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/*
* 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.impl;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.List;
import java.util.Map;
import org.apache.tuscany.sca.databinding.DataBindingExtensionPoint;
import org.apache.tuscany.sca.databinding.DataPipe;
import org.apache.tuscany.sca.databinding.DataPipeTransformer;
import org.apache.tuscany.sca.databinding.Mediator;
import org.apache.tuscany.sca.databinding.PullTransformer;
import org.apache.tuscany.sca.databinding.PushTransformer;
import org.apache.tuscany.sca.databinding.TransformationContext;
import org.apache.tuscany.sca.databinding.TransformationException;
import org.apache.tuscany.sca.databinding.Transformer;
import org.apache.tuscany.sca.databinding.TransformerExtensionPoint;
import org.apache.tuscany.sca.interfacedef.DataType;
import org.apache.tuscany.sca.interfacedef.Operation;
import org.apache.tuscany.sca.interfacedef.impl.DataTypeImpl;
/**
* Default Mediator implementation
*
* @version $Rev$ $Date$
*/
public class MediatorImpl implements Mediator {
private DataBindingExtensionPoint dataBindings;
private TransformerExtensionPoint transformers;
public MediatorImpl(DataBindingExtensionPoint dataBindings, TransformerExtensionPoint transformers) {
this.dataBindings = dataBindings;
this.transformers = transformers;
}
@SuppressWarnings("unchecked")
public Object mediate(Object source, DataType sourceDataType, DataType targetDataType, Map<String, Object> metadata) {
if (sourceDataType == null || sourceDataType.getDataBinding() == null) {
if (source != null) {
Operation operation = (Operation) metadata.get("source.operation");
sourceDataType = dataBindings.introspectType(source, operation);
}
}
if (sourceDataType == null || targetDataType == null) {
return source;
} else if (sourceDataType.equals(targetDataType)) {
return source;
}
List<Transformer> path = getTransformerChain(sourceDataType, targetDataType);
Object result = source;
int size = path.size();
int i = 0;
while (i < size) {
Transformer transformer = path.get(i);
TransformationContext context =
createTransformationContext(sourceDataType, targetDataType, size, i, transformer, metadata);
// the source and target type
if (transformer instanceof PullTransformer) {
// For intermediate node, set data type to null
result = ((PullTransformer)transformer).transform(result, context);
} else if (transformer instanceof PushTransformer) {
DataPipeTransformer dataPipeFactory = (i < size - 1) ? (DataPipeTransformer)path.get(++i) : null;
DataPipe dataPipe = dataPipeFactory == null ? null : dataPipeFactory.newInstance();
((PushTransformer)transformer).transform(result, dataPipe.getSink(), context);
result = dataPipe.getResult();
}
i++;
}
return result;
}
private TransformationContext createTransformationContext(DataType sourceDataType,
DataType targetDataType,
int size,
int index,
Transformer transformer,
Map<String, Object> metadata) {
DataType sourceType =
(index == 0) ? sourceDataType : new DataTypeImpl<Object>(transformer.getSourceDataBinding(), Object.class,
sourceDataType.getLogical());
DataType targetType =
(index == size - 1) ? targetDataType : new DataTypeImpl<Object>(transformer.getTargetDataBinding(),
Object.class, targetDataType.getLogical());
//FIXME The ClassLoader should be passed in
// Allow privileged access to get ClassLoader. Requires RuntimePermission in security
// policy.
ClassLoader classLoader = AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
public ClassLoader run() {
return Thread.currentThread().getContextClassLoader();
}
});
TransformationContext context = new TransformationContextImpl(sourceType, targetType, classLoader, metadata);
return context;
}
@SuppressWarnings("unchecked")
public void mediate(Object source,
Object target,
DataType sourceDataType,
DataType targetDataType,
Map<String, Object> metadata) {
if (source == null) {
// Shortcut for null value
return;
}
if (sourceDataType == null || sourceDataType.getDataBinding() == null) {
Operation operation = (Operation) metadata.get("source.operation");
sourceDataType = dataBindings.introspectType(source, operation);
}
if (sourceDataType == null) {
return;
} else if (sourceDataType.equals(targetDataType)) {
return;
}
List<Transformer> path = getTransformerChain(sourceDataType, targetDataType);
Object result = source;
int size = path.size();
for (int i = 0; i < size; i++) {
Transformer transformer = path.get(i);
TransformationContext context =
createTransformationContext(sourceDataType, targetDataType, size, i, transformer, metadata);
if (transformer instanceof PullTransformer) {
result = ((PullTransformer)transformer).transform(result, context);
} else if (transformer instanceof PushTransformer) {
DataPipeTransformer dataPipeFactory = (i < size - 1) ? (DataPipeTransformer)path.get(++i) : null;
DataPipe dataPipe = dataPipeFactory == null ? null : dataPipeFactory.newInstance();
Object sink = dataPipe != null ? dataPipe.getSink() : target;
((PushTransformer)transformer).transform(result, sink, context);
result = (dataPipe != null) ? dataPipe.getResult() : null;
}
}
}
private List<Transformer> getTransformerChain(DataType sourceDataType, DataType targetDataType) {
String sourceId = sourceDataType.getDataBinding();
String targetId = targetDataType.getDataBinding();
List<Transformer> path = transformers.getTransformerChain(sourceId, targetId);
if (path == null) {
TransformationException ex =
new TransformationException("No path found for the transformation: " + sourceId + "->" + targetId);
ex.setSourceDataBinding(sourceId);
ex.setTargetDataBinding(targetId);
throw ex;
}
return path;
}
public DataBindingExtensionPoint getDataBindings() {
return dataBindings;
}
public TransformerExtensionPoint getTransformers() {
return transformers;
}
}
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