User Guide

20 Chapter 2: Basic ColdFusion MX Administration
Client Variables page
Client variables let you store user information and preferences between sessions. Using
information from client variables, you can customize page content for individual users.
You enable client variable default settings in ColdFusion MX on the Client Variables page of the
Administrator. ColdFusion MX lets you store client variables in the following ways:
• In database tables
If your data source uses one of the JDBC drivers bundled with ColdFusion, ColdFusion can
automatically create the necessary tables. If your data source uses the ODBC Socket or a third-
party JDBC driver, you must manually create the necessary CDATA and CGLOBAL database
tables. For more information, see Developing ColdFusion MX Applications.
• As cookies in users’ web browsers
• In the operating system registry
Caution: Macromedia recommends that you do not store client variables in the registry because it
can critically degrade performance of the server. If you do use the registry to store client variables,
you must allocate sufficient memory and disk space.
You can override settings specified in the Client Variables page using the attributes of the
cfapplication tag. For more information, see Developing ColdFusion MX Applications.
The following table compares these storage options:
Storage type Advantages Disadvantages
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
Browser cookies • Simple implementation
• Good performance
• Can be set to expire automatically
• Client-side control
• Users can configure browsers to
disallow cookies
• Cookie data to is limited to 4 KB
• Netscape Navigator allows only 20
cookies from one host; ColdFusion MX
uses three cookies to store read-only
data, leaving only 17 cookies available
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 in Windows 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.