ovidiu 02/03/13 10:52:57
Added: src/scratchpad/schecoon/src/org/apache/cocoon/components/flow
Interpreter.java
Log:
Provides the interface between Cocoon and a scripting engine used for
the flow control.
Revision Changes Path
1.1
xml-cocoon2/src/scratchpad/schecoon/src/org/apache/cocoon/components/flow/Interpreter.java
Index: Interpreter.java
===================================================================
package org.apache.cocoon.components.flow;
import java.io.Reader;
import java.util.HashMap;
import org.apache.avalon.framework.parameters.Parameters;
import org.apache.avalon.framework.thread.ThreadSafe;
import org.apache.cocoon.components.treeprocessor.InvokeContext;
import org.apache.cocoon.environment.Environment;
/**
* The interface to the flow scripting languages. This interface is
* for a component, which implements the appropriate language to be
* used for describing the flow. A system could have multiple
* components that implement this interface, each of them for a
* different scripting language.
*
* <p>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.
*
* <p>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.
*
* <p>The component represented by this interface is called in three
* situations:
*
* <ul>
*
* <li>
*
* <p>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:
*
* <pre>
* <map:call function="..." language="..."/>
* </pre>
*
* <p>The <code>language</code> attribute can be ignored if the *
* default language is used.
*
* <li>
*
* <p>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.
*
* <p>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.
*
* <li>
*
* <p>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.
*
* </ul>
*
* @author <a href="mailto:[EMAIL PROTECTED]";>Ovidiu Predescu</a>
* @since March 11, 2002
* @see InterpreterSelector
*/
public interface Interpreter
{
public static String ROLE = "org.apache.cocoon.components.flow.Interpreter";
/**
* Load a script from Reader.
*
* @param in a <code>Reader</code> value
*/
void readScript(Reader in)
throws Exception;
/**
* This method is called from the sitemap, using the syntax
*
* <pre>
* <map:call function="..."/>
* </pre>
*
* 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. 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.
*
* <p>The current implementation assumes the sitemap implementation
* is TreeProcessor.
*
* @param funName a <code>String</code> value, the name of the
* function to call
* @param params a <code>Parameters</code> value, parameters to pass
* to the function. The interpretation of the parameters is left
* @param env an <code>Environment</code> value
* @param ctx an <code>InvokeContext</code> value
*/
void callFunction(String funName, Parameters params,
Environment env, InvokeContext ctx)
throws Exception;
/**
* Process a named pipeline defined using
* <code><map:resource/></code> in the sitemap.
*
* @param name a <code>String</code> value, the name of the pipeline
* (resource) in the sitemap.
* @param pipelineArgs a <code>HashMap</code> value, the arguments
* to be passed to the sitemap.
* @param bizData a <code>Object</code> value, the Java object or
* <code>null</code> which contains the business data to be passed
* to the generator of the pipeline (usually XSP or JSP).
*/
void processPipeline(String name, HashMap pipelineArgs, Object bizData)
throws Exception;
}
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