Contents > Developing ColdFusion MX Applications > Building and Using ColdFusion Components > About ColdFusion components > ColdFusion component features and use CFC invocation and instantiation

CFC invocation and instantiation

There are two ways to use a CFC:

• You can invoke (call) a method of the CFC transiently. In this case, you do not create an instance of the CFC object that you can reuse elsewhere in your CFML. Instead, the CFC instance exists only from the time you invoke the method until the method returns. No data is preserved between invocations. Code that is outside all cffunction definitions executes at each transient invocation.

  Invoke a CFC method transiently if your CFML request uses the CFC only once. Also, if you transiently invoke a CFC method frequently, consider creating a user defined function to replace the CFC method.

• You can instantiate a CFC object. This is called instantiating the CFC or creating 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.

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.

ColdFusion provides many ways to instantiate CFCs and invoke CFC methods. For detailed information, see Using ColdFusion components.

Contents > Developing ColdFusion MX Applications > Building and Using ColdFusion Components > About ColdFusion components > ColdFusion component features and use CFC invocation and instantiation

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