Package org.apache.airavata.core.gfac.services.impl

Source Code of org.apache.airavata.core.gfac.services.impl.AbstractSimpleService

/*
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements.  See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership.  The ASF licenses this file
* to you 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.apache.airavata.core.gfac.services.impl;

import java.util.Map;
import java.util.Map.Entry;

import org.apache.airavata.core.gfac.context.invocation.InvocationContext;
import org.apache.airavata.core.gfac.exception.ExtensionException;
import org.apache.airavata.core.gfac.exception.GfacException;
import org.apache.airavata.core.gfac.exception.ServiceException;
import org.apache.airavata.core.gfac.extension.DataServiceChain;
import org.apache.airavata.core.gfac.extension.ExitableChain;
import org.apache.airavata.core.gfac.extension.PostExecuteChain;
import org.apache.airavata.core.gfac.extension.PreExecuteChain;
import org.apache.airavata.core.gfac.provider.Provider;
import org.apache.airavata.core.gfac.scheduler.Scheduler;
import org.apache.airavata.core.gfac.services.GenericService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
* The abstract service wraps up steps of execution for {@link GenericService}. Also, it adds input/output plug-ins
* before/after {@link Provider} execution. <br/>
* The steps in execution are <br/>
* - preProcess <br/>
* - Determine Provider (Scheduling) <br/>
* - {@link DataServiceChain} Plugins <br/>
* - {@link Provider} initialization <br/>
* - {@link PreExecuteChain} Plugins <br/>
* - {@link Provider} execution <br/>
* - {@link PostExecuteChain} Plugins <br/>
* - {@link Provider} disposal <br/>
* - postProcess <br/>
* Users who wants built in notification in to their service has to implement this class
*/
public abstract class AbstractSimpleService implements GenericService {

    private static Logger log = LoggerFactory.getLogger(AbstractSimpleService.class);

    public abstract void preProcess(InvocationContext context) throws ServiceException;

    public abstract void postProcess(InvocationContext context) throws ServiceException;

    public abstract Scheduler getScheduler(InvocationContext context) throws ServiceException;

    public abstract PreExecuteChain[] getPreExecutionSteps(InvocationContext context) throws ServiceException;

    public abstract PostExecuteChain[] getPostExecuteSteps(InvocationContext context) throws ServiceException;

    public abstract DataServiceChain[] getDataChains(InvocationContext context) throws ServiceException;

    public final void execute(InvocationContext context) throws GfacException {

        log.debug("Before preprocess");

        /*
         * Pre-Process
         */
        preProcess(context);

        log.debug("After preprocess, try to get Scheduler and schedule");

        /*
         * Determine provider
         */
        Scheduler scheduler = getScheduler(context);
        context.getExecutionContext().getNotifier().startSchedule(context);
        Provider provider = scheduler.schedule(context);
        context.getExecutionContext().getNotifier().finishSchedule(context);

        log.debug("After scheduling, try to run data chain");

        /*
         * Load data necessary data
         */
        buildChains(getDataChains(context)).start(context);

        log.debug("After data chain, try to init provider");

        /*
         * Init
         */
        provider.initialize(context);

        log.debug("After provider initialization, try to run pre-execution chain");

        /*
         * Pre-Execution
         */
        buildChains(getPreExecutionSteps(context)).start(context);

        log.debug("After pre-execution chain, try to execute provider");

        try {
            /*
             * Execute
             */
            Map<String, ?> result = provider.execute(context);

            log.debug("After provider execution, try to run post-execution chain");

            /*
             * Fill MessageContext with the output from Provider
             */
            for (Entry<String, ?> entry : result.entrySet()) {
                context.getOutput().setValue(entry.getKey(), entry.getValue());
            }

            /*
             * Post-Execution
             */
            buildChains(getPostExecuteSteps(context)).start(context);

            log.debug("After pre-execution chain, try to dispose provider");

        } finally {
            /*
             * Destroy
             */
            provider.dispose(context);

            log.debug("After provider disposal, try to run postprocess");
        }

        /*
         * Pre-Process
         */
        postProcess(context);

        log.debug("After postprocess");
    }

    private ExitableChain buildChains(ExitableChain[] list) {

        /*
         * Validation check and return doing-nothing chain object
         */
        if (list == null || list.length == 0) {
            return new NullChain();
        }

        ExitableChain currentPoint = list[0];
        for (int i = 1; i < list.length; i++) {
            currentPoint = currentPoint.setNext(list[i]);
        }
        return currentPoint;
    }

    /**
     * Inner class for no chain
     */
    private static class NullChain extends ExitableChain {
        @Override
        protected boolean execute(InvocationContext context) throws ExtensionException {
            return true;
        }
    }

}
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