/*
* Copyright 2013 Red Hat, Inc. and/or its affiliates.
*
* 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.kie.api.executor;
/**
* Executor's Command are dedicated to contain purely business logic that should be executed.
* It should not have any reference to underlying process engine and should not be concerned
* with any process runtime related logic such us completing work item, sending signals, etc.
* <br>
* Information that are taken from process will be delivered as part of data instance of
* <code>CommandContext</code>. Depending on the execution context that data can vary but
* in most of the cases following will be given:
* <ul>
* <li></li>
* <li>businessKey - usually unique identifier of the caller</li>
* <li>callbacks - FQCN of the <code>CommandCollback</code> that shall be used on command completion</li>
* </ul>
* When executed as part of the process (work item handler) additional data can be expected:
* <ul>
* <li>workItem - the actual work item that is being executed with all it's parameters</li>
* <li>processInstanceId - id of the process instance that triggered this work</li>
* <li>deploymentId - if given process instance is part of an active deployment</li>
* </ul>
* Important note about implementations is that it shall always be possible to be initialized with default constructor
* as executor service is an async component so it will initialize the command on demand using reflection.
* In case there is a heavy logic on initialization it should be placed in another service implementation that
* can be looked up from within command.
*/
public interface Command {
/**
* Executed this command's logic.
* @param ctx - contextual data given by the executor service
* @return returns any results in case of successful execution
* @throws Exception in case execution failed and shall be retried if possible
*/
ExecutionResults execute(CommandContext ctx) throws Exception;
}