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CS120 Lecture 17a:
Publishing Web pages
John Magee
9 November 2012
1
Overview/Questions
– So I got some HTML pages and stuff. How do
I make them show up on the web?
– What are web servers, anyway?
– How do we transfer files to a web server?
– Who can see my pages?
– URLs, absolute path, and relative path
revisited.
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How to Publish a Web Page
Create HTML document, locate ancillary
files (e.g images).
 Transfer files to web server
 Set permissions for read access
 Test the URL in your browser

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Recall: Displaying a WWW Page
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What’s a Web Server?
Is it hardware?
 yes!
Is it software?
 yes!
How is it both?
What hardware is needed?
What software is needed?
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What’s a Web Server?
Web server: a software application which
waits for /responds to HTTP requests.
Tim Berners-Lee wrote 2 applications to
make the web:
– A web browser called WorldWideWeb
– A server called HTTPd
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The first WWW Server at CERN.
What’s a Web Server?
Today’s web servers use
high-performance
hardware like this:
(fast network and disk
access)
Pictured: IBM Blade Servers hosting
files.myopera.com, photo from Wikipedia
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What’s a web server?
The Apache HTTP Server is the most
popular web server (since 1996).
Roles:
– Processing HyperText Transfer Protocol
– Logging
– Delivering static content from the file system
– Running scripts to deliver dynamic content
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LAMP Model
The most common structure for web applications
uses this configuration:
Linux operating system for a server
Apache web server software
MySQL database software
PHP/Perl/Python scripting language to create
dynamic HTML
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How a Web Server Works
Receives HTTP Request
 Search for resource (file) on disk
 Send HTTP Response (status code + data)

– If not found: status 404 (NOT FOUND)
– If not permitted: status 403 (FORBIDDEN)
–…
– Else: status 200 (OK) + send data
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cs-people.bu.edu
Our WWW server is www.cs.clarku.edu.
The web server has a file system which it
searches for a URI (resource pathnames).
– Subdirectories for individual users:
 http://www.cs.clarku.edu/<username>
– Example:
 http://www.cs.clarku.edu/~jmagee
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Your UNIX Home Directory
With the CS UNIX account, each user has a
“home” directory:
General form:
/home/<username>/
Example:
/home/jmagee/
This has a UNIX pseudonym of ~.
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Your WWW Directory
The web server will map this URL:
http://www.cs.clarku.edu/~<username>/
to your CS UNIX’s account’s
~/public_html/ directory
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Locate files in
Finder/Windows Explorer
Find your files on your local computer
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How to Transfer Files
to csgateway.clarku.edu
Use a file transfer client-program:
– Fetch (Mac)
http://fetchsoftworks.com/
(a free academic license is available)
– WinSCP (Windows)
http://winscp.net/eng/index.php
(also free)
- SSH Secure Shell (Windows)
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Connecting by WinSCP:
– Hostname: csgateway.clarku.edu
– Be sure to use the “SFTP” protocol
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WinSCP to csa2.bu.edu
After you
connect,
transfer files
by drag’n’drop.
Then rightclick to set
permissions.
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File Permissions
File Permissions
Each file has its own set of permissions for:
– Reading, writing or executing
– Owner, group, or others
– This leads to a 3x3 matrix of permissions:
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Setting Permissions by WinSCP

Right-click to open this dialog

Set the permissions to 644
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Transferring File by Fetch

Use drag’n’drop interface to transfer files…

Then use the Get Info button to set permissions.
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Setting Permissions by Fetch

Set permissions to 644
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Testing the Webpage:
After uploading the files, test in your
browser:
There are two special filenames that the
web server looks for automatically:
– home.html
– index.html
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Take-Away Points
– Web server
– UNIX home directory
– File Transfer Protocol
– UNIX File Permissions
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