ISYS254 Lecture Notes - Lecture 3: Filing Cabinet, Parent Process, Process State

• School: Macquarie University
• Department: Information Systems
• Course: ISYS254
• Professor: Charanya

Document Summary

Data flow diagrams are graphically characterized data processes and flows in a business system. Freedom from commuting to the technical implementation too early. Understanding of the interrelatedness of systems and subsystems. Represent another department a business, a person or a machine. A source or destination of data, outside the boundaries of the system. Shows movement of data from one point to another. Represents data about a person, place or thing isys254 page 1. Denotes a change in or transformation of data. Assign the name of the whole system when naming a high-level process. To name a major subsystem attach the word subsystem to the name. Use the form verb-adjective noun for detailed processes. A depository for data that allows examination, addition and retrieval of data. Data sto(cid:396)es a(cid:396)e usually give(cid:374) a u(cid:374)i(cid:395)ue (cid:396)efe(cid:396)e(cid:374)(cid:272)e (cid:374)u(cid:373)(cid:271)e(cid:396) su(cid:272)h as d(cid:1005), d(cid:1006) . The highest level in a data flow diagram. Contains only one process, representing the entire system.