HSC Context and data flow diagrams ( DFD )

22,244 views

Published on

Context and data flow diagrams dfd

3 Comments
9 Likes
Statistics
Notes
No Downloads
Views
Total views
22,244
On SlideShare
0
From Embeds
0
Number of Embeds
4,711
Actions
Shares
0
Downloads
520
Comments
3
Likes
9
Embeds 0
No embeds

No notes for slide

HSC Context and data flow diagrams ( DFD )

  1. 1. HSC IPT Context & Dataflow Diagrams
  2. 2. CONTEXT DIAGRAM
  3. 3. <ul><li>A context diagram is a graphical method of </li></ul><ul><li>representing using a single process together </li></ul><ul><li>with inputs and outputs (external entities) </li></ul><ul><li>Three symbols only exist </li></ul><ul><li>The process; </li></ul><ul><li>The data flow; </li></ul><ul><li>The external entity . </li></ul>Entity Process
  4. 4. Entity Process Entity Data flow Data flow A context diagram
  5. 5. Student Use Search engine Student Keyword URL A context diagram Student searches the internet
  6. 6. <ul><li>Create a context diagram for: </li></ul><ul><li>Searching an online telephone database. </li></ul><ul><li>Use of an ATM. </li></ul><ul><li>Use self server check out. </li></ul>
  7. 7. DFD DFD DFD DFD DFD DFD DFD DFD
  8. 8. <ul><li>A DFD is a graphical method of </li></ul><ul><li>Representing a system using a number of </li></ul><ul><li>processes together with </li></ul><ul><li>inputs; </li></ul><ul><li>outputs; </li></ul><ul><li>storage. </li></ul>
  9. 9. Process The 4 main symbols used to show : the process; the data flow; the data store; the external entity. External Entity Database Data store
  10. 10. Customer Search Customer details details Call number Call details A data flow diagram Database
  11. 11. Customer Order is processed Customer order Invoice & book Customer & order details invoice A data flow diagram Database invoice is generated and sent
  12. 12. student Use search engine Load website keyword keyword URL URL A data flow diagram search for image graphic Database Of website Project
  13. 13. A video store is considering installing a ‘self-checkout’ system where customers can borrow videos by scanning their membership cards and videos and pay by EFTPOS. A ‘self-checkout’ transaction has three steps: • membership validation; • borrowing limit check; • payment processing. For membership validation the barcode on the membership card is used to access the member database to find a match. The customer proceeds to the scanning of videos if the membership is valid, otherwise a message is displayed. Using the video barcode data and details from the member database, the system checks that no more than six videos are borrowed. A message is displayed if the limit is exceeded. Payment processing involves the calculation of borrowing charges, the scanning of the customer’s EFTPOS card, the entry of a personal identification number and the electronic communication of these details to the financial institution. Video charges are obtained from the video database via the video barcodes. Transaction details are written to the transaction file for each video borrowed.
  14. 14. (i) Draw a dataflow diagram with the three processes that represents this proposed ‘self-checkout’ system, ensuring that you show external entities and data stores. (Refer standards package section 2 Q.25)
  15. 15. <ul><li>Create a data flow diagram for the borrowing of a book . </li></ul><ul><li>STEPS I TAKE WHEN CREATING SUCH A TOOL. </li></ul><ul><li>Decide upon the: </li></ul><ul><li>processes , </li></ul><ul><li>entities, </li></ul><ul><li>dataflow </li></ul><ul><li>storage. </li></ul><ul><li>2. Draw rough diagram adding the: </li></ul><ul><li>processes , </li></ul><ul><li>entities, </li></ul><ul><li>dataflow </li></ul><ul><li>storage. </li></ul><ul><li>3. Label as you go. </li></ul>
  16. 16. Create a data flow diagram for the borrowing of a book: D/b of borrowers, books & library transactions Storage Result of d/b search Information about library transactions Update borrower & book records Information about books Locate book, scan book & user bar code Information about borrower Search d/b for details of requested book Borrowers details & book request Search d/b of borrowers for borrowing eligibility borrower Data flow Processes Entity
  17. 17. Process Process Process Process borrower 1 2 3 4 5 6 7 8 9 10 6 Database
  18. 18. Create a data flow diagram for the: 1.Searching of an online telephone database. 2.Use of an ATM. 3.Use self server check out.
  19. 19. A video store is considering installing a ‘self-checkout’ system where customers can borrow videos by scanning their membership cards and videos and pay by EFTPOS. A ‘self-checkout’ transaction has three steps: • membership validation; • borrowing limit check; • payment processing. For membership validation the barcode on the membership card is used to access the member database to find a match. The customer proceeds to the scanning of videos if the membership is valid, otherwise a message is displayed. Using the video barcode data and details from the member database, the system checks that no more than six videos are borrowed. A message is displayed if the limit is exceeded. Payment processing involves the calculation of borrowing charges, the scanning of the customer’s EFTPOS card, the entry of a personal identification number and the electronic communication of these details to the financial institution. Video charges are obtained from the video database via the video barcodes. Transaction details are written to the transaction file for each video borrowed.
  20. 20. (i) Draw a dataflow diagram with the three processes that represents this proposed ‘self-checkout’ system, ensuring that you show external entities and data stores. (Refer standards package section 2 Q.25)
  21. 22. http://www.getahead-direct.com/gwbadfd.htm http://www.agilemodeling.com/artifacts/dataFlowDiagram.htm http://www.cems.uwe.ac.uk/~tdrewry/dfds.htm http://spot.colorado.edu/~kozar/DFDtechnique.html http://www.infoarchgroup.com/qrdfd.htm Link to DFD tutorials

×