An example on DFD : Draw the DFD for a distance education university. The enrolment process works as follows: Students send in an application form containing their personal details, and their desired course The university checks that the course is available and that the student has necessary academic qualifications. If the course is available movement/exchange the student is of enrolled information/data the course, between and external the university entities to process and processes to processes => data flows (DF) confirms the enrolment by sending a confirmation letter to the student. If the course is unavailable the student is sent a rejection letter. 2. It often helps to walk through the system in its logical sequence; eg starting with an external en (source), add data flows, processes and data stores as the data provided by the entity is manipulate actions/doing words/verbs => Processes (P) the system. movement/exchange of information/data between external entities to proce! A student (EE) sends in application form (DF) containing their personal details, and their desi course and processes to processes => data flows (DF)! The university checks (P) that the course is available.! If the course store/record is available information/data the student is enrolled => data (P) stores(ds) in the course, and the university confirms (P) enrolment by sending a confirmation letter (DF) that they are registered for the course to the stud! Or if the course is unavailable the student is sent a rejection letter (DF). 2. It often helps to walk through the system in its logical sequence; eg starting with an external (source), add data flows, processes and data stores as the data provided by the entity is manipul the Note: system. The university, or more specifically the administration section, is the system being modelle is not an EE. actions/doing words/verbs => Processes (P) store/record information/data => data stores(ds)! A student (EE) sends in an application form (DF) containing their personal details, and their de System/Level course 0 DFD External entity! The - university Student checks (P) that the course is available. Processes! If the - Check course available, is available Enrol the student, is Confirm enrolled Registration Context diagram (P) in the course, and the university confirms ( Data Flows enrolment - Application by sending Form, a Course confirmation Details, letter Course (DF) that Enrolment they are Details, registered Student for the Details, course to the s Confirmation/Rejection! Or if the course Letter is unavailable the student is sent a rejection letter (DF). Data Stores Highest - Courses, level DFD. Students. Has data flows, external entities, one process (system in focus) and no data stores. Note: The university, or more specifically the administration section, is the system being mod Shows is not the an system EE. boundary and interactions with external entities. System/Level In this case: 0 DFD External entity - Student External entity Student Process - Student Administration process application Processes Check available, Enrol student, Confirm Registration Data Context Flows diagram - Application Form, Confirmation/Rejection Letter Data Flows Application Form, Course Details, Course Enrolment Details, Student Details, Confirmation/Rejection Letter Data Stores Highest - Courses, level DFD. Students. Has data flows, external entities, one process (system in focus) and no data stores. Shows the system boundary and interactions with external entities. In this case: External entity - Student Process - Student Administration process application Data Flows - Application Form, Confirmation/Rejection Letter
level 0 : DFD Example System/Level 0 DFD This System/Level External System/Level entity 0 DFD - Student raises some questions: This External System/Level Processes entity 0 DFD - Student - Check raises available, some questions: Enrol student, Confirm Registration Q. Processes The Data Data Flows Store Courses - Check - Application has available, only Form, data Enrol flows Course student, entering Details, it, Confirm how Course does Registration the Enrolment data get stored Details, in Student the first place? Details, Q. A. The Data This Data Confirmation/Rejection Flows DFD Store is part Courses of - Application a larger, has only higher Letter Form, data level flows Course DFD entering that Details, models it, how Course more does than the Enrolment just data the get enrolment stored Details, in process. Student the first place? There Details, A. must This Confirmation/Rejection Data DFD be another Stores is part DFD of a - larger, that Courses, stores higher Letter course Students. level details, DFD that eg the models university s more than course just development the enrolment process. There must Data be another Stores DFD - that Courses, stores course Students. details, eg the university s course development process. Q. The process Enrol Student has many different data flows entering into and leaving it, how can we model Q. this The process in Enrol more Student detail? has many different data flows entering into and leaving it, how can we model this A. process Develop in a more detail? detail, lower level DFD for this process, that shows the processes that make up this A. process Develop a more detail, lower level DFD for this process, that shows the processes that make up this process You are here: InfoCom Homepage -> Courses -> spr2000 -> 95169 -> Extra Examples -> You are here: InfoCom Homepage -> Courses -> spr2000 -> 95169 -> Extra Examples -> Edit Last Modified: Tue Nov 21 10:30:12 2000 by webmaster. Contact Details Edit Disclaimers Last Modified: 2000 Tue CQU Nov Infocom 21 10:30:12 2000 by webmaster. Contact Details Disclaimers 2000 CQU Infocom file:///d /PSI/CMS_Materi/5DFD.htm (6 of 6)8/2/2005 3:49:16 AM file:///d /PSI/CMS_Materi/5DFD.htm (6 of 6)8/2/2005 3:49:16 AM
Textbook Inventory System DFD Given the following narrative description, draw a context DFD for the portion of the activities described. The purpose of the TEXTBOOK INVENTORY SYSTEM at a campus bookstore is to supply textbooks to students for classes at a local university. The university s Textbook Inventory System DFD academic departments submit initial data about courses, instructors, textbooks and Given the following narrative description, draw a context DFD for the portion of the activities described. projected enrollments to the bookstore on a TEXTBOOK MASTER LIST. The bookstore generates a PURCHASE ORDER, which is sent to publishing company s The purpose of the TEXTBOOK INVENTORY SYSTEM at a campus bookstore is to supply textbooks to students for classes at a local university. The university s academic departments submit initial data about courses, instructors, textbooks and projected enrollments to the bookstore on a TEXTBOOK MASTER LIST. The bookstore generates a PURCHASE ORDER, which is sent to publishing company s supplying textbooks. Book orders arrive at the bookstore accompanied by a PACKING SLIP, which is checked and verified by the receiving department. Students fill out a BOOK REQUEST that includes course information. When they pay for their books the students are given a SALES RECEIPT. supplying textbooks. Book orders arrive at the bookstore accompanied by a PACKING SLIP, which is checked and verified by the receiving department. Students fill out a BOOK REQUEST that includes course information. When they pay for their books the students are given a SALES RECEIPT. STUDENTS Book Request ACADEMIC DEPARTMENTS Sales Receipt Purchase Orders TEXTBOOK INVENTORY SYSTEM Textbook master list PUBLISHING COMPANIES Packing slip (accompanying order)
Suggest a context diagram and level-0 diagram Using the example of a retail clothing store in a mall, list relevant data flows, data stores, processes, and sources/sinks. Observe several sales transactions. Draw a context diagram and a level-0 diagram that represent the selling system at the store. Explain why you chose certain elements as processes versus sources/sinks.