1. A method for automatic configuration of a portal composite application comprising a portal composite application infrastructure, wherein configuration parameters are managed within a composite application interface of the portal, wherein the interface defines a runtime behavior of instances of the composite application within a predetermined range of variability, and wherein each parameter defines a respective point of variability, the method comprising: storing a collection of parameter values for each of the points of variability; defining a policy infrastructure including a plurality of policies cooperating with the composite application via a rules engine and having read access to the collection of parameter values defined by the policies; invoking the rules engine containing a plurality of rules after or at instantiation time of the composite application, in response to an identification of a parameter definition in an application template, for selecting a best matching policy in the policy infrastructure; applying the best matching policy to yield a configuration parameter value; including the configuration parameter value into a control for an instance of the composite application; automatically configuring the instance of the composite application with the included configuration parameter value; updating at least one policy in the policy infrastructure based on an updated parameter value; and updating, in response to the updating of the at least one policy, the rules in the rules engine and the instance of the composite application, to reflect the updated parameter value.