001: /*
002: * Copyright 2002-2006 the original author or authors.
003: *
004: * Licensed under the Apache License, Version 2.0 (the "License");
005: * you may not use this file except in compliance with the License.
006: * You may obtain a copy of the License at
007: *
008: * http://www.apache.org/licenses/LICENSE-2.0
009: *
010: * Unless required by applicable law or agreed to in writing, software
011: * distributed under the License is distributed on an "AS IS" BASIS,
012: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013: * See the License for the specific language governing permissions and
014: * limitations under the License.
015: */
016:
017: package org.springframework.beans.factory.parsing;
018:
019: import org.springframework.beans.BeanMetadataElement;
020: import org.springframework.beans.factory.config.BeanDefinition;
021: import org.springframework.beans.factory.config.BeanReference;
022:
023: /**
024: * Interface that describes the logical view of a set of {@link BeanDefinition BeanDefinitions}
025: * and {@link BeanReference BeanReferences} as presented in some configuration context.
026: *
027: * <p>With the introduction of {@link org.springframework.beans.factory.xml.NamespaceHandler pluggable custom XML tags},
028: * it is now possible for a single logical configuration entity, in this case an XML tag, to
029: * create multiple {@link BeanDefinition BeanDefinitions} and {@link BeanReference RuntimeBeanReferences}
030: * in order to provide more succinct configuration and greater convenience to end users. As such, it can
031: * no longer be assumed that each configuration entity (e.g. XML tag) maps to one {@link BeanDefinition}.
032: * For tool vendors and other users who wish to present visualization or support for configuring Spring
033: * applications it is important that there is some mechanism in place to tie the {@link BeanDefinition BeanDefinitions}
034: * in the {@link org.springframework.beans.factory.BeanFactory} back to the configuration data in a way
035: * that has concrete meaning to the end user. As such, {@link org.springframework.beans.factory.xml.NamespaceHandler}
036: * implementations are able to publish events in the form of a <code>ComponentDefinition</code> for each
037: * logical entity being configured. Third parties can then {@link org.springframework.beans.factory.parsing.ReaderEventListener subscribe to these events},
038: * allowing for a user-centric view of the bean metadata.
039: *
040: * <p>Each <code>ComponentDefinition</code> has a {@link #getSource source object} which is configuration-specific.
041: * In the case of XML-based configuration this is typically the {@link org.w3c.dom.Node} which contains the user
042: * supplied configuration information. In addition to this, each {@link BeanDefinition} enclosed in a
043: * <code>ComponentDefinition</code> has its own {@link BeanDefinition#getSource() source object} which may point
044: * to a different, more specific, set of configuration data. Beyond this, individual pieces of bean metadata such
045: * as the {@link org.springframework.beans.PropertyValue PropertyValues} may also have a source object giving an
046: * even greater level of detail. Source object extraction is handled through the
047: * {@link org.springframework.beans.factory.parsing.SourceExtractor} which can be customized as required.
048: *
049: * <p>Whilst direct access to important {@link BeanReference BeanReferences} is provided through
050: * {@link #getBeanReferences}, tools may wish to inspect all {@link BeanDefinition BeanDefinitions} to gather
051: * the full set of {@link BeanReference BeanReferences}. Implementations are required to provide
052: * all {@link BeanReference BeanReferences} that are required to validate the configuration of the
053: * overall logical entity as well as those required to provide full user visualisation of the configuration.
054: * It is expected that certain {@link BeanReference BeanReferences} will not be important to
055: * validation or to the user view of the configuration and as such these may be ommitted. A tool may wish to
056: * display any additional {@link BeanReference BeanReferences} sourced through the supplied
057: * {@link BeanDefinition BeanDefinitions} but this is not considered to be a typical case.
058: *
059: * <p>Tools can determine the important of contained {@link BeanDefinition BeanDefinitions} by checking the
060: * {@link BeanDefinition#getRole role identifier}. The role is essentially a hint to the tool as to how
061: * important the configuration provider believes a {@link BeanDefinition} is to the end user. It is expected
062: * that tools will <strong>not</strong> display all {@link BeanDefinition BeanDefinitions} for a given
063: * <code>ComponentDefinition</code> choosing instead to filter based on the role. Tools may choose to make
064: * this filtering user configurable. Particular notice should be given to the
065: * {@link BeanDefinition#ROLE_INFRASTRUCTURE INFRASTRUCTURE role identifier}. {@link BeanDefinition BeanDefinitions}
066: * classified with this role are completely unimportant to the end user and are required only for
067: * internal implementation reasons.
068: *
069: * @author Rob Harrop
070: * @author Juergen Hoeller
071: * @since 2.0
072: * @see AbstractComponentDefinition
073: * @see CompositeComponentDefinition
074: * @see BeanComponentDefinition
075: * @see ReaderEventListener#componentRegistered(ComponentDefinition)
076: */
077: public interface ComponentDefinition extends BeanMetadataElement {
078:
079: /**
080: * Get the user-visible name of this <code>ComponentDefinition</code>.
081: * <p>This should link back directly to the corresponding configuration data
082: * for this component in a given context.
083: */
084: String getName();
085:
086: /**
087: * Return a friendly description of the described component.
088: * <p>Implementations are encouraged to return the same value from
089: * <code>toString()</code>.
090: */
091: String getDescription();
092:
093: /**
094: * Return the {@link BeanDefinition BeanDefinitions} that were registered
095: * to form this <code>ComponentDefinition</code>.
096: * <p>It should be noted that a <code>ComponentDefinition</code> may well be related with
097: * other {@link BeanDefinition BeanDefinitions} via {@link BeanReference references},
098: * however these are <strong>not</strong> included as they may be not available immediately.
099: * Important {@link BeanReference BeanReferences} are available from {@link #getBeanReferences()}.
100: * @return the array of BeanDefinitions, or an empty array if none
101: */
102: BeanDefinition[] getBeanDefinitions();
103:
104: /**
105: * Return the {@link BeanDefinition BeanDefinitions} that represent all relevant
106: * inner beans within this component.
107: * <p>Other inner beans may exist within the associated {@link BeanDefinition BeanDefinitions},
108: * however these are not considered to be needed for validation or for user visualization.
109: * @return the array of BeanDefinitions, or an empty array if none
110: */
111: BeanDefinition[] getInnerBeanDefinitions();
112:
113: /**
114: * Return the set of {@link BeanReference BeanReferences} that are considered
115: * to be important to this <code>ComponentDefinition</code>.
116: * <p>Other {@link BeanReference BeanReferences} may exist within the associated
117: * {@link BeanDefinition BeanDefinitions}, however these are not considered
118: * to be needed for validation or for user visualization.
119: * @return the array of BeanReferences, or an empty array if none
120: */
121: BeanReference[] getBeanReferences();
122:
123: }
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