INT21CN Computer Networks

Tutorial #20

Caution: Under Construction

1. The basis of Web commerce is dynamically-generated Web pages. What does this mean?

2. What is a shopping cart application?

3. What is meant by state maintenance in the context of a shopping cart application? What are the two major technologies which can be used to implement state maintenance?

4. What are some of the advantages of cookies over hidden fields? What disadvantages do they have?

5. Under what conditions is a cookie stored on a client system's local disk between "browser sessions"?

6. Discuss the security implications of cookies. In particular, if someone asked you whether it's safe to accept cookies from Web servers, what would you tell them, and why?

7. Many commercial sites, such as Amazon.com, put the session identifier in URL Extra Path Information. Explain the advantage this has over hidden field and cookie-based systems.

8. On many Web Commerce sites (for example, Amazon.com and The New York Times), cookies are used to authenticate repeated visits to the site. For example, if you have "shopped" at either of the above businesses, they will set a cookie so that you can subsequently "one-click" (or somesuch) to order. It's obviously important that no one else can generate your cookie, or they could impersonate you. How could this be implemented?

9. (Hard) What controls do the domain and path specifiers impose on when your browser sends a cookie to a server? In other words, how are the domain and path specifiers interpreted in the browser?

10. (Discussion question) There's obviously lots of potential for using Java and/or Javascript to build a shopping cart application which runs on the client (browser) instead of using FORMS and server-side code. Is this a good idea? Why, or why not?