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/* 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.activiti.engine.delegate;

import org.activiti.engine.history.HistoricVariableUpdate;
import org.activiti.engine.impl.interceptor.Command;
import org.activiti.engine.impl.persistence.entity.VariableInstance;

import java.util.Collection;
import java.util.Map;
import java.util.Set;

/**
 * Interface for class that acts as a scope for variables: i.e. the implementation
 * can be used to set and get variables.
 * 
 * Typically, executions (and thus process instances) and tasks are the primary use case
 * to get and set variables. The {@link DelegateExecution} for example is often used
 * in {@link JavaDelegate} implementation to get and set variables.
 * 
 * Variables are typically stored on the 'highest parent'. For executions, this
 * means that when called on an execution the variable will be stored on the process instance
 * execution. Variables can be stored on the actual scope itself though, by calling the xxLocal methods.
 * 


 */
public interface VariableScope {

  /**
   * Returns all variables. 
   * This will include all variables of parent scopes too. 
   */
  Map getVariables();
  
  /**
   * Returns all variables, as instances of the {@link VariableInstance} interface,
   * which gives more information than only the the value (type, execution id, etc.)
   */
  Map getVariableInstances();
  
  /**
   * Similar to {@link #getVariables()}, but limited to only the variables with the provided names.
   */
  Map getVariables(Collection variableNames);
  
  /**
   * Similar to {@link #getVariableInstances()}, but limited to only the variables with the provided names.
   */
  Map getVariableInstances(Collection variableNames);

  /**
   * Similar to {@link #getVariables(Collection))}, but with a flag that indicates that all 
   * variables should be fetched when fetching the specific variables.
   *  
   * If set to false, only the specific variables will be fetched.
   * Dependening on the use case, this can be better for performance, as it avoids fetching and processing 
   * the other variables. However, if the other variables are needed further on, getting them in
   * one go is probably better (and the variables are cached during one {@link Command} execution).
   */
  Map getVariables(Collection variableNames, boolean fetchAllVariables);
  
  /**
   * Similar to {@link #getVariables(Collection, boolean)} but returns the variables 
   * as instances of the {@link VariableInstance} interface,
   * which gives more information than only the the value (type, execution id, etc.)
   */
  Map getVariableInstances(Collection variableNames, boolean fetchAllVariables);

  /**
   * Returns the variable local to this scope only.
   * So, in contrary to {@link #getVariables()}, the variables from the parent scope won't be returned. 
   */
  Map getVariablesLocal();
  
  /**
   * Returns the variables local to this scope as instances of the {@link VariableInstance} interface,
   * which provided additional information about the variable.
   */
  Map getVariableInstancesLocal();

  /**
   * Similar to {@link #getVariables(Collection)}, but only for variables local to this scope.
   */
  Map getVariablesLocal(Collection variableNames);
  
  /**
   * Similar to {@link #getVariableInstances(Collection)}, but only for variables local to this scope.
   */
  Map getVariableInstancesLocal(Collection variableNames);

  /**
   * Similar to {@link #getVariables(Collection, boolean)}, but only for variables local to this scope.
   */
  Map getVariablesLocal(Collection variableNames, boolean fetchAllVariables);
  
  /**
   * Similar to {@link #getVariableInstances(Collection, boolean)}, but only for variables local to this scope.
   */
  Map getVariableInstancesLocal(Collection variableNames, boolean fetchAllVariables);

  /**
   * Returns the variable value for one specific variable.
   * Will look in parent scopes when the variable does not exist on this particular scope. 
   */
  Object getVariable(String variableName);
  
  /**
   * Similar to {@link #getVariable(String)}, but returns a {@link VariableInstance} instance,
   * which contains more information than just the value. 
   */
  VariableInstance getVariableInstance(String variableName);

  /**
   * Similar to {@link #getVariable(String)}, but has an extra flag that indicates whether or not 
   * all variables need to be fetched when getting one variable.
   * 
   * By default true (for backwards compatibility reasons), which means that calling {@link #getVariable(String)}
   * will fetch all variables, of the current scope and all parent scopes.
   * Setting this flag to false can thus be better for performance. However, variables are cached, and 
   * if other variables are used later on, setting this true might actually be better for performance.
   */
  Object getVariable(String variableName, boolean fetchAllVariables);
  
  /**
   * Similar to {@link #getVariable(String, boolean)}, but returns an instance of {@link VariableInstance}, 
   * which has some additional information beyond the value. 
   */
  VariableInstance getVariableInstance(String variableName, boolean fetchAllVariables);

  /**
   * Returns the value for the specific variable and only checks this scope and not any parent scope.
   */
  Object getVariableLocal(String variableName);
  
  /**
   * Similar to {@link #getVariableLocal(String)}, but returns an instance of {@link VariableInstance}, 
   * which has some additional information beyond the value. 
   */
  VariableInstance getVariableInstanceLocal(String variableName);

  /**
   * Similar to {@link #getVariableLocal(String)}, but has an extra flag that indicates whether or not 
   * all variables need to be fetched when getting one variable.
   * 
   * By default true (for backwards compatibility reasons), which means that calling {@link #getVariableLocal(String)}
   * will fetch all variables, of the current scope.
   * Setting this flag to false can thus be better for performance. However, variables are cached, and 
   * if other variables are used later on, setting this true might actually be better for performance.
   */
  Object getVariableLocal(String variableName, boolean fetchAllVariables);
  
  /**
   * Similar to {@link #getVariableLocal(String, boolean)}, but returns an instance of {@link VariableInstance}, 
   * which has some additional information beyond the value.
   */
  VariableInstance getVariableInstanceLocal(String variableName, boolean fetchAllVariables);

  /**
   * Typed version of the {@link #getVariable(String)} method. 
   */
   T getVariable(String variableName, Class variableClass);

  /**
   * Typed version of the {@link #getVariableLocal(String)} method.
   */
   T getVariableLocal(String variableName, Class variableClass);

  /**
   * Returns all the names of the variables for this scope and all parent scopes. 
   */
  Set getVariableNames();

  /**
   * Returns all the names of the variables for this scope (no parent scopes).
   */
  Set getVariableNamesLocal();

  /**
   * Sets the variable with the provided name to the provided value.
   * 
   * 

* A variable is set according to the following algorithm: * *

*

  • If this scope already contains a variable by the provided name as a * local variable, its value is overwritten to the provided * value.
  • *
  • If this scope does not contain a variable by the * provided name as a local variable, the variable is set to this scope's * parent scope, if there is one. If there is no parent scope (meaning this * scope is the root scope of the hierarchy it belongs to), this scope is * used. This applies recursively up the parent scope chain until, if no scope * contains a local variable by the provided name, ultimately the root scope * is reached and the variable value is set on that scope.
  • *

    * In practice for most cases, this algorithm will set variables to the scope * of the execution at the process instance’s root level, if there is no * execution-local variable by the provided name. * * @param variableName * the name of the variable to be set * @param value * the value of the variable to be set */ void setVariable(String variableName, Object value); /** * Similar to {@link #setVariable(String, Object)}, but with an extra flag to indicate whether * all variables should be fetched while doing this or not. * * The variable will be put on the highest possible scope. For an execution this is the process instance execution. * If this is not wanted, use the {@link #setVariableLocal(String, Object)} method instead. * * The default (e.g. when calling {@link #setVariable(String, Object)}), is true, for backwards * compatibility reasons. However, in some use cases, it might make sense not to fetch any other variables * when setting one variable (for example when doing nothing more than just setting one variable). */ void setVariable(String variableName, Object value, boolean fetchAllVariables); /** * Similar to {@link #setVariable(String, Object)}, but the variable is set to this scope specifically. */ Object setVariableLocal(String variableName, Object value); /** * Similar to {@link #setVariableLocal(String, Object, boolean)}, but the variable is set to this scope specifically. */ Object setVariableLocal(String variableName, Object value, boolean fetchAllVariables); /** * Sets the provided variables to the variable scope. * *

    * Variables are set according algorithm for {@link #setVariable(String, Object)}, applied separately to each variable. * * @param variables * a map of keys and values for the variables to be set */ void setVariables(Map variables); /** * Similar to {@link #setVariables(Map)}, but the variable are set on this scope specifically. */ void setVariablesLocal(Map variables); /** * Returns whether this scope or any parent scope has variables. */ boolean hasVariables(); /** * Returns whether this scope has variables. */ boolean hasVariablesLocal(); /** * Returns whether this scope or any parent scope has a specific variable. */ boolean hasVariable(String variableName); /** * Returns whether this scope has a specific variable. */ boolean hasVariableLocal(String variableName); /** * Removes the variable and creates a new;@link HistoricVariableUpdateEntity} */ void removeVariable(String variableName); /** * Removes the local variable and creates a new {@link HistoricVariableUpdate}. */ void removeVariableLocal(String variableName); /** * Removes the variables and creates a new * {@link HistoricVariableUpdate} for each of them. */ void removeVariables(Collection variableNames); /** * Removes the local variables and creates a new * {@link HistoricVariableUpdate} for each of them. */ void removeVariablesLocal(Collection variableNames); /** * Removes the (local) variables and creates a new * {@link HistoricVariableUpdate} for each of them. */ void removeVariables(); /** * Removes the (local) variables and creates a new * {@link HistoricVariableUpdate} for each of them. */ void removeVariablesLocal(); /** * Similar to {@link #setVariable(String, Object)}, but the variable is transient: * * - no history is kept for the variable * - the variable is only available until a waitstate is reached in the process * - transient variables 'shadow' persistent variable (when getVariable('abc') * where 'abc' is both persistent and transient, the transient value is returned. */ void setTransientVariable(String variableName, Object variableValue); /** * Similar to {@link #setVariableLocal(String, Object)}, but for a transient variable. * See {@link #setTransientVariable(String, Object)} for the rules on 'transient' variables. */ void setTransientVariableLocal(String variableName, Object variableValue); /** * Similar to {@link #setVariables(Map)}, but for transient variables. * See {@link #setTransientVariable(String, Object)} for the rules on 'transient' variables. */ void setTransientVariables(Map transientVariables); /** * Similar to {@link #getVariable(String)}, including the searching via the parent scopes, but * for transient variables only. * See {@link #setTransientVariable(String, Object)} for the rules on 'transient' variables. */ Object getTransientVariable(String variableName); /** * Similar to {@link #getVariables()}, but for transient variables only. * See {@link #setTransientVariable(String, Object)} for the rules on 'transient' variables. */ Map getTransientVariables(); /** * Similar to {@link #setVariablesLocal(Map)}, but for transient variables. * See {@link #setTransientVariable(String, Object)} for the rules on 'transient' variables. */ void setTransientVariablesLocal(Map transientVariables); /** * Similar to {@link #getVariableLocal(String)}, but for a transient variable. * See {@link #setTransientVariable(String, Object)} for the rules on 'transient' variables. */ Object getTransientVariableLocal(String variableName); /** * Similar to {@link #getVariableLocal(String)}, but for transient variables only. * See {@link #setTransientVariable(String, Object)} for the rules on 'transient' variables. */ Map getTransientVariablesLocal(); /** * Removes a specific transient variable (also searching parent scopes). * See {@link #setTransientVariable(String, Object)} for the rules on 'transient' variables. */ void removeTransientVariableLocal(String variableName); /** * Removes a specific transient variable. * See {@link #setTransientVariable(String, Object)} for the rules on 'transient' variables. */ void removeTransientVariable(String variableName); /** * Remove all transient variable of this scope and its parent scopes. * See {@link #setTransientVariable(String, Object)} for the rules on 'transient' variables. */ void removeTransientVariables(); /** * Removes all local transient variables. * See {@link #setTransientVariable(String, Object)} for the rules on 'transient' variables. */ void removeTransientVariablesLocal(); }





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