All Known Implementing Classes:
    AbstractInterpreter, CompilingInterpreter, SchemeInterpreter, JavaScriptInterpreter, FOM_JavaScriptInterpreter, ApplesProcessor, JavaInterpreter

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.

author: < - a href="mailto:ovidiu@cup.hp.com">Ovidiu Predescu

since: March - 11, 2002

version: CVS - $Id: Interpreter.java 433543 2006-08-22 06:22:54Z crossley $

 public  void callFunction(String funName,
    List params,
    Redirector redirector) throws Exception
This method is called from the sitemap, using the syntax

<map:call function="..."/>


The method will execute the named function, which must be defined
in the given language. There is no assumption made on how various
arguments are passed to the function.

The params argument is a List object
that contains Interpreter.Argument instances,
representing the parameters to be passed to the called
function. An Argument instance is a key-value pair,
where the key is the name of the parameter, and the value is its
desired value. Most languages will ignore the name value and
simply pass to the function, in a positional order, the values of
the argument. Some languages however can pass the arguments in a
different order than the original prototype of the function. For
these languages the ability to associate the actual argument with
a formal parameter using its name is essential.

A particular language implementation may decide to put the
environment, request, response etc. objects in the dynamic scope
available to the function at the time of the call. Other
implementations may decide to pass these as arguments to the
called function.

The current implementation assumes the sitemap implementation
is TreeProcessor.

 public  void forwardTo(String uri,
    Object bizData,
    WebContinuation continuation,
    Redirector redirector) throws Exception
Forward the request to a Cocoon pipeline.

 public String getInterpreterID()

 public  void handleContinuation(String continuationId,
    List params,
    Redirector redirector) throws Exception
Continues a previously started processing. The continuation
object where the processing should start from is indicated by the
continuationId string.

 public  void setInterpreterID(String interpreterID)
Set the unique ID for this interpreter.