CA fairly common pattern in JSF is for container components to temporarily set up context that is available while processing children - eg. UIData sets up the "var" value before executing child lifecycle methods. In Trinidad and ADF Faces we have a variety of components that establish similar context.
An issue with this is that there is no way to unwind/suspend this context in cases where it is necessary to interrupt processing in order to start over in a new context - eg. when invokeOnComponent() or visitTree() is called.
Trinidad has solved this problem via its ComponentContextManager API. See:
This provides a common mechanism that components can use for pushing/popping/suspending their context and allows for new invokeOnComponent()/visitTree() calls to be initiated in a clean environment.
In addition, Trinidad's UIXComponent provides a number of hooks to assist components with their context setup/teardown.
One problem with Trinidad's solution is that it only applies to Trinidad-based components. Ideally this problem should be solved by the JSF specification in a generic manner so that all components can participate.