Adobe 38043740 - ColdFusion Standard - Mac Development Manual page 307

DEVELOPING COLDFUSION 9 APPLICATIONS
Developing CFML Applications
Variable scope Description
Client Contains variables that are available for a single client browser over multiple browser sessions in an application.
For information about browser sessions, see,
Useful for client-specific information, such as client preferences, that you want to store for a significant period of
time.
Data is stored as cookies, database entries, or Registry values. Client variables can time out after an extended
period.
Although do not have to use the Client scope prefix in the variable name, code that uses the prefix is more
efficient and easier to maintain.
Session Contains variables that are available for a single client browser for a single browser session in an application.
Useful for client-specific information, such as shopping cart contents, that you want to persist while the client is
visiting your application.
Data is stored in memory and times out after a period of inactivity or when the server shuts down.
ColdFusion Administrator lets you select between two kinds of session management, Standard ColdFusion
Session management and J2EE session management. For information about types of session management, see
"ColdFusion and J2EE session
Use the Session scope prefix in the variable name.
Application Contains variables that are available to all pages in an application for all clients.
Useful for application-specific information, such as contact information, that can vary over time and should be
stored in a variable.
Data is stored in memory and times out after a period of inactivity or when the server shuts down.
Use the Application scope prefix in the variable name.
Server Contains variables that are available to all applications in a server and all clients.
Useful for information that applies to all pages on the server, such as an aggregate page-hit counter.
Data is stored in memory. The variables do not time out, but you can delete variables you create, and all server
variables are automatically deleted when the server stops running.
Use the Server scope prefix in the variable name.
The following sections provide information that is common to all or several of these variables. Later sections describe
how to use the Client, Session, Application, and Server scopes in your applications, and provide detailed information
about locking code.
ColdFusion persistent variables and ColdFusion structures
All persistent scopes are available as ColdFusion structures. As a result, you can use ColdFusion structure functions to
access and manipulate Client, Session, Application, and Server scope contents. Information about using these
functions in detail is not covered, but information about features or limitations that apply to specific scopes is
provided.
Note: Although you can use the
delete the names of the variables, only their values, and it does not delete the contents of the Server.os and
Server.ColdFusion structures. Using the
scope, including the built-in variables. Using the
the server memory, but does not delete the stored copies of the variables.
management" on page 312.
function to clear your data from the Server scope, the function does not
StructClear
function to clear the Session, or Application scope clears the entire
StructClear
StructClear
Last updated 1/20/2012
"What is a session?" on page 311.
function to clear the Client scope clears the variables from
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