Implementing the new match query

src/main/java/org/gcube/informationsystem/resourceregistry/queries/json/JsonQuery.java

@@ -103,6 +103,13 @@ public class JsonQuery {
 		return entryPoint.createQuery(new StringBuffer());
 	}
 	
+	
+	public StringBuffer createMatchQuery() throws SchemaException, InvalidQueryException, ResourceRegistryException {
+		entryPoint = getJsonQueryERElement(jsonQuery);
+		entryPoint.setEntryPoint(true);
+		return entryPoint.createMatchQuery(new StringBuffer());
+	}
+	
 	public String query() throws InvalidQueryException, ResourceRegistryException {
 		ODatabaseDocument current = ContextUtility.getCurrentODatabaseDocumentFromThreadLocal();
 		oDatabaseDocument = null;

src/main/java/org/gcube/informationsystem/resourceregistry/queries/json/base/JsonQueryERElement.java

@@ -1,7 +1,9 @@
 package org.gcube.informationsystem.resourceregistry.queries.json.base;
 
+import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.Iterator;
+import java.util.List;
 import java.util.Set;
 
 import org.gcube.com.fasterxml.jackson.databind.JsonNode;
@@ -44,6 +46,51 @@ public abstract class JsonQueryERElement {
 	protected Direction direction;
 	protected boolean entryPoint;
 	
+	/* Start of variables used to create in MATCH queries */
+	/**
+	 * Instruct the JSON query analyzer if it is a projection
+	 */
+	protected boolean projection;
+	/**
+	 * The caller of this instance analyzer.
+	 * It is null if this instance is an entry point. 
+	 * (e.g. a JsonQueryResource instance for a JsonQueryConsistsOf instance)
+	 * 
+	 */
+	protected JsonQueryERElement caller;
+	/**
+	 * The chain of callers of this instance analyzer.
+	 * breadcrumb.get(breadcrumb.size-1) == caller
+	 * breadcrumb is empty if this instance is an entry point
+	 */
+	protected List<JsonQueryERElement> breadcrumb;
+	/**
+	 * The breadcrumb.size() provide the level of nesting. 
+	 * The position which element number at the same level.
+	 * E.g. the index of a ConsistsOf when the caller is a Resource.
+	 * 
+	 * It is used in conjunction with breadcrumb.size() to attach a number to the alias.
+	 * This allows to generate a predictive not clashing alias instead of using random string/number.
+	 * This is useful for testing purposes.
+	 */
+	protected int position;
+
+	/**
+	 * Contains the alias if needed by the class
+	 */
+	protected String alias;
+	
+	/**
+	 * This field is used by entry point only.
+	 * Any class at any level can retrieve the entry point using
+	 * breadcrumb.get(0);
+	 */
+	protected List<String> fieldsToEmit;
+	/* Start of variables used to create in MATCH queries */
+	
+	
+	
+	
 	/** 
 	 * it indicates the number of properties in this.jsonNode
 	 * This number is manipulated while analyzing the jsonNode
@@ -62,6 +109,12 @@ public abstract class JsonQueryERElement {
 		this.entryPoint = false;
 		this.traverseBack = true;
 		
+		this.projection = false;
+		this.caller = null;
+		this.breadcrumb = new ArrayList<>();
+		this.position = 0;
+		
+		
 		this.fieldNamesToRemove = new HashSet<>();
 		this.fieldNamesToRemove.add(Element.TYPE_PROPERTY);
 		this.fieldNamesToRemove.add(ModelElement.SUPERTYPES_PROPERTY);
@@ -91,6 +144,76 @@ public abstract class JsonQueryERElement {
 		this.traverseBack = !entryPoint;
 	}
 	
+	public boolean isProjection() {
+		return projection;
+	}
+
+	public void setProjection(boolean projection) {
+		this.projection = projection;
+		if(projection && !entryPoint) {
+			breadcrumb.get(0).setEntryPoint(projection);
+		}
+	}
+
+	public JsonQueryERElement getCaller() {
+		return caller;
+	}
+
+	public void setCaller(JsonQueryERElement caller) {
+		this.caller = caller;
+	}
+
+	public List<JsonQueryERElement> getBreadcrumb() {
+		return breadcrumb;
+	}
+
+	public void setBreadcrumb(List<JsonQueryERElement> breadcrumb) {
+		this.breadcrumb = breadcrumb;
+	}
+
+	public int getPosition() {
+		return position;
+	}
+
+	public void setPosition(int position) {
+		this.position = position;
+	}
+
+	public String getAlias() {
+		return alias;
+	}
+
+	public String getAlias(boolean generateifNull) {
+		if(alias==null && generateifNull) {
+			alias = generateAlias().toString();
+		}
+		return alias;
+	}
+	
+	protected StringBuffer generateAlias() {
+		StringBuffer sb = new StringBuffer();
+		sb.append(type.toLowerCase());
+		
+		// The entry point will have 00 as suffix
+		sb.append(breadcrumb.size());
+		sb.append(position);
+		return sb;
+	}
+	
+	/**
+	 * Add a field to emit only if this instance is the entry point
+	 * @param fieldToEmit
+	 */
+	protected void addFieldToEmit(String fieldToEmit) {
+		if(entryPoint) {
+			fieldsToEmit.add(fieldToEmit);
+			logger.trace("The field to emit ({}) has been added to entry point, i.e. {} with alias {}", fieldToEmit, this.type, this.alias);
+		}else {
+			logger.trace("The field to emit ({}) will be added to entry point", fieldToEmit);
+			breadcrumb.get(0).addFieldToEmit(fieldToEmit);
+		}
+	}
+	
 	public boolean isTraverseBack() {
 		return traverseBack;
 	}
@@ -103,9 +226,7 @@ public abstract class JsonQueryERElement {
 		return createTraversalQuery(stringBuffer);
 	}
 	
-	protected abstract StringBuffer createTraversalQuery(StringBuffer stringBuffer) throws SchemaNotFoundException, InvalidQueryException, SchemaException, ResourceRegistryException;
-	
-	protected abstract StringBuffer createMatchQuery(StringBuffer stringBuffer) throws SchemaNotFoundException, InvalidQueryException, SchemaException, ResourceRegistryException;
+	public abstract StringBuffer createTraversalQuery(StringBuffer stringBuffer) throws SchemaNotFoundException, InvalidQueryException, SchemaException, ResourceRegistryException;
 	
 	protected StringBuffer addConstraints(JsonNode jsonNode, LogicalOperator queryLogicalOperator, String fieldNamePrefix) throws InvalidQueryException {
 		StringBuffer stringBuffer = new StringBuffer();
@@ -240,4 +361,82 @@ public abstract class JsonQueryERElement {
 		}
 		return stringBuffer;
 	}
+	
+	protected List<JsonQueryERElement> getChildrenBreadcrumb() {
+		List<JsonQueryERElement> childrenBreadcrumb = new ArrayList<>(this.breadcrumb);
+		childrenBreadcrumb.add(this);
+		return childrenBreadcrumb;
+	}
+	
+	protected StringBuffer wrapMatchQuery(StringBuffer buffer) throws InvalidQueryException {
+		if(entryPoint) {
+			alias = getAlias(true);
+			
+			StringBuffer entryBuffer = new StringBuffer();
+			entryBuffer.append("MATCH\n");
+			entryBuffer.append("\t{class: "); // The { has to be closed
+			entryBuffer.append(type);
+			entryBuffer.append(", as: ");
+			entryBuffer.append(alias);
+			entryBuffer.append(", where: ");
+			entryBuffer.append("(($currentMatch['@class'] INSTANCEOF '"); // The first and the second ( has to be closed
+			entryBuffer.append(type);
+			entryBuffer.append("')"); // close the second (
+			
+			if(size>1) {
+				entryBuffer.append(" AND (");
+				entryBuffer.append(addConstraints(jsonNode, null, null));
+				entryBuffer.append(")");
+			}
+			entryBuffer.append(")"); // close the first (
+			
+			entryBuffer.append("}");
+			entryBuffer.append(buffer);
+			
+			entryBuffer.append("\nRETURN\n");
+			
+			if(!projection) {
+				entryBuffer.append("\tDISTINCT(");
+				entryBuffer.append(alias);
+				entryBuffer.append(") as ret");
+				
+				StringBuffer wrap = new StringBuffer();
+				wrap.append("SELECT EXPAND(ret) FROM (\n");
+				wrap.append(entryBuffer);
+				wrap.append("\n)");
+				
+				entryBuffer = wrap;
+			}else {
+				int size = fieldsToEmit.size();
+				for(int i=0; i<size; i++) {
+					entryBuffer.append("\t");
+					entryBuffer.append(fieldsToEmit.get(i));
+					if(i<(size-1)) {
+						entryBuffer.append(",\n");
+					}
+				}
+			}
+			return entryBuffer;
+		}else {
+			return buffer;
+		}
+		
+	}
+	
+	protected abstract StringBuffer getSpecificMatchQuery(List<JsonQueryERElement> childrenBreadcrumb) throws SchemaException, ResourceRegistryException;
+	
+	public StringBuffer createMatchQuery(StringBuffer stringBuffer) throws SchemaException, ResourceRegistryException {
+		List<JsonQueryERElement> childrenBreadcrumb = getChildrenBreadcrumb();
+		
+		if(entryPoint) {
+			alias = getAlias();
+		}
+		
+		StringBuffer buffer = getSpecificMatchQuery(childrenBreadcrumb);
+		buffer = wrapMatchQuery(buffer);
+		
+		stringBuffer.append(buffer);
+		
+		return stringBuffer;
+	}
 }

src/main/java/org/gcube/informationsystem/resourceregistry/queries/json/base/entities/JsonQueryFacet.java

@@ -1,11 +1,14 @@
 package org.gcube.informationsystem.resourceregistry.queries.json.base.entities;
 
+import java.util.List;
+
 import org.gcube.com.fasterxml.jackson.databind.JsonNode;
 import org.gcube.informationsystem.base.reference.AccessType;
 import org.gcube.informationsystem.base.reference.Direction;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.queries.InvalidQueryException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.types.SchemaException;
+import org.gcube.informationsystem.resourceregistry.queries.json.base.JsonQueryERElement;
 import org.gcube.informationsystem.resourceregistry.queries.json.base.relations.JsonQueryConsistsOf;
 import org.gcube.informationsystem.resourceregistry.utils.OrientDBUtility;
 
@@ -87,9 +90,11 @@ public class JsonQueryFacet extends JsonQueryEntity {
 		
 		return newBuffer;
 	}
-	
+
 	@Override
-	public StringBuffer createMatchQuery(StringBuffer stringBuffer) throws SchemaException, ResourceRegistryException {
+	protected StringBuffer getSpecificMatchQuery(List<JsonQueryERElement> childrenBreadcrumb)
+			throws SchemaException, ResourceRegistryException {
+		// TODO Auto-generated method stub
 		return null;
 	}
 	

src/main/java/org/gcube/informationsystem/resourceregistry/queries/json/base/entities/JsonQueryResource.java

@@ -1,5 +1,7 @@
 package org.gcube.informationsystem.resourceregistry.queries.json.base.entities;
 
+import java.util.List;
+
 import org.gcube.com.fasterxml.jackson.databind.JsonNode;
 import org.gcube.com.fasterxml.jackson.databind.node.ArrayNode;
 import org.gcube.informationsystem.base.reference.AccessType;
@@ -7,6 +9,7 @@ import org.gcube.informationsystem.base.reference.Direction;
 import org.gcube.informationsystem.model.reference.entities.Resource;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.types.SchemaException;
+import org.gcube.informationsystem.resourceregistry.queries.json.base.JsonQueryERElement;
 import org.gcube.informationsystem.resourceregistry.queries.json.base.relations.JsonQueryConsistsOf;
 import org.gcube.informationsystem.resourceregistry.queries.json.base.relations.JsonQueryIsRelatedTo;
 import org.gcube.informationsystem.resourceregistry.utils.OrientDBUtility;
@@ -115,8 +118,89 @@ public class JsonQueryResource extends JsonQueryEntity {
 	}
 	
 	@Override
-	public StringBuffer createMatchQuery(StringBuffer stringBuffer) throws SchemaException, ResourceRegistryException {
-		return null;
+	protected StringBuffer getSpecificMatchQuery(List<JsonQueryERElement> childrenBreadcrumb) throws SchemaException, ResourceRegistryException {
+		
+		StringBuffer buffer = new StringBuffer();		
+		
+		int isRelatedToSize = 0;
+		
+		ArrayNode consistsOfArray = (ArrayNode) jsonNode.get(Resource.CONSISTS_OF_PROPERTY);
+		int consistsOfSize = 0;
+		if(consistsOfArray!=null) {
+			consistsOfSize = consistsOfArray.size();
+		}
+		
+		ArrayNode isRelatedToArray = (ArrayNode) jsonNode.get(Resource.IS_RELATED_TO_PROPERTY);
+		if(isRelatedToArray!=null && isRelatedToArray.size()>0) {
+			--size;
+			isRelatedToSize = isRelatedToArray.size();
+			for(int i=0; i<isRelatedToSize; i++) {
+				JsonNode isRelatedToJsonNode = isRelatedToArray.get(i);
+				JsonQueryIsRelatedTo jsonQueryIsRelatedTo = new JsonQueryIsRelatedTo(isRelatedToJsonNode);
+				jsonQueryIsRelatedTo.setRequestedResourceType(type);
+				jsonQueryIsRelatedTo.setDirectionByJson();
+				jsonQueryIsRelatedTo.setCaller(this);
+				jsonQueryIsRelatedTo.setBreadcrumb(childrenBreadcrumb);
+				jsonQueryIsRelatedTo.setPosition(i);
+				
+				boolean traverseBack = false;
+				if(i<(isRelatedToSize-1) || consistsOfSize>0) {
+					traverseBack = true;
+				}
+				jsonQueryIsRelatedTo.setTraverseBack(traverseBack);
+				
+				buffer = jsonQueryIsRelatedTo.createMatchQuery(buffer);
+				
+				if(traverseBack) {
+					buffer.append(jsonQueryIsRelatedTo.getDirection().opposite().name().toLowerCase());
+					buffer.append("V('");
+					buffer.append(type);
+					buffer.append("') ");
+					if(alias!=null || entryPoint) {
+						buffer.append("{ where: ($matched.");
+						buffer.append(alias);
+						buffer.append(" == $currentMatch)}\n");
+					}
+				}
+			}
+		}
+		
+		
+		if(consistsOfSize>0) {
+			--size;
+			for(int i=0; i<consistsOfArray.size(); i++) {
+				JsonNode consistsOfJsonNode = consistsOfArray.get(i);
+				JsonQueryConsistsOf jsonQueryConsistsOf = new JsonQueryConsistsOf(consistsOfJsonNode);
+				jsonQueryConsistsOf.setRequestedResourceType(type);
+				jsonQueryConsistsOf.setDirection(Direction.IN);
+				jsonQueryConsistsOf.setCaller(this);
+				jsonQueryConsistsOf.setBreadcrumb(childrenBreadcrumb);
+				jsonQueryConsistsOf.setPosition(isRelatedToSize+i);
+				
+				boolean traverseBack = false;
+				if(i<(consistsOfSize-1)) {
+					traverseBack = true;
+				}
+				jsonQueryConsistsOf.setTraverseBack(traverseBack);
+				
+				buffer = jsonQueryConsistsOf.createMatchQuery(buffer);
+				
+				if(traverseBack) {
+					buffer.append(jsonQueryConsistsOf.getDirection().opposite().name().toLowerCase());
+					buffer.append("V('");
+					buffer.append(type);
+					buffer.append("') ");
+					if(alias!=null || entryPoint) {
+						buffer.append("{ where: ($matched.");
+						buffer.append(alias);
+						buffer.append(" == $currentMatch)}\n");
+					}
+				}
+			}
+		}
+		
+		return buffer;
 	}
 	
+	
 }

src/main/java/org/gcube/informationsystem/resourceregistry/queries/json/base/relations/JsonQueryConsistsOf.java

@@ -1,11 +1,14 @@
 package org.gcube.informationsystem.resourceregistry.queries.json.base.relations;
 
+import java.util.List;
+
 import org.gcube.com.fasterxml.jackson.databind.JsonNode;
 import org.gcube.informationsystem.base.reference.AccessType;
 import org.gcube.informationsystem.base.reference.Direction;
 import org.gcube.informationsystem.model.reference.relations.ConsistsOf;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.types.SchemaException;
+import org.gcube.informationsystem.resourceregistry.queries.json.base.JsonQueryERElement;
 import org.gcube.informationsystem.resourceregistry.queries.json.base.entities.JsonQueryFacet;
 import org.gcube.informationsystem.resourceregistry.queries.json.base.entities.JsonQueryResource;
 import org.gcube.informationsystem.resourceregistry.utils.OrientDBUtility;
@@ -134,9 +137,11 @@ public class JsonQueryConsistsOf extends JsonQueryRelation {
 		
 		return stringBuffer;
 	}
-	
+
 	@Override
-	public StringBuffer createMatchQuery(StringBuffer stringBuffer) throws SchemaException, ResourceRegistryException {
+	protected StringBuffer getSpecificMatchQuery(List<JsonQueryERElement> childrenBreadcrumb)
+			throws SchemaException, ResourceRegistryException {
+		// TODO Auto-generated method stub
 		return null;
 	}
 	

src/main/java/org/gcube/informationsystem/resourceregistry/queries/json/base/relations/JsonQueryIsRelatedTo.java

@@ -1,5 +1,7 @@
 package org.gcube.informationsystem.resourceregistry.queries.json.base.relations;
 
+import java.util.List;
+
 import javax.ws.rs.InternalServerErrorException;
 
 import org.gcube.com.fasterxml.jackson.databind.JsonNode;
@@ -9,6 +11,7 @@ import org.gcube.informationsystem.model.reference.relations.IsRelatedTo;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.queries.InvalidQueryException;
 import org.gcube.informationsystem.resourceregistry.api.exceptions.types.SchemaException;
+import org.gcube.informationsystem.resourceregistry.queries.json.base.JsonQueryERElement;
 import org.gcube.informationsystem.resourceregistry.queries.json.base.entities.JsonQueryResource;
 import org.gcube.informationsystem.resourceregistry.utils.OrientDBUtility;
 
@@ -192,10 +195,20 @@ public class JsonQueryIsRelatedTo extends JsonQueryRelation {
 		
 		return stringBuffer;
 	}
-	
+
 	@Override
-	public StringBuffer createMatchQuery(StringBuffer stringBuffer) throws SchemaException, ResourceRegistryException {
-		return null;
+	protected StringBuffer getSpecificMatchQuery(List<JsonQueryERElement> childrenBreadcrumb) {
+		
+		if(!entryPoint && direction==null) {
+			throw new InternalServerErrorException("Caller Resource must invoke setDirectionByJson() first. This is a server bug. Please contact the administator. ");
+		}
+		
+		StringBuffer buffer = new StringBuffer();
+		
+		
+		
+		return buffer;
 	}
 	
+	
 }

src/test/java/org/gcube/informationsystem/resourceregistry/queries/JsonQueryTest.java

@@ -188,4 +188,34 @@ public class JsonQueryTest extends ContextTest {
 			logger.info("No limit listing: Got {} with UUID {}", Entity.NAME, uuid);
 		}
 	}
+	
+	@Test
+	public void testCreateMatchQuery() throws Exception {
+		File queriesDirectory = getQueriesDirectory();
+		File jsonQueryFile = new File(queriesDirectory, "query6.json");
+		ObjectMapper objectMapper = new ObjectMapper();
+		JsonNode jsonNode = objectMapper.readTree(jsonQueryFile);
+		logger.info("Going to test the following JSON query {}", jsonNode.toString());
+		
+		JsonQuery jsonQuery = new JsonQuery();
+		jsonQuery.setJsonQuery(jsonNode);
+		StringBuffer createdStringBuffer = jsonQuery.createMatchQuery();
+		
+		logger.info("Created Query from JSON:\n{}", createdStringBuffer.toString());
+		
+//		StringBuffer expectedStringBuffer = new StringBuffer();
+//		File expectedQueryFile = new File(queriesDirectory, jsonQueryFile.getName().replace("json", "match.oquery"));
+//		try(BufferedReader br = new BufferedReader(new FileReader(expectedQueryFile))) {
+//		    for(String line; (line = br.readLine()) != null; ) {
+//		    	expectedStringBuffer.append(line);
+//		    }
+//		}
+//		
+//		logger.info("Expected Query from JSON: {}", expectedStringBuffer.toString());
+//		
+//		Assert.assertTrue(createdStringBuffer.toString().compareTo(expectedStringBuffer.toString())==0);
+//		
+//		String result = jsonQuery.query();
+//		logger.info("Result : {}", result);
+	}
 }

src/test/resources/projection-queries/EService-query-output.json

@@ -0,0 +1,10 @@
+[
+	{
+		"Id" : "",
+		"Group": "",
+		"Name" : "",
+		"Version" : "",
+		"Status" : "",
+		"Host" ""
+	}
+]

src/test/resources/projection-queries/EService-query.json

@@ -0,0 +1,49 @@
+{
+	"_projection" : {
+		"type": "EService",
+		"_emit" : { 
+			"id" : "id" 
+		},
+		"consistsOf": [
+			{
+				"type": "IsIdentifiedBy",
+				"target": {
+					"type": "SoftwareFacet",
+					"_emit" : { 
+						"group" : "Group", 
+						"name": "Name", 
+						"version" : "Version" 
+					}
+				}
+			},
+			{
+				"type": "ConsistsOf",
+				"target": {
+					"type": "StateFacet",
+					"_emit" : { 
+						"value" : "Status" 
+					}
+				}
+			}
+		],
+		"isRelatedTo" : [
+			{
+				"type": "Activates",
+				"source": {
+					"type": "HostingNode",
+					"consistsOf": [
+						{
+							"type": "IsIdentifiedBy",
+							"target": {
+								"type": "NetworkingFacet",
+								"_emit" : { 
+									"hostName" : "Host" 
+								}
+							}
+						}
+					]
+				}
+			}
+		]
+	}
+}

src/test/resources/projection-queries/EService.match.oquery

@@ -0,0 +1,16 @@
+MATCH 
+	{class: EService, as: eservice, where: ($currentMatch['@class'] INSTANCEOF 'EService')}
+    .outE('IsIdentifiedBy').inV('SoftwareFacet') {as: softwarefacet, where: ($currentMatch['@class'] INSTANCEOF 'SoftwareFacet')}
+    .inE('IsIdentifiedBy')
+    .outV('Eservice') {where: ($matched.eservice == $currentMatch)}
+    .outE('ConsistsOf').inV("StateFacet") {as: statefacet, where: (($currentMatch['@class'] INSTANCEOF 'StateFacet'))}
+    .inE('ConsistsOf')
+    .outV('Eservice') {where: ($matched.eservice == $currentMatch)}
+    .inE('Activates').outV('HostingNode').outE('IsIdentifiedBy').inV('NetworkingFacet') {as: networkingfacet, where: ($currentMatch['@class'] INSTANCEOF 'NetworkingFacet')}
+RETURN
+	eservice.id AS ID, 
+	softwarefacet.group AS Group, 
+	softwarefacet.name AS Name, 
+	softwarefacet.version AS Version, 
+	statefacet.value AS Status,
+	networkingfacet.hostName AS Host

src/test/resources/projection-queries/EService.traversal.oquery

@@ -0,0 +1,37 @@
+SELECT id, 
+		outE("IsIdentifiedBy").inV("SoftwareFacet").name[0] AS `Name`, 
+        outE("IsIdentifiedBy").inV("SoftwareFacet").group[0] AS `Group`, 
+        outE("IsIdentifiedBy").inV("SoftwareFacet").version[0] AS `Version`,
+        outE("ConsistsOf").inV("StateFacet").value AS `Status`, 
+        inE("Activates").outV("HostingNode").outE("IsIdentifiedBy").inV("NetworkingFacet").hostName[0] AS `Host` 
+	FROM (
+	TRAVERSE outV("EService") FROM ( 
+		TRAVERSE inE("ConsistsOf") FROM ( 
+			SELECT FROM ( 
+				TRAVERSE inV("StateFacet") FROM ( 
+					TRAVERSE outE("ConsistsOf") FROM ( 
+						TRAVERSE outV("EService") FROM ( 
+							TRAVERSE inE("IsIdentifiedBy") FROM ( 
+								SELECT FROM ( 
+									TRAVERSE inV("SoftwareFacet") FROM ( 
+										TRAVERSE outE("IsIdentifiedBy") FROM ( 
+											TRAVERSE inV("EService") FROM ( 
+												TRAVERSE outE("Activates") FROM ( 
+													TRAVERSE outV("HostingNode") FROM ( 
+														TRAVERSE inE("IsIdentifiedBy") FROM ( 
+															SELECT FROM NetworkingFacet
+														)
+													)
+												)
+											)
+										)
+									)
+								)
+							)
+						)
+					)
+				)
+			)
+		)
+	)
+) WHERE @class INSTANCEOF "EService"

src/test/resources/projection-queries/HostingNode-query-output.json

@@ -0,0 +1,18 @@
+[
+	{
+		"id" : "",
+		"Last Update Time": "",
+		"HostName" : "",
+		"Status" : "",
+		"HD Space Left" : "34 Gb",
+		"Mem. Available." "1,23 Gb"
+	},
+	{
+		"id" : "",
+		"Last Update Time": "",
+		"HostName" : "",
+		"Status" : "",
+		"HD Space Left" : "42 Gb",
+		"Mem. Available." "2,54 Gb"
+	}
+]

src/test/resources/projection-queries/HostingNode-query.json

@@ -0,0 +1,66 @@
+{
+	"_projection" : {
+		"type": "HostingNode",
+		"_emit" : { 
+			"id" : "Id",
+		},
+		"metadata" : {
+			"_emit" : {
+				"lastUpdateTime" : "Last Update Time"
+			}
+		},
+		"consistsOf": [
+			{
+				"type": "IsIdentifiedBy",
+				"target": {
+					"type": "NetworkingFacet",
+					"_emit" : {
+						"hostName" : "HostName"
+					}
+				}
+			},
+			{
+				"type": "ConsistsOf",
+				"target": {
+					"type": "StateFacet",
+					"_emit" : {
+						"value" : "Status"
+					}	
+				}
+			},
+			{
+				"type": "HasPersistentMemory",
+				"target": {
+					"type": "MemoryFacet",
+					"_concat" : { 
+						"values" : [
+							{
+								"_sub" : [ 
+									"size", 
+									"used" 
+								]
+							},
+							"unit" 
+						],
+						"separator" : " ",
+						"as" : "HD Space Left"
+					}
+				}
+			},
+			{
+				"type": "HasVolatileMemory",
+				"target": {
+					"type": "MemoryFacet",
+					"_concat" : {
+						"values" : [
+							"size",
+							"unit" 
+						],
+						"separator" : " ",
+						"as" : "Mem. Available."
+					}
+				}
+			}
+		]
+	}
+}