Due: Sunday, September 20, 2020 by 11:59pm

• CS 432 students may complete this report in Markdown. Or, you may choose to use LaTeX instead.
• CS 532 students must complete this report using LaTeX generated to a PDF file (GitHub repo must contain both the LaTeX source and PDF).
• Any graphs required for your reports must be done in R or using a Python plotting library (see "The 7 most popular ways to plot data in Python") -- Excel graphs are unacceptable!
• When you include an image in your report, do not change the aspect ratio of the image. If you have trouble with this, ask for help in our Piazza group.

Reports are not just a list of questions and answers, but should include descriptions, screenshots, copy-paste of code output, references, as necessary. For each question you address, you must describe how you answered the question. I've provided a LaTeX template at https://www.overleaf.com/project/5f3d84d024c3ac0001fdaa1a. You can view the PDF generated there as well, so those who are using Markdown may want to look at it, too.

You may use existing code, but you must document and reference where you adapted the code -- give credit where credit is due! Use without attribution is plagiarism!

Your report should be named HW1-report.{md, tex, pdf}, with the proper extension. Do not edit this file, README.md

All reports must include your name, class (make sure to distinguish between CS 432 and CS 523), assignment number/title, and date. You do not need a title page.

Write a report that contains the answers and explains how you arrived at the answers to the following questions.

Consider the "bow-tie" structure of the web in the Broder et al. paper (http://snap.stanford.edu/class/cs224w-readings/broder00bowtie.pdf) that was described in Week 1.

Now consider the following links:

A --> B
B --> A
B --> C
C --> D
C --> G
D --> A
D --> H
E --> F
E --> O
F --> G
G --> P
H --> L
J --> N
K --> I
M --> A
N --> L
O --> J
P --> C

Draw the resulting graph (either sketch on paper or use another tool) and include an image in your report.

For the above graph, list the nodes (in alphabetical order) that are each of the following categories:

• IN:
• SCC:
• OUT:
• Tendrils:
  • indicate if the tendril is reachable from IN or can reach OUT
• Tubes:
  • explain how the nodes serve as tubes
• Disconnected:

Demonstrate that you know how to use curl and are familiar with the available options.

URI to request: http://www.cs.odu.edu/~mweigle/courses/cs532/ua_echo.php

a) In a single curl command, request the URI, show the HTTP response headers, follow any redirects, and change the User-Agent HTTP request field to "CS432/532". Show command you used and the result of your execution on the command line. (Either take a screenshot of your terminal or copy/paste into a code segment.)

b) Then make the same request again, but without showing the HTTP response headers and with saving the HTML output to a file. Show the command you used and the result of your execution on the command line. View that file in a browser and take a screenshot.

c) Finally, load the URI directly from your browser and take a screenshot.

Explain the results you get for each of these steps.

Write a Python program to find links to PDFs in a webpage.

Your program must do the following:

• take the URI of a webpage as a command-line argument
• extract all the links from the page
• for each link, use the Content-Type HTTP response header to determine if the link references a PDF file
• for all links that reference a PDF file, print the original URI (found in the source of the original HTML), the final URI (after any redirects), and the number of bytes in the PDF file. (Hint: Content-Length HTTP response header)

Show that the program works on 3 different URIs, one of which must be https://www.cs.odu.edu/~mweigle/courses/cs532/pdfs.html

Here is a snippet of the expected operation:

% python3 findPDFs.py https://www.cs.odu.edu/~mweigle/courses/cs532/pdfs.html

URI: http://www.cs.odu.edu/~mln/pubs/ht-2015/hypertext-2015-temporal-violations.pdf
Final URI: https://www.cs.odu.edu/~mln/pubs/ht-2015/hypertext-2015-temporal-violations.pdf
Content Length: 2,184,076 bytes

URI: http://www.cs.odu.edu/~mln/pubs/tpdl-2015/tpdl-2015-annotations.pdf
Final URI: https://www.cs.odu.edu/~mln/pubs/tpdl-2015/tpdl-2015-annotations.pdf
Content Length: 622,981 bytes

Make sure that you have committed and pushed your local repo to GitHub. Your repo should contain any code you developed to answer the questions. Include "Ready to grade @weiglemc @brutushammerfist" in your final commit message.

Submit the URL of your report in Blackboard:

• Click on HW1 under Week 2 in Blackboard
• Under "Assignment Submission", click the "Write Submission" button.
• Copy/paste the URL of your report into the edit box
  • should be something like https://github.com/cs432-websci-fall20/hw1-websci-username/blob/master/HW1-report.{pdf,md}
• Make sure to "Submit" your assignment.