api/src/main/java/org/apache/edgent/topology/services/ApplicationService.java

/*
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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

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*/
package org.apache.edgent.topology.services;

import java.util.Set;

import org.apache.edgent.execution.Submitter;
import org.apache.edgent.function.BiConsumer;
import org.apache.edgent.topology.Topology;
import org.apache.edgent.topology.mbeans.ApplicationServiceMXBean;

import com.google.gson.JsonObject;

/**
 * A service that allows registration of applications and
 * the ability to submit them through a control MBean.
 *
 * @see ApplicationServiceMXBean
 */
public interface ApplicationService {
    
	/**
	 * Default alias a service registers its control MBean as.
	 * Value is {@value}.
	 */
    String ALIAS = "edgent";
    
    /**
     * Prefix ({@value}) reserved for system application names.
     */
    String SYSTEM_APP_PREFIX = "edgent";
    
    /**
     * Add a org.apache.edgent.org.apache.edgent.topology that can be started though a control mbean.
     * Any registration replaces any existing application with the same name.
     * <BR>
     * When a {@link ApplicationServiceMXBean#submit(String, String) submit}
     * is invoked {@code builder.accept(org.apache.edgent.org.apache.edgent.topology, config)} is called passing:
     * <UL>
     * <LI>
     * {@code org.apache.edgent.org.apache.edgent.topology} - An empty org.apache.edgent.org.apache.edgent.topology with the name {@code applicationName}.
     * </LI>
     * <LI>
     * {@code config} - JSON submission configuration from
     * {@link ApplicationServiceMXBean#submit(String, String) submit}.
     * </LI>
     * </UL>
     * Once {@code builder.accept(org.apache.edgent.org.apache.edgent.topology, config)} returns it is submitted
     * to the {@link Submitter} associated with the implementation of this service.
     * <P>
     * Application names starting with {@link #SYSTEM_APP_PREFIX edgent} are reserved
     * for system applications.
     * </P>
     * 
     * @param applicationName Application name to register.
     * @param builder How to build the org.apache.edgent.org.apache.edgent.topology for this application.
     * 
     * @see ApplicationServiceMXBean
     */
    void registerTopology(String applicationName, BiConsumer<Topology, JsonObject> builder);
    
    /**
     * Register a jar file containing new applications.
     * 
     * <p>Any {@link java.util.ServiceLoader service provider} 
     * within the jar of type {@link TopologyBuilder}
     * will be {@link #registerTopology(String, BiConsumer) registered}.
     * 
     * The jar cannot have any new dependencies, its classpath will
     * be the classpath of this service.
     * 
     * @param jarURL URL of Jar containing new applications.
     * @param jsonConfig JSON configuration serialized as a String (currently unused).
     * @throws Exception if failure
     * 
     * @see java.util.ServiceLoader
     */
    void registerJar(String jarURL, String jsonConfig) throws Exception;
    
    /**
     * Returns the names of applications registered with this service.
     * 
     * @return the names of applications registered with this service.
     */
    Set<String> getApplicationNames();
}