Detailed system design

DETAILED SYSTEM DESIGN-UNIT 4  Once scope & general configuration of the MIS have been established ,the DETAIL DESIGN of the system may be started.  General approach provide the framework but detailed procedure will bring substance to framework. 1)INFORM AND INVOLVE THE ORGANIZATION  Gaining support for the work that follows  System designer must have support from most member of organization to obtain acceptance of final system.  Members of organization should be informed of objectives & nature of system.  It is desirable to reassure the employees .that changes will benefit them and they will not suffer financially from the implementation of system.  Employees should not be disturbed during system design  When people are not informed they construct wrong concepts 2)AIM OF DETAILED DESIGN  Is to furnish a description of system that achieves the goals of conceptual design requirements.  Description consist of drawings ,flowchart, procedure, operating manuals required to run the system.  The design must be in sufficiently detailed that operating management & personnel implement the system The difference Conceptual design gives overall performance specifications for MIS, detailed design yields construction & operating specification 3)Project management of MIS detailed design  Once project manager & key people are designated the steps in project management fall into two classes: PROJECT PLANNING  PROJECT CONTROL PROJECT PLANNING  ESTABLISH PROJECT OBECTIVE:Involves review ,subdivision & refinement of performance objective establish by conceptual design.  Define the project task:identifies the hierarchical structure of tasks to be performed in the design  Plan the logical development of sequential & concurrent tasks:requires Network diagram of events & activities Schedule the work as required by management Established end date ,use PERT to tie work & schedule together. Estimate Labor, equipment & other cost for the project

Establish a budget for project by allocating funds to each task & expenditure month by month over the life of the project. PROJECT CONTROL  Determine whether project objectives are being met as the project progresses.  Maintain the control over the schedule by changing work loads & emphasis as required by delays in critical activities.  Evaluate expenditure of funds in terms of both work accomplished & time  Evaluate work force utilization & individuals work progress ,make adjustment as required  Evaluate time, cost & work performance in terms of schedule ,budgets & technical plans to identify interaction problems 4)IDENTIFY DOMINANT & TRADEOFF CRITERIA  Dominant criteria for a system are those that make an activity so important it overrides all other activities.  Example:-a dominant criteria might be that system operates so that there is never stock out.  This overrides the criteria of minimizing the inventory cost.  Like company selling human blood, life preserving drugs, electric power Other examples  One day customer service, zero defect product, specified price range for products  Identification of dominant criteria is necessary before subsequent design steps can proceed. TRADE OFF CRITERIA  Are those in which the criteria for performance of an activity may be reduced to increase performance of another activity.  EXAMPLE:-criteria of low manufacturing cost might be balanced against the long range public image of firm by reduction in environment pollution 5)DEFINE THE SUBSYSTEM  Each large block or system must be broken down to determine all activities required & the necessary information inputs & outputs of each activity.  Careful analyses of each activities is critical in detailed design.  The degree of breakdown of major activities ,determine the size & complexity of network.  If activities are broken too finely the design will never be completed.  Hierarchy of activities can be: System- subsystem -functional components –task- subtask- operation element Grouping of system into a subsystem based upon various considerations: Common functions  Common techniques or procedure

 Common inputs & outputs Information for defining subsystem  Dominant & trade off criteria  Available resources  Required activities for achievement  Necessary control position in the system  Management decision points  Information for programmed decision  Specific output requirements  of all system Obtaining information    

Task force meeting Personal interviews Internal & external source documents Personal observation of operation & communication

6)Sketch detailed operating subsystem & information flows  System flow chart Task oriented charts:-show the relationship among various tasks Form oriented charts:-these charts identify the forms used in communication Program flowchart :-prepared by people who give instruction to computer 7)Determine the degree of automation of each operation  we can automate most processes to different degrees ,depending upon management desires: No automation:-people continue to do work manual aids.  Work automated ,control manual:-electromechanical devices do work, but they must do work by human intervention(ID card reader & sounds alarm on invalid card)  Work automated, control automated, feedback automated:-require no automation.  Example:-humidity control system. Low level Automation is preferred  Problems are not well structured.  Decision criteria cannot be well defined  Rules for making decision must be constantly well modified.  Data entering in the system in ambiguous  The processing steps are few & simple 8)Inform & involve the organization again  It is important not to disturb the company’s main business as we build MIS.

 Upper management should be given brief overview of design & status of design effort.  Lower level management should shown the system & subsystem flowcharts.  This may generate comments, suggestions,  It’s a valuable tool to determine which manager is supportive & which resisting change. 9)Inputs ,outputs & processing  We will define subsystem inputs, outputs in more detail .  Two tasks: 1)specify inputs ,output exactly. Also show where the information can be obtained & whom it will go. 2)Designing useful forms  We must identify  Function of the form.  When the form is used  Who fills out the form & who uses the form 10)Early system testing  Three ways to get early feedback  Modeling  Simulation  Test planning  Problem describe at design time is much cheaper to fix then is found after the system put into operation. Modeling the system quantitatively  We now attempt to determine the quantitative ranges for inputs & outputs  Decision tables must be developed  If these conditions exist… then perform these actions… If will show the condition stub Then shows action stub Testing the system by simulation-procedure  By random methods ,select value of data from within the anticipated ranges of each variable.  Trace the effect of inputs through the system  Examine outputs of various subsystems 11)software,hardware,tools  Software: Develop standards & procedure for programming

 Develop conceptual design specifications & work with system designer in development of the detailed design  Develop data processing logic & prepare programming flow chart Hardware  Buy enough computer power to do the whole job  Buy enough external storage to hold the database  Buy other peripheral devices  Buy computer supplies(paper,ribbons,tapes)  Buy maintenance /support packages 12)Propose an organization to operate the system  MIS group will work on the system  Manager should recognize that their main objective is that system should function in a way that is best for whole system. 13)Document the detailed design  End of detailed design is production of the documents that specify the system,its operation,& its design justification Design consists of  A summary flowchart  Detailed flowchart  Operation activity sheet showing inputs,outputs,transfer  Specification of database  Computer hardware requirements  Software(programs)  Cost of installation & implementation 14)revisit the manager user  Reporting the status to upper management  Feedback to & request for support from lower level management  Training given to persons