CS 330 Class 10

1
CS 330 Class 10

• One more CGI examples with files
• pizza.htm
• CGI on UNIX and Windows

2
Conducting as Survey via a Form

• pizza.htm viewers vote for favorite topping
• pizza.cgi saves the vote
• results.cgi display results
• Data is stored in ../data/pizza.dat in the form
• CheesePepperoniAnchoviesMushroomsBlackOliv
  es
• 10423292121
• Request to vote is of the form
  pizza.cgi?toppingCheese

3

• pizza.cgi
• !/usr/bin/perl
• parse the form data
• _at_pairs split (//,ENV'QUERY_STRING')
• foreach pair (_at_pairs)
• (field_name, value) split(//,pair)
• formfield_namevalue
• user_selection form'topping'
• retrieve the current survey information
• if (open SURVEY, "lt../data/pizza.dat")
• for (i0 ilt2 i)
• linei ltSURVEYgt
• chop(linei)
• close SURVEY
• else

4

• unpack the stored survey information
• _at_options split("", line0)
• _at_data split("", line1)
• find and increment the selected item
• for (i0 iltoptions i)
• if (optionsi eq user_selection)
• item_noi
• last
• dataitem_no
• store the updated survey information
• line1 join ('', _at_data)
• if(open SURVEY, "gt../data/pizza.dat")
• print SURVEY line0, "\n"
• print SURVEY line1, "\n"

5

• presults.cgi
• !/usr/bin/perl
• read and display data from the pizza topping
  survey
• retrieve the current survey information
• if (open SURVEY, "lt../data/pizza.dat")
• for (i0 ilt2 i)
• linei ltSURVEYgt
• chop(linei)
• close SURVEY
• else
• error handling code
• unpack the stored survey information
• _at_options split("", line0)
• _at_data split("", line1)

6

• print the results
• print "Content-type text/html\n\n"
• print "lthtmlgt\n"
• print "ltheadgtlttitlegtPizza Surveylt/titlegtlt/headgt\n"
  
• print "ltbodygt\n"
• print "lttablegt\n"
• print "ltbgtlttrgtltthgtTopping lt/thgtltthgtVoteslt/thgtlt/trgt
  lt/bgt\n"
• for (i0 iltoptions i)
• print "lttrgtlttdgtoptionsilt/tdgtlttdgtdatailt/
  tdgtlt/trgt\n"
• print "lt/tablegt\n"
• print "lt/bodygtlt/htmlgt\n"
• Comment
• options is the size of the array
• Enhancements?
• Detect spurious votes
• Be able to add a new topping

7
Summary of CGI on UNIX

• HTTP the language that web clients and servers
  use to communicate with each other
• CGI the part of a web server that can
  communicate with other programs that are running
  on the server
• Our approach to CGI so far
• UNIX platform with scripts written in Perl
• Scripts use information from
• HTTP environment variables
• files on the server
• Output to
• print statements that create an HTML document
• files on the server

8
Higher Level Approaches to CGI

• Cold Fusion
• Owned by Macromedia
• A giant leap in usability from Perl
• Interfaces with most commercial databases
• ASP (Active Server Pages)
• Microsofts answer to CF
• Many companies migrated to it from CF
• Now being supplanted by ASP.NET
• PHP
• Free, interfaces with MySQL (free) and other
  commercial dbs
• Stable but evolving.
• All are multi-platform, but ASP is best-supported
  on IIS.
• Cold Fusion tags, ASP code, or PHP code are
  embedded in HTML page
• and preprocessed before resulting page is sent to
  the client.

9
Client/Server Communication
10
Cold Fusion Processing

• A user requests a page in a Cold Fusion
  application by submitting a form or clicking on a
  hyperlink.
• The web server passes the data submitted by the
  client and the requested page to the Cold Fusion
  application server.
• Cold Fusion reads the data from the client and
  processes the CFML tags in the page.
• Based on the CFML, the Cold Fusion Application
  Server executes the application logic and
  interacts with a wide range of server
  technologies.
• Cold Fusion dynamically generates an HTML page
  and returns it to the Web server.
• The web server returns the page to the users
  browser.

11
Cold Fusion Markup Language (CFML)

• Tags embedded in HTML
• ltCFQUERYgt lt/CFQUERYgt is used to submit any SQL
  statements to an OBDC data source.
• ltCFOUTPUTgt lt/CFOUTPUTgt to mark code that Cold
  Fusion should process prior to submitting it to
  the web server for sending to a browser
• Links to data sources are set up with an ODBC
• driver and referred to in queries.

12

• lt!--- Database query ---gt
• ltCFQUERY NAME"Animal" DATASOURCE"DW Database"gt
• SELECT FROM Animal
• lt/CFQUERYgt
• ltHTMLgtltHEADgtltTITLEgtAnimals at the DeWitt Animal
  Hospitallt/TITLEgtlt/HEADgt
• ltBODYgtltCENTERgtltH1gtThe DeWitt Animal Hospitallt/H1gt
• ltPgtltIgtThis is a Cold Fusion query of the DW
  Database for the DeWitt Animal Hospital. The
  query selects all of the Animal table and outputs
  animal name and animal breed in a table.lt/Igtlt/Pgt
• ltTABLE BORDER5gt
• ltTRgtltTH COLSPAN2gtltH2gtAnimal Name and
  Breedlt/H2gtlt/THgtlt/TRgt
• lt!--- Output of database query ---gt
• ltCFOUTPUT QUERY"Animal"gt
• ltTRgt
• ltTDgtAnimalNamelt/TDgt
• ltTDgtBreedlt/TDgt
• lt/CFOUTPUTgt
• lt/TABLEgt
• lt/CENTERgtlt/BODYgtlt/HTMLgt