More Diagrams Damian Gordon Damian Diagrams Context Diagram

More Diagrams Damian Gordon Damian

Diagrams • Context Diagram • Data Flow Diagram 2

Context Diagram 3

Context Diagram • One of the first things you need to do when specifying a system is to decide on the system boundaries. • This means deciding what functionality should be included in the system and what is provided by the system’s environment. 4

Context Diagram • You should look at possible overlaps in functionality with existing systems and decide where new functionality should be implemented. • These decisions should be made early in the process to limit the system costs and the time. 5

Context Diagram Other System 1 Other System 5 Other System 3 The System we are developing Other System 6 Other System 4 Other System 2 6

Context Diagram ATM Machine 7

Data Flow Diagram 8

Data Flow Diagram • Used to show end-to-end processing in a system • DFDs show the entire sequence of actions that take place from an input being processed to the corresponding output that is the system’s response. 9

Data Flow Diagram Sink External Entities Source 10

Data Flow Diagram Sink External Entities An outside system that sends or receives data, communicating with the system being diagrammed. Source 11

Data Flow Diagram Data Flow 12

Data Flow Diagram Data Flow The route that data takes between the external entities, processes and data stores. 13

Data Flow Diagram Process 14

Data Flow Diagram Process A process is anything that changes the data, to produce an output. 15

Data Flow Diagram Data Store 16

Data Flow Diagram Data Store Files or repositories that hold information for later use, such as a database table or a membership form. 17

Data Flow Diagram Source Sink Process Data Store Data Flow

Data Flow Diagram Data Flow Source Process Sink Data Store

Data Flow Diagram

Data Flow Diagram A CUSTOMER orders food, and that process returns a bill to the customer. The order goes to the KITCHEN. The process of ordering the food, also sends inventory details to the INVENTORY database and the order to the ORDER database. The INVENTORY database sends inventory details onto a Generate Reports process, which also receives the order from the ORDER database. The Generate Reports process sends a Report to the MANAGER who sends the inventory order to the Order Inventory process, and that process sends the inventory details back to the INVENTORY database, and sends the inventory order to the SUPPLIER. 21

Data Flow Diagram A CUSTOMER(EXTERNAL ENTITY) will ORDER FOOD(PROCESS); The ORDER FOOD process will send an ORDER to the KITCHEN(EXTERNAL ENTITY); The ORDER FOOD process will send an ORDER to the ORDER(DATA STORE); The ORDER FOOD process will send an INVENTORY DETAILS to the INVENTORY(DATA STORE); The INVENTORY data store sends the INVENTORY DETAILS to the GENERATE REPORTS(PROCESS); The ORDER data store sends the ORDER to the GENERATE REPORTS(PROCESS); The GENERATE REPORTS process sends REPORTS to the MANAGER(EXTERNAL ENTITY); The MANAGER external entity sends the INVENTORY ORDER to the ORDER INVENTORY(PROCESS); The ORDER INVENTORY process send INVENTORY DETAIL back to the INVENTORY(DATA STORE); The ORDER INVENTORY process send INVENTORY ORDER to the SUPPLIER(EXTERNAL ENTITY); 22

Data Flow Diagram

Data Flow Diagram

Data Flow Diagram When renting a video, a CUSTOMER requests a video from the Rent Video process, which sends a bill back to the CUSTOMER. The Rent Video process send rental information to the RENTAL database which sends the rental information onto the Generate Rental Report process, which passes a Rental report onto the MANAGER. When returning a video, a CUSTOMER sends the Video and Rental Information onto the Return Video process, which sends a Return Receipt back to the CUSTOMER. The Return Video process sends Video Information onto the VIDEO LIBRARY database, which sends Video Information back to the Rent Video Process (mentioned previously). The Return Video process also sends Rental information onto the RENTAL database (mentioned previously). 25

Data Flow Diagram A CUSTOMER(EXTERNAL ENTITY) send a VIDEO REQUEST to RENT VIDEO(PROCESS); The RENT VIDEO process will send a BILL to the CUSTOMER(EXTERNAL ENTITY); The RENT VIDEO process will send RENTAL INFO to the RENTAL(DATA STORE); A CUSTOMER(EXTERNAL ENTITY) send VIDEO RENTAL INFO to RETURN VIDEO(PROCESS); The RETURN VIDEO process send a RETURN RECEIPT to the CUSTOMER(EXTERNAL ENTITY); The RETURN VIDEO process send VIDEO INFO to the VIDEO LIBRARY(DATA STORE); The RETURN VIDEO process send RENTAL INFO to the RENTAL(DATA STORE); The VIDEO LIBRARY data store send VIDEO INFO to RENT VIDEO(PROCESS); The RENTAL data store send RENTAL INFO to GENERATE RENTAL REPORT(PROCESS); The GENERATE RENTAL REPORT process sends a RENTAL REPORT to the MANAGER(EXTERNAL ENTITY) ; 26

Data Flow Diagram

Data Flow Diagram