Software Engineering for Internet Applications - Student Community

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You need a Web programming environment powerful enough thatyou can build something that we'll call a request processor. Thisprogram looks at an incoming abstract URL, e.g., "one-topic", andfollows the following logic:• is there a .jsp file in the file system; if so, execute it• look for headers requesting XHTML Mobile Profile for a cellphone browser; if so and there is a .mobile file in the filesystem, serve it, if not, continue• look for a .html file• look for a .jpg• look for a .gif(You'll want to customize the preference order for your server.)centralized logging of RDBMS queriesThe main job of your Web scripts will be to formulate SQL queriesand transactions. If things go wrong the most valuable informationthat you can get is "what did my Web scripts tell the RDBMS to doand in what order". The best Web/application server programs have asingle error log file into which they will optionally write all the queriesthat are sent to the RDBMS.2.9 ExercisesAfter solving these problems you will know• How to log into your development server• Rudiments of whatever programming language you'vechosen• How to create, execute, test, and debug a dynamic Webpage• How to write a Web page that queries a foreign server• Rudiments of SQL• How to query an RDBMS from the shell• How to write a Web page that queries an RDBMS• How to personalize Web applications by issuing and readingcookies• How to read and write data in XML• How to load a flat-file of data into an RDBMS tableHTMLHTTPIISJavaJPEGHyper Text Markup Language. Developed by Tim Berners-Lee, this specifies a format for the most popular kind ofdocument distributed over the Web (via HTTP).Documented sketchily in this book, documented badly athttp://www.w3.org, and documented well in HTML: TheDefinitive Guide (Musciano and Kennedy 2002; O'Reilly).Hyper Text Transfer Protocol. Developed by Tim Berners-Lee, this specifies how a Web browser asks for a documentfrom a Web server. Question such as "how does a servertell the browser that a document has moved?" or "how doesa browser ask the time that a document was last modified?"may be answered by reference to this protocol, which isdocumented badly at http://www.w3.org and documentedwell in various books such as HTTP: The Definitive Guide(David Gourley, Brian Totty; O'Reilly 2002).Internet Information Server. A threaded Web server programthat is included by Microsoft when you purchase theWindows operating system.Java is first a programming language, developed by SunMicrosystems around 1992, intended for use on the tinycomputers inside cell phones and similar devices. Java issecond an interpreter, the Java virtual machine, formerlycompiled into popular Web browsers (back when NetscapeNavigator was popular and before Sun sued Microsoft).Java is third a security system that purports to guaranteethat a program downloaded from an untrusted source on theInternet can run safely inside the interpreter. Java is the onlyrealistic way for a Web publisher to take advantage of thecomputing power available on a user's desktop. Java isgenerally a cumbersome language for server-side softwaredevelopment. For more background on the language, seethe Java chapter from Database Backed Web Sites athttp://philip.greenspun.com/wtr/dead-trees/53008.htm.Joint Photographic Experts Group. A bunch of people whosat down and designed a standard for image compression,conveniently titled "IS 10918-1 (ITU-T T.81)". This standardworks particularly well for 24-bit color photographs. C-CubeMicrosystems came up with the JFIF standard for encodingcolor images in a file. Such a file is what people commonlyrefer to as "a JPEG" and typically ends in ".jpg" or ".jpeg".The main problem with JFIF files is that they only record 830319
FilterFirewallFlat-fileGIF318functioning as a mail reader, USENET news reader, Webbrowser, shell, calendar, calculator, and Lisp evaluator.Emacs is infinitely customizable because users can writetheir own commands in Lisp. You can find out more aboutEmacs at ftp://publications.ai.mit.edu/aipublications/pdf/AIM-519A.pdf(Stallman's 1979 MIT AI Labreport), at www.gnu.org (where you can download thesource code for free), or by reading Learning Emacs(Cameron et al 1996; O'Reilly). If you want to programEmacs and then you'll want Writing Gnu Emacs Extensions(Bob Glickstein 1997; O'Reilly).The best Web server APIs allow the programmer to say "runthis little piece of code before [or after] serving files thatmatch a particular URL pattern." Filters that run after a file isserved are useful if you want to add extra logging to anapplication. Filters that run before a file is served or a scriptis run are useful for implementing a security policy in aconsistent fashion rather than relying on the authors ofindividual scripts to insert an authentication check.A computer that sits between a company's internal networkof computers and the public Internet. The firewall's job is tomake sure that internal users can get out to enjoy thebenefits of the Internet while external crackers are unable tomake connections to machines behind the firewall.A flat-file database keeps information organized in astructured manner, typically in one big file. A desktopspreadsheet application is an example of a flat-file databasemanagement system. These are useful for Web publisherspreparing content because a large body of information canbe assembled and then distributed in a consistent format.Flat-file databases typically lack support for processingtransactions (inserts and updates) from concurrent users.Thus, collaboration or ecommerce Web sites generally relyon a relational database management system as a backend.Graphical Interchange Format. Developed in 1987 byCompuServe, this is a way of storing compressed imageswith up to 256 colors. It became popular on the Webbecause it was the only format that could be displayed inlineby the first multi-platform Web browser (NCSA Mosaic).The JPEG image file format results in much better lookingimages with much smaller sized files.If you're using Microsoft .NET, you'll find the examples inhttp://philip.greenspun.com/seia/examples-basics/dot-net-examples/helpful.Exercise 1: Finding your place in the worldFind your Web server's page root, the directory where the Webserver begins looking for files. Put a file there named "index.html"and fill it with text identifying this as your server. Include yourhyperlinked email address at the bottom of the page.Connect to your server from a Web browser, using only the hostname. For the rest of this problem set we're going to assume thatyour hostname is "yourhostname.com". Verify that when you requesthttp://yourhostname.com your customized page is presented (if youget a directory listing instead your Web server is probably notconfigured to look for index files named "index.html"; you'll have toreconfigure your server). Now use an HTML validator to make surethat your HTML is legal (seehttp://dir.yahoo.com/Computers_and_Internet/Data_Formats/HTML/Validation_and_Checkers/ for a list of programs and services).You've made at least two requests from your Web server now. Thesewill have been logged in the server access log. Find it in the filesystem and verify that the times and files requested shown makesense to you.Exercise 2: Your first programCreate a subdirectory called "basics" at the same level in the filesystem as the index.html file that you just created, i.e., basics shouldbe one level below the Web server root. This directory should beaccessible at http://yourhostname.com/basics/Put a file in the directory so that it is accessible athttp://yourhostname.com/basics/my-first-program (if you haven't yetfigured out how to implement abstract URLs, this may be "my-firstprogram.pl"or "my-first-program.asp" or similar).When we visit http://yourhostname.com/basics/my-first-program weshould see the current time wrapped in a legal HTML page of somesort, signed with your email address.Add some code that will generate a divide-by-zero error to yourprogram. Find and visit the server error log to see how this error is31
Page 1 and 2: SoftwareEngineering forInternetAppl
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Page 5 and 6: end-users. We use every opportunity
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Page 13 and 14: What to do during lecturesWe try to
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Page 27 and 28: OraclePerlnamed XYZ" without the pr
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systems. What would a knowledge man
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spreadsheet". Other users can comme
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Chapter 15Metadata (and Automatic C
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{site url}{site description}en-usCo
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drawing on the intermodule API that
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At this point you have something of
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• description• URL for a photo
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Here's a raw SOAP request/response
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Chapter 14Distributed Computing wit
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conduct programmer job interviews h
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Most admin pages can be excluded fr
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content that should distinguish one
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Chapter 13Planning ReduxA lot has c
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the Internet-specific problem of no
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wouldn't see these dirty tricks unl
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12.8 Exercise 4: Big BrotherGeneral
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than one call to contains in the sa
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A third argument against the split
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way 1 1/16One might argue that this
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absquatulate 612bedizen 36, 9211cry
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What if the user typed multiple wor
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Chapter 12S E A R C HRecall from th
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long as it is much easier to remove
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features that are helpful? What fea
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made it in 1938)? Upon reflection,
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environment, we identify users by t
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those updates by no more than 1 min
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Balancer and mod_backhand, a load b
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translation had elapsed--the site w
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It seems reasonable to expect that
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11.1.5 Transport-Layer EncryptionWh
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such as ticket bookings would colla
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give their site a unique look and f
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It isn't challenging to throw hardw
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Chapter 11Scaling GracefullyLet's l
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10.15 Beyond VoiceXML: Conversation
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Consider that if you're authenticat
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In this example, we:194• ask the
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As in any XML document, every openi
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(http://www.voicegenie.com). These
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Chapter 10Voice (VoiceXML)questions
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9.15 MoreStandards information:•
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9.14 The FutureIn most countries th
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9.10 Exercise 7: Build a Pulse Page
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9.6 Keypad HyperlinksLet's look at
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text/xml,application/xml,applicatio
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Protocol (IP) routing, a standard H
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