A flow script defines what is the page flow in an interactive Web application. Usually the flow is defined in a high level programming language which provides the notion of continuations, which allows for the flow of the application to be described as a simple procedural program, without having to think about the application as a finite state machine which changes its internal state on each HTTP request from the client browser.
However an implementation may choose to use its own representation of an application, which may include XML representations of finite state machines. Note: this API has no provision for such implementations.
The component represented by this interface is called in three situations:
From the sitemap, to invoke a top level function defined in a * given implementation language of the flow. This is done from the * sitemap using the construction:
<map:call function="..." language="..."/>
The language
attribute can be ignored if the default language is used.
From the sitemap, to continue a previously started computation. A previously started computation is saved in the form of a continuation inside the flow implementation language.
This case is similar with the above one, but the function invoked has a special name, specific to each language implementation. See the language implementation for more information on the function name and the arguments it receives.
From a program in the flow layer. This is done to invoke a pipeline defined in the sitemap, to generate the response of the request.
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