sdks/java/basys.sdk/src/main/java/org/eclipse/basyx/aas/restapi/MultiSubmodelProvider.java - basyx/basyx - Git at Google

 /*******************************************************************************
  * Copyright (C) 2021 the Eclipse BaSyx Authors
  *
  * This program and the accompanying materials are made
  * available under the terms of the Eclipse Public License 2.0
  * which is available at https://www.eclipse.org/legal/epl-2.0/
  *
  * SPDX-License-Identifier: EPL-2.0
  ******************************************************************************/
 package org.eclipse.basyx.aas.restapi;

 import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;

 import org.eclipse.basyx.aas.metamodel.map.AssetAdministrationShell;
 import org.eclipse.basyx.aas.metamodel.map.descriptor.AASDescriptor;
 import org.eclipse.basyx.aas.metamodel.map.descriptor.SubmodelDescriptor;
 import org.eclipse.basyx.aas.registration.api.IAASRegistry;
 import org.eclipse.basyx.aas.restapi.api.IAASAPI;
 import org.eclipse.basyx.aas.restapi.api.IAASAPIFactory;
 import org.eclipse.basyx.aas.restapi.vab.VABAASAPIFactory;
 import org.eclipse.basyx.submodel.metamodel.api.identifier.IIdentifier;
 import org.eclipse.basyx.submodel.metamodel.map.Submodel;
 import org.eclipse.basyx.submodel.restapi.SubmodelProvider;
 import org.eclipse.basyx.submodel.restapi.api.ISubmodelAPI;
 import org.eclipse.basyx.submodel.restapi.api.ISubmodelAPIFactory;
 import org.eclipse.basyx.submodel.restapi.vab.VABSubmodelAPIFactory;
 import org.eclipse.basyx.vab.exception.provider.MalformedRequestException;
 import org.eclipse.basyx.vab.exception.provider.ProviderException;
 import org.eclipse.basyx.vab.exception.provider.ResourceNotFoundException;
 import org.eclipse.basyx.vab.modelprovider.VABPathTools;
 import org.eclipse.basyx.vab.modelprovider.api.IModelProvider;
 import org.eclipse.basyx.vab.protocol.api.IConnectorFactory;
 import org.eclipse.basyx.vab.protocol.http.connector.HTTPConnectorFactory;

 /**
  * Provider class that implements the AssetAdministrationShellServices <br />
  * This provider supports operations on multiple sub models that are selected by
  * path<br />
  * <br />
  * Supported API:<br />
  * - getModelPropertyValue<br />
  * /aas Returns the Asset Administration Shell<br />
  * /aas/submodels Retrieves all Submodels from the current Asset Administration
  * Shell<br />
  * /aas/submodels/{subModelId} Retrieves a specific Submodel from a specific
  * Asset Administration Shell<br />
  * /aas/submodels/{subModelId}/properties Retrieves all Properties from the
  * current Submodel<br />
  * /aas/submodels/{subModelId}/operations Retrieves all Operations from the
  * current Submodel<br />
  * /aas/submodels/{subModelId}/events Retrieves all Events from the current
  * Submodel<br />
  * /aas/submodels/{subModelId}/properties/{propertyId} Retrieves a specific
  * property from the AAS's Submodel<br />
  * /aas/submodels/{subModelId}/operations/{operationId} Retrieves a specific
  * Operation from the AAS's Submodel<br />
  * /aas/submodels/{subModelId}/events/{eventId} Retrieves a specific event from
  * the AAS's submodel
  * <br /><br />
  * - createValue <br />
  * /aas/submodels Adds a new Submodel to an existing Asset Administration Shell
  * <br /><br />
  * /aas/submodels/{subModelId}/properties Adds a new property to the AAS's
  * submodel <br />
  * /aas/submodels/{subModelId}/operations Adds a new operation to the AAS's
  * submodel <br />
  * /aas/submodels/{subModelId}/events Adds a new event to the AAS's submodel
  * <br /><br />
  * - invokeOperation<br />
  * /aas/submodels/{subModelId}/operations/{operationId} Invokes a specific
  * operation from the AAS' submodel with a list of input parameters
  * <br /><br />
  * - deleteValue<br />
  * /aas/submodels/{subModelId} Deletes a specific Submodel from a specific Asset
  * Administration Shell <br />
  * /aas/submodels/{subModelId}/properties/{propertyId} Deletes a specific
  * Property from the AAS's Submodel<br />
  * /aas/submodels/{subModelId}/operations/{operationId} Deletes a specific
  * Operation from the AAS's Submodel<br />
  * /aas/submodels/{subModelId}/events/{eventId} Deletes a specific event from
  * the AAS's submodel
  * <br /><br />
  * - setModelPropertyValue<br />
  * /aas/submodels/{subModelId}/properties/{propertyId} Sets the value of the
  * AAS's Submodel's Property
  *
  *
  * @author kuhn, pschorn
  *
  */
 public class MultiSubmodelProvider implements IModelProvider {

 	public static final String AAS = "aas";

 	/**
 	 * Store aas providers
 	 */
 	protected AASModelProvider aas_provider = null;

 	/**
 	 * Store aasId
 	 */
 	protected IIdentifier aasId = null;

 	/**
 	 * Store submodel providers
 	 */
 	protected Map<String, SubmodelProvider> submodel_providers = new HashMap<>();

 	/**
 	 * Store AAS Registry
 	 */
 	protected IAASRegistry registry = null;

 	/**
 	 * Store HTTP Connector
 	 */
 	protected IConnectorFactory connectorFactory = null;

 	/**
 	 * Store AAS API Provider. By default, uses the VAB API Provider
 	 */
 	protected IAASAPIFactory aasApiProvider;

 	/**
 	 * Store Submodel API Provider. By default, uses the VAB Submodel Provider
 	 */
 	protected ISubmodelAPIFactory smApiProvider;

 	/**
 	 * Constructor with empty default aas and default VAB APIs
 	 */
 	public MultiSubmodelProvider() {
 		this.aasApiProvider = new VABAASAPIFactory();
 		this.smApiProvider = new VABSubmodelAPIFactory();
 		IAASAPI aasApi = aasApiProvider.getAASApi(new AssetAdministrationShell());
 		setAssetAdministrationShell(new AASModelProvider(aasApi));
 	}

 	/**
 	 * Constructor for using custom APIs
 	 */
 	public MultiSubmodelProvider(AASModelProvider contentProvider, IAASAPIFactory aasApiProvider,
 			ISubmodelAPIFactory smApiProvider) {
 		this.aasApiProvider = aasApiProvider;
 		this.smApiProvider = smApiProvider;
 		setAssetAdministrationShell(contentProvider);
 	}

 	/**
 	 * Constructor that accepts an AAS
 	 */
 	public MultiSubmodelProvider(AASModelProvider contentProvider) {
 		this.aasApiProvider = new VABAASAPIFactory();
 		this.smApiProvider = new VABSubmodelAPIFactory();
 		// Store content provider
 		setAssetAdministrationShell(contentProvider);
 	}

 	/**
 	 * Constructor that accepts Submodel
 	 */
 	public MultiSubmodelProvider(SubmodelProvider contentProvider) {
 		this();
 		// Store content provider
 		addSubmodel(contentProvider);
 	}

 	/**
 	 * Constructor that accepts a registry and a connection provider
 	 * @param registry
 	 * @param provider
 	 */
 	public MultiSubmodelProvider(IAASRegistry registry, IConnectorFactory provider) {
 		this();
 		this.registry = registry;
 		this.connectorFactory = provider;
 	}

 	/**
 	 * Constructor that accepts a registry, a connection provider and API providers
 	 */
 	public MultiSubmodelProvider(AASModelProvider contentProvider, IAASRegistry registry,
 			IConnectorFactory connectorFactory, ISubmodelAPIFactory smApiProvider, IAASAPIFactory aasApiProvider) {
 		this(contentProvider, aasApiProvider, smApiProvider);
 		this.registry = registry;
 		this.connectorFactory = connectorFactory;
 	}

 	/**
 	 * Constructor that accepts a aas provider, a registry and a connection provider
 	 *
 	 * @param contentProvider
 	 * @param registry
 	 * @param provider
 	 */
 	public MultiSubmodelProvider(AASModelProvider contentProvider, IAASRegistry registry, HTTPConnectorFactory provider) {
 		this(contentProvider);
 		this.registry = registry;
 		this.connectorFactory = provider;
 	}

 	/**
 	 * Set an AAS for this provider
 	 *
 	 * @param elementId
 	 *            Element ID
 	 * @param modelContentProvider
 	 *            Model content provider
 	 */
 	@SuppressWarnings("unchecked")
 	public void setAssetAdministrationShell(AASModelProvider modelContentProvider) {
 		// Add model provider
 		aas_provider = modelContentProvider;
 		aasId = AssetAdministrationShell.createAsFacade((Map<String, Object>) modelContentProvider.getValue("")).getIdentification();
 	}

 	@SuppressWarnings("unchecked")
 	public void addSubmodel(SubmodelProvider modelContentProvider) {
 		Submodel sm = Submodel.createAsFacade((Map<String, Object>) modelContentProvider.getValue("/submodel"));
 		addSubmodel(sm, modelContentProvider);
 	}

 	@SuppressWarnings("unchecked")
 	private void createSubmodel(Object newSM) throws ProviderException {
 		// Adds a new submodel to the registered AAS
 		Submodel sm = Submodel.createAsFacade((Map<String, Object>) newSM);

 		ISubmodelAPI smApi = smApiProvider.getSubmodelAPI(sm);
 		addSubmodel(sm, new SubmodelProvider(smApi));
 	}

 	private void addSubmodel(Submodel sm, SubmodelProvider modelContentProvider) {
 		String smIdShort = sm.getIdShort();
 		submodel_providers.put(smIdShort, modelContentProvider);
 		aas_provider.createValue("/submodels", sm);
 	}

 	/**
 	 * Remove a provider
 	 *
 	 * @param elementId
 	 *            Element ID
 	 */
 	public void removeProvider(String elementId) {
 		// Remove model provider
 		submodel_providers.remove(elementId);
 	}

 	/**
 	 * Get the value of an element
 	 */
 	@Override
 	public Object getValue(String path) throws ProviderException {
 		VABPathTools.checkPathForNull(path);
 		path = VABPathTools.stripSlashes(path);
 		String[] pathElements = VABPathTools.splitPath(path);
 		if (pathElements.length > 0 && pathElements[0].equals(AAS)) {
 			if (pathElements.length == 1) {
 				return aas_provider.getValue("");
 			}
 			if (pathElements[1].equals(AssetAdministrationShell.SUBMODELS)) {
 				if (pathElements.length == 2) {
 					return retrieveSubmodels();
 				} else {
 					IModelProvider provider = submodel_providers.get(pathElements[2]);

 					if (provider == null) {
 						// Get a model provider for the submodel in the registry
 						provider = getModelProvider(pathElements[2]);
 					}

 					// - Retrieve submodel or property value
 					return provider.getValue(VABPathTools.buildPath(pathElements, 3));
 				}
 			} else {
 				// Handle access to AAS
 				return aas_provider.getValue(VABPathTools.buildPath(pathElements, 1));
 			}
 		} else {
 			throw new MalformedRequestException("The request " + path + " is not allowed for this endpoint");
 		}
 	}

 	/**
 	 * Retrieves all submodels of the AAS. If there's a registry, remote Submodels
 	 * will also be retrieved.
 	 *
 	 * @return
 	 * @throws ProviderException
 	 */
 	@SuppressWarnings("unchecked")
 	private Object retrieveSubmodels() throws ProviderException {
 		// Make a list and return all local submodels
 		Collection<Submodel> submodels = new HashSet<>();
 		for (IModelProvider submodel : submodel_providers.values()) {
 			submodels.add(Submodel.createAsFacade((Map<String, Object>) submodel.getValue("/submodel")));
 		}

 		// Check for remote submodels
 		if (registry != null) {
 			AASDescriptor desc = registry.lookupAAS(aasId);

 			// Get the address of the AAS e.g. http://localhost:8080
 			// This address should be equal to the address of this server
 			String aasEndpoint = desc.getFirstEndpoint();
 			String aasServerURL = getServerURL(aasEndpoint);

 			List<String> localIds = submodels.stream().map(sm -> sm.getIdentification().getId()).collect(Collectors.toList());
 			List<IIdentifier> missingIds = desc.getSubmodelDescriptors().stream().map(d -> d.getIdentifier()).
 					filter(id -> !localIds.contains(id.getId())).collect(Collectors.toList());

 			if(!missingIds.isEmpty()) {
 				List<String> missingEndpoints = missingIds.stream().map(id -> desc.getSubmodelDescriptorFromIdentifierId(id.getId()))
 						.map(smDesc -> smDesc.getFirstEndpoint()).collect(Collectors.toList());

 				// Check if any of the missing Submodels have the same address as the AAS.
 				// This would mean, that the Submodel should be present on the same
 				// server of the AAS but is not

 				// If this error would not be caught here an endless loop would develop
 				// as the registry would be asked for this Submodel and then it would be requested
 				// from this server again, which would ask the registry about it again

 				// Such a situation might originate from a deleted but not unregistered Submodel
 				// or from a manually registered but never pushed Submodel
 				for(String missingEndpoint: missingEndpoints) {
 					if(getServerURL(missingEndpoint).equals(aasServerURL)) {
 						throw new ResourceNotFoundException("The Submodel at Endpoint '" + missingEndpoint +
 								"' does not exist on this server. It seems to be registered but not actually present.");
 					}
 				}

 				List<Submodel> remoteSms = missingEndpoints.stream().map(endpoint -> connectorFactory.getConnector(endpoint)).
 						map(p -> (Map<String, Object>) p.getValue("")).map(m -> Submodel.createAsFacade(m)).collect(Collectors.toList());
 				submodels.addAll(remoteSms);
 			}
 		}

 		return submodels;
 	}

 	/**
 	 * Change a model property value
 	 */
 	@Override
 	public void setValue(String path, Object newValue) throws ProviderException {
  		VABPathTools.checkPathForNull(path);
 		path = VABPathTools.stripSlashes(path);
 		// Split path
 		String[] pathElements = VABPathTools.splitPath(path);
 		String propertyPath = VABPathTools.buildPath(pathElements, 3);
 		// - Ignore first 2 elements, as it is "/aas/submodels" --> 'aas','submodels'

 		String submodelsPath = VABPathTools.concatenatePaths(AAS, AssetAdministrationShell.SUBMODELS);
 		if (path.equals(AAS)) {
 			createAssetAdministrationShell(newValue);
 		} else if (!path.startsWith(submodelsPath)) {
 			throw new MalformedRequestException("Access to MultiSubmodelProvider always has to start with \"" + submodelsPath + "\", was " + path);
 		} else if (propertyPath.isEmpty()) {
 			createSubmodel(newValue);
 		} else {
 			IModelProvider provider;
 			if (isSubmodelLocal(pathElements[2])) {
 				provider = submodel_providers.get(pathElements[2]);
 			} else {
 				// Get a model provider for the submodel in the registry
 				provider = getModelProvider(pathElements[2]);
 			}
 			provider.setValue(propertyPath, newValue);
 		}
 	}

 	@Override
 	public void createValue(String path, Object newValue) throws ProviderException {
 		throw new MalformedRequestException("Create is not supported by VABMultiSubmodelProvider. Path was: " + path);
 	}


 	@SuppressWarnings("unchecked")
 	private void createAssetAdministrationShell(Object newAAS) {
 		Map<String, Object> aas = (Map<String, Object>) newAAS;
 		AssetAdministrationShell shell = AssetAdministrationShell.createAsFacade(aas);
 		IAASAPI aasApi = aasApiProvider.getAASApi(shell);
 		aas_provider = new AASModelProvider(aasApi);
 	}


 	@SuppressWarnings("unchecked")
 	@Override
 	public void deleteValue(String path) throws ProviderException {
 		VABPathTools.checkPathForNull(path);
 		path = VABPathTools.stripSlashes(path);
 		String[] pathElements = VABPathTools.splitPath(path);
 		String propertyPath = VABPathTools.buildPath(pathElements, 3);
 		// - Ignore first 2 elements, as it is "/aas/submodels" --> 'aas','submodels'
 		if (pathElements.length == 3) {
 			// Delete Submodel from registered AAS
 			String smIdShort = pathElements[2];
 			if (!isSubmodelLocal(smIdShort)) {
 				return;
 			}

 			// Delete submodel reference from aas
 			// TODO: This is a hack until the API is further clarified
 			Submodel sm = Submodel.createAsFacade((Map<String, Object>) submodel_providers.get(smIdShort).getValue("/submodel"));
 			aas_provider.deleteValue("aas/submodels/" + sm.getIdentification().getId());

 			// Remove submodel provider
 			submodel_providers.remove(smIdShort);
 		} else if (propertyPath.length() > 0) {
 			IModelProvider provider;
 			if (isSubmodelLocal(pathElements[2])) {
 				provider = submodel_providers.get(pathElements[2]);
 			} else {
 				// Get a model provider for the submodel in the registry
 				provider = getModelProvider(pathElements[2]);
 			}

 			provider.deleteValue(propertyPath);
 		}
 	}

 	@Override
 	public void deleteValue(String path, Object obj) throws ProviderException {
 		throw new MalformedRequestException("DeleteValue with a parameter is not supported. Path was: " + path);
 	}

 	@Override
 	public Object invokeOperation(String path, Object... parameter) throws ProviderException {
 		VABPathTools.checkPathForNull(path);
 		path = VABPathTools.stripSlashes(path);
 		String[] pathElements = VABPathTools.splitPath(path);
 		String operationPath = VABPathTools.buildPath(pathElements, 3);
 		// - Ignore first 2 elements, as it is "/aas/submodels" --> 'aas','submodels'
 		// - Invoke provider and return result
 		IModelProvider provider;
 		if (isSubmodelLocal(pathElements[2])) {
 			provider = submodel_providers.get(pathElements[2]);
 		} else {
 			// Get a model provider for the submodel in the registry
 			provider = getModelProvider(pathElements[2]);
 		}

 		return provider.invokeOperation(operationPath, parameter);
 	}

 	/**
 	 * Check whether the given submodel exists in submodel provider
 	 * @param key to search the submodel
 	 * @return boolean true/false
 	 */
 	private boolean isSubmodelLocal(String submodelId) {
 		return submodel_providers.containsKey(submodelId);
 	}

 	/**
 	 * Check whether a registry exists
 	 * @return boolean true/false
 	 */
 	private boolean doesRegistryExist() {
 		return this.registry != null;
 	}

 	/**
 	 * Get submodel descriptor from the registry
 	 * @param submodelId to search the submodel
 	 * @return a specifi submodel descriptor
 	 */
 	private SubmodelDescriptor getSubmodelDescriptorFromRegistry(String submodelIdShort) {
 		AASDescriptor aasDescriptor = registry.lookupAAS(aasId);
 		SubmodelDescriptor desc = aasDescriptor.getSubmodelDescriptorFromIdShort(submodelIdShort);
 		if(desc == null) {
 			throw new ResourceNotFoundException("Could not resolve Submodel with idShort " + submodelIdShort + " for AAS " + aasId);
 		}
 		return desc;
 	}

 	/**
 	 * Get a model provider from a submodel descriptor
 	 * @param submodelDescriptor
 	 * @return a model provider
 	 */
 	private IModelProvider getModelProvider(SubmodelDescriptor submodelDescriptor) {
 		String endpoint = submodelDescriptor.getFirstEndpoint();

 		// Remove "/submodel" since it will be readded later
 		endpoint = endpoint.substring(0, endpoint.length() - SubmodelProvider.SUBMODEL.length() - 1);

 		return connectorFactory.getConnector(endpoint);
 	}

 	/**
 	 * Get a model provider from a submodel id
 	 * @param submodelId to select a specific submodel
 	 * @throws ResourceNotFoundException if no registry is found
 	 * @return a model provider
 	 */
 	private IModelProvider getModelProvider(String submodelId) {
 		if (!doesRegistryExist()) {
 			throw new ResourceNotFoundException("Submodel with id " + submodelId + " cannot be resolved locally, but no registry is passed");
 		}

 		SubmodelDescriptor submodelDescriptor = getSubmodelDescriptorFromRegistry(submodelId);
 		return getModelProvider(submodelDescriptor);
 	}

 	/**
 	 * Gets the server URL of a given endpoint.
 	 * e.g. http://localhost:1234/x/y/z/aas/submodels/Sm1IdShort would return
 	 * http://localhost:1234/x/y/z
 	 *
 	 * @param endpoint
 	 * @return the server URL part of the given endpoint
 	 */
 	public static String getServerURL(String endpoint) {
 		int endServerURL = endpoint.indexOf("/aas");
 		// if indexOf returned -1 ("/aas" not present in String)
 		// return the whole given path
 		if(endServerURL < 0) {
 			return endpoint;
 		}
 		return endpoint.substring(0, endServerURL);
 	}
 }
	/*******************************************************************************
	* Copyright (C) 2021 the Eclipse BaSyx Authors
	*
	* This program and the accompanying materials are made
	* available under the terms of the Eclipse Public License 2.0
	* which is available at https://www.eclipse.org/legal/epl-2.0/
	*
	* SPDX-License-Identifier: EPL-2.0
	******************************************************************************/
	package org.eclipse.basyx.aas.restapi;

	import java.util.Collection;
	import java.util.HashMap;
	import java.util.HashSet;
	import java.util.List;
	import java.util.Map;
	import java.util.stream.Collectors;

	import org.eclipse.basyx.aas.metamodel.map.AssetAdministrationShell;
	import org.eclipse.basyx.aas.metamodel.map.descriptor.AASDescriptor;
	import org.eclipse.basyx.aas.metamodel.map.descriptor.SubmodelDescriptor;
	import org.eclipse.basyx.aas.registration.api.IAASRegistry;
	import org.eclipse.basyx.aas.restapi.api.IAASAPI;
	import org.eclipse.basyx.aas.restapi.api.IAASAPIFactory;
	import org.eclipse.basyx.aas.restapi.vab.VABAASAPIFactory;
	import org.eclipse.basyx.submodel.metamodel.api.identifier.IIdentifier;
	import org.eclipse.basyx.submodel.metamodel.map.Submodel;
	import org.eclipse.basyx.submodel.restapi.SubmodelProvider;
	import org.eclipse.basyx.submodel.restapi.api.ISubmodelAPI;
	import org.eclipse.basyx.submodel.restapi.api.ISubmodelAPIFactory;
	import org.eclipse.basyx.submodel.restapi.vab.VABSubmodelAPIFactory;
	import org.eclipse.basyx.vab.exception.provider.MalformedRequestException;
	import org.eclipse.basyx.vab.exception.provider.ProviderException;
	import org.eclipse.basyx.vab.exception.provider.ResourceNotFoundException;
	import org.eclipse.basyx.vab.modelprovider.VABPathTools;
	import org.eclipse.basyx.vab.modelprovider.api.IModelProvider;
	import org.eclipse.basyx.vab.protocol.api.IConnectorFactory;
	import org.eclipse.basyx.vab.protocol.http.connector.HTTPConnectorFactory;

	/**
	* Provider class that implements the AssetAdministrationShellServices <br />
	* This provider supports operations on multiple sub models that are selected by
	* path<br />
	* <br />
	* Supported API:<br />
	* - getModelPropertyValue<br />
	* /aas Returns the Asset Administration Shell<br />
	* /aas/submodels Retrieves all Submodels from the current Asset Administration
	* Shell<br />
	* /aas/submodels/{subModelId} Retrieves a specific Submodel from a specific
	* Asset Administration Shell<br />
	* /aas/submodels/{subModelId}/properties Retrieves all Properties from the
	* current Submodel<br />
	* /aas/submodels/{subModelId}/operations Retrieves all Operations from the
	* current Submodel<br />
	* /aas/submodels/{subModelId}/events Retrieves all Events from the current
	* Submodel<br />
	* /aas/submodels/{subModelId}/properties/{propertyId} Retrieves a specific
	* property from the AAS's Submodel<br />
	* /aas/submodels/{subModelId}/operations/{operationId} Retrieves a specific
	* Operation from the AAS's Submodel<br />
	* /aas/submodels/{subModelId}/events/{eventId} Retrieves a specific event from
	* the AAS's submodel
	* <br /><br />
	* - createValue <br />
	* /aas/submodels Adds a new Submodel to an existing Asset Administration Shell
	* <br /><br />
	* /aas/submodels/{subModelId}/properties Adds a new property to the AAS's
	* submodel <br />
	* /aas/submodels/{subModelId}/operations Adds a new operation to the AAS's
	* submodel <br />
	* /aas/submodels/{subModelId}/events Adds a new event to the AAS's submodel
	* <br /><br />
	* - invokeOperation<br />
	* /aas/submodels/{subModelId}/operations/{operationId} Invokes a specific
	* operation from the AAS' submodel with a list of input parameters
	* <br /><br />
	* - deleteValue<br />
	* /aas/submodels/{subModelId} Deletes a specific Submodel from a specific Asset
	* Administration Shell <br />
	* /aas/submodels/{subModelId}/properties/{propertyId} Deletes a specific
	* Property from the AAS's Submodel<br />
	* /aas/submodels/{subModelId}/operations/{operationId} Deletes a specific
	* Operation from the AAS's Submodel<br />
	* /aas/submodels/{subModelId}/events/{eventId} Deletes a specific event from
	* the AAS's submodel
	* <br /><br />
	* - setModelPropertyValue<br />
	* /aas/submodels/{subModelId}/properties/{propertyId} Sets the value of the
	* AAS's Submodel's Property
	*
	*
	* @author kuhn, pschorn
	*
	*/
	public class MultiSubmodelProvider implements IModelProvider {

	public static final String AAS = "aas";

	/**
	* Store aas providers
	*/
	protected AASModelProvider aas_provider = null;

	/**
	* Store aasId
	*/
	protected IIdentifier aasId = null;

	/**
	* Store submodel providers
	*/
	protected Map<String, SubmodelProvider> submodel_providers = new HashMap<>();

	/**
	* Store AAS Registry
	*/
	protected IAASRegistry registry = null;

	/**
	* Store HTTP Connector
	*/
	protected IConnectorFactory connectorFactory = null;

	/**
	* Store AAS API Provider. By default, uses the VAB API Provider
	*/
	protected IAASAPIFactory aasApiProvider;

	/**
	* Store Submodel API Provider. By default, uses the VAB Submodel Provider
	*/
	protected ISubmodelAPIFactory smApiProvider;

	/**
	* Constructor with empty default aas and default VAB APIs
	*/
	public MultiSubmodelProvider() {
	this.aasApiProvider = new VABAASAPIFactory();
	this.smApiProvider = new VABSubmodelAPIFactory();
	IAASAPI aasApi = aasApiProvider.getAASApi(new AssetAdministrationShell());
	setAssetAdministrationShell(new AASModelProvider(aasApi));
	}

	/**
	* Constructor for using custom APIs
	*/
	public MultiSubmodelProvider(AASModelProvider contentProvider, IAASAPIFactory aasApiProvider,
	ISubmodelAPIFactory smApiProvider) {
	this.aasApiProvider = aasApiProvider;
	this.smApiProvider = smApiProvider;
	setAssetAdministrationShell(contentProvider);
	}

	/**
	* Constructor that accepts an AAS
	*/
	public MultiSubmodelProvider(AASModelProvider contentProvider) {
	this.aasApiProvider = new VABAASAPIFactory();
	this.smApiProvider = new VABSubmodelAPIFactory();
	// Store content provider
	setAssetAdministrationShell(contentProvider);
	}

	/**
	* Constructor that accepts Submodel
	*/
	public MultiSubmodelProvider(SubmodelProvider contentProvider) {
	this();
	// Store content provider
	addSubmodel(contentProvider);
	}

	/**
	* Constructor that accepts a registry and a connection provider
	* @param registry
	* @param provider
	*/
	public MultiSubmodelProvider(IAASRegistry registry, IConnectorFactory provider) {
	this();
	this.registry = registry;
	this.connectorFactory = provider;
	}

	/**
	* Constructor that accepts a registry, a connection provider and API providers
	*/
	public MultiSubmodelProvider(AASModelProvider contentProvider, IAASRegistry registry,
	IConnectorFactory connectorFactory, ISubmodelAPIFactory smApiProvider, IAASAPIFactory aasApiProvider) {
	this(contentProvider, aasApiProvider, smApiProvider);
	this.registry = registry;
	this.connectorFactory = connectorFactory;
	}

	/**
	* Constructor that accepts a aas provider, a registry and a connection provider
	*
	* @param contentProvider
	* @param registry
	* @param provider
	*/
	public MultiSubmodelProvider(AASModelProvider contentProvider, IAASRegistry registry, HTTPConnectorFactory provider) {
	this(contentProvider);
	this.registry = registry;
	this.connectorFactory = provider;
	}

	/**
	* Set an AAS for this provider
	*
	* @param elementId
	* Element ID
	* @param modelContentProvider
	* Model content provider
	*/
	@SuppressWarnings("unchecked")
	public void setAssetAdministrationShell(AASModelProvider modelContentProvider) {
	// Add model provider
	aas_provider = modelContentProvider;
	aasId = AssetAdministrationShell.createAsFacade((Map<String, Object>) modelContentProvider.getValue("")).getIdentification();
	}

	@SuppressWarnings("unchecked")
	public void addSubmodel(SubmodelProvider modelContentProvider) {
	Submodel sm = Submodel.createAsFacade((Map<String, Object>) modelContentProvider.getValue("/submodel"));
	addSubmodel(sm, modelContentProvider);
	}

	@SuppressWarnings("unchecked")
	private void createSubmodel(Object newSM) throws ProviderException {
	// Adds a new submodel to the registered AAS
	Submodel sm = Submodel.createAsFacade((Map<String, Object>) newSM);

	ISubmodelAPI smApi = smApiProvider.getSubmodelAPI(sm);
	addSubmodel(sm, new SubmodelProvider(smApi));
	}

	private void addSubmodel(Submodel sm, SubmodelProvider modelContentProvider) {
	String smIdShort = sm.getIdShort();
	submodel_providers.put(smIdShort, modelContentProvider);
	aas_provider.createValue("/submodels", sm);
	}

	/**
	* Remove a provider
	*
	* @param elementId
	* Element ID
	*/
	public void removeProvider(String elementId) {
	// Remove model provider
	submodel_providers.remove(elementId);
	}

	/**
	* Get the value of an element
	*/
	@Override
	public Object getValue(String path) throws ProviderException {
	VABPathTools.checkPathForNull(path);
	path = VABPathTools.stripSlashes(path);
	String[] pathElements = VABPathTools.splitPath(path);
	if (pathElements.length > 0 && pathElements[0].equals(AAS)) {
	if (pathElements.length == 1) {
	return aas_provider.getValue("");
	}
	if (pathElements[1].equals(AssetAdministrationShell.SUBMODELS)) {
	if (pathElements.length == 2) {
	return retrieveSubmodels();
	} else {
	IModelProvider provider = submodel_providers.get(pathElements[2]);

	if (provider == null) {
	// Get a model provider for the submodel in the registry
	provider = getModelProvider(pathElements[2]);
	}

	// - Retrieve submodel or property value
	return provider.getValue(VABPathTools.buildPath(pathElements, 3));
	}
	} else {
	// Handle access to AAS
	return aas_provider.getValue(VABPathTools.buildPath(pathElements, 1));
	}
	} else {
	throw new MalformedRequestException("The request " + path + " is not allowed for this endpoint");
	}
	}

	/**
	* Retrieves all submodels of the AAS. If there's a registry, remote Submodels
	* will also be retrieved.
	*
	* @return
	* @throws ProviderException
	*/
	@SuppressWarnings("unchecked")
	private Object retrieveSubmodels() throws ProviderException {
	// Make a list and return all local submodels
	Collection<Submodel> submodels = new HashSet<>();
	for (IModelProvider submodel : submodel_providers.values()) {
	submodels.add(Submodel.createAsFacade((Map<String, Object>) submodel.getValue("/submodel")));
	}

	// Check for remote submodels
	if (registry != null) {
	AASDescriptor desc = registry.lookupAAS(aasId);

	// Get the address of the AAS e.g. http://localhost:8080
	// This address should be equal to the address of this server
	String aasEndpoint = desc.getFirstEndpoint();
	String aasServerURL = getServerURL(aasEndpoint);

	List<String> localIds = submodels.stream().map(sm -> sm.getIdentification().getId()).collect(Collectors.toList());
	List<IIdentifier> missingIds = desc.getSubmodelDescriptors().stream().map(d -> d.getIdentifier()).
	filter(id -> !localIds.contains(id.getId())).collect(Collectors.toList());

	if(!missingIds.isEmpty()) {
	List<String> missingEndpoints = missingIds.stream().map(id -> desc.getSubmodelDescriptorFromIdentifierId(id.getId()))
	.map(smDesc -> smDesc.getFirstEndpoint()).collect(Collectors.toList());

	// Check if any of the missing Submodels have the same address as the AAS.
	// This would mean, that the Submodel should be present on the same
	// server of the AAS but is not

	// If this error would not be caught here an endless loop would develop
	// as the registry would be asked for this Submodel and then it would be requested
	// from this server again, which would ask the registry about it again

	// Such a situation might originate from a deleted but not unregistered Submodel
	// or from a manually registered but never pushed Submodel
	for(String missingEndpoint: missingEndpoints) {
	if(getServerURL(missingEndpoint).equals(aasServerURL)) {
	throw new ResourceNotFoundException("The Submodel at Endpoint '" + missingEndpoint +
	"' does not exist on this server. It seems to be registered but not actually present.");
	}
	}

	List<Submodel> remoteSms = missingEndpoints.stream().map(endpoint -> connectorFactory.getConnector(endpoint)).
	map(p -> (Map<String, Object>) p.getValue("")).map(m -> Submodel.createAsFacade(m)).collect(Collectors.toList());
	submodels.addAll(remoteSms);
	}
	}

	return submodels;
	}

	/**
	* Change a model property value
	*/
	@Override
	public void setValue(String path, Object newValue) throws ProviderException {
	VABPathTools.checkPathForNull(path);
	path = VABPathTools.stripSlashes(path);
	// Split path
	String[] pathElements = VABPathTools.splitPath(path);
	String propertyPath = VABPathTools.buildPath(pathElements, 3);
	// - Ignore first 2 elements, as it is "/aas/submodels" --> 'aas','submodels'

	String submodelsPath = VABPathTools.concatenatePaths(AAS, AssetAdministrationShell.SUBMODELS);
	if (path.equals(AAS)) {
	createAssetAdministrationShell(newValue);
	} else if (!path.startsWith(submodelsPath)) {
	throw new MalformedRequestException("Access to MultiSubmodelProvider always has to start with \"" + submodelsPath + "\", was " + path);
	} else if (propertyPath.isEmpty()) {
	createSubmodel(newValue);
	} else {
	IModelProvider provider;
	if (isSubmodelLocal(pathElements[2])) {
	provider = submodel_providers.get(pathElements[2]);
	} else {
	// Get a model provider for the submodel in the registry
	provider = getModelProvider(pathElements[2]);
	}
	provider.setValue(propertyPath, newValue);
	}
	}

	@Override
	public void createValue(String path, Object newValue) throws ProviderException {
	throw new MalformedRequestException("Create is not supported by VABMultiSubmodelProvider. Path was: " + path);
	}


	@SuppressWarnings("unchecked")
	private void createAssetAdministrationShell(Object newAAS) {
	Map<String, Object> aas = (Map<String, Object>) newAAS;
	AssetAdministrationShell shell = AssetAdministrationShell.createAsFacade(aas);
	IAASAPI aasApi = aasApiProvider.getAASApi(shell);
	aas_provider = new AASModelProvider(aasApi);
	}


	@SuppressWarnings("unchecked")
	@Override
	public void deleteValue(String path) throws ProviderException {
	VABPathTools.checkPathForNull(path);
	path = VABPathTools.stripSlashes(path);
	String[] pathElements = VABPathTools.splitPath(path);
	String propertyPath = VABPathTools.buildPath(pathElements, 3);
	// - Ignore first 2 elements, as it is "/aas/submodels" --> 'aas','submodels'
	if (pathElements.length == 3) {
	// Delete Submodel from registered AAS
	String smIdShort = pathElements[2];
	if (!isSubmodelLocal(smIdShort)) {
	return;
	}

	// Delete submodel reference from aas
	// TODO: This is a hack until the API is further clarified
	Submodel sm = Submodel.createAsFacade((Map<String, Object>) submodel_providers.get(smIdShort).getValue("/submodel"));
	aas_provider.deleteValue("aas/submodels/" + sm.getIdentification().getId());

	// Remove submodel provider
	submodel_providers.remove(smIdShort);
	} else if (propertyPath.length() > 0) {
	IModelProvider provider;
	if (isSubmodelLocal(pathElements[2])) {
	provider = submodel_providers.get(pathElements[2]);
	} else {
	// Get a model provider for the submodel in the registry
	provider = getModelProvider(pathElements[2]);
	}

	provider.deleteValue(propertyPath);
	}
	}

	@Override
	public void deleteValue(String path, Object obj) throws ProviderException {
	throw new MalformedRequestException("DeleteValue with a parameter is not supported. Path was: " + path);
	}

	@Override
	public Object invokeOperation(String path, Object... parameter) throws ProviderException {
	VABPathTools.checkPathForNull(path);
	path = VABPathTools.stripSlashes(path);
	String[] pathElements = VABPathTools.splitPath(path);
	String operationPath = VABPathTools.buildPath(pathElements, 3);
	// - Ignore first 2 elements, as it is "/aas/submodels" --> 'aas','submodels'
	// - Invoke provider and return result
	IModelProvider provider;
	if (isSubmodelLocal(pathElements[2])) {
	provider = submodel_providers.get(pathElements[2]);
	} else {
	// Get a model provider for the submodel in the registry
	provider = getModelProvider(pathElements[2]);
	}

	return provider.invokeOperation(operationPath, parameter);
	}

	/**
	* Check whether the given submodel exists in submodel provider
	* @param key to search the submodel
	* @return boolean true/false
	*/
	private boolean isSubmodelLocal(String submodelId) {
	return submodel_providers.containsKey(submodelId);
	}

	/**
	* Check whether a registry exists
	* @return boolean true/false
	*/
	private boolean doesRegistryExist() {
	return this.registry != null;
	}

	/**
	* Get submodel descriptor from the registry
	* @param submodelId to search the submodel
	* @return a specifi submodel descriptor
	*/
	private SubmodelDescriptor getSubmodelDescriptorFromRegistry(String submodelIdShort) {
	AASDescriptor aasDescriptor = registry.lookupAAS(aasId);
	SubmodelDescriptor desc = aasDescriptor.getSubmodelDescriptorFromIdShort(submodelIdShort);
	if(desc == null) {
	throw new ResourceNotFoundException("Could not resolve Submodel with idShort " + submodelIdShort + " for AAS " + aasId);
	}
	return desc;
	}

	/**
	* Get a model provider from a submodel descriptor
	* @param submodelDescriptor
	* @return a model provider
	*/
	private IModelProvider getModelProvider(SubmodelDescriptor submodelDescriptor) {
	String endpoint = submodelDescriptor.getFirstEndpoint();

	// Remove "/submodel" since it will be readded later
	endpoint = endpoint.substring(0, endpoint.length() - SubmodelProvider.SUBMODEL.length() - 1);

	return connectorFactory.getConnector(endpoint);
	}

	/**
	* Get a model provider from a submodel id
	* @param submodelId to select a specific submodel
	* @throws ResourceNotFoundException if no registry is found
	* @return a model provider
	*/
	private IModelProvider getModelProvider(String submodelId) {
	if (!doesRegistryExist()) {
	throw new ResourceNotFoundException("Submodel with id " + submodelId + " cannot be resolved locally, but no registry is passed");
	}

	SubmodelDescriptor submodelDescriptor = getSubmodelDescriptorFromRegistry(submodelId);
	return getModelProvider(submodelDescriptor);
	}

	/**
	* Gets the server URL of a given endpoint.
	* e.g. http://localhost:1234/x/y/z/aas/submodels/Sm1IdShort would return
	* http://localhost:1234/x/y/z
	*
	* @param endpoint
	* @return the server URL part of the given endpoint
	*/
	public static String getServerURL(String endpoint) {
	int endServerURL = endpoint.indexOf("/aas");
	// if indexOf returned -1 ("/aas" not present in String)
	// return the whole given path
	if(endServerURL < 0) {
	return endpoint;
	}
	return endpoint.substring(0, endServerURL);
	}
	}