Systems analysis and design

introduction

usually it use to created another program for example from android kitkat to android lollipop system analysts is use to review the system and will suggest to make a improvement to the new system 

analysts stage

use to review the system 

for example

-review the old system

-agreeing the objective with the customer 

-identify and agreeing customer's requirements

-interpreting the customer requirement

Design stage

use to design the key parts of the recommend system 
-like designing the screen layout 
-selecting the validation rules that needs to be used 
-and designing the strategy plan

Verification

use to prevent errors because who want errors to the new system 
-2 method:
-double entry
the data is entered twice with two people they will compare the two entries and they will identify the difference 
-visual check 
checking errors by comparing the data on the screen with the original document 

Implementation and Developing and Testing

implementation 

implementation is like changing the old program with the new program and installed it

if implementing  some times we need to 

-buy a new hardware and software

-writing the programs  

-train the staff

user documentation

-taking screenshot

-try the program

-studying the user guide 

this use for staff to get familiarise with the program

methods of changeover

-direct change over

the old system immediately change with the new system with this option  sometimes the system it self still have problems and full of risk

-pararel changeover

running both the old system and the new system its use to sure if the system works correctly 

and if the system have problems you can go to the old system until the new system have been corrected its the safest option 

 

-phased change over 

use the old system to be a reminder but still change it to the new system by phase one at time and it split by stage and time 

-pilot change over 

 this option tried out at a test site before launched wide its the effective way since the use of parallel change over is expensive 

 

all option  use to change the old program with the new one

developing and testing

after the design was complete its time to try out the system and test it this use to make sure that every system works properly 

testing normally involves

-The structures of file/ table

-The validation routines

-Data entry processes

-Data output processes

testing strategies 

use to improve the input and output methods, file and database structures, validation and verification methods

 

Normal data - like the real data that will be entered into the system

Extreme data - data that could possibly be entered but at the edge of what is allowed

Abnormal data - bad data that would never be acceptable but that system should deal with without crashing