Exercise14 - Systems Analysis and Design in a Changing...

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Systems Analysis and Design in a Changing World, Fourth Edition 14-1 Chapter 14 – Designing System Interfaces, Controls, and Security Solutions to End-of-Chapter Material Review Questions 1. What does XML stand for? Explain how XML is similar to HTML. Also, discuss the differences between XML and HTML. XML stands for eXtensible Markup Language. Like HTML, XML uses markup codes that are identified with brackets (< >) and that are embedded in an ASCII text file. The markup codes as well as the text file are in human- readable format. Unlike HTML, the markup codes in XML are not predefined. The language is extensible because the markup codes are self-defining. An additional file, called the Document Type Definition (DTD) file, is needed to define the meaning of the markup codes. 2. Compare the strengths and weaknesses of using a DFD to define inputs with using a sequence diagram to define inputs. Which do you like the best? Why ? DFDs: The arrows on a DFD describe information flows. As such, they define logical inputs of data. The design of the inputs and outputs might be more detailed, requiring several screens. Sequence diagrams: The messages on a sequence diagram identify interactions. The parameters define the data that is passed. If the developer does not carefully define the parameters, the message might give an incomplete design. A sequence diagram also describes the various steps that are required to complete a business transaction, which might help define the set of required screens. Preferences will vary. 3. Explain the system boundary. Why was one used on a DFD but not used on a system sequence diagram? The system boundary divides the automated system from the manual system. It is used on a DFD because a DFD includes both manual and automated processes. To identify which data flows cross the boundary, a boundary must be superimposed on the diagram. The flow of information from actors to objects is by definition a flow of data from external to internal.
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Systems Analysis and Design in a Changing World, Fourth Edition 14-2 4. What additional information does the structure chart provide that is not obtained from a DFD in the development of input forms? A structure chart gives more detailed information about access to individual input screens or files. A structure chart provides more details about the set of individual forms that might be required to support an input data flow. 5. How are the data fields identified using the structured approach? Data fields primarily come from the data flows that cross the system boundary. These data flows can be checked by ensuring that adequate input data is available to support the fields in the data stores. 6. How are the data fields identified using UML and the object-oriented approach? The primary source of data fields is the class diagram. Fields are identified in the classes.
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Exercise14 - Systems Analysis and Design in a Changing...

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