Beginning Web Development With Perl : From Novice to ... - Nabo

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CHAPTER 1 ■ THE CGI MODULE 15Update your code on the web server with this new code. Don’t forget to click the refreshbutton in your web browser to ensure that you have the new code within your version of thepage. If you fail to reload the page after saving the new code, you won’t get the same results asthe rest of us.Now you can fill in your name and click the Submit Query button. If your name is Steve,you’ll see the output shown in Figure 1-4.Figure 1-4. Printing the name based on what was submittedCookiesCookies are tokens or data sent in the HTTP header. Cookies sometimes reside in volatilememory for the duration of the browser setting and can also be saved as persistent text fileson the user’s computer. You can use cookies for many reasons, including carrying informationabout users to enhance their browsing experience. Cookies offer a very useful way to maintainstate between visits or during a session.■Caution Cookies are often overused and relied upon unnecessarily. Additionally, some users overestimatethe risks of allowing cookies and misunderstand the privacy concerns related to their use. For these reasons,some users will disable cookies in their browsers. Therefore, you shouldn’t design an application that relieson cookies for session state or other client-side settings.The CGI module includes powerful functions to assist in creating and managing browsercookies. Here, I’ll show you some examples. But first, let’s see what goes into a cookie. (I find itdifficult to resist clever but overdone metaphors when writing about cookies; therefore, I’llapologize in advance for some of the titles of the forthcoming sections.)
16CHAPTER 1 ■ THE CGI MODULECookie IngredientsCookies consist of up to the following six parameters:• Name: This is the name of the cookie itself and is the only required parameter fora cookie.• Value: The value of a cookie is an optional item that contains the object or subject ofthe cookie. In other words, if you have a cookie with a name of sessionid, the value forthat sessionid might be 515093028943.• Domain: The domain parameter refers to the Internet domain within which thecookie is valid. Cookies are valid only within the domain in which they are set. Forexample, as an operator of example.com, you cannot read cookies that are tied to thedomain example.net.• Secure: The secure parameter refers to whether or not the cookie will be transmittedover an unsecure connection; that is, a connection that doesn’t use SSL. The default forthis parameter is off, meaning that cookies can be transmitted over SSL and non-SSLconnections alike.• Path: The path parameter further refines the area of the domain in which the cookieis valid. For example, a cookie with a path of /shoppingcart will be sent only topages below /shoppingcart within the domain. That cookie would be sent tohttp://www.example.com/shoppingcart/checkout.cgi, but would not be sent tohttp://www.example.com/index.html, since index.html is not hierarchically belowthe /shoppingcart path in the URL.• Expiration date: The expiration date is the time at which the cookie will no longer bevalid. If no expiration date is set, or—and this is important—if the expiration date is setincorrectly, the cookie will expire at the close of the browser session. Some browserswon’t accept the cookie at all if the expiration date is not set correctly. The format forthe expiration date is specific and is as follows: Weekday, DD-MM-YYYY HH:MM:SS GMT.■Tip To clear a cookie, it's usually sufficient to set the value to null, or "".Cookie LimitationsThe following are some inherent limitations set by the cookie standard itself:• A 4KB total size for any single cookie• A total of 300 cookies stored by a browser• A total of 20 cookies for any given server or domainWhile some of these limitations are merely recommendations, it’s a good idea to keepthese in mind when working with cookies. In addition, although not required, it is recommendedthat elements within a cookie be properly encoded. Usually, this means escaping
Page 3 and 4: Beginning Web Development with Perl
Page 5 and 6: PART 5 ■ ■ ■ Creating Web Tem
Page 8 and 9: ■CONTENTSvii■CHAPTER 4 System I
Page 10 and 11: ■CONTENTSixCreating a SOAP Listen
Page 12 and 13: ■CONTENTSxiTemplate Toolkit Synta
Page 14 and 15: About the Author■STEVE SUEHRING i
Page 16 and 17: AcknowledgmentsThanks to James Lee
Page 18 and 19: xx■INTRODUCTIONThis book will use
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Page 54 and 55: CHAPTER 2 ■ POPULAR CGI MODULES 3
Page 66 and 67: 50CHAPTER 3 ■ DATABASES AND PERLT
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68CHAPTER 3 ■ DATABASES AND PERLm
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70CHAPTER 3 ■ DATABASES AND PERLT
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72CHAPTER 3 ■ DATABASES AND PERLT
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74CHAPTER 4 ■ SYSTEM INTERACTION
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76CHAPTER 4 ■ SYSTEM INTERACTIONt
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78CHAPTER 4 ■ SYSTEM INTERACTIONc
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80CHAPTER 4 ■ SYSTEM INTERACTIONA
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84CHAPTER 4 ■ SYSTEM INTERACTIONs
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86CHAPTER 4 ■ SYSTEM INTERACTIONr
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CHAPTER 5■ ■ ■LWP ModulesLWP
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CHAPTER 5 ■ LWP MODULES 91HTTP Re
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CHAPTER 5 ■ LWP MODULES 93Get Fun
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CHAPTER 5 ■ LWP MODULES 95When ca
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CHAPTER 5 ■ LWP MODULES 99Recall
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CHAPTER 5 ■ LWP MODULES 101which
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CHAPTER 5 ■ LWP MODULES 103For th
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CHAPTER 5 ■ LWP MODULES 105Obviou
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108CHAPTER 6 ■ NET:: TOOLSCreatin
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110CHAPTER 6 ■ NET:: TOOLSThe out
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112CHAPTER 6 ■ NET:: TOOLSmy $pop
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114CHAPTER 6 ■ NET:: TOOLSthe POP
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116CHAPTER 6 ■ NET:: TOOLS($messa
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118CHAPTER 6 ■ NET:: TOOLSListing
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120CHAPTER 6 ■ NET:: TOOLSFor the
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122CHAPTER 6 ■ NET:: TOOLSNet::SM
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124CHAPTER 6 ■ NET:: TOOLS$smtpco
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126CHAPTER 6 ■ NET:: TOOLSuse Net
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128CHAPTER 6 ■ NET:: TOOLSListing
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130CHAPTER 6 ■ NET:: TOOLSFor exa
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132CHAPTER 6 ■ NET:: TOOLSSending
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PART 3■ ■ ■XML and RSS
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138CHAPTER 7 ■ SOAP-BASED WEB SER
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154CHAPTER 8 ■ PERL AND RSSFigure
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156CHAPTER 8 ■ PERL AND RSShttp:/
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158CHAPTER 8 ■ PERL AND RSSDebugg
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160CHAPTER 8 ■ PERL AND RSS$rsswr
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162CHAPTER 8 ■ PERL AND RSSListin
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CHAPTER 9■ ■ ■XML Parsing wit
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CHAPTER 9 ■ XML PARSING WITH PERL
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PART 4■ ■ ■PerformanceEnhance
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184CHAPTER 10 ■ APACHE AND MOD_PE
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202CHAPTER 11 ■ DEVELOPMENT WITH
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CHAPTER 12■ ■ ■The Template T
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CHAPTER 12 ■ THE TEMPLATE TOOLKIT
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CHAPTER 13■ ■ ■Perl Web Sites
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CHAPTER 13 ■ PERL WEB SITES WITH
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284APPENDIX ■ PERL BASICSKeywords
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286APPENDIX ■ PERL BASICS$ perl n
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288APPENDIX ■ PERL BASICSAnd line
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290APPENDIX ■ PERL BASICSCan you
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292APPENDIX ■ PERL BASICSBy defau
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294APPENDIX ■ PERL BASICS#!/usr/b
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296APPENDIX ■ PERL BASICSThe last
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298APPENDIX ■ PERL BASICSThe NOT
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300APPENDIX ■ PERL BASICSprint "S
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302APPENDIX ■ PERL BASICSthe syst
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304APPENDIX ■ PERL BASICS$ perl s
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306APPENDIX ■ PERL BASICSThis cod
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308APPENDIX ■ PERL BASICS$a = 6 *
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310APPENDIX ■ PERL BASICS$a = "A9
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312APPENDIX ■ PERL BASICS#!/usr/b
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314APPENDIX ■ PERL BASICSmy $name
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316APPENDIX ■ PERL BASICSis short
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318APPENDIX ■ PERL BASICSLet’s
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320APPENDIX ■ PERL BASICSOther Te
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322APPENDIX ■ PERL BASICS}}}actio
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324APPENDIX ■ PERL BASICSNotice t
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326APPENDIX ■ PERL BASICSLooping
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328APPENDIX ■ PERL BASICSuse stri
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330APPENDIX ■ PERL BASICSuntil ($
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332APPENDIX ■ PERL BASICSuse stri
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334APPENDIX ■ PERL BASICSdoneAll
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336APPENDIX ■ PERL BASICS$ perl r
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338APPENDIX ■ PERL BASICSSummaryT
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340■INDEXmethods for retrieving r
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342■INDEXdo() method for, 62dumpi
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344■INDEXhello option for Net::SM
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346■INDEXNet::DNS module, 125-128
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348■INDEXrecord with Net::DNS mod
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350■INDEXstoring mail server in e
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352■INDEXlogging based on, 229pri
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