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System. A System is a set of interrelated elements that collectively work together to achieve some common purpose or Goal. e.g. Communication System. Computer System. Business / Firm. System’s Attribute.
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System A System is a set of interrelated elements that collectively work together to achieve some common purpose or Goal. e.g. • Communication System. • Computer System. • Business / Firm.
System’s Attribute • Elements of the System.- These are the units within the system which interact with each other to produce desire results. These may be tangible objects, abstract concepts (intangible) or an event. • Boundary of the System.- Boundary is the area that separates one system from another. Any thing within the boundary is part of the system(element). It is a filter of inputs and outputs between system and surroundings. • Surroundings of the System.- Any thing outside the boundary of the system that influences the operation of system and cannot be directly controlled by the system. • Input of the System.- These are the energies taken into the system. Results/Outputs are produced after processing of these inputs. e.g. Electric Current, Computer Program.. • Output of a System.- These are the energies discharged from the system into the environment. e.g. Financial Statements are output of an Accounting Information System(AIS). • Interface.- It is the medium for transporting the output from one system into another system as input.
Open System A system which accepts input from the environment and returns output to its surroundings. Almost all systems are open in nature. Close System Close Systems do not interact with environment. It means that no inputs are fed into systems and no outputs are returned.
Why we replace existing Systems New Systems (CBIS) frequently replace existing manual systems and new systems may themselves be replaced after sometime due to introduction of new Technologies/Applications. Some of the reasons why users and MIS professionals consider an existing system to be inadequate are:- Existing System does not support business objectives and strategies efficiently. It does not satisfy the needs and requirements of users. It has inadequate system controls. It has software that is unstructured and difficult to maintain. Less use of modern technologies. It contains various flaws and errors in its design. It is poorly documented and difficult to use.
Successful MIS In order to develop a successful System different methods/techniques are used. These methods enable the professionals to build information system that not only satisfy the user's requirements but also are delivered in time and within a budget. • High level of user involvement are present throughout the system development process. • Project management techniques are used to implement systems plan. • Alternative system designs are developed and critically evaluated prior to committing to final design, technology and software.
Successful MIS • Structured program designing and coding is used. • Clear, complete and accurate documentation for the new system is generated throughout the system development process. • System implementation and user training are carefully planned and coordinated. • Post implementation reviews are conducted to ensure that user and management needs were met. • New systems are designed for easy maintenance. No System is guaranteed of success but if above points are considered, chances that users and mangers will satisfy should increase.
SYSTEM DEVELOPMENT LIFE CYCLE (SDLC) The process of replacing the old system by the new one take in a series of stages and the whole process is called System Development Life Cycle. It comprises the following stages: • Preliminary Investigation of the System. • Detailed System Analysis or Requirement Analysis. • System Design. • System Acquisition and System Development. • System Implementation and Evaluation. • System Maintenance.
What is SDLC…. 1. PRELIMINARY INVESTIGATION OF SYSTEM. • Initial study/system study. • Problem identification. • Feasibility study/report. 2. REQUIREMENT ANALYSIS • Detail system study. • System analysis. • Preparation of statement of requirements. 3. SYSTEM DESIGN. • Review of TORs (Term of references). • Specification of proposed system. • User interface designing. (Screen design / Reports layout etc.) • Reporting to management about 3rd phase.
…. What is SDLC 4. SYSTEM ACQUISITION AND DEVELOPMENT. • Acquisition of hardware and software. • Software Development. • Documentation. 5. SYSTEM IMPLEMENTATION. • System testing. • User training. • Implementation method. • Post implementation reviews. 6. SYSTEM MAINTENANCE.
Preliminary Investigation Preliminary Investigation of system First phases of SDLC start when a user found some problem/difficulties in the operation of existing system or management decides to change the current system to met the changing requirement. Normally consultant are hired to observe/study the existing system them recommend a propose system which fulfill all requirement. It consist of different sub activities. The preliminary investigation is the first step in system development. After a user need or opportunity is identified, a system analyst determines if a new or modified system is necessary. Preliminary Investigation is also known as project feasibility study.
Preliminary Investigation The main objective of this phase (step) is to determine whether or not work on a new/modified system is capable of being accomplished. Following areas are considered to evaluate the feasibility of a project. • Technical feasibility. • Operational feasibility. • Economic feasibility. • Schedule feasibility.
Preliminary Investigation The main task performed by the system analyst in this step are:- • Identifying and defining the problem and its back ground. • Determining the size of the development effort involved. • Recommendations of different possible solution. • Cost and Benefits of each option. Result of these tasks are listed in a report known as “Project Feasibility Report” and will be sent to steering committee/Top management for further consideration and approval.
Requirements Analysis (System Analysis)…. If management decides to continue developing the system after reading the Systems Analyst’s report (Project feasibility Report), the second phase of development begins. In traditional approach, the full requirement analysis is performed before system design begins. User typically sign a document at the end of this phase, confirming the requirements identified by System Analyst. In prototype approach, requirement analysis and system design phases proceed in simultaneously. In requirement analysis phase following activities are performed:- • Users requirements are determined in detail. • Existing system is studied in depth to analyze the data and its processing. • Preparation of statement of requirements.
.…Requirements Analysis (System Analysis) The systems analyst will explore a no. of routes and use a variety of methods to establish a full picture of the existing system. Following techniques/methods will be used to collect data about the existing system in this phase:- • Documents. • Questionnaires. • Interviews. • Observation. In system analysis and system design phase Data Flow Diagrams (DFD) and system flow charts are used to represent the movement of data in an organization. The last step of this phase is to report finding to management. This includes a recommendation from the list of alternative solution, an assessment of costs and benefits and a schedule covering future system activities. (Design, Development Acquisition and implementation).
System Design System design consists, generally, of three activities: reviewing informational and functional requirements, developing a model of the new system, and reporting the results to management. Developing a model of the new system comprises the bulk of system design. When designing a new system, Systems Analysts determine, at both the logical and physical levels, the components of the system in the areas of input, output, processing, storage, procedures, and personnel. A logical description of information describes how elements of the system relate to each other - without mention, perhaps, of specific hardware deceives or software packages. A physical description, in contrast, identifies specific devices or products. The impact of systems software and computing hardware must also be assessed in the design process. Some issues to consider are the types of computations involved, whether or not telecommunication or real-time processing is necessary, and throughput (which relates to how much work a given computer system can do in a given amount of time). After system design activities are completed, they are reviewed by users and reported to management.
System Acquisition After the system design details are resolved, such resource needs as specific types of hardware, software, and services are determined. Subsequently, choices are made regarding which products to buy or lease from which vendors. These activities are part of system acquisition. System Development • In this stage following activities are performed:- • Establish a Project Development Schedule • Produce Specification for each Programme to be Developed • Coding, Testing and Debugging of each Programme. • Create the Documentation for the System
System Implementation After development and successful testing of the system, the next stage is to put it into action, i.e. system implementation. Usually there are four distinct alternatives approaches are used to implement a new system: • Direct Implementation • Parallel Implementation • Pilot Implementation • Phased Implementation System Maintenance • Once the system has been introduced successfully, it does not mean the end of the systems analyst’s work. The system has to be maintained, added to, adapted and amended in the light of subsequent developments. These may be due to • Error Elimination • New Developments in Technology • Other External Circumstances • After implementation, the system is maintained, it is modified to adapt to changing user and business needs so that the system can be useful to the organization for as long as possible.
APPROACHES TO SYSTEM DEVELOPMENT Approaches to systems development are often classified according to how the five systems development activities are carried out or whether the development efforts are top-down or bottom-up. The first of these classifications divides systems development process into three basic approaches: the traditional approach, prototyping approaches, and end-user development. Traditional Approach • In the traditional approach, developmental activities are followed in strict sequence, one after the other. This approach is criticized because it is often difficult for users to formulate their needs in advance. This approach can be used in following circumstances. • User have significant experience with the type of system to be designed. • Many important features can be readily identified before development begins. • Data requirements can be identified in advance. • Management requires a comprehensive “picture” of the new system before giving approval. • The development staff is not experienced with prototyping tools.
Prototyping Approaches With prototyping approaches, a small or pilot version of the system--called a prototype-- is developed. Users work with the prototype, and feedback provided to the systems analyst leads to further prototype refinements or enhancements. This process of gradually improving the prototype through iterative user feedback continues until a final, acceptable system is developed. Normally this approach is used in following circumstances. • User do not have a feel for the information or system capabilities they require. • User needs are changing rapidly. • Users have little experience with the type of system under development • The risk associated with delivering the wrong system is high. • The way users will react to the new system is an important development variable. • Many alternative design strategies must be tested. • The system must be developed quickly and at the lowest possible cost.
End-user Development Approach With end-user development, the end-user is responsible for developing the system. The end-user may select a traditional type of approach, a prototyping approach, or an intuitive approach. It is used in following circumstances. • The system under development is local rather than enterprise-wide. • The system under development is inexpensive. • A suitable environment of end-user development tools and professional expertise is available. • Standards exist to minimize divergent efforts by the end-users and other dangers to the organization. • High levels of security are not necessary for the system being developed. • The system under development involves numerous customized queries and reports. • The system under development can easily be built and supported by the end-user. • The system under development does not involve high-volume transaction processing. • The development time is short and cannot be accommodated by the MIS department (possibly because of a huge application backlog). • The user must be heavily involved in the development process. Top-down systems development views the organization's needs from a strategic perspective, and a new system is developed to meet that perspective. Bottom-up systems development looks at the existing organizational systems and tries to meet new systems needs within the constraints posed by those existing systems. In most cases, a combination of top-down and bottom-up approaches is used.
Documentation Documentation is the term used to describe all types of written instructions associated with using, operating, developing or maintaining a computer system. The primary objective of documentation must be to provide easy-to-flow, unambiguous, user friendly instructions and explanations. Good documentation is highly important to the success of any system. Good documentation however, is very often under rated. It is also true that the skills required to produce a good documentation is quite different from those required for systems analysis and design and is rare. Many analysts treat documentation rather casually and wait until the entire system is almost finished to begin preparing it. The documentation process is thus rushed to meet the deadline and a poor documentation is the result. Luckily, modern 4th GLS have built in facility to produce part of the documentation while systems development is taking place. Documentation can broadly be classified as: User Manual Systems/Technical Manual
User Manual User documentation consists of either a written or disk tutorial and a reference manual. The tutorial is designed to get the user started with using the system and help him to solve the many problems that may crop up while he is trying to gain command over the use of the system. The reference manual, intended for advanced users, is really the “bible” for the package. If the user cannot figure out how a command works, he may consult the manual to solve the problem. System Manual Systems manuals are actually meant for the DP professionals, the systems analyst and programmers who may be required to run the system and make amendments and additions to it later on. The Systems manual comprises of the following: • Systems Specification - which will include all of the materials that are necessary to show how a particular system operates. This includes system requirements, diagrams, such as data flow diagrams or systems flow charts, written narratives of job descriptions and so forth. • Program listing - the manual will include listing of all the programs’ source codes. • An English narrative describing what the program and programs modules are supposed to do together with program flowcharts. • * Files - the names and descriptions of all the files used in the system together with their structures, i.e. the names and descriptions of the variables used. A cross reference of all files called by each program is also included. • Forms Layout - a complete list of all the forms for inputs and outputs used by the system together with their layouts.
Implementation Techniques…. Direct Implementation – Using this method of implementation, the old system is completely replaced by the new system in one move. While this method is comparatively cheap it is risky (system or program corrections are difficult while the system has to remain operational). The new system should be introduced during slack periods. This requires a great deal of effort and there might be considerable disruption. Parallel Implementation – This is a form of implementation whereby the old and new systems are run in parallel for a period of time. There may be some errors in the new system ,this method provides a degree of safety. However, if there are differences between the two systems cross-checking may be difficult. Furthermore, there is a delay in the actual implementation of the new system, a possible indication of lack of confidence in the new system, and a need for more staff to cope with both systems running in parallel. As far as the company is concerned, this is likely to prove too expensive and unwieldy given the volume of data processed.
…. Implementation Techniques Pilot Implementation – This is cheaper and easier to control than parallel running, and provides a greater degree of safety than does a direct changeover. In this approach a complete logical part of the whole system file is chosen and run as a unit on the new system. If that is shown to be working well the remaining parts are then transferred. Gradually the whole system can be transferred in this piecemeal fashion. Two systems have to be controlled and additional staff, as well as a longer period for implementation, may be required. However, this would seem to be an appropriate option for the company. Phased Implementation – This is particularly suitable for large projects. It is a process of changing over from the old system to the new one in segments for example on a department by department basis. This may be done either by a series of periods of parallel running, or by a series of direct changeovers. In the former case, instead of running two complete systems (old and new) in parallel in order to compare the results of living processing on the new system with those generated by the old, only a portion of the data is run in parallel, e.g. for one department only. In the latter case, the same considerations apply as for an organization-wide direct changeover. Where this approach is adopted care must be taken to control any systems amendments incorporated in the later phases in order to ensure that the overall system remains totally compatible.
What is SDLC…. In order to develop a new CBIS, consultants have to perform a no. of activities. Collection of activities to be performed during system development is called SDLC. It include following phases. 1. PRELIMINARY INVESTIGATION OF SYSTEM. • Initial study/system study. • Problem identification. • Feasibility study/report. 2. REQUIREMENT ANALYSIS • Detail system study. • System analyses. • Preparation of statement of requirements. 3. SYSTEM DESIGN. • Review of TORs (Term of references). • Specification of proposed system. • User interface designing. (Screen design / Reports layout etc.) • Reporting to management about 3rd phase.
…. What is SDLC 4. SYSTEM DEVELOPMENT. • Acquisition of hardware and software. • Software Development. • Documentation. 5. SYSTEM IMPLEMENTATION. • System testing. • User training. • Implementation method. • Post implementation reviews. 6. SYSTEM MAINTENANCE. Preliminary Investigation of system First phases of SDLC start when a user found some problem/difficulties in the operation of existing system or management decides to change the current system to met the changing requirement. Normally consultant are hired to observe/study the existing system them recommend a propose system which fulfill all requirement. It consist of different sub activities.
INITIAL STUDY…. In this sub activities consultant have to observe the working of system to find out its working and objective (short term as well as long term). During initial study consultant have to locate/indicate factor which are creating problems in the working/operation of current system. These sub activities called identification of problem in the existing system. It is the responsibility of consultant to recommend more than one procedure/alternative to solve/remove identified problem. Composition of each option is made on bases of benefits, limitation and cost estimate. Propose solution are evaluated to check their suitability/feasibility with respect to following factors. • Technical feasibility. • Operational feasibility. • Economic feasibility. • Organization feasibility.
…. INITIAL STUDY At the end of 1st phase reports is prepared by consultant for the consideration/approval of top management about the development of new system. This report contains following information: - • Introduction of end user organization. • Introduction of consultant. • Brief description of the system/project being studied. • Problem area of existing system. • Different alternative to solved remove the problem. • Comparison of each option. • Recommendation of consultant.
REQUIRMENT ANALYSES…. 2NDphase of SDLC starts when top management/project steering committee decide to continue the development of new system after evaluating the feasibility report prepare in first phase. Normally system analysts are deputed by consultant to determine the detail requirement of end user organization. Following sub activities have to be perform by system analyst during this phase. • In this sub activities the end user organization is studied in depth understand the data and processing requirement of organization. For this purpose system analyst have to use different data collections techniques some of them are: - • By observing facts. • By conducting interviews. • By floating questioner. • By reading office manual.
….REQUIRMENT ANALYSES • After collecting necessary information about data and data processing requirement of existing system, it is the responsibility of system analyst to create a relation among these requirements. It helps the system analyst to determine the requirement of organization with respect to propose system. Different type of data analysis tools are used by system analyst during this phase. • Data flow diagram DFD. • System flow charts. • Organogram (Organizational chart). • Decision Table. • Decision tree. • At the end of 2nd phase system analyst have to prepare a report/statement describing all requirement of end user organization. This report act as agreement between consultant and organization. Both parties have to follow these TORS. It means that consultant have to develop a system which fulfill all requirements describe in TOR’s according to specified time schedule. End user organization have to pay extra amount if the add some requirement latest stages.
System Design…. In the 3rd phase of SDLC system analyst/system designer have to prepare the specification (logical model) of proposed system. These specification are based on the requirement identified in 2nd phase. • It is better to review all identified requirement before preparing the specification of proposed system. It is easier to add additional requirement at this stage. • What type of data processing are made in the propose system and what type of devices are required in propose system. These type of question are assume by SA/SD during this activities. What type of procedure are used in proposed system to fulfill the requirement or achieve defined targets. Almost all paper work about the propose system is finalizes in the face.
…. System Design • In this sub activities different issue regarding user interface are design by SA/SD for example: - • Screen design/form designing. • Lay out of report. • Style of message / dialogue boxes. • File designing (Structure of tables, field size, field type and relation among table). A set of system design tools used in this phase which are E. • ERD entity relationship diagram. • HIPO charts (hierarchical input processing output ). • Structured English. • Pseudo code • Algorithms. • Program flow chart. • At the end of 3rd phase a consolidated report prepare for Management to inform the current status of system development and to direct the system developer about system designing phases.
Why we replace a new system with existing system? There are three reasons: • According to changing environment there may be a chance that the existing system doesn’t fulfill all requirements of a n organization. • Introduction of modern / latest technologies. • There may be chance that existing system produce incorrect & delayed results. • Programs of existing systems are difficult to modify /maintain due to un-structured programming & poor documentation.
System Development Techniques…. 1. WATER FALL MODEL:- It is also known as traditional approach of system development process. It this model all activities / phases of SDLC are performed in sequential order (top to bottom ). This approach of system development requires more development time as compared to other approaches. It is the most effective system developed according to fulfillment of requirements due to the season that all phase are perfumed in a very detailed manner. 2. RAD RAPID APPLICATION DEVELOPMENT:- This technique of system development is introduced to seduce the system development time. In this model more than one activities / phases are performed in parallel. This technique of system development use different methods of developing new system. • Prototyping • Incremental model. 3. PROTOTYPING:- It is a type of RAD. It the first instance project manager /system analyst develop a very sough model of a new system and handed over to the uses\r for its input. This sough model is changed / modified repeatedly acceding to user requirements/ input.
…. System Development Techniques 4. JOINT APPLICATION DEVELOPMENT (JAD):- A technique developed by the professional of IBM. In this technique a team / work group of consultants, IT Professionals and end-users is selected and assigned the development of new system. This work group is mere effective to determine the requirement of new system and to develop an acceptable system. 5. INCREMENTAL SYSTEM DEVELOPMENT MODEL:- In this model first phase of SDLC is again performed after the completion of last phase. Using this approach a new system become more acceptable for an organization for a longer period. 6. SPIRAL MODEL:- It is also an incremental model in which activities of SDLC are performed repeatedly to get an acceptable system. 7. OBJECT ORIENTED SYSTEM DEVELOPMENT:- It is also known as component based system development. This technique uses the object oriented techniques for system development. First of all main abject of new systems are defined /created and them these object are combined effectively to develop a system which fulfills all requirement of an organization.
