org.nebulaframework.deployment.classloading.node.exporter.GridNodeClassExporterImpl.java Source code

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Here is the source code for org.nebulaframework.deployment.classloading.node.exporter.GridNodeClassExporterImpl.java

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/*
 * Copyright (C) 2008 Yohan Liyanage. 
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); 
 * you may not use this file except in compliance with the License. 
 * You may obtain a copy of the License at 
 * http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS, 
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 * See the License for the specific language governing permissions and 
 * limitations under the License.
 */

package org.nebulaframework.deployment.classloading.node.exporter;

import java.io.IOException;
import java.io.InputStream;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.nebulaframework.deployment.classloading.service.ClassLoadingService;
import org.nebulaframework.util.io.IOSupport;

/**
 * Implementation of {@code GridNodeClassExporter},  that allows the local 
 * {@code GridNode} to export classes to worker {@code GridNode}s which
 * cannot load a required class locally, for a job submitted this local node. 
 * This is a remote enabled service, which runs on each {@code GridNode}.
 * <p>
 * This is done through the {@code ClassLoadingService}, which is implemented
 * as a remote service at the {@code ClusterManager}. When a worker node
 * requests a class from the {@code ClassLoadingService}, it calls the
 * {@link GridNodeClassExporter} service remotely, using a client proxy,
 * and attempts to obtain the class file. 
 * <p>
 * Note that visibility of this class is <b>default</b> (package private) scope.
 * This class is used by {@link GridNodeClassExporterSupport} class.
 * 
 * @author Yohan Liyanage
 * @version 1.0
 * 
 * @see GridNodeClassExporter
 * @see ClassLoadingService
 */
class GridNodeClassExporterImpl implements GridNodeClassExporter {

    private static Log log = LogFactory.getLog(GridNodeClassExporterImpl.class);

    /**
     * {@inheritDoc}
     */
    public byte[] exportClass(String name) throws ClassNotFoundException {
        try {

            // Build the physical class name
            String resName = "/" + name.replaceAll("\\.", "/") + ".class";

            // Attempt to get the input stream for the class file
            InputStream is = Class.forName(name).getResourceAsStream(resName);

            if (is == null) {
                log.warn("[GridNodeClassExporter] InputStream NULL : " + resName);
                throw new IOException("Error retreiving InputStream for Class file, NULL");
            }

            log.debug("[GridNodeClassExporter] Exporting " + name);
            return IOSupport.readBytes(is);
        } catch (IOException ex) {
            log.warn("Unable to export class due to IOException", ex);
            throw new ClassNotFoundException("Unable to export class due to IOException", ex);
        } catch (NullPointerException ex) {
            log.warn("Unable to locate class with in Node", ex);
            throw new ClassNotFoundException("Unable to locate class with in Node", ex);
        }
    }

}