FlowServiceLocator


1   /*
2    * Copyright 2002-2006 the original author or authors.
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  package org.springframework.webflow.engine.builder;
17  
18  import org.springframework.beans.factory.BeanFactory;
19  import org.springframework.binding.convert.ConversionService;
20  import org.springframework.binding.expression.ExpressionParser;
21  import org.springframework.core.io.ResourceLoader;
22  import org.springframework.webflow.action.AbstractBeanInvokingAction;
23  import org.springframework.webflow.action.BeanInvokingActionFactory;
24  import org.springframework.webflow.engine.Flow;
25  import org.springframework.webflow.engine.FlowAttributeMapper;
26  import org.springframework.webflow.engine.FlowExecutionExceptionHandler;
27  import org.springframework.webflow.engine.State;
28  import org.springframework.webflow.engine.TargetStateResolver;
29  import org.springframework.webflow.engine.Transition;
30  import org.springframework.webflow.engine.TransitionCriteria;
31  import org.springframework.webflow.engine.ViewSelector;
32  import org.springframework.webflow.execution.Action;
33  
34  /**
35   * A support interface used by flow builders at configuration time. Acts as a
36   * "service locator" responsible for:
37   * <ol>
38   * <li> Retrieving dependent (but externally managed) flow services needed to
39   * configure flow and state definitions. Such services are usually hosted in a
40   * backing registry and may be shared by multiple flows.
41   * <li> Providing access to abstract factories to create core flow definitional
42   * artifacts such as {@link Flow}, {@link State}, {@link Transition}, and
43   * {@link AbstractBeanInvokingAction bean invoking actions}. These artifacts
44   * are unique to each flow and are typically not shared.
45   * </ol>
46   * <p>
47   * In general, implementations of this interface act as facades to accessing and
48   * creating flow artifacts during {@link FlowAssembler flow assembly}.
49   * <p>
50   * Finally, this interface also exposes access to generic infrastructure
51   * services also needed by flow assemblers such as a {@link ConversionService}
52   * and {@link ExpressionParser}.
53   * 
54   * @see org.springframework.webflow.engine.builder.FlowBuilder
55   * @see org.springframework.webflow.engine.builder.BaseFlowBuilder
56   * @see org.springframework.webflow.engine.builder.FlowAssembler
57   * 
58   * @author Keith Donald
59   * @author Erwin Vervaet
60   */
61  public interface FlowServiceLocator {
62  
63      /**
64       * Returns the Flow to be used as a subflow with the provided id.
65       * @param id the flow id
66       * @return the flow to be used as a subflow
67       * @throws FlowArtifactLookupException when no such flow is found
68       */
69      public Flow getSubflow(String   id) throws FlowArtifactLookupException;
70  
71      /**
72       * Retrieve an action to be executed within a flow with the assigned id.
73       * @param id the id of the action
74       * @throws FlowArtifactLookupException when no such action is found
75       */
76      public Action getAction(String   id) throws FlowArtifactLookupException;
77  
78      /**
79       * Returns the flow attribute mapper with the provided id. Flow attribute
80       * mappers are used from subflow states to map input and output attributes.
81       * @param id the attribute mapper id
82       * @return the attribute mapper
83       * @throws FlowArtifactLookupException when no such mapper is found
84       */
85      public FlowAttributeMapper getAttributeMapper(String   id) throws FlowArtifactLookupException;
86  
87      /**
88       * Returns the transition criteria to drive state transitions with the
89       * provided id.
90       * @param id the transition criteria id
91       * @return the transition criteria
92       * @throws FlowArtifactLookupException when no such criteria is found
93       */
94      public TransitionCriteria getTransitionCriteria(String   id) throws FlowArtifactLookupException;
95  
96      /**
97       * Returns the transition target state resolver with the specified id.
98       * @param id the target state resolver id
99       * @return the target state resolver
100      * @throws FlowArtifactLookupException when no such resolver is found
101      */
102     public TargetStateResolver getTargetStateResolver(String   id) throws FlowArtifactLookupException;
103 
104     /**
105      * Returns the view selector to make view selections in view states with the
106      * provided id.
107      * @param id the view selector id
108      * @return the view selector
109      * @throws FlowArtifactLookupException when no such selector is found
110      */
111     public ViewSelector getViewSelector(String   id) throws FlowArtifactLookupException;
112 
113     /**
114      * Returns the exception handler to handle flow execution exceptions with
115      * the provided id.
116      * @param id the exception handler id
117      * @return the exception handler
118      * @throws FlowArtifactLookupException when no such handler is found
119      */
120     public FlowExecutionExceptionHandler getExceptionHandler(String   id) throws FlowArtifactLookupException;
121 
122     /**
123      * Returns the factory for core flow artifacts such as Flow and State.
124      * @return the flow artifact factory
125      */
126     public FlowArtifactFactory getFlowArtifactFactory();
127 
128     /**
129      * Returns the factory for bean invoking actions.
130      * @return the bean invoking action factory
131      */
132     public BeanInvokingActionFactory getBeanInvokingActionFactory();
133 
134     /**
135      * Returns a generic bean (service) registry for accessing arbitrary beans.
136      * @return the generic service registry
137      * @throws UnsupportedOperationException when not supported by this locator
138      */
139     public BeanFactory getBeanFactory() throws UnsupportedOperationException  ;
140 
141     /**
142      * Returns a generic resource loader for accessing file-based resources.
143      * @return the generic resource loader
144      */
145     public ResourceLoader getResourceLoader();
146 
147     /**
148      * Returns the expression parser for parsing expression strings.
149      * @return the expression parser
150      */
151     public ExpressionParser getExpressionParser();
152 
153     /**
154      * Returns a generic type conversion service for converting between types,
155      * typically from string to a rich value object.
156      * @return the generic conversion service
157      */
158     public ConversionService getConversionService();
159 }
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