Package org.apache.commons.chain

Interface Context

All Superinterfaces:
Map<String,Object>
All Known Implementing Classes:
ContextBase, FacesWebContext, FacesWebContext, PortletWebContext, ServletWebContext, ServletWebContext, WebContext, WebContext
public interface Context extends Map<String,Object>
A Context represents the state information that is accessed and manipulated by the execution of a Command or a Chain. Specialized implementations of Context will typically add JavaBeans properties that contain typesafe accessors to information that is relevant to a particular use case for this context, and/or add operations that affect the state information that is saved in the context.

Implementations of Context must also implement all of the required and optional contracts of the java.util.Map interface.

It is strongly recommended, but not required, that JavaBeans properties added to a particular Context implementation exhibit Attribute-Property Transparency. In other words, a value stored via a call to setFoo(value) should be visible by calling get("foo"), and a value stored via a call to put("foo", value) should be visible by calling getFoo(). If your Context implementation class exhibits this feature, it becomes easier to reuse the implementation in multiple environments, without the need to cast to a particular implementation class in order to access the property getter and setter methods.

To protect applications from evolution of this interface, specialized implementations of Context should generally be created by extending the provided base class (ContextBase) rather than directly implementing this interface.

Applications should NOT assume that Context implementations, or the values stored in its attributes, may be accessed from multiple threads simultaneously unless this is explicitly documented for a particular implementation.

Version:
$Revision$ $Date$
Author:
Craig R. McClanahan