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Tuesday, November 4, 2008

DFD explanation

DFD (Data Flow Diagram):

DFD is a designing concept used to transform a textual problem into pictorial or graphical form in a hierarchical order.

It describes how   data and information are transformed in a system in a pictorial manner.

DFD provides a complete description of:-

      (a) What data are processed?

       (b)  How processing is done?

(c)  What data are stored?

(d) Which stored data are used and

 (e)  Where the result flows?

DFD is top-down designing approach in which

(a)A high-level function is decomposed into a set of easy understandable function.

(b)Each function performed by system is analyzed and decomposed into more detailed description.

  • A  DFD models a system by using external entities from which data flows to a process which transform the data  and creates output data flow which go to other processes or external entities or data stores .  From data stores, stored data may also flow to process as inputs.

Dfd with example

Here External entity 1 gives input data to process1 after this processed data 1 is stored in data store , now stored data  is given to process 2 and finally processed data 2  is consumed by External entity 2.

Physical DFD to issue a book from library:-

Logical DFD to issue a book from library(above)

Saturday, January 5, 2008

DFD for university routine management project

zero level DFD for university routine management project.
Question:- Draw a DFD for universiy class management project
Objective/vision:our solution is supposed to automate the routine teaching-learning support activities so the academics authority can monitor it and control the things. It starts from Time-table generation on available resources like programmes, courses, subjects, teachers, lecture room/lab preferences. Assignments/lecture notes upload , Daily class attendance, student feedback, exams marks updation and students/faculty profile management would be the integral part of this system.
User of the System:                  
  A. End-user/students
  B. Data Manager
  C. Subject Teacher
  D. Admin/Dean/Director

Tuesday, November 6, 2007

first and second level DFD of university management

Description for zero level DFD
  • As stated in the question there are 4 users in the project.
  • Here detailed informations regarding each student and teacher  are given and in response every student has got SIN(student identification num) or Roll No. and for teacher it is TIN(teacher identification num).
  • Database Manager will perform all the data entry job.
  • After giving routine generating command a routne will be generated. 
  • Admin can veiw the every user , his peformance and get the result by giving the query.                                                                                                                                                                                                         first level DFD of university management:
Description of 1st level:
                                  every student , every teacher , evey class room and every subject should be                                    registerd
                                  Here  student_info datastore contain information regarding student.
                                  Here  teacher_info datastore contain information regarding teacher.
                                  Here  class_info datastore contain information regarding class.
                                  Here subject_info datastore contain information regarding 

                    second level DFD of university management:
Description of second level DFD:
     class will be managed by  the process -Attendance Submit
                                                                       -Lectute plan given by teacher.
                                                                       -Student feedback given by teacher.
                                                                       -Teacher feedback given by student.

  Here Datastores are:
                                       - Attendence
                                       -Lecture-plan info
                                       -Student feedback
                                       -Teacher feedback.  

  DFD of university management: