Encyclopedia of Computer Science and Technology

116 cookiesunlike most traditional publications, are under constantrevision and review.Once created, material will often be reused or repurposedfor different projects. Thus an important part of most contentmanagement systems is the repository, which makes thematerial easily searchable and retrievable for later use. Materialthat is less likely to be used but still must be retained(such as for legal reasons) may be stored in a separate archive(see backup and archive systems). Note: The term digitalasset management is also sometimes used for such systems.SoftwareContent management Systems are usually built upon aframework or programming interface (see applicationprogram interface), often using languages such as Java,Perl, Python, or PHP. There are many products to choosefrom, including free and open-source alternatives.An interesting alternative for some projects is to usea wiki as a content management system (see wikis andWikipedia). Especially for textual content, wikis offer theadvantage of already having revision tracking built in, andfull-scale wikis such as MediaWiki have many additionalfeatures or plug-ins to aid in content management.Further ReadingBoiko, Bob. Content Management Bible. 2nd ed. Indianapolis:Wiley, 2005.CMS Matrix. Available online. URL: http://www.cmsmatrix.org/.Accessed September 4, 2007.CMS Review. Available online. URL: http://www.cmsreview.com/.Accessed September 4, 2007.Hackos, JoAnn T. Content Management for Dynamic Web Delivery.New York: Wiley, 2001.cookiesCookies are simply tiny text files that a Web server sendsto the browser and retrieves each time the user accesses theWeb site. The purpose is to maintain a sort of profile of theuser containing such things as preferences as to how theuser wants to view or use the site, shopping cart selectionsfrom previous sessions, and so on. In short, cookies enable aWeb site to provide a more customized or personalized formof service and minimize the amount of repetitive data entryon the part of the user. (This type of cookie is called persistent,since it survives across sessions. There can also be temporarycookies that apply only to the current session.)However, cookies also have benefits for the Web siteowner. They can be used to track which pages or items theuser has looked at in the past. This information can then beused (see data mining) to create generic user profiles thatcan help with marketing or targeting advertising. In thecase of some companies (notably Amazon.com) much moreelaborate profiles associated with the cookie’s identity canbe used to create personalized recommendations, in effectcontinually directing targeted advertising at the user.Security and Privacy ConcernsThere are many popular misconceptions about cookies.Cookies contain only data, not executable code. This meansthey cannot function as worms or viruses or otherwiseinteract with the user’s system. However, while cookies donot in themselves represent a security threat, they do haveprivacy implications. Although most profiles created usingcookies are anonymous (containing no personal identifyingdata), an unscrupulous site could attach such data (such asaddresses or credit card numbers entered by the user) to aprofile and sell it for purposes ranging from spamming toidentity theft.Another risk comes from “third party” cookies such asare often included in advertisements (see online advertising).Potentially, these could be used to create a much morecomprehensive profile of a user based on his or her actionson multiple Web sites.Users do have some control over how cookies are stored.Most browsers allow the user to reject all cookies, accept orreject cookies from certain sites, or store cookies only temporarily.However, sites may in turn refuse services to userswho do not accept cookies, and at any rate the user wouldsee only a generic rather than a personalized view.There has been a certain amount of government regulationof Web cookies. The U.S. government has strict rulesfor the use of cookies on federal Web sites. The EuropeanUnion also has recommended (but not fully implemented)regulations that require that users be told how the storeddata will be used and be given the opportunity to opt out.Further ReadingKuner, Christopher. European Data Privacy Laws and Online Business.New York: Oxford University Press, 2003.Kymin, Jennifer. “What are HTTP Cookies?” Available online. URL:http://webdesign.about.com/cs/cookies/a/aa082498a.htm.Accessed September 4, 2007.Levine, John R., Ray Everett-Church, and Gregg Stebben. InternetPrivacy for Dummies. New York: Wiley, 2002.cooperative processingHistorically there have been two basic ways to bring greatercomputer power to bear on a task. One is to build morepowerful single computers (see supercomputer). The otheris to link one or more computers or processors together andtightly coordinate them to process the data (see grid computing).Both of these approaches require great expertiseand considerable expense.However, there is another quite interesting ad hocapproach to cooperative processing that first appeared withthe SETI@Home project launched in 1999. The basic idea isto take advantage of the fact that millions of computer usersare already connected via the Internet. The typical PC hasmany processing cycles to spare—idle time when the user isdoing nothing and the operating system is doing very little.A program like SETI@Home is designed to be downloadedto volunteer users. The program can run only whenno other applications are being used (one way to ensurethis is to make the program a screen saver), or it can runcontinuously but only use cycles not being requested byanother program.The data to be analyzed (signals from space in this case)is broken up into chunks or “work units” that are parceled