In this chapter, we discussed the Hypertext Transfer Protocol (HTTP) and several HTTP request types that specify how a client makes requests from a server. You learned that a three-tier application contains an information tier (also called the data tier or the bottom tier), a middle tier (also called the business logic), and a client tier (also called the top tier). We also discussed how a Web browser is able to locate documents on a Web server in response to client requests. You then learned how the Common Gateway Interface (CGI) enables applications to interact with Web servers and clients (e.g., Web browsers). We demonstrated how to write CGI scripts in C++ and presented CGI scripts that display the local time, display system environment variables, read data passed through the query string, and read data passed through an XHTML form. We also presented a case study that provides an interactive portal for the fictional Bug2Bug Travel Web site. This case study contains both static XHTML documents and CGI scripts that generate dynamic Web content. You learned how to use CGI scripts to read and write cookies to maintain state information. We then discussed using server-side files as another way to maintain state information. Finally, we presented a case study that controls user access using server-side files and tracks user purchases with a cookie-based shopping cart.
In the next chapter, we discuss the binary search algorithm and the merge sort algorithm. We also use Big O notation to analyze and compare the efficiency of various searching and sorting algorithms.