Package org.apache.tuscany.sca.implementation.spring

Source Code of org.apache.tuscany.sca.implementation.spring.SpringArtifactProcessor

/*
* 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.implementation.spring;

import static javax.xml.stream.XMLStreamConstants.END_ELEMENT;

import javax.xml.namespace.QName;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.XMLStreamWriter;

import org.apache.tuscany.sca.assembly.AssemblyFactory;
import org.apache.tuscany.sca.assembly.ComponentType;
import org.apache.tuscany.sca.assembly.xml.Constants;
import org.apache.tuscany.sca.contribution.ModelFactoryExtensionPoint;
import org.apache.tuscany.sca.contribution.processor.StAXArtifactProcessor;
import org.apache.tuscany.sca.contribution.resolver.ModelResolver;
import org.apache.tuscany.sca.contribution.service.ContributionReadException;
import org.apache.tuscany.sca.contribution.service.ContributionResolveException;
import org.apache.tuscany.sca.contribution.service.ContributionWireException;
import org.apache.tuscany.sca.contribution.service.ContributionWriteException;
import org.apache.tuscany.sca.implementation.spring.xml.SpringXMLComponentTypeLoader;
import org.apache.tuscany.sca.interfacedef.java.JavaInterfaceFactory;
import org.apache.tuscany.sca.policy.PolicyFactory;

/**
* SpringArtifactProcessor is responsible for processing the XML of an <implementation.spring.../>
* element in an SCA SCDL file.
*
* @version $Rev: 511195 $ $Date: 2007-02-24 02:29:46 +0000 (Sat, 24 Feb 2007) $
*/
public class SpringArtifactProcessor implements StAXArtifactProcessor<SpringImplementation> {

    private static final String LOCATION = "location";
    private static final String IMPLEMENTATION_SPRING = "implementation.spring";
    private static final QName IMPLEMENTATION_SPRING_QNAME = new QName(Constants.SCA10_TUSCANY_NS, IMPLEMENTATION_SPRING);
    private static final String MSG_LOCATION_MISSING = "Reading implementation.spring - location attribute missing";

    private AssemblyFactory assemblyFactory;
    private JavaInterfaceFactory javaFactory;
    private PolicyFactory policyFactory;
   
    public SpringArtifactProcessor(ModelFactoryExtensionPoint modelFactories) {
        this.assemblyFactory = modelFactories.getFactory(AssemblyFactory.class);
        this.javaFactory = modelFactories.getFactory(JavaInterfaceFactory.class);
        this.policyFactory = modelFactories.getFactory(PolicyFactory.class);
    }

    /*
     * Read the XML and parse out the attributes.
     *
     * <implementation.spring.../> has a single required attribute:
     * "location" - which is the target URI of of an archive file or a directory that contains the Spring
     * application context files.
     * If the resource identified by the location attribute is an archive file, then the file
     * META-INF/MANIFEST.MF is read from the archive.
     * If the location URI identifies a directory, then META-INF/MANIFEST.MF must exist
     * underneath that directory.
     * If the manifest file contains a header "Spring-Context" of the format:
     *    Spring-Context ::= path ( ';' path )*
     *   
     * Where path is a relative path with respect to the location URI, then the set of paths
     * specified in the header identify the context configuration files.
     * If there is no MANIFEST.MF file or no Spring-Context header within that file,
     * then the default behaviour is to build an application context using all the *.xml files
     * in the METAINF/spring directory.
     */
    public SpringImplementation read(XMLStreamReader reader) throws ContributionReadException {

        try {
            /* Read the location attribute for the spring implementation  */
            String springLocation = reader.getAttributeValue(null, LOCATION);
            if (springLocation == null) {
                throw new ContributionReadException(MSG_LOCATION_MISSING);
            }
            /* Create the Spring implementation and set the location into it */
            SpringImplementation springImplementation = new SpringImplementation();
            springImplementation.setSpringLocation(springLocation);

            // Skip to end element
            while (reader.hasNext()) {
                if (reader.next() == END_ELEMENT && IMPLEMENTATION_SPRING_QNAME.equals(reader.getName())) {
                    break;
                }
            } // end while

            processComponentType(springImplementation);

            return springImplementation;

        } catch (XMLStreamException e) {
            throw new ContributionReadException(e);
        }
    } // end read

    /*
     * Handles the component type for the Spring implementation
     * @param springImplementation - a Spring implementation.  The component type information
     * is created for this implementation
     * 
     */
    private void processComponentType(SpringImplementation springImplementation) {

        // Create a ComponentType and mark it unresolved
        ComponentType componentType = assemblyFactory.createComponentType();
        componentType.setUnresolved(true);
        springImplementation.setComponentType(componentType);
    } // end processComponentType

    /*
     * Write out the XML representation of the Spring implementation
     * <implementation.spring location="..." />
     */
    public void write(SpringImplementation springImplementation, XMLStreamWriter writer)
        throws ContributionWriteException {
        try {

            writer.writeStartElement(Constants.SCA10_NS, IMPLEMENTATION_SPRING);
            if (springImplementation.getSpringLocation() != null) {
                writer.writeAttribute(LOCATION, springImplementation.getSpringLocation());
            }
            writer.writeEndElement();

        } catch (XMLStreamException e) {
            throw new ContributionWriteException(e);
        }
    } // end write

    /**
     * Resolves the Spring implementation - loads the Spring application-context XML and
     * derives the spring implementation componentType from it
     */
    public void resolve(SpringImplementation springImplementation, ModelResolver resolver)
        throws ContributionResolveException {

        /* Load the Spring component type by reading the Spring application context */
        SpringXMLComponentTypeLoader springLoader =
            new SpringXMLComponentTypeLoader(assemblyFactory, javaFactory, policyFactory);
        try {
            // Load the Spring Implementation information from its application context file...
            springLoader.load(springImplementation);
        } catch (ContributionReadException e) {
            throw new ContributionResolveException(e);
        }

        ComponentType ct = springImplementation.getComponentType();
        if (ct.isUnresolved()) {
            // If the introspection fails to resolve, try to find a side file...
            ComponentType componentType = resolver.resolveModel(ComponentType.class, ct);
            if (componentType.isUnresolved()) {
                throw new ContributionResolveException(
                                                       "SpringArtifactProcessor: unable to resolve componentType for Spring component");
            }
            springImplementation.setComponentType(componentType);

            springImplementation.setUnresolved(false);
        } // end if

    } // end method resolve

    public void wire(SpringImplementation model) throws ContributionWireException {
        // TODO Auto-generated method stub
    }

    public QName getArtifactType() {
        return IMPLEMENTATION_SPRING_QNAME;
    }

    public Class<SpringImplementation> getModelType() {
        return SpringImplementation.class;
    }

} // end class SpringArtifactProcessor
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