System Analysis Mr Ahmad AlGhoul Learning Objectives n

System Analysis - Mr. Ahmad Al-Ghoul

Learning Objectives n n n Understand the purpose and goals of producing process description Discuss and understand the modular design Use structured English to analyze and describe processes Avicenna System Analysis and Design System Analysis 2

Process Description Tools n n A process description or specification documents the details of a functional primitive, which represents a specific set of processing steps and business logic Process description link the process to the DFD and the data dictionary. Process description can be represented in a variety of tools, the most popular are: n n n Structured English Decision Tables Decision Trees [2] Avicenna System Analysis and Design System Analysis 3

Process Description Tools n The goals of producing process description are n Reduce process ambiguity n Obtain a precise description of what is accomplished n Validate the system design, including data flow diagrams and the data dictionary Avicenna System Analysis and Design System Analysis 4

Process Description Tools Process specifications are not created for: Physical input and/or output processes, such as read and write. n Processes that represent simple data validation. n Processes for which prewritten code. These processes are generally included in a system as subprograms and functions. n Avicenna System Analysis and Design System Analysis 5

Process Description Tools n Modular Design n n Based on combinations of three logical structures, sometimes called control structures which serve as building blocks for the process Each logical structure must have a single entry and exit point In modular design a rectangle represents a step or process, diamond shape represents lines in the direction indicated by the arrows Three structures Sequence 2. Selection 3. Iteration - looping 1. Avicenna System Analysis and Design System Analysis 6

Process Description Tools n Modular Design n Sequence n The completion of steps in sequential order, one after anther [1] Avicenna System Analysis and Design System Analysis 7

Process Description Tools n Modular Design n Selection n describe a series of alternative policies from which only one is selected. Represented by IF ELSE <condition> <statement> CASE WHEN <condition> <statements> <statement> … ………. . . [1] Avicenna System Analysis and Design System Analysis 8

Process Description Tools n Modular Design n Iteration – looping n A policy or series of actions is repeated until a specific condition changes. Represented by DO…WHILE construct or a REPEAT … UNTIL construct [1] Avicenna System Analysis and Design System Analysis 9

Process Description Tools Structured English n Structured English is based on structured logic and Simple English statements n Modified form of English used to specify the logic of information processes n Uses a subset of English n n n Action verbs Noun phrases No adjectives or adverbs No specific standards, Standards vary between organisations n n Must conform to the following rules n n n Avicenna Use only the three building blocks of sequence, selection, and iteration Use indentation for readability Use a limited vocabulary, including standard terms used in the data dictionary and specific words that describe the processing rules System Analysis and Design System Analysis 10

Process Description Tools Structured English Example n The VERIFY ORDER process description includes logical rules and a structured English version of the policy. Notice the alignment and indentation of the logic statements. [1] Avicenna System Analysis and Design System Analysis 11

Process Description Tools Structured English Example n Sample of a policy with logical rules, and a structured English version of the policy. Notice the alignment and indentation of the logic statements. [1] Avicenna System Analysis and Design System Analysis 12

Process Description Tools Data Dictionary and Structured English The data dictionary is a starting point for creating structured English: n Sequenced data dictionary entries become simple structured English statements. n Selection [] entries become IF. . THEN. . . ELSE statements. n Iteration { } entries become DO WHILE, DO UNTIL, or PERFORM UNTIL structured English statements. n Avicenna System Analysis and Design System Analysis 13

Process Description Tools Structured English Advantages: n n n consice and precise, allow easy reading without ambiguity & misunderstanding language notation may be tailored to suit user must exist a cross-referencing with any DFD & DD entries thus perimitting thourough verification Disadvantages: n n Avicenna formality may be alien when first read or write Avoid assuming that anything written in SE is correct System Analysis and Design System Analysis 14

Sequence Summary n Modular Design based on combinations of three logical structures, sometimes called control structures which serve as building blocks for the process n n Three structures, sequence, selection, and iteration – looping Structured English uses a subset of standard English that defines each process with combinations of the basic building blocks of sequence, selection, and iteration Avicenna System Analysis and Design System Analysis 15

Sequence Summary n In this Sequence we have n Explained the modular design and its three logical structures, sometimes called control structures which serve as building blocks for the process n Defined and described the three structures, sequence, selection, and iteration – looping n Explained how to use structured English to analyze and describe processes n Explained the advantages and disadvantages foe structured English Avicenna System Analysis and Design System Analysis 16

Reference [1] System Analysis and Design, Sixth Edition Authors: Gary B. Shelly, Thomas J. Cashman and Harry J. Rosenblatt , Publisher: SHELLY CASHMAN SEWIES. [2] system analysis and design, sixth edition Authors: Kenneth E. Kendall and Julie E. Kendall Publisher: Prentice Hall [3] Modern Systems Analysis and Design Third Edition Authors: Jeffrey A. Hoffer , Joey F. George, Joseph S. Valacich Publisher: prentice hall [4] System Analysis and Design, 3 rd Edition Authors: Dennis, Wixom, & Roth Publisher: John Wiley & sons Avicenna System Analysis and Design System Analysis 17