Java Doc for RequestContext.java in  » Workflow-Engines » spring-webflow-1.0.4 » org » springframework » webflow » execution » Java Source Code / Java DocumentationJava Source Code and Java Documentation

The term request is used to describe a single call (thread) into the flow system by an external actor to manipulate exactly one flow execution.

A new instance of this object is typically created when one of the core operations supported by a flow execution is invoked, either start to launch the flow execution, signalEvent to resume the flow execution, or refresh to reconstitute the flow execution's last view selection for purposes of reissuing a user response.

Once created this context object is passed around throughout flow execution request processing where it may be accessed and reasoned upon by SWF-internal artifacts such as states, user-implemented action code, and state transition criteria.

When a call into a flow execution returns this object goes out of scope and is disposed of automatically. Thus a request context is an internal artifact used within a FlowExecution: this object is not exposed to external client code, e.g. a view implementation (JSP).

The RequestContext.getRequestScope() requestScope property may be used as a store for arbitrary data that should exist for the life of this object. Request-scoped data, along with all data in RequestContext.getFlashScope() flash scope , RequestContext.getFlowScope() flow scope and RequestContext.getConversationScope() conversation scope is available for exposing to view templates via a RequestContext.getModel() model property.

The web flow system will ensure that a RequestContext object is local to the current thread. It can be safely manipulated without needing to worry about concurrent access.

Note: this request context is in no way linked to an HTTP or Portlet request. It uses the familiar "request" naming convention to indicate a single call to manipulate a runtime execution of a flow definition.
author:
   Keith Donald
author:
   Erwin Vervaet

Acting as a facade, the returned context object provides a single point of access to the calling client's environment.

Acting as a facade, the returned context object provides a single point of access to the calling client's environment. It provides normalized access to attributes of the client environment without tying you to specific constructs within that environment.

In addition, this context may be downcastable to a specific context type for a specific client environment, such as a org.springframework.webflow.context.servlet.ServletExternalContext for servlets or a org.springframework.webflow.context.portlet.PortletExternalContext for portlets. Such downcasting will give you full access to a native HttpServletRequest, for example. With that said, for portability reasons you should avoid coupling your flow artifacts to a specific deployment environment when possible. the originating external context, the one that triggered thecurrent execution request

This is typically a convenient shortcut for accessing the ExternalContext.getRequestParameterMap directly.
See Also:   RequestContext.getExternalContext()