Web Database Applications with PHP & MySQL
April 24, 2002
|
Web Database Applications with PHP and MySQL offers web developers
a mixture of theoretical and practical information on creating web
database applications. Using PHP, and MySQL, two open source
technologies the are often combined to develop web applications,
the book offers detailed information on designing relational
databases and on web application architecture, both of which
will be useful to readers who have never dealt with these issues
before. The book also introduces Hugh and Dave's Online Wine Store,
a complete (but fictional) online retail site implemented using
PHP and MySQL.
|
Chapter 8
Sessions
A fundamental characteristic of the Web is the stateless interaction
between browsers and web servers. As discussed in Chapter 1, HTTP is a
stateless protocol. Each HTTP request a browser sends to a web server is
independent of any other request. The stateless nature of HTTP allows users to
browse the Web by following hypertext links and visiting pages in any order.
HTTP also allows applications to distribute or even replicate content across
multiple servers to balance the load generated by a high number of requests.
These features are possible because of the stateless nature of HTTP.
This stateless nature suits applications that allow users to browse or
search collections of documents. However, applications that require complex
user interaction can't be implemented as a series of unrelated, stateless web
pages. An often-cited example is a shopping cart in which items are added to
the cart while searching or browsing a catalog. The state of the shopping
cart--the selected items--needs to be stored somewhere. When the user requests
the order page, the items for that user need to be displayed.
Stateful web database applications can be built using sessions,
and session management is the topic of this chapter. In this chapter we:
- Discuss how sessions are managed in the stateless environment of the Web
and introduce the three characteristics of server-side session management
- Introduce cookies for storing state
- Show how to use and configure the PHP session management library
- Use PHP session management to improve the client entry
<form> in the winestore case study
- Provide a brief list of reasons for using, or avoiding, session
management over the Web
The focus of this chapter is on the session management provided by PHP.
However, other techniques to keep state are briefly discussed, including the
use of cookies.
Web Database Applications with PHP & MySQL
Building Applications That Keep State - Page 2
|
