Context Diagram Yong Choi BPA CSUB What is

Context Diagram Yong Choi BPA CSUB What is

Context Diagram Yong Choi BPA CSUB What is it? System Context Diagrams are diagrams used in systems design to represent the more important external actors that interact with the system at hand.

This type of diagram usually pictures the system at the center, with no details of its interior structure, surrounded by all its interacting systems, environment and activities. The objective of a system context diagram is to focus attention on external factors and events that should be considered in developing a complete set of system requirements and constraints.

Context Diagram Building Procedure Identify the system and its boundaries (the context) Identify external entities (providers, receivers of system info) Identify external data flows (input, output) However, NO DATA STORE !!! Note: the whole system itself is a process (it receives input and transforms into output)

3 Vending Machine Example Assumption: there is no revise order option Submit order Customer Send order

Vending Machine System ATM Example Assumption: ONLY withdrawing money (not transfer, checking balance, or other services.) Request transaction

Customer Complete transaction Or Revise transaction ATM System

Food Order processing System University system Example Business and Tax system Example Context diagram example A student sends in an application form containing their personal details, and their desired course

The university checks that the course is available. If the course is available and the student is enrolled in the course, the university confirms the enrolment by sending a confirmation letter that they are registered for the course to the student. Or if the course is unavailable the student is sent a rejection letter. What system is being modeled?

9 Context diagram example Practice 1 Letters of complaint received from citizens are entered into a complaints master file by the City Clerks office. The date, department code, and a complaint description are stored for each letter.

Weekly reports are produced from the complaints master file and given to the City Manager. Two weekly reports are produced: a department summary and a detail report of complaint. Practice 1 - Answer Practice 2 The purpose of the campus bookstore is to supply textbooks

to students for classes at a local university. The universitys 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 companies 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. Practice 3 The purpose of the plant science office is to document the study results from a wide variety of experiments performed on selected plants. A study is initiated by a researcher who submits a research proposal. After a panel review by a group of scientists, the researcher is required to submit a research plan and schedule. A FDA research permit request is sent to

the Food and Drug Administration, which sends back a research permit. As the experiment progresses, the researcher submits experimental notes. At the conclusion of the project, the researchers results are reported on an experimental histogram. Practice 4 Your client, Econ MiniBank, requests for a simple Automatic Teller Machine (ATM) system with the following requirements:

The system must be able to accept a customer's ATM card via a card reader and validate the account number using an account numbers file. The customer's transaction information, on the other hand, is entered via a key panel and also validated by the system. For valid account holders issuing valid transactions, the system determines the transaction type, which can be one of the following : display of account statement, hardcopy of account statement, cash transfers and requests for cheque book.

Practice 4 (cont) Transaction information would therefore include items like the customer's request (transaction type), cash transfer amount, and transferee's account number. For account statement requests, the system retrieves the account information from a customer database and formats the information accordingly depending on whether a hardcopy or display is requested. For cash transfer requests,

the cash amount and transferee's account number must be specified. Finally, for cheek book requests, the system uses a valid account number to determine the collection center and collection date from a collection schedule log and prints a collection slip for the customer.

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