org.objectledge.web.mvc.builders
Class BuilderExecutorValve

java.lang.Object
  org.objectledge.web.mvc.builders.BuilderExecutorValve

All Implemented Interfaces:

Valve

public class BuilderExecutorValve
extends Object
implements Valve

Pipeline component for executing MVC view building.

The BuilderExecutorValve starts with a view name selected by the configured view request parameter (WebConfigurator.getViewToken()). This parameter has to be defined and if not an UndefinedViewParameterException is thrown. At the same time the view name must point to either an existing Builder class or an existing template. If none of these exists a MissingViewException is thrown. If either the template or a builder has been found, the view building starts.

For a given view name either a builder class or a template may be found using the defaulting strategy. This is useful for instance for applications having a set of different templates for presenting the same data. But be warned - defaulting may cause a lot of trouble and You should be aware of it.

If the builder is found it is given the possiblity to route the processing to another builder. This is a rarely used functionality and has been introduced for similarity with older web application frameworks. Routing changes the currently selected view name and forces a new builder and template lookup.

Having the either a builder or a template or both at the same time the build method of the builder is executed (missing builders and templates are replaced with DefaultBuilder and DefaultTemplate objects). Building creates a String represenation of view contents. The only exception is in case of a Builder which creates a direct response and writes it's content directly to the response (via HttpContext), in such case view processing is stopped.

Having the build results for a view, an enclosing view is looked up. The choice of the enclosing view is made upon:

• the EnclosingView object given by the current builder,
• or the choice made by the template designer using the ViewEnclosureTool,
• or by means of defaulting strategy executed using ViewFallbackSequence.

A detailed diagram of the enclosing view choice algorithm follows:

Version:

$Id: BuilderExecutorValve.java,v 1.36 2006/04/04 12:34:14 pablo Exp $

Author:

Damian Gajda

Field Summary

protected MVCClassFinder	classFinder Finder for builder objects.
protected Builder	defaultBuilder the default builder.
protected Template	defaultTemplate the default template.
protected int	maxEnclosures maximum number of builder enclosures.
protected int	maxRouteCalls maximum number of route calls per builder.
protected SecurityHelper	securityHelper SecurityHelper for access checking.
protected MVCTemplateFinder	templateFinder Finder for template objects.
protected ViewEnclosureManager	viewEnclosureManager ViewEnclosureManager for access template based view enclosures.

Constructor Summary

BuilderExecutorValve(Context context, MVCClassFinder classFinder, MVCTemplateFinder templateFinder, SecurityHelper securityHelper, ViewEnclosureManager viewEnclosureManager, int maxRouteCalls, int maxEnclosures)
Component constructor.

Method Summary

void	process(Context context) Run view building starting from a view builder chosen in request parameters.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

classFinder

protected MVCClassFinder classFinder

Finder for builder objects.

templateFinder

protected MVCTemplateFinder templateFinder

Finder for template objects.

securityHelper

protected SecurityHelper securityHelper

SecurityHelper for access checking.

viewEnclosureManager

protected ViewEnclosureManager viewEnclosureManager

ViewEnclosureManager for access template based view enclosures.

maxRouteCalls

protected int maxRouteCalls

maximum number of route calls per builder.

maxEnclosures

protected int maxEnclosures

maximum number of builder enclosures.

defaultBuilder

protected Builder defaultBuilder

the default builder.

defaultTemplate

protected Template defaultTemplate

the default template.

Constructor Detail

BuilderExecutorValve

public BuilderExecutorValve(Context context,
                            MVCClassFinder classFinder,
                            MVCTemplateFinder templateFinder,
                            SecurityHelper securityHelper,
                            ViewEnclosureManager viewEnclosureManager,
                            int maxRouteCalls,
                            int maxEnclosures)

Component constructor.

Parameters:

context - used application context

classFinder - finder for builder objects

templateFinder - finder for template objects

securityHelper - security helper for access checking

viewEnclosureManager - the template based enclosure manager

maxRouteCalls - maxmimal number of Builder.route(String) calls per Builder

maxEnclosures - maxmimal number of Builder enclosures (also Builder.getEnclosingView(String) calls)

Method Detail

process

public void process(Context context)
             throws ProcessingException

Run view building starting from a view builder chosen in request parameters.

Specified by:

process in interface Valve

Parameters:

context - the thread's processing context.

Throws:

ProcessingException - if the processing fails.