System Analysis System Analysis - Mr. Ahmad Al-Ghoul System Analysis and Design

Avicenna System Analysis and Design System Analysis2 Learning Objectives Understand the purpose and goals of producing process description Understand the purpose and goals of producing process description Discuss and understand the modular design Discuss and understand the modular design Use structured English to analyze and describe processes Use structured English to analyze and describe processes

Avicenna System Analysis and Design System Analysis3 Process Description Tools A process description or specification A process description or specificationprocess description or specificationprocess description or specification documents the details of a functional primitive, which represents a specific set of processing steps and business logic 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 link the process to the DFD and the data dictionary. Process description can be represented in a variety of tools, the most popular are: Process description can be represented in a variety of tools, the most popular are: Structured English Structured English Decision Tables Decision Tables Decision Trees Decision Trees [2]

Avicenna System Analysis and Design System Analysis4 Process Description Tools The goals of producing process description are The goals of producing process description are Reduce process ambiguity Reduce process ambiguity Obtain a precise description of what is accomplished Obtain a precise description of what is accomplished Validate the system design, including data flow diagrams and the data dictionary Validate the system design, including data flow diagrams and the data dictionary

Avicenna System Analysis and Design System Analysis5 Process Description Tools Process specifications are not created for: Physical input and/or output processes, such as read and write. Physical input and/or output processes, such as read and write. Processes that represent simple data validation. Processes that represent simple data validation. Processes for which prewritten code. These processes are generally included in a system as subprograms and functions. Processes for which prewritten code. These processes are generally included in a system as subprograms and functions.

Avicenna System Analysis and Design System Analysis6 Process Description Tools Modular Design Modular Design Modular Design Modular Design Based on combinations of three logical structures, sometimes called control structures which serve as building blocks for the process Based on combinations of three logical structures, sometimes called control structures which serve as building blocks for the processlogical structurescontrol structures logical structurescontrol structures Each logical structure must have a single entry and exit point 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 In modular design a rectangle represents a step or process, diamond shape represents lines in the direction indicated by the arrows Three structures Three structures 1. Sequence Sequence 2. Selection Selection 3. Iteration - looping Iterationlooping Iterationlooping

Avicenna System Analysis and Design System Analysis7 Process Description Tools Modular Design Modular Design Modular Design Modular Design Sequence Sequence The completion of steps in sequential order, one after anther The completion of steps in sequential order, one after anther [1]

Avicenna System Analysis and Design System Analysis8 Process Description Tools Modular Design Modular Design Modular Design Modular Design Selection Selection describe a series of alternative policies from which only one is selected. Represented by describe a series of alternative policies from which only one is selected. Represented by IF CASE WHEN WHEN ELSE WHEN ELSE WHEN ………….. …... ………….. …... [1]

Avicenna System Analysis and Design System Analysis9 Process Description Tools Modular Design Modular Design Modular Design Modular Design Iteration – looping Iteration – looping A policy or series of actions is repeated until a specific condition changes. Represented by DO…WHILE construct or a REPEAT … UNTIL construct 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 Analysis10 Process Description Tools Structured English Structured English is based on structured logic and Simple English statements Structured English is based on structured logic and Simple English statements Modified form of English used to specify the logic of information processes Modified form of English used to specify the logic of information processes Uses a subset of English Uses a subset of English Action verbs Action verbs Noun phrases Noun phrases No adjectives or adverbs No adjectives or adverbs No specific standards, Standards vary between organisations No specific standards, Standards vary between organisations Must conform to the following rules Must conform to the following rules Use only the three building blocks of sequence, selection, and iteration Use only the three building blocks of sequence, selection, and iteration Use indentation for readability Use indentation for readability Use a limited vocabulary, including standard terms used in the data dictionary and specific words that describe the processing rules Use a limited vocabulary, including standard terms used in the data dictionary and specific words that describe the processing rules

Avicenna System Analysis and Design System Analysis11 Process Description Tools Structured English Example 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. 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 Analysis12 Process Description Tools Structured English Example Sample of a policy with logical rules, and a structured English version of the policy. Notice the alignment and indentation of the logic statements. 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 Analysis13 Process Description Tools Data Dictionary and Structured English Data Dictionary and Structured English The data dictionary is a starting point for creating structured English: The data dictionary is a starting point for creating structured English: Sequenced data dictionary entries become simple structured English statements. Sequenced data dictionary entries become simple structured English statements. Selection [] entries become IF..THEN...ELSE statements. Selection [] entries become IF..THEN...ELSE statements. Iteration { } entries become DO WHILE, DO UNTIL, or PERFORM UNTIL structured English statements. Iteration { } entries become DO WHILE, DO UNTIL, or PERFORM UNTIL structured English statements.

Avicenna System Analysis and Design System Analysis14 Process Description Tools Structured English Advantages: consice and precise, allow easy reading without ambiguity & misunderstanding consice and precise, allow easy reading without ambiguity & misunderstanding language notation may be tailored to suit user language notation may be tailored to suit user must exist a cross-referencing with any DFD & DD entries thus perimitting thourough verification must exist a cross-referencing with any DFD & DD entries thus perimitting thourough verificationDisadvantages: formality may be alien when first read or write formality may be alien when first read or write Avoid assuming that anything written in SE is correct Avoid assuming that anything written in SE is correct

Avicenna System Analysis and Design System Analysis15 Sequence Summary Modular Design based on combinations of three logical structures, sometimes called control structures which serve as building blocks for the process Modular Design based on combinations of three logical structures, sometimes called control structures which serve as building blocks for the process Three structures, sequence, selection, and iteration – looping 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 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 Analysis16 Sequence Summary In this Sequence we have In this Sequence we have Explained the modular design and its three logical structures, sometimes called control structures which serve as building blocks for the process Explained the modular design and its three logical structures, sometimes called control structures which serve as building blocks for the process Defined and described the three structures, sequence, selection, and iteration – looping Defined and described the three structures, sequence, selection, and iteration – looping Explained how to use structured English to analyze and describe processes Explained how to use structured English to analyze and describe processes Explained the advantages and disadvantages foe structured English Explained the advantages and disadvantages foe structured English

Avicenna System Analysis and Design System Analysis17 Reference [1] System Analysis and Design, Sixth Edition Authors: Gary B. Shelly, Thomas J. Cashman and Harry J. Rosenblatt, Authors: Gary B. Shelly, Thomas J. Cashman and Harry J. Rosenblatt, Publisher: SHELLY CASHMAN SEWIES. Publisher: SHELLY CASHMAN SEWIES. [2] system analysis and design, sixth edition Authors: Kenneth E. Kendall and Julie E. Kendall Authors: Kenneth E. Kendall and Julie E. Kendall Publisher: Prentice Hall Publisher: Prentice Hall [3] Modern Systems Analysis and Design Third Edition Authors: Jeffrey A. Hoffer, Joey F. George, Joseph S. Valacich Authors: Jeffrey A. Hoffer, Joey F. George, Joseph S. Valacich Publisher: prentice hall Publisher: prentice hall [4] System Analysis and Design, 3 rd Edition Authors: Dennis, Wixom, & Roth Authors: Dennis, Wixom, & Roth Publisher: John Wiley & sons Publisher: John Wiley & sons