasible, we move to the detailed design stage.
Structured or Detailed Design: In the detailed design stage, computer oriented work begins in earnest. At this stage, the design of the system becomes more structured. Structure design is a blueprint of a computer system.
There are several tools and techniques used for describing the system design of the system. These tools and techniques are: l Flowchart l Data flow diagram (DFD) l Data dictionary l Structured English l Decision table l Decision tree
steps The system design involves: i. Defining precisely the required system output ii. Determining the data requirement for producing the output iii. Determining the medium and format of files and databases iv. Devising processing methods and use of software to produce output v. Determine the methods of data capture and data input vi. Designing Input forms vii. Designing Codification Schemes viii. Detailed manual procedures ix. Documenting the Design
SYSTEM IMPLEMENTATIONIt is the process of carrying out the operational plans developed as a part of information system planning . Implementation includes all the activities required to replace the old system by the new system. . The implementation process involves acquisition of IS resources , testing , documentation , installation and conversion process.
STEPS Hiring and training the personnels Program development Site preparation Acquisition and installation of hardware Software aquisition File conversion Documentation
FACTORS FOR SUCESSFULIMPLEMENTATION Involving users in project implementation Setting up a cohesive project mgt for implementation Using project mgt tools like , PERT ,CPM etc. Use of formal controltools to monitor project implementation Overcoming user resistance
CausesLower user involvement in project implementation Lack of commitment from top mgt for the project Complexity of project Poor mgt of project implementation process.
External versus Internal Auditing External auditors represent the interests of third party stakeholders, while internal auditors serve as an independent appraisal function within the organization. Internal auditors often perform tasks which can reduce external audit fees and help to achieve audit efficiency and reduce audit fees.
Elements of an Audit Systematic procedures are used Evidence is obtained ◦ tests of internal controls ◦ substantive tests Determination of materiality for weaknesses found Prepare audit report & audit opinion
COMPUTER NETWORKS A computer network, or simply a network, is a collection of computers and other hardware interconnected by communication channels that allow sharing of resources and information. Where at least one process in one device is able to send/receive data to/from at least one process residing in a remote device, then the two devices are said to be in a network. A network is a group of devices connected to each other.
Intranets and extranets Intranets and extranets are parts or extensions of a computer network, usually a LAN. An intranet is a set of networks, using the Internet Protocol and IP-based tools such as web browsers and file transfer applications, that are under the control of a single administrative entity. That administrative entity closes the intranet to all but specific, authorized users. Most commonly, an intranet is the internal network of an organization. A large intranet will typically have at least one web server to provide users with organizational information. An extranet is a network that is limited in scope to a single organization or entity and also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations .Technically, an extranet may also be categorized as a CAN, MAN, WAN, or other type of network, although an extranet cannot consist of a single LAN; it must have at least one connection with an external network.
Router, Switch, Hub, Modem, Routers are small physical devices that join multiple networks together. Technically, a router is a gateway device, meaning that it connects two or more networks and that the router operates at the network layer of the OSI model.Home networks typically use a wireless or wired Internet Protocol (IP) router, IP being the most common OSI network layer protocol. An IP router such as a DSL or cable modembroadband router joins the homes local area network (LAN) to the wide-area network (WAN)of the Internet.
A network switch is a small hardware device that joins multiple computers together within one local area network (LAN). Network switches appear nearly identical to network hubs, but a switch generally contains more intelligence (and a slightly higher price tag) than a hub. Unlike hubs, network switches are capable of inspecting data packets as they are received, determining the source and destination device of each packet, and forwarding them appropriately .
Hub Hub is used to create connections between stations in a physical star topology. Hub is a central n/w device that connects network nodes. It is also referred as concentrators. It enables central n/w management. It can have multiple inputs & outputs all active at one time. It Permits large numbers of computer to be connected on a single or multiple LANs. It enables high speed communication. Provide connection for several different media types. (Coaxial, fiber optic, twisted pair).
Modem is a computer device that modulates and demodulates data signals. It enables the computer to transmit the data over the phone line. The data over the telephone line is transmitted in the analog form and when it reaches at the computer at other end it must be presented in the digital form so that computer can understand it. The modem takes the data and converts it in the readable form for your computer i.e. digital form. Modem IS used on dialup networks convert data between the analog form used on telephone lines and the digital form used on computers.
TOPOLOGIES Incomputernetworking, topology refers to the layout of connected devices. Network topologies are categorized into the following basic types: bus ring star tree mesh
Bus Topology Bus networks (not to be confused with the system bus of a computer) use a common backbone to connect all devices. A single cable, the backbone functions as a shared communication medium that devices attach or tap into with an interface connector. A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message.
Ring Topology In a ring network, every device has exactly two neighbors for communication purposes. All messages travel through a ring in the same direction (either "clockwise" or "counterclockwise"). A failure in any cable or device breaks the loop and can take down the entire network. THE ring network, topologies are found in some office buildings or school campuses.
Star Topology Many home networks use the star topology. A star network features a central connection point called a "hub node" that may be a network hub, switch orrouter. Compared to the bus topology, a star network generally requires more cable, but a failure in any star network cable will only take down one computers network access and not the entire LAN. (If the hub fails, however, the entire network also fails.)
Tree Topology Tree topologies integrate multiple star topologies together onto a bus. In its simplest form, only hub devices connect directly to the tree bus, and each hub functions as the root of a tree of devices. This bus/star hybrid approach supports future expandability of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub connection points) alone.
Mesh topologies Mesh topologies involve the concept of routes. Unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination. (Recall that even in a ring, although two cable paths exist, messages can only travel in one direction.) Some WANs, most notably the Internet, employ mesh routing.