/*
* 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.brooklyn.core.resolve.entity;
import java.util.ServiceLoader;
import java.util.Set;
import javax.annotation.Nullable;
import org.apache.brooklyn.api.entity.EntitySpec;
import org.apache.brooklyn.api.mgmt.classloading.BrooklynClassLoadingContext;
import org.apache.brooklyn.core.mgmt.ManagementContextInjectable;
/**
* Resolves and decorates {@link EntitySpec entity specifications} based on the {@code serviceType} in a template.
* <p>
* The resolver implementation will use the rest of the local part of the service type information
* to create and decorate an appropriate {@link EntitySpec entity}.
* <p>
* The resolvers are loaded using the {@link ServiceLoader} mechanism, allowing external libraries
* to add extra service type implementations that will be picked up at runtime.
*/
public interface EntitySpecResolver extends ManagementContextInjectable {
/**
* Uniquely identifies the resolver, can be used to address the same resolver at a later point in time.
* For implementations: this usually matches the service type prefix, but not required.
*/
String getName();
/**
* @return if the resolver can create a spec for the service type
*/
boolean accepts(String type, BrooklynClassLoadingContext loader);
/**
* Create a spec for the service type
*
* @param type - the string representation which should be converted to an EntitySpec
* @param loader - use it to load any Java classes
* @param encounteredTypes - an immutable set of the items which are currently being resolved up the stack,
* used to prevent cycles. Implementations should not try to resolve the type if the symbolicName is
* already contained in here. When resolving a type add it to a copy of the list before
* passing the new instance down the stack. See {@link CatalogEntitySpecResolver} for example usage.
*
* @return The {@link EntitySpec} corresponding to the passed {@code type} argument, possibly pre-configured
* based on the information contained in {@code type}. Return {@code null} value to indicate that
* the implementation doesn't know how to convert {@code type} to an {@link EntitySpec}. Throw an
* exception if {@code type} looks like a supported value, but can't be loaded.
*/
@Nullable EntitySpec<?> resolve(String type, BrooklynClassLoadingContext loader, Set<String> encounteredTypes);
}