tailieunhanh - Lecture Business system development - Lecture 12: Structuring system logical requirements

We today’s lecture we will: Use structured English as a tool for representing steps in logical processes in data flow diagrams; use decision tables and decision trees to represent logical choice in conditional statements; select among structured English, decision tables, and decision trees. | Business System Development CSC581 Lecture 12 Structuring System Logical Requirements 2 Summary of the previous lecture In previous lecture, we : Balanced high-level and low-level DFDs. Explained differences between current physical, current logical, new physical, and new logical DFDs. Used DFDs for analyzing information systems. Explained use cases and use case diagrams. Outlines We today’s lecture we will: Use structured English as a tool for representing steps in logical processes in data flow diagrams. Use decision tables and decision trees to represent logical choice in conditional statements. Select among structured English, decision tables, and decision trees Logic Modeling Data flow diagrams do not show the logic inside the processes. Logic modeling involves representing internal structure and functionality of processes depicted on a DFD. Logic modeling can also be used to show when processes on a DFD occur. 6 Logic Modeling Deliverables and Outcomes Structured English . | Business System Development CSC581 Lecture 12 Structuring System Logical Requirements 2 Summary of the previous lecture In previous lecture, we : Balanced high-level and low-level DFDs. Explained differences between current physical, current logical, new physical, and new logical DFDs. Used DFDs for analyzing information systems. Explained use cases and use case diagrams. Outlines We today’s lecture we will: Use structured English as a tool for representing steps in logical processes in data flow diagrams. Use decision tables and decision trees to represent logical choice in conditional statements. Select among structured English, decision tables, and decision trees Logic Modeling Data flow diagrams do not show the logic inside the processes. Logic modeling involves representing internal structure and functionality of processes depicted on a DFD. Logic modeling can also be used to show when processes on a DFD occur. 6 Logic Modeling Deliverables and Outcomes Structured English Decision Tables Decision Trees State-transition diagrams Sequence diagrams Activity diagrams 7 Modeling Logic with Structured English Modified form of English used to specify the logic of information processes Uses a subset of English Action verbs Noun phrases No adjectives or adverbs No specific standards 8 Structured English is used here to describe input and output. Structured English is used here to describe arithmetic operations. Structured English is used here to describe repetition. Structured English is used here to describe decisions. Structured English is used here to describe invoking other processes. Modeling Logic with Decision Tables A matrix representation of the logic of a decision Specifies the possible conditions and the resulting actions Best used for complicated decision logic 15 3 Parts of a Decision Table Condition stubs Lists condition relevant to decision Action stubs Actions that result from a given set of conditions Rules Specify which actions are to be followed .