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72 Chapter 5 Basic ColdFusion Server Administration
Client Variables
Client variables let you perform tasks like determining the IP address of a site
visitor’s Web browser. Using information from client variables, you can customize
page content for individual users.
You enable client variable default settings in ColdFusion Server on the Client
Variables page of the Administrator. ColdFusion Server lets you store client variables
in these ways:
•
The operating system registry
•
As cookies in users’ Web browsers
•
In a data source.
Note
You can override settings specified in the Client Variables page using the attributes of
the
cfapplication
tag. For more information, see the Developing ColdFusion
Applications book.
The following table compares these storage options:
Storage Type Advantage Disadvantage
System registry
•
Simple implementation
•
Good performance
•
Registry can be exported
easily to other systems
•
Server-side control
•
Possible restriction of the
registry’s maximum size limit on
Windows NT and WIndows 2000
in the Control Panel
•
Integrated with the host system:
not practical for clustered servers
•
Solaris, Linux, and HP-UX
registries are text files. Their
registries deliver slow
performance and low scalability.
Browser cookies
•
Simple implementation
•
Good performance
•
Can be set to expire
automatically
•
Client-side control
•
Users can configure browsers to
disallow cookies
•
ColdFusion Server limits a
cookie’s data to 4 KB
•
Netscape Navigator allows only
20 cookies from one host;
ColdFusion Server uses three
cookies to store read-only data,
leaving only 17 cookies available
Data source
•
Can use existing data
source
•
Portable: not tied to the
host system or operating
system
•
Requires database transaction to
read/write variables
•
More complex to implement
install.book Page 72 Thursday, May 10, 2001 12:59 PM