1 homework / exam exam 3 –solutions posted –questions? hw8 due next class final exam –see...
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Homework / Exam
• Exam 3– Solutions Posted– Questions?
• HW8 due next class• Final Exam
– See posted schedule
• Websites on UNIX systems• Course Evaluations
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Final Exam• Final Exam
– See posted day, time, and location– It will be 1-1/2 hours – not 3 hours
• Watch your email for any late breaking announcements!
• Review HW7 and HW8• See the posted practice final exam• Review Session Next Class
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Websites on UNIX Systems
• Many websites are hosted on UNIX Systems
• My website is supported on our www server in the same way that I will be teaching now
• Learn a few basic rules and HTML coding and you can have your own website!
• Warning: For your educational or personal use only – No commercial websites allowed!
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The Big Picture
UNIX System
ApacheServer
Software
BrowserSoftware
PC/MAC
TheInternet
TCP/IPSoftware
TCP/IPSoftware
FileSystem
HTMLFiles
HTTPProtocol
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Browser
• Browser interacts with user to get URL
• Browser converts URL to an IP address
• Opens a connection to IP address and port 80
• Sends an HTTP “request” containing URL
• Receives HTTP “response” containing HTML
• Interprets and displays the HTML
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Web Server
• Apache server on UNIX system (Typical)– Interacts with browser clients via HTTP– Accesses HTML files on UNIX file system– Standard mapping from URL to path/file name
• http://www.cs.umb.edu/~bobw maps to
• ~bobw/public_html/index.html
– This home page can have links to other pages
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HTTP Protocol
• Application Layer Protocol– Requests– Responses
• Sent using TCP connections over IPTCP = Transport Control Protocol
IP = Internet Protocol
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To set up your website
• Use mkdir to create a sub-directory on your home directory named:public_html
• Edit and save a text file containing HTML document (program) in that directory as:index.html
• Use chmod to allow “others” read access• Remember UNIX is case sensitive!
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Basic HTML Document
<html>
<head>
<title>Display Title</title>
</head>
<body>
Contents of body defines what the browser displays
</body>
</html>
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Hello World HMTL File~yourname/public_html/index.html
<html>
<head>
<title>Your Name’s Hello World Website</title>
</head>
<body>
<p>Hello world!</p>
</body>
</html>
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Proper Nesting of <tag> and </tag>
<html>
<head>
<title> … </title>
</head>
<body>
<p> … </p>
</body>
</html>
Start/End onone line is OK
Start/End onone line is OK
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Basic HTML Tags
• Various font/format control pairsHeadings Level 1 <h1> </h1>Paragraph <p> </p>Bold <b> </b>Italics <i> </i>Center Text <center> </center>
• Some format control tags are not a tag pair:Break (new line) <br>
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Basic HTML Tags• Unordered Lists (Bullets at start of each line)
<ul> <li>List Item</li> <li>List Item</li></ul>
• Ordered Lists (Numbers at start of each line)<ol>
<li>List Item 1</li><li>List Item 2</li>
</ol>
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Links to Other Files
• Display a hyper-link to another html file:<a href=“filename.html"> Display Text</a>
• Display a link to download a non-html file:<a href=“filename.doc”> Display Text</a>
• Display an image from a non-html file:<img src="bob.jpg"> (Note: not a tag pair)
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HTML Forms and/or Get Requests• Forms defined using tags <form> </form>• Many useful form “widgets”:
– Text (Free Format Text Entry)– Check Boxes/Radio Boxes (on or off)– Select (Multiple Choice)
• Browser submits data to server programs:GET or POST methods
• Simple “GET” = URL followed by ?request:e.g.: url?parameter1=value1¶meter2=value2
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HTML Forms and/or Get Requests• Webpage reflect.html sends either:
– A POST request via submitting the form or– A GET request via the encoded URL
• Reflect.html form using “post” method:<form name = "reflect" method="post“ action=
"http://cgi1.cs.umb.edu/~bobw/cgi-bin/reflect.cgi”>
• Reflect.html encoded “get” URL:<a href="http://cgi1.cs.umb.edu/~bobw/cgi-bin/
reflect.cgi?Name=John+Jones&Phone=555-1234">
Get Request to reflect.cgi Program</a>
• URL is: http://www.cs.umb.edu/~bobw/reflect.html
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Dynamic Web Pages
• The URL points to an “executable program” file instead of to a “static” HTML document file
• The program generates response based on input request parameters and data stored on the server
• It writes response in HTML format to stdout
• These programs can be scripts PERL, PHP, etc. or Java servlets (e.g. generated from .jsp files)
• They can also be compiled C programs!
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CGI C Programs
• Compile your C program with executable file name suffix .cgi (e.g. makefile definition)reflect.cgi: reflect.c makefile
gcc -o reflect.cgi reflect.c
• Save executable file in a sub-directory in your public_html directory (e.g. “cgi-bin”)
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CGI C Programs• Environment variable REQUEST_METHOD
contains indicator of type of input (Get/Post)
• reflect.cgi figures out request method used:char *rm = getenv(“REQUEST_METHOD”);
• For a “Get” request, reflect.cgi uses:char *s = getenv(“QUERY_STRING”);
• For a “Post” request, reflect.cgi uses:int len = atoi(getenv("CONTENT_LENGTH"));
/* and reads len characters via getchar */
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CGI C Programs
• reflect.cgi just responds to browser with standard html “boilerplate” and a copy of the input data in the body without parsing it:arguments = 1, /home/bobw/public_html/cgi-bin/reflect.cgi
cgiRequestMethod = GET
QUERY_STRING: Name=John+Jones&Phone=555-1234
• A production cgi program would parse this input data, process it, and provide a response in html to the browser
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Course Evaluations
• Please fill out the course evaluation forms
• Give to assigned student for turn-in
• Thank you