Exceptions to the plural name rule are collective nouns that represent multiple occurrences of objects. a name is a plural name consisting of a noun and adjectives, if needed. name of the data store appears between the lines and identifies the data it contains Gane and Sarson symbol = a flat rectangle that is open on the right side and closed on the left side Since data stores represent data storage for use by another process in the future, in each case, the data store has at least one incoming and one outgoing data flow and is connected to a process symbol with a data flow. what is important: a process needs access to the data at some later time (provided by this)
physical characteristics of this are unimportant because logical model is the only concern at this point Similarly, a company stores employee salary and deduction data during the year in order to print W-2 forms with total earnings and deductions at the end of the year. instructors need to store student scores on tests and assignments during the semester so they can assign final grades at the end of the term. this symbol MUST be connected to a process with a data flow A DFD does not show the detailed contents of a data store - the specific structure and data elements are defined in the data dictionary A data store is used in a DFD to represent data that the system stores because one or more processes need to use the data at a later time in DFD, process appears as black box where inputs, outputs, and general function of process are known, but underlying details are not can be referred to as BLACK BOX (A metaphor for a process or action that produces results in a non-transparent or non-observable manner) to document logic, process description created APPLY RENT PAYMENT, CALCULATE COMMISSION name identifies a specific function and consists of a verb (and an adjective, if necessary) followed by a singular noun. symbol = a rectangle with rounded corners examples: calculating sales trends, filing online insurance claims, ordering inventory from a supplier's system example names: "print bill," "add customer" Process number does NOT signify precedence Process name identifies its function (verb) Contains business logic that transforms the data and produces desired results Must have at least one input and at least one output contain the business logic/business rules (Rules to determine how a system handles data and produces useful information, reflecting the operational requirements of the business) A process receives input data and produces output that has a different content, form, or both.
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