An Introduction to Object-Oriented Systems Analysis and Design with UML and the Unified Process McGraw-Hill, 2004 Stephen R. Schach [email protected] 18Chapter OverviewPrelude to the Web (contd)Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Security IssuesSecurity Issues (contd)Analysis and Design Implications of NetworksSlide 23Slide 24Slide 25Web-Based Information SystemsWeb-Based Information Systems (contd)Slide 18.1Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. An Introduction toObject-Oriented Systems Analysis and Design with UML and the Unified Process McGraw-Hill, 2004Stephen R. [email protected] 18.2Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. CHAPTER 18WEB-BASED INFORMATION SYSTEMSSlide 18.3Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Chapter OverviewPrelude to the WebSecurity IssuesAnalysis and Design Implications of NetworksWeb-Based Information SystemsSlide 18.4Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Prelude to the Web (contd)Stage 1: The first electronic computers (1940s)–They were huge and and unbelievably expensive They could be used by only one user at a timeThey were operated in batch mode–There was no interaction between user and computer from program initiation until terminationSlide 18.5Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Prelude to the Web (contd)Deployment diagram of a first-generation computerSlide 18.6Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Prelude to the Web (contd)Stage 2: Interactive timesharing (early 1960s)–The computer was connected via a wire to dumb terminalsAdvantage:–Many users could use an expensive computer at the same timeDisadvantages:–Cost of the computer–Complex operating systemSlide 18.7Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Prelude to the Web (contd)Deployment diagram of a interactive timesharing computerSlide 18.8Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Prelude to the Web (contd)Stage 3: The IBM personal computer or PC (1981)–Was used by one person at a timeIt was –Small, and –CheapSlide 18.9Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Prelude to the Web (contd)Deployment diagram of a personal computerSlide 18.10Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Prelude to the Web (contd)Personal computers and first-generation computers–Supported only one user at a time, and–Were similar in computing powerThe personal computer was over a thousand times–Cheaper, and–LighterSlide 18.11Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Prelude to the Web (contd)Stage 4: Networking–Connecting a set of personal computers together so that they can communicate with one anotherOne important configuration–Client–server network (1990s)–Personal computers (the clients), are connected to a central computer (the server), which has a large diskSlide 18.12Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Prelude to the Web (contd)Client–server networkSlide 18.13Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Prelude to the Web (contd)A client–server network is identical to a timesharing compute except–Each dumb terminal is replaced by a personal computerSlide 18.14Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Prelude to the Web (contd)A client–server network can be used in two basic ways–As a timesharing computer–As a distributed computerSlide 18.15Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Prelude to the Web (contd)It can be hard for a client to communicate with the server–Middleware is needed to achieve interoperability»The mutual cooperation of compiled code»From different vendors, »Implemented in different languages, and »running on different platformsSlide 18.16Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Prelude to the Web (contd)A larger client–server network with different types of clients and serversSlide 18.17Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Prelude to the Web (contd)The World Wide WebSlide 18.18Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Prelude to the Web (contd)The Web is highly heterogeneous–Portability is therefore a nonnegotiable requirement of all Web-based information systemsThis problem has been solved–There are strict standards regarding the format of files that are passed over the Web–Examples: »HTML (HyperText Markup Language)»XML (eXtensible Markup Language, an extension of HTML)Slide 18.19Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Prelude to the Web (contd)The World Wide Web can also be used in two basic ways:–As a page reader (browser)–As a distributed computerSlide 18.20Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Security IssuesE-commerce systems encrypt (encode) credit card numbers–If an order goes astray there is no danger that a person who sees it can misuse the credit card numberHowever, encryption of credit card numbers may not be of critical importance–Very few messages go astray–An unintended recipient may be honest–There are better ways for crooks to acquire credit card numbersSlide 18.21Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Security Issues (contd)The real problem is–How credit card numbers are stored on the e-commerce company computerCredit card numbers (and other sensitive data) should be stored in encrypted form–Because hackers can break into the data store after the numbers have been receivedIf they have to be stored in unencrypted form–They must be protected by passwords and other security mechanismsSlide 18.22Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Analysis and Design Implications of NetworksAn information system is to be implemented on a single computer:–The systems analysis and design is described in Chapters 1 through 17Slide 18.23Copyright