Using ColdFusion components
You can use a CFC in two ways:
You can instantiate a CFC object, which creates
a CFC instance. You then invoke the methods of the instance. You
can access the CFC methods and data as instance elements. You can
also use the instance in the cfinvoke tag to invoke the CFC methods.
When you instantiate a CFC, data in the CFC is preserved as long
as the CFC instance exists, and ColdFusion does not incur the overhead of
creating the instance each time you call a method.
Instantiate
CFCs to preserve data in the CFC. To ensure processing efficiency
if you use the CFC more than once on a page, instantiate the CFC
before you invoke its methods.
Methods that are executed remotely
through Flash Remoting and web services always create an instance
of the CFC before executing the method.
You can invoke (call) a method of the CFC without
creating an instance of the CFC, which is referred to as transiently invoking
a method. In this case, ColdFusion creates an instance of the CFC
that exists only from the time you invoke the method until the method
returns a result. No data is preserved between invocations and ColdFusion
does not keep an instance of the CFC that you can reuse elsewhere
in your CFML. It is considered a best practice to create an instance
of a CFC before invoking any of its methods, unless your CFML request
uses the CFC only once. If you transiently invoke a method frequently,
consider creating a user-defined function to replace the CFC method.
You can create persistent CFCs by assigning the CFC instance
to a persistent scope, such as the Session or Application scope.
This way, you can create CFCs for objects, such as shopping carts
or logged-in users, that must persist for sessions. You can also
create CFCs that provide application-specific data and methods.
