B. H. Gardi College of Engineering & Technology, RAJKOT Department of Master of Computer Application. MCA Lecturer At GARDI VIDYAPITH RAJKOT.

Transcription

1 Prepared By :- Mr. Ajay A. Ardeshana MCA Lecturer At GARDI VIDYAPITH RAJKOT. - Mobile : Chap5er - 6 SYSTEM ENGINEERING (SSAD SSAD) Mobile :

2 System Concepts System provide a meaningful framework for describing and understanding the features and functions of the subjects. Definition :- Systemisdefinedasasetofelementsinanorderlymannerto accomplish an objective. Systemisasetofelementsthataretogethertoperformthe functionalities or set of task for particular subject. A system is not a randomly arranged set. It is arranged with some logic governed by rules, regulations, principles and policies. Examples of System :- Systems Elements Objectives Computer Accounting Business Organization Input, Process and Output Devices. Operating Systems, Compilers, Packages. Financial Transactions, Accounting Principles and Rules, Transaction Processing Method of Accounting People, Plant and Machinery, Product and services, Communications, Transport, Materials. Process the data and provide the information. Process the transaction and produce the monthly books of accounts and the information for financial management. Produce goods and services to achieve the business objectives of services, turnover and profits. Mobile :

3 For Example :- If a computer system is designed to perform a commercial data processing, then the elements will be a data entry devices, a CPU, a disk, a memory, an application programs and a printer. Any system has three basic parts, which are organized in orderly manner. These three parts can be represented as : Input Process Output System may have single input and multiple outputs or may have several inputs and outputs. If additional objective is to be introduced in the system, it may be possible as the new objective may fall outside the boundaries or the scope of the system. For example a computer designed for processing the commercial data can not achieve the objectives of design and drafting. Environment Input Process Output Filter The environment influences the choice of inputs, the method of processing, and the nature and the content of the outputs. Since the systems are design for specific objectives/outputs, the designer provides a filter around the system to control the influence on the system. For example take the manufacture system, where the objective is to produced products of desired quality. Since the row material and the design processes are selected with the objective, the quality control systems exercise a control on a quality of row material and keep a continuous watch on process parameter to keep the desire quality. Mobile :

4 System Control Input Process Output Sensor Corrective Unit Channels Of Feedback Comparison Unit Control System Model Standard Since the systems are design to achieve the specific objectives, ensuring the achievement of an objective, becomes an integral part of a system. The control calls the measurement of an output in some terms. Sensor :- The that measures the output is called a Sensor. Sensor measure the output and compare it with the standards. If the measure output compares well with the standards, the system provide the feedback to continue the operation. Comparison Unit :- If the measure output compares well with the standards, the system provide the feedback to continue the operation. If the measured output does not compare well with the standard, then the feedback provides to the system to stop the operation. The process of comparison of a measured output with the standard is done by a unit called Comparison Unit. Feedback Mechanism :- The mechanism, which provides a signal to the system, about the quality of performance, is called a Feedback Mechanism. Mobile :

5 Corrective Unit :- Many a ties system may not have an appropriate mechanism to act on the signal which it receive. It is, therefore, necessary to provide an in-built mechanism, which will decide based on the feedback to stop, regulate or continue the system operations. Such a mechanism is called a Corrective Unit and is responsible for ensuring the system performance. The process of measuring the output, comparing with the standard, sending the signal to the corrective unit an the corrective unit active upon it, is called a control. The concept of control is based on the condition of feedback. If the feedback is positive means the measure of the output compares favorably with the standards or norm, the control will keep the system operating in the same condition. If the feedback is negative means the measure of output is unfavorable when compare to the standard or norms, the control will act on the input or process back to bring back the system to the state of equilibrium. the concept of the control system model is applied to data processing where all the features are used in the programs of the data processing. Input Data Use of Program for Processing Computed Result Decision Control Change the Program if Necessary Feedback Positive or Negative Summary of Result Compare Result V/s Target Target Results Control System Model for Data Processing Mobile :

6 Row Material Data on Measures of Quality Manufacturing Process Analysis of Quality Data Weight, Size, Color, Quality Designated Measures of Quality Action to correct the Process of Manufacturing Weight One Measure of Quality Quality Assurance Manager Corrective Unit Feedback Through Plotting of Weights Weight Control Chart Tools to Compare MIS Model of Quality Assurance Upper & Lower Limits Quality Control Limits Types of System A system is an arrangement of smaller systems in a logical order. When many smaller system together make a large system the smaller systems are called a subsystems of a large system. A large system can be split or decomposed into smaller subsystems up to a certain levels. Decomposition of a system into subsystems can be in a serial form or it could be in matrix from. In serial system processing the output of one subsystem is the input of next subsystem and so on. Subsystem 1 Manufacturing Subsystem 2 Quality Control Subsystem in Serial Order Subsystem 3 Marketing Mobile :

7 We say that the process is transparent to us when we are able to understand the system. But if the process of input transformation is not visible and understandable then we say that the system is a Black Box System and the process is not transparent. Subsystem 1 Manufacturing Subsystem 2 Marketing In matrix arrangement the different outputs goes to the different subsystems. Subsystem 3 Quality Control Subsystem 4 Accounting Inputs Outputs Subsystem operating in Matrix Order Black Box System Breaking the system in a hierarchical manner provide a way to structured system analysis. It gives a clear understanding of the contribution of each subsystem in terms of data flow and decisions and its interface to the other subsystem. Hierarchical Structure of the System Mobile :

8 The system can be classified based on the predictability of its output and the degree of information exchange with the environment. A system is called Deterministic when the inputs, the process and the outputs are known with certainty. (e.g. Accounting System) A system is called Probabilistic when the output can only be predicted in probabilistic terms. (e.g. Demand Forecasting) If a system is functioning in isolation from the environment, then the system does not have any exchange with the environment nor it is affected by the environment changes. Such a system is called a Closed System. Most of the systems based on the rules and principles are closed system. If the system has exchange with the environment and is affected by the environment changes is called Open System. The systems which are required to respond to changes in the environment, such as Marketing, Communication and forecasting are Open System. Handling System Complexity Information is relatively complex compare to the physical system, and therefore they should be handle properly. To handle the complexity, the system can be viewed as an assembly of subsystems each with the clear definition of boundary, interface and their connectivity. The subsystems then put in hierarchical order to provide a structural view. This process is called Factorization. Another method of handling the complexity is to resort to simplification by clustering the subsystems together. Mobile :

9 Handling all the subsystem together with their interconnection is difficult. Each interconnection acts as a channel for the input-output communication. The process of simplification provides a way to handle this interconnection and reduce the complexity. The method of simplification is as follows : 1. Identify the subsystems which have to be together for the functional. 2. Form a cluster of these subsystems and identify interconnection between these clusters. 3. Form cluster of the remaining subsystems. 4. Connect the cluster with an interface. For Example :- Material Management System Divided into 7 different subsystems as follows : A. Procurement System. B. Purchase Order Follow up system. C. Receipt Accounting System. D. Material Receipt Planning System. E. Material Issue Requisition System. F. Bill Passing and Payment System. G. Inventory Control System. B A E C D G F Step-2 Subsystem with Interconnections Mobile :

10 The subsystems can be clustered in number of ways. In the example we have clustered the system I base on the management functional such as purchase account and planning. The choice of the basis for clustering will be depend in the view taken by the designer of the system to handle the complexity. A B F Cluster 1 Purchase Function C E Cluster 2 Stock Accounting Function Step-3 Formation of Clusters D G Cluster 3 Material Planning & Control Function When the subsystems are cluster together and connected, the designer face the problem of tight connectivity. The connectivity becomes tight because the close coordination requires among the clusters in term of time and resources. When the systems are of open type, the environmental changes causes a lot of behavioral influences. The solution to the problem of tight connectivity is to decouple the cluster from each other by providing the interface between the clusters. The problem of tight connectivity and providing interface arises from the requirement of heaving the input information from other subsystem on time. So basically it the problem of synchronized communication in the information exchange between the two clusters. The use of decoupling mechanism should be considered as the last alternative for reducing the rigid requirements of a communication exchange. A B Purchase Information C Stock Information D F Interface E Interface G Step-4 Decoupling of subsystem s clusters by stock information interface. Mobile :

11 System Efficiency and Effectiveness The performance of the system can be measured by two factors : the Efficiency and the Effectiveness The efficiency indicate the manner in which the inputs are used by the system. Being efficient means the system use inputs in a right way. If the input-output ration is adverse, we say that the system is inefficient. The effectiveness is the measure for deciding whether the system provides the desired output or not. Being effective, means producing the right output in terms of quality and quantity. Post Implementation Problem in the System When the systems are allowed to run for some time, they tend to become disorganized, resulting into a inefficiency. The process of disorganized and its causes are called Entropy. The designer is thus call upon to introduce a negative Entropy whereby the disorganization is arrested and the system is brought back to the state of balance. The process of providing the negative entropy is called the system maintenance. The negative entropy is provided as a part of the system routine. Mobile :

12 The steps for providing the negative entropy are as follows: a) A periodical review of the system. b) User meeting to assess the current utility of the system and the level of satisfaction. c) Subjecting the system to an audit check through the test data. d) Running the system under audit trail. e) Bringing out system modifications. System Indication of Entropy Negative Entropy Human Body Computer Data Processing Loss of Weight, Headache System halts, read and write errors. Errors and omissions in the data on increase. Medical check-up and prescribed diet and medicines. Preventive maintenance and replacement of subjective components. Review and introduction of streamlined procedures. The another problem that the system designer face is that the change in goal of organization due to the environmental changes. If the system is enough capable to handle the change in goal, then the system disorganization is not required, but the system design is inflexible, then it is not possible to handle the changes by the system and the system disorganization is required. Problem of system disorganization arise in the organization because the business environment changes, leading to a modification in the business goal and objectives. Such a changes in the requirement forces the changes in the MIS goal, calling modification to the information system to meet the revised information needs. The designer should keep in mind that the organization is an Open System bound to receive new input in an unplanned and unscheduled manner and the organization should adapt itself. Keys to handle the post implementation problems : System must be comprehensive and flexible. Associated peripheral systems should be built with a flexible design. Mobile :

13 Classes of Systems The systems performs different roles through different processes to achieve a system goal. Though at the core they satisfy all the attributes of the system, they differ in the nature due to the goal assigned to them. MIS is classified in five classes as under : 1. Data Processing System (DPS) 2. Transaction Processing System (TPS) 3. Application Processing System (APS) 4. Business Function Processing System (BPS) 5. Integrated Information Processing System (IPS) DPS is design to capture, collect or enter the data to process in certain specified manner to achieve the following: Data is complete, correct and valid. Such a data is processed and organized in some further processing. Data Processing System (DPS) :- DPS is design to capture, collect or enter the data to process in a certain specified manner to achieve the followings : Data is complete correct and valid from all aspects. Such a data then is processed and organized in some form for processing. DPS may have algorithm using one or more data inputs and may produce one or more outputs. System of Capture, Collect, Enter System of Security, Checking, Validating System of Result Processing Reports Master Files Display Results Record File(s) Query Processing Model of DPS Mobile :

14 Transaction Processing System (TPS) :- TPS is design to handle the transaction between parties. A parties could be two or more heaving designated role in TPS. TPS use data file, master files and transaction records to execute transaction. Example of TPS is Payroll system. Transaction Data Files Master Files TPS for accuracy, completeness, consistency, validity and decision for acceptance or rejection Reports or Documents Display Transaction Process Algorithm Processed Transaction File(s) Records Query Processing Output Model of TPS Application Processing System (APS) :- APS id built over DPS and TPS. APS use files created by DPS and TPS and applies application processing rules to execute the application. APS may have an output as a documents, report or a set of results required further in Business Function System (BFS). Processed Transaction File(s) Master Files APS for : Verification, Checking, Selecting Rules, Computing Formulas and formatting. Display Reports or Document Results Application Processing Rules Application Output Filed and Records Query Processing Report Model of APS Mobile :

15 Business Function Processing System (BPS) :- BPS aids in business function processing and help management in decisionmaking required within the scope of business function. It brings out more MIS report for business function management such as Sales, Production, Materials, Customer Relation and so on. Application Process system Output Files System Processing after checking file consistency and validity. Future MIS Reports Transaction Output File(s) System Processing Rules Application Output Filed and Records Application Output Filed and Records Display Query Processing Model of BPS Integrated Information Processing System (IPS) :- IPS sits on the top of the rest of the system discussed so far namely DPS, TPS, APS, BPS. IPS draws its inputs from these systems, and applies information processing rules to bring out an output. IPS generally meet the requirements of top management in the area of planning, budgeting and strategic control. TPS Output Files. APS Output File(s). Function Databases and Management Knowledge Database Model of BPS Reports IPS Rules, Models, Algorithms Use of Information Process Tools Result Database Spread Sheet Application Executive Informatio n System Data Warehousin g System Data mining System Knowledge Process System Mobile :

16 General Model of MIS SOURCING SYSTEM PRODUCTION SYSTEM DATA PROCESSING TRANSACTION PROCESSING APPLICATION PROCESSING SYSTEM PROCESSING INTEGRATION OF SYSTEM BIS, DWS, DMS, SPAs PROCESSING MIS MODEL QUERY PROCESSING EXCEPTION REPORTING DATABASE, KNOWLEDGE BASE DECISION SUPPORT SYSTEM OPERATIONAL RESEARCH AND APPLICATION PACKAGES EXPERT, AND ARTIFICIAL INTELLIGENCE SYSTEM General Model of Management Information System The MIS is the arrangement of the data processing and information system in an orderly manner to support the management in achieving the objectives. The MIS boundaries cross the limits of the organization and draw the data from the external source to the organization. MIS is design to provide the information which is exceptional in nature from the business point of view. By nature, MIS is an open system interfacing continuously with the internal and external environment and is self organizing to meet the ever increasing and changing information need of the organization. This is made possible by organizing the MIS in hierarchical structure. The performance of the MIS design starts disorganizing in the post implementation period and it is necessary to provide the negative entropy to bring back the system to its original balance. Though the MIS design as an open system, its failure arise on account of the degree of flexibility kept in the system. It is observed that the core systems are not required to change but the peripheral systems often undergo a change. Mobile :