/*
* org.openmicroscopy.shoola.util.concur.tasks.ResultAssembler
*
*------------------------------------------------------------------------------
* Copyright (C) 2006 University of Dundee. All rights reserved.
*
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
*------------------------------------------------------------------------------
*/
package org.openmicroscopy.shoola.util.concur.tasks;
//Java imports
//Third-party libraries
//Application-internal dependencies
/**
* Defines a contract between the {@link CmdProcessor} and a class that
* provides a specific way to assemble computatation results from partial
* results.
* <p>You might want to implement this interface when you break down a
* computation into steps (by using an {@link Invocation} chain or a
* {@link MultiStepTask}) and need to implement a custom algorithm to
* assemble the partial results of each step into the final result of the
* computation.</p>
* <p>The {@link CmdProcessor} calls the {@link #add(Object) add} method at
* the end of each step, passing the partial result computed by that step.
* The order of the calls to the {@link #add(Object) add} method is the same
* as the order in which the partial results are produced. After the last
* step has been performed, the {@link CmdProcessor} calls the
* {@link #assemble() assemble} method, which has to return the final result
* of the computation — however, this method is never called in the case
* an exception is raised during the computation or the computation is
* cancelled.</p>
* <p>Calls to the {@link #add(Object) add}/{@link #assemble() assemble} method
* are dispatched <i>within the same thread that executes the computation</i>,
* so they can never overlap. However, keep in mind that, in general, the
* computation is executed in a thread different from the one that triggered
* execution by invoking one of the <code>exec</code> methods.
* </p>
*
* @author Jean-Marie Burel
* <a href="mailto:j.burel@dundee.ac.uk">j.burel@dundee.ac.uk</a>
* @author <br>Andrea Falconi
* <a href="mailto:a.falconi@dundee.ac.uk">
* a.falconi@dundee.ac.uk</a>
* @version 2.2
* <small>
* (<b>Internal version:</b> $Revision$ $Date$)
* </small>
* @since OME2.2
*/
public interface ResultAssembler
{
/**
* Called at the end of each step in the computation, passing the
* <code>partialResult</code> computed by that step.
*
* @param partialResult The partial result just computed.
*/
public void add(Object partialResult);
/**
* Called after the last step in the computation has been performed,
* this method has to return the final result of the computation.
* This is usually done by assembling all partial results into a
* single object.
*
* @return The result of the computation.
*/
public Object assemble();
}