providers/direct/src/main/java/org/apache/edgent/providers/direct/DirectProvider.java

/*
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,
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"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
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*/
package org.apache.edgent.providers.direct;

import java.util.concurrent.Future;

import org.apache.edgent.execution.DirectSubmitter;
import org.apache.edgent.execution.Job;
import org.apache.edgent.execution.services.ControlService;
import org.apache.edgent.execution.services.ServiceContainer;
import org.apache.edgent.runtime.jsoncontrol.JsonControlService;
import org.apache.edgent.topology.Topology;
import org.apache.edgent.topology.TopologyProvider;
import org.apache.edgent.topology.spi.AbstractTopologyProvider;

import com.google.gson.JsonObject;

/**
 * {@code DirectProvider} is a {@link TopologyProvider} that
 * runs a submitted org.apache.edgent.org.apache.edgent.topology as a {@link Job} in threads
 * in the current virtual machine.
 * <P> 
 * A job (execution of a org.apache.edgent.org.apache.edgent.topology) continues to execute
 * while any of its elements have remaining work,
 * such as any of the org.apache.edgent.org.apache.edgent.topology's source streams are capable
 * of generating tuples.
 * <BR>
 * "Endless" source streams never terminate - e.g., a stream
 * created by {@link Topology#generate(org.apache.edgent.function.Supplier) generate()},
 * {@link Topology#poll(org.apache.edgent.function.Supplier, long, java.util.concurrent.TimeUnit) poll()},
 * or {@link Topology#events(org.apache.edgent.function.Consumer) events()}.
 * Hence a job with such sources runs until either it or some other
 * entity terminates it.
 * </P>
 */
public class DirectProvider extends AbstractTopologyProvider<DirectTopology>
        implements DirectSubmitter<Topology, Job> {

    private final ServiceContainer services;
    
    public DirectProvider() {
        this.services = new ServiceContainer();
        
        getServices().addService(ControlService.class, new JsonControlService());
    }

    /**
     * {@inheritDoc}
     * <P>
     * The returned services instance is shared
     * across all jobs submitted to this provider. 
     * </P>
     */
    @Override
    public ServiceContainer getServices() {
        return services;
    }

    @Override
    public DirectTopology newTopology(String name) {
        checkName(name);
        return new DirectTopology(name, services);
    }

    @Override
    public Future<Job> submit(Topology topology) {
        return submit(topology, new JsonObject());
    }
    
    @Override
    public Future<Job> submit(Topology topology, JsonObject config) {
        return ((DirectTopology) topology).executeCallable(config);
    }
}