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Java > Open Source Codes > org > apache > lenya > workflow > Condition


1 /*
2  * Copyright 1999-2004 The Apache Software Foundation
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  *
16  */
17
18 /* $Id: Condition.java 42598 2004-03-01 16:18:28Z gregor $ */
19
20 package org.apache.lenya.workflow;
21
22 /**
23  * <p>A condition can prevent a transition from firing,
24  * based on the current situation. Examples:</p>
25  * <ul>
26  * <li>Does the current user have a certain role on the current URL?</li>
27  * <li>Does a certain state variable have a certain value (e.g., is the document published)? (BooleanVariableCondition)<li>
28  * <li>Is the sun shining? (e.g., if the weather report may only be published on sunny days)</li>
29  * </ul>
30  */
31 public interface Condition {
32
33     /**
34      * Returns if the condition is complied in a certain situation.
35      * @param situation The situation to check.
36      * @param instance The workflow instance to check the condition on.
37      * @return if the condition is complied.
38      * @throws WorkflowException when the expression could not be evaluated.
39      */
40     boolean isComplied(Situation situation, WorkflowInstance instance) throws WorkflowException;
41
42     /** Sets the expression for this condition.
43      * @param expression The expression.
44      * @throws WorkflowException when the expression is not valid.
45      */
46     void setExpression(String JavaDoc expression) throws WorkflowException;
47 }
48
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