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Diffstat (limited to 'openecomp-be/lib/openecomp-core-lib/openecomp-facade-lib/openecomp-facade-api/src/main/java/org/openecomp/core/factory/api/AbstractFactory.java')
-rw-r--r-- | openecomp-be/lib/openecomp-core-lib/openecomp-facade-lib/openecomp-facade-api/src/main/java/org/openecomp/core/factory/api/AbstractFactory.java | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/openecomp-be/lib/openecomp-core-lib/openecomp-facade-lib/openecomp-facade-api/src/main/java/org/openecomp/core/factory/api/AbstractFactory.java b/openecomp-be/lib/openecomp-core-lib/openecomp-facade-lib/openecomp-facade-api/src/main/java/org/openecomp/core/factory/api/AbstractFactory.java new file mode 100644 index 0000000000..53b8f00fc0 --- /dev/null +++ b/openecomp-be/lib/openecomp-core-lib/openecomp-facade-lib/openecomp-facade-api/src/main/java/org/openecomp/core/factory/api/AbstractFactory.java @@ -0,0 +1,81 @@ +/*- + * ============LICENSE_START======================================================= + * SDC + * ================================================================================ + * Copyright (C) 2017 AT&T Intellectual Property. All rights reserved. + * ================================================================================ + * 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. + * ============LICENSE_END========================================================= + */ + +package org.openecomp.core.factory.api; + +import org.openecomp.core.factory.impl.AbstractFactoryBase; + +/** + * This class provides generic implementation of an abstract factory. Components exposed as Java + * interfaces should have their own concrete factories derived from the given class. This assures + * code alignment and consistency across all Service Management components. + * The class actually + * uses singleton pattern to instantiate and reuse just one instance of a factory. Therefore, each + * factory implementation has to be <i>thread-safe</i>. + * In a general case, the hierarchy of + * factory objects for an Java interface <tt>IUknown</tt> may look as follows: + * <pre> + * AbstractFactory<IUnknown> + * ^ + * | + * Application code ----> ConcreteFactory + * ^ + * | + * +---------+---------+ + * | | + * BaselineFactoryImpl CustomFactoryImpl + * </pre> + * Where the classes responsibility is: <ul> <li>Abstract factory - common logic to retrieve the + * implementation class name from a central repository.</li> <li>Concrete factory - abstract class + * that only exposes to application layer the type specific API such as: <ul> <li><tt>public static + * ConcreteFactory getInstance()</tt></li> </ul> <li>Baseline factory - out of the box + * implementation of concrete factory (that can be replaced by a custom one depending on customer + * needs) which actually implements method: <ul> <li><tt>public IUnknown createInterface()</tt></li> + * </ul> </ul> The normal concrete factory class may look like: + * <pre> + * public abstract class ConcreteFactory extends AbstractFactory<IUnknown> { + * static { + * registerFactory(ConcreteFactory.class, BaselineFactoryImpl.class); + * } + * public static ConcreteFactory getInstance() { + * return AbstractFactory.<IUnknown, ConcreteFactory.class>getInstance(ConcreteFactory.class); + * } + * } + * </pre> + * + * @param <I> Java interface type created by the factory. + */ +public abstract class AbstractFactory<I> extends AbstractFactoryBase { + + + /** + * Returns the interface implementor instance. + * <b>Note</b>: It's up to the concrete factory to decide on the actual + * implementation of the returned interface. Therefore, the call can get the + * same instance per each call in case of singleton implementation or new + * instance otherwise. However, the API consumer may not assume anything + * regarding the underlying logic and has always go through the factory to + * obtain the reference. + * + * @return Implementor of the exposed Java interface. + */ + public abstract I createInterface(); + +} // End of class |