1. CSE 190: Internet E-Commerce Lecture 5

2. Exam Material Lectures 1-4 (Presentation Tier) –3-tier architecture –HTML –Style sheets –Javascript –DOM –HTTP –Web servers

3. Exam: 3-Tier Architecture What are the three tiers? Presentation: purpose of –Firewall –Cache –Load balancing server –Web server –How to recover from failure? Application Tier –How to recover from failure? Data Tier –Why can’t this be combined with application tier?

4. Exam: HTML Purpose; difference with other doc formats Structure of an HTML document General tag syntax Familiar with tags: html, head, body, H#, A, UL, OL, form, input, table, tr, td, br, img, center, frame, script Components of URL URL encoding ( url?arg1=ab+cd&arg2=ef%20 ) Difference between relative and absolute URL

5. Exam: Stylesheets Purpose What is meant by cascading? General CSS syntax Applying style to: –All tags of type X –All elements of class X Specify an external stylesheet, internal stylesheet, and inline style

6. Exam: Javascript Purpose How to include in a page Writing text to HTML page Declaring variables Declaring functions Returning a value Displaying an alert When the script executes

7. Exam: HTTP Status codes, classes of Purpose of: GET, POST, HEAD Syntax of: GET, POST Request fields: Host, Content-Length Response fields: Content-Type

8. Exam: Web Servers Purpose of Apache multi-client model Apache configuration: Purpose of –Port –DocumentRoot –ServerName –User HTTP authentication SSL Virtual Hosts CGI

9. Example Exam Questions (2 pts) Draw & explain the relationship between a load balancer and a cluster of web servers. (3 pts) Show the URL that represents a GET request for domain ucsd.edu and document /student/ski/home.asp with two arguments, task with value open and the second shibboleth with “ali baba” (no quotes). (3 pts) Explain two advantages of stylesheets over plain HTML. Write an HTML file that applies an internal style to all DIV tags such that the attribute font-size is 18.

10. Example Exam (cot’d) (3 pts) Write an HTML page that contains a form taking username and password and submits it to ucsd.edu/form.cgi using HTTPS. Onlookers may not view the password. (3 pts) Write HTML code that uses Javascript to write “Hello World!” to the browser window. (2 pts) Write a Javascript function that takes two numbers and returns their sum. (2 pts) Using Javascript to access the DOM, access the second form on the page and assign it to a variable.

11. Example Exam (cot’d) (3 pts) Show an HTTP/1.0 client send a request for a document hello.gif from an HTTP 1.1 server. Show both request and response headers. Indicate when the connection closes. (2 pts) What is the purpose of DocumentRoot in Apache’s configuration file (httpd.conf)? (2 pts) What happens to your web server if a hostile user crashes a child process? How does the parent recover? Are pages still served?