core/api/src/main/java/org/apache/zest/api/unitofwork/concern/UnitOfWorkPropagation.java

/*
 * Copyright (c) 2008, Edward Yakop. All Rights Reserved.
 * Copyright (c) 2009, Niclas Hedhman. 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.
 *
 */
package org.apache.zest.api.unitofwork.concern;

import java.lang.annotation.Documented;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

/**
 * Annotation to denote the unit of work propagation.
 * <p>
 * Usage example:
 * </p>
 * <pre>
 * <code>
 *
 * &#64;Concerns( UnitOfWorkConcern.class )
 * public class MyBusinessServiceMixin implements BusinessService
 * {
 *   &#64;Structure UnitOfWorkFactory uowf;
 *
 *   &#64;UnitOfWorkPropagation
 *   public void myBusinessMethod()
 *   {
 *     // Must invoke current unit of work.
 *     UnitOfWork uow = uowf.currentUnitOfWork();
 *
 *     // Perform business logic
 *   }
 * }
 * </code>
 * </pre>
 */
@Retention( RUNTIME )
@Target( METHOD )
@Inherited
@Documented
public @interface UnitOfWorkPropagation
{
    Propagation value() default Propagation.REQUIRED;

    String usecase() default "";

    /**
     * Propagation behaviors.
     */
    enum Propagation
    {
        /**
         * Default propagation behavior.
         * Behavior: <br>
         * If no current transaction: creates a new UnitOfWork <br>
         * If there is a current UnitOfWork: use the current UnitOfWork.
         */
        REQUIRED,

        /**
         * Behavior: <br>
         * If no current UnitOfWork: throw an exception <br>
         * If there is a current UnitOfWork: use the current UnitOfWork.
         */
        MANDATORY,

        /**
         * Behavior: <br>
         * If no current UnitOfWork: creates a new UnitOfWork <br>
         * If there is a current UnitOfWork: suspend the current UnitOfWork and create a new UnitOfWork.
         */
        REQUIRES_NEW
    }
}