là sai, và vị {HD1, LP4, RC5} là sự thật. Một tập đặc biệt là tities tập rỗng liên quan đến các tập rỗng là A = A và cho bất kỳ tập hợp A, = A được gọi là các nhà điều hành công đoàn, đôi khi được gọi là chén;. Điều này tương ứng với số không trong toán học bình thường. | 774 PART FIVE ADVANCED TOPICS IN SOFTWARE ENGINEERING FIGURE Quality requirements tree OLS99 Web application quality Maintainability Global site understandability On-line feedback and help features Interface and aesthetic features Special features Searching and retrieving capability Navigation and browsing features Application domain-related features Correct link processing Error recovery User input validation and recovery Response time performance Page generation speed Graphics generation speed Ease of correction Adaptability Extensibility The Internet is a risky place to conduct business or store assets. Hackers crackers snoops spoofers spammers scammers shammers jammers intruders thieves purloiners conspirators vandals Trojan horse dealers virus launchers and rouge program purveyors run loose. Dorothy Denning and Peter Denning Security If a WebApp resides on a network it is open to unauthorized access. In some cases unauthorized access may be attempted by internal personnel. In others outsiders hackers may attempt access for sport for profit or with more malevolent intent. A variety of security measures are provided by the network infrastructure encryption techniques firewalls and other measures. A comprehensive discussion of this important topic is beyond the scope of this book. For more information the interested reader should see ATK97 KAE99 and BRE99 . Internet Standards For the last decade the dominant standard for the creation of WebApp content and structure has been HTML a markup language that enables the developer to provide a series of tags that describe the appearance of a wide array of data objects text graphics audio video forms etc. . However as the size and complexity of applications grow a new standard XML has been adopted for the next generation of WebApps. XML extensible markup language is a strictly defined subset of the metalanguage SGML BRA97 allowing developers to define custom tags within Web page descriptions. Using an XML .
