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org.apache.tuscany.sca.databinding.DefaultTransformerExtensionPoint Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.tuscany.sca.databinding;
import java.io.IOException;
import java.lang.reflect.Constructor;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.apache.tuscany.sca.core.ExtensionPointRegistry;
import org.apache.tuscany.sca.databinding.impl.DirectedGraph;
import org.apache.tuscany.sca.extensibility.ServiceDeclaration;
import org.apache.tuscany.sca.extensibility.ServiceDiscovery;
/**
* @version $Rev: 830738 $ $Date: 2009-10-28 19:29:50 +0000 (Wed, 28 Oct 2009) $
*/
public class DefaultTransformerExtensionPoint implements TransformerExtensionPoint {
private static final Logger logger = Logger.getLogger(DefaultTransformerExtensionPoint.class.getName());
private boolean loadedTransformers;
private ExtensionPointRegistry registry;
private final DirectedGraph graph = new DirectedGraph();
public DefaultTransformerExtensionPoint(ExtensionPointRegistry registry) {
this.registry = registry;
}
public void addTransformer(String sourceType, String resultType, int weight, Transformer transformer, boolean publicTransformer) {
if (logger.isLoggable(Level.FINE)) {
String className = transformer.getClass().getName();
boolean lazy = false;
boolean pull = (transformer instanceof PullTransformer);
if (transformer instanceof LazyPullTransformer) {
className = ((LazyPullTransformer)transformer).transformerDeclaration.getClassName();
lazy = true;
}
if (transformer instanceof LazyPushTransformer) {
className = ((LazyPushTransformer)transformer).transformerDeclaration.getClassName();
lazy = true;
}
logger.fine("Adding transformer: " + className
+ ";source="
+ sourceType
+ ",target="
+ resultType
+ ",weight="
+ weight
+ ",type="
+ (pull ? "pull" : "push")
+ ",lazy="
+ lazy);
}
graph.addEdge(sourceType, resultType, transformer, weight, publicTransformer);
}
public void addTransformer(Transformer transformer, boolean publicTransformer) {
addTransformer(transformer.getSourceDataBinding(),
transformer.getTargetDataBinding(),
transformer.getWeight(),
transformer, publicTransformer);
}
public boolean removeTransformer(String sourceType, String resultType) {
return graph.removeEdge(sourceType, resultType);
}
public Transformer getTransformer(String sourceType, String resultType) {
loadTransformers();
DirectedGraph.Edge edge = graph.getEdge(sourceType, resultType);
return (edge == null) ? null : edge.getValue();
}
/**
* Dynamically load transformers registered under META-INF/services.
*
*/
private synchronized void loadTransformers() {
if (loadedTransformers) {
return;
}
loadedTransformers = true;
loadTransformers(PullTransformer.class);
loadTransformers(PushTransformer.class);
}
/**
* Dynamically load transformers registered under META-INF/services.
*
* @param transformerClass
*/
private synchronized void loadTransformers(Class transformerClass) {
// Get the transformer service declarations
Collection transformerDeclarations;
try {
transformerDeclarations = registry.getServiceDiscovery().getServiceDeclarations(transformerClass.getName());
} catch (IOException e) {
throw new IllegalStateException(e);
}
// Load transformers
for (ServiceDeclaration transformerDeclaration : transformerDeclarations) {
Map attributes = transformerDeclaration.getAttributes();
String source = attributes.get("source");
String target = attributes.get("target");
int weight = Integer.valueOf(attributes.get("weight"));
String b = attributes.get("public");
boolean pub = true;
if (b != null) {
pub = Boolean.valueOf(b);
}
// Create a transformer wrapper and register it
Transformer transformer;
if (transformerClass == PullTransformer.class) {
transformer = new LazyPullTransformer(source, target, weight, transformerDeclaration);
} else {
transformer = new LazyPushTransformer(source, target, weight, transformerDeclaration);
}
addTransformer(transformer, pub);
}
}
/**
* A transformer facade allowing transformers to be lazily loaded
* and initialized.
*/
private class LazyPullTransformer implements PullTransformer {
private String source;
private String target;
private int weight;
private ServiceDeclaration transformerDeclaration;
private PullTransformer transformer;
public LazyPullTransformer(String source, String target, int weight, ServiceDeclaration transformerDeclaration) {
this.source = source;
this.target = target;
this.weight = weight;
this.transformerDeclaration = transformerDeclaration;
}
/**
* Load and instantiate the transformer class.
*
* @return The transformer.
*/
@SuppressWarnings("unchecked")
private PullTransformer getTransformer() {
if (transformer == null) {
try {
Class> transformerClass =
(Class>)transformerDeclaration.loadClass();
try {
Constructor> constructor = transformerClass.getConstructor();
transformer = constructor.newInstance();
} catch (NoSuchMethodException e) {
Constructor> constructor =
transformerClass.getConstructor(ExtensionPointRegistry.class);
transformer = constructor.newInstance(registry);
}
} catch (Exception e) {
throw new IllegalStateException(e);
}
}
return transformer;
}
public String getSourceDataBinding() {
return source;
}
public String getTargetDataBinding() {
return target;
}
public int getWeight() {
return weight;
}
public Object transform(Object source, TransformationContext context) {
return getTransformer().transform(source, context);
}
@Override
public String toString() {
StringBuffer sb = new StringBuffer(super.toString());
sb.append(";className=").append(transformerDeclaration.getClassName());
return sb.toString();
}
}
/**
* A transformer facade allowing transformers to be lazily loaded
* and initialized.
*/
private class LazyPushTransformer implements PushTransformer {
private String source;
private String target;
private int weight;
private ServiceDeclaration transformerDeclaration;
private PushTransformer transformer;
public LazyPushTransformer(String source, String target, int weight, ServiceDeclaration transformerDeclaration) {
this.source = source;
this.target = target;
this.weight = weight;
this.transformerDeclaration = transformerDeclaration;
}
/**
* Load and instantiate the transformer class.
*
* @return The transformer.
*/
@SuppressWarnings("unchecked")
private PushTransformer getTransformer() {
if (transformer == null) {
try {
Class> transformerClass =
(Class>)transformerDeclaration.loadClass();
try {
Constructor> constructor = transformerClass.getConstructor();
transformer = constructor.newInstance();
} catch (NoSuchMethodException e) {
Constructor> constructor =
transformerClass.getConstructor(ExtensionPointRegistry.class);
transformer = constructor.newInstance(registry);
}
} catch (Exception e) {
throw new IllegalStateException(e);
}
}
return transformer;
}
public String getSourceDataBinding() {
return source;
}
public String getTargetDataBinding() {
return target;
}
public int getWeight() {
return weight;
}
public void transform(Object source, Object sink, TransformationContext context) {
getTransformer().transform(source, sink, context);
}
@Override
public String toString() {
StringBuffer sb = new StringBuffer(super.toString());
sb.append(";className=").append(transformerDeclaration.getClassName());
return sb.toString();
}
}
//FIXME The following methods should be on a different class from
// extension point
public List getTransformerChain(String sourceType, String resultType) {
loadTransformers();
String source = sourceType;
String result = resultType;
List transformers = new ArrayList();
// First check if there is a direct path, if yes, use it regardless of the weight
DirectedGraph.Edge link = graph.getEdge(sourceType, resultType);
if (link != null) {
transformers.add(link.getValue());
} else {
DirectedGraph.Path path = graph.getShortestPath(source, result);
if (path == null) {
return null;
}
for (DirectedGraph.Edge edge : path.getEdges()) {
transformers.add(edge.getValue());
}
}
return transformers;
}
@Override
public String toString() {
loadTransformers();
return graph.toString();
}
}
