/** * * 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.samples.sdo.advanced; import java.io.InputStream; import org.apache.tuscany.samples.sdo.SampleBase; import org.apache.tuscany.samples.sdo.internal.SampleInfrastructure; import org.apache.tuscany.sdo.api.SDOUtil; import commonj.sdo.DataGraph; import commonj.sdo.DataObject; import commonj.sdo.helper.HelperContext; import commonj.sdo.helper.XMLDocument; /** * This sample program demonstrates a variety of methods available to obtain the root DataObject * contained within an xml representation of a DataGraph. This is currently a grey * area of the specification and this sample demonstrates spec compliant methods, as * well as utility methods that have been added to Tuscany to address issues within * the specification. * * The following sample is from the Apache Tuscany project. It was written to help users * understand and experiment with SDO. It is based upon example code contained * within, and is meant for use with, and reference to the SDO Specification. This sample attempts to clarify aspects of * the the AccessDataObjectsUsingXPath example from the Examples section of the SDO * specification.
*
* To define the correct Types for each DataObject ( CompanyType, DepartmentType etc ) * this sample relies upon * {@link org.apache.tuscany.samples.sdo.internal.SampleInfrastructure#COMPANY_XSD} which is * provided in the resources directory of these samples. The xml file * {@link org.apache.tuscany.samples.sdo.internal.SampleInfrastructure#COMPANY_DATAGRAPH_XML} is * used to load the DataGraph and is also located in this resources directory.
*

*

Running this Sample

See the main overview for instructions on how to run this * sample. */ public class ObtainingDataGraphFromXml extends SampleBase { HelperContext scope; public ObtainingDataGraphFromXml(Integer userLevel) { super(userLevel, SAMPLE_LEVEL_ADVANCED); } public static void main(String[] args) { /* * Create an instance of the sample program. Edit the "commentaryLevel" argument to suit * your experience, COMMENTARY_FOR_NOVICE, COMMENTARY_FOR_INTERMEDIATE or COMMENTARY_FOR_ADVANCED */ ObtainingDataGraphFromXml sample = new ObtainingDataGraphFromXml(COMMENTARY_FOR_ADVANCED); sample.run(); } /* * metadata for the sample documenting the areas of SDO that are explored */ public static int [] CORE_FUNCTION = { SDOFacets.WRAPPING_DATA_GRAPH_IN_A_DATAGRAPH_INSTANCE }; public static int [] SIGNIFICANT_FUNCTION = { SDOFacets.USING_BUILT_IN_TYPES }; public void runSample () { banner('*', "SDO Sample " + this.getClass().getName() + "\n\n" + "This sample touches an area of the SDO API where the emphasis has changed over the various\n"+ "version of the specification, and so it's important to be clear what's going on\n"+ "First off lets be sure of our terminology ...\n"+ "1) A \"data graph\" is a just collection of DataObjects, all contained within a single\n"+ "containment hierarchy, with a single root object, and possibly having some non-containment\n"+ "references\n"+ "2) A \"DataGraph\" is an instance of the SDO DataGraph class, used as a container for the root\n"+ "DataObject of a data graph, and providing a means to access a change summary for the data graph.\n\n"+ "More recent versions of the SDO specification have provided alternative means of containment\n"+ "of a data graph ...\n"+ "3) The graph can be contained in a DataObject of a built-in SDO Type with namespace URI \"commonj.sdo\"\n" + "and name \"DataGraph\": so this is a modeled version of the special DataGraph class.\n"+ "4) The Graph can be contained in an XMLDocument instance, which provides for things such as\n"+ "naming the root element of an XML instance document" ); scope = useDefaultScopeForTypes(); loadTypesFromXMLSchemaFile(scope, SampleInfrastructure.COMPANY_XSD); try { DataObject company = null; commentary( "Here we see the specification's example for obtaining dealing with\n"+ "loading a data graph which uses a method, XMLHelper.load(). This loads an XML instance document\n"+ "into an instance of XMLDocument ...\n\n"+ "XMLDocument doc = scope.getXMLHelper().load(\n"+ "ClassLoader.getSystemResourceAsStream(SampleInfrastructure.COMPANY_DATAGRAPH_XML));" ); InputStream is = ClassLoader.getSystemResourceAsStream(SampleInfrastructure.COMPANY_DATAGRAPH_XML); int x= is.available(); byte b[]= new byte[x]; is.read(b); String instanceDoc = new String(b); System.out.println(instanceDoc); XMLDocument doc = scope.getXMLHelper().load( ClassLoader.getSystemResourceAsStream(SampleInfrastructure.COMPANY_DATAGRAPH_XML)); commentary( "Now we can get the wrapper for the data graph, which in this case is the DataObject\n"+ "of type commonj.sdo#DataGraph. Note how there's no magic here; no special class for\n"+ "DataGraph, no special handling, this is just a standard pattern of using a built in SDO Type.\n"+ "The wrapper is there purely because it was serialized\n"+ "into the XML document, using the standard serialization technique.\n\n" + "DataObject dataObjectRepresentingDataGraph = doc.getRootObject();"); DataObject dataObjectRepresentingDataGraph = doc.getRootObject(); System.out.println(dataObjectRepresentingDataGraph); commentary( "If you are confused by the fact that what we really get is an instance of DataGraphTypeImpl\n"+ "This really is a DataObject, but it is a generated class extending DataObjectImpl\n+"+ "representing the DataGraph model."); company = dataObjectRepresentingDataGraph.getDataObject("company"); commentary( "We've obtained a DataObject representing the data graph, and from that we have obtained\n"+ "the true root object of the business data"); System.out.println(company); System.out.println(); commentary( "Using an instance of DataGraph can perhaps be seen as an older style pattern of wrapping a data graph\n"+ "and the first approach is likely to get more emphasis and attention in future revisions of the spec.\n"+ "The SDO API has some limitations in the area of saving and loading instances of the\n"+ "Java DataGraph type, so Tuscany has an API for doing this ...\n\n"+ "DataGraph datagraph = SDOUtil.loadDataGraph(\n"+ " ClassLoader.getSystemResourceAsStream(SampleInfrastructure.COMPANY_DATAGRAPH_XML), null);" ); DataGraph datagraph = SDOUtil.loadDataGraph(ClassLoader.getSystemResourceAsStream(SampleInfrastructure.COMPANY_DATAGRAPH_XML), null); System.out.println(datagraph); commentary( "In this case we directly receive an instance of DataGraph and can retrieve the root\n"+ "business object from the DataGraph\n\n"+ "DataObject company = datagraph.getRootObject();"); company = datagraph.getRootObject(); System.out.println(company); System.out.println(); } catch (Exception e) { somethingUnexpectedHasHappened(e); } } }