refactor: introduce concepts for ConstructableType, HierarchicalType, IInstance,…

src/main/java/org/apache/metadata/IInstance.java

+/**
+ * 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.metadata;
+
+/**
+ * Represents a Struct or Trait or Object.
+ */
+public interface IInstance {
+
+    String getTypeName();
+    Object get(String attrName) throws MetadataException;
+    void set(String attrName, Object val) throws MetadataException;
+
+}

src/main/java/org/apache/metadata/IReferencableInstance.java

+/**
+ * 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.metadata;
+
+import com.google.common.collect.ImmutableList;
+import org.apache.metadata.storage.Id;
+
+/**
+ * Represents and instance of a ClassType. These have identity.
+ * Transient instances will have a UNASSIGNED identity.
+ */
+public interface IReferencableInstance extends IStruct {
+
+    ImmutableList<String> getTraits();
+    Id getId();
+
+    IStruct getTrait(String typeName);
+}

src/main/java/org/apache/metadata/IStruct.java

@@ -18,9 +18,9 @@
 
 package org.apache.metadata;
 
-public interface IStruct {
+/**
+ * A marker interface for StructType and TraitType instances.
+ */
+public interface IStruct extends IInstance {
 
-    String getTypeName();
-    Object get(String attrName) throws MetadataException;
-    void set(String attrName, Object val) throws MetadataException;
 }

src/main/java/org/apache/metadata/ITypedInstance.java

+/**
+ * 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.metadata;
+
+import org.apache.metadata.types.FieldMapping;
+
+/**
+ * An instance whose structure is associated with a IDataType.
+ * This is obtained by a call to 'createInstance' or the result of a Query.
+ * A ITypedInstance can only contain information on attributes of the associated Type.
+ * Instance can still be invalid because of missing required fields or incorrect multiplicity.
+ * But user can only get/set on a known field of the associated type. Type values have to match
+ * the IDataType of the associated attribute.
+ */
+public interface ITypedInstance extends IInstance {
+
+    FieldMapping fieldMapping();
+}

src/main/java/org/apache/metadata/ITypedReferencableInstance.java

+/**
+ * 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.metadata;
+
+public interface ITypedReferencableInstance extends ITypedInstance, IReferencableInstance {
+}

src/main/java/org/apache/metadata/ITypedStruct.java

+/**
+ * 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.metadata;
+
+public interface ITypedStruct extends IStruct, ITypedInstance {
+}

src/main/java/org/apache/metadata/storage/Id.java

@@ -24,14 +24,16 @@ public class Id {
 
     public final int id;
     public final String className;
+    public final int version;
 
-    public Id(int id, String className) {
+    public Id(int id, int version, String className) {
         this.id = id;
         this.className = className;
+        this.version = version;
     }
 
     public Id(String className) {
-        this(UNASSIGNED, className);
+        this(UNASSIGNED, 0, className);
     }
 
     public boolean isUnassigned() {

src/main/java/org/apache/metadata/storage/StructInstance.java

@@ -20,6 +20,7 @@ package org.apache.metadata.storage;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import org.apache.metadata.IStruct;
+import org.apache.metadata.ITypedStruct;
 import org.apache.metadata.MetadataException;
 import org.apache.metadata.types.AttributeInfo;
 import org.apache.metadata.types.FieldMapping;
@@ -30,7 +31,7 @@ import java.math.BigInteger;
 import java.util.Date;
 import java.util.Map;
 
-public class StructInstance implements IStruct {
+public class StructInstance implements ITypedStruct {
     public final String dataTypeName;
     public final FieldMapping fieldMapping;
     public final boolean nullFlags[];
@@ -84,6 +85,11 @@ public class StructInstance implements IStruct {
     }
 
     @Override
+    public FieldMapping fieldMapping() {
+        return fieldMapping;
+    }
+
+    @Override
     public Object get(String attrName) throws MetadataException {
         return fieldMapping.get(this, attrName);
     }

src/main/java/org/apache/metadata/types/IConstructableType.java

+package org.apache.metadata.types;
+
+
+import org.apache.metadata.ITypedInstance;
+
+public interface IConstructableType<U, T extends ITypedInstance> extends IDataType<U> {
+
+    T createInstance();
+    FieldMapping fieldMapping();
+}

src/main/java/org/apache/metadata/types/StructType.java

@@ -20,6 +20,7 @@ package org.apache.metadata.types;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import org.apache.metadata.IStruct;
+import org.apache.metadata.ITypedStruct;
 import org.apache.metadata.MetadataException;
 import org.apache.metadata.Struct;
 import org.apache.metadata.storage.StructInstance;
@@ -28,12 +29,14 @@ import java.math.BigDecimal;
 import java.math.BigInteger;
 import java.util.*;
 
-public class StructType  extends AbstractDataType<IStruct> {
+public class StructType  extends AbstractDataType<IStruct>
+        implements IConstructableType<IStruct, ITypedStruct> {
 
     public final ITypeBrowser typeSystem;
     public final String name;
     public final FieldMapping fieldMapping;
     public final int numFields;
+    private final TypedStructHandler handler;
 
     /**
      * Used when creating a StructType, to support recursive Structs.
@@ -43,6 +46,7 @@ public class StructType  extends AbstractDataType<IStruct> {
         this.name = name;
         this.fieldMapping = null;
         this.numFields = numFields;
+        this.handler = null;
     }
 
     protected StructType(ITypeBrowser typeSystem, String name,
@@ -52,6 +56,11 @@ public class StructType  extends AbstractDataType<IStruct> {
         this.fieldMapping = constructFieldMapping(superTypes,
                 fields);
         this.numFields = this.fieldMapping.fields.size();
+        this.handler = new TypedStructHandler(this);
+    }
+
+    public FieldMapping fieldMapping() {
+        return fieldMapping;
     }
 
     @Override
@@ -156,77 +165,21 @@ public class StructType  extends AbstractDataType<IStruct> {
 
 
     @Override
-    public StructInstance convert(Object val, Multiplicity m) throws MetadataException {
-        if ( val != null ) {
-            if ( val instanceof Struct ) {
-                Struct s = (Struct) val;
-                if ( s.typeName != name ) {
-                    throw new ValueConversionException(this, val);
-                }
-                StructInstance ts = createInstance();
-                for(Map.Entry<String,AttributeInfo> e : fieldMapping.fields.entrySet() ) {
-                    String attrKey = e.getKey();
-                    AttributeInfo i = e.getValue();
-                    Object aVal = s.get(attrKey);
-                    try {
-                        ts.set(attrKey, aVal);
-                    } catch(ValueConversionException ve) {
-                        throw new ValueConversionException(this, val, ve);
-                    }
-                }
-                return ts;
-            } else if ( val instanceof StructInstance && ((StructInstance)val).getTypeName() == getName() ) {
-                return (StructInstance) val;
-            } else {
-                throw new ValueConversionException(this, val);
-            }
-        }
-        if (!m.nullAllowed() ) {
-            throw new ValueConversionException.NullConversionException(m);
-        }
-        return null;
+    public DataTypes.TypeCategory getTypeCategory() {
+        return DataTypes.TypeCategory.STRUCT;
     }
 
     @Override
-    public DataTypes.TypeCategory getTypeCategory() {
-        return DataTypes.TypeCategory.STRUCT;
+    public ITypedStruct convert(Object val, Multiplicity m) throws MetadataException {
+        return handler.convert(val, m);
     }
 
-    public StructInstance createInstance() {
-        return new StructInstance(getName(),
-                fieldMapping,
-                new boolean[fieldMapping.fields.size()],
-        fieldMapping.numBools == 0 ? null : new boolean[fieldMapping.numBools],
-                fieldMapping.numBytes == 0 ? null : new byte[fieldMapping.numBytes],
-                fieldMapping.numShorts == 0 ? null : new short[fieldMapping.numShorts],
-                fieldMapping.numInts == 0 ? null : new int[fieldMapping.numInts],
-                fieldMapping.numLongs == 0 ? null : new long[fieldMapping.numLongs],
-                fieldMapping.numFloats == 0 ? null : new float[fieldMapping.numFloats],
-                fieldMapping.numDoubles == 0 ? null : new double[fieldMapping.numDoubles],
-                fieldMapping.numBigDecimals == 0 ? null : new BigDecimal[fieldMapping.numBigDecimals],
-                fieldMapping.numBigInts == 0 ? null : new BigInteger[fieldMapping.numBigInts],
-                fieldMapping.numDates == 0 ? null : new Date[fieldMapping.numDates],
-                fieldMapping.numStrings == 0 ? null : new String[fieldMapping.numStrings],
-                fieldMapping.numArrays == 0 ? null : new ImmutableList[fieldMapping.numArrays],
-                fieldMapping.numMaps == 0 ? null : new ImmutableMap[fieldMapping.numMaps],
-                fieldMapping.numStructs == 0 ? null : new StructInstance[fieldMapping.numStructs]);
+    public ITypedStruct createInstance() {
+        return handler.createInstance();
     }
 
     @Override
     public void output(IStruct s, Appendable buf, String prefix) throws MetadataException {
-        TypeUtils.outputVal("{", buf, prefix);
-        if ( s == null ) {
-            TypeUtils.outputVal("<null>\n", buf, "");
-            return;
-        }
-        TypeUtils.outputVal("\n", buf, "");
-        String fieldPrefix = prefix + "\t";
-        for(AttributeInfo i : fieldMapping.fields.values()) {
-            Object aVal = s.get(i.name);
-            TypeUtils.outputVal(i.name + " : ", buf, fieldPrefix);
-            i.dataType().output(aVal, buf, "");
-            TypeUtils.outputVal("\n", buf, "");
-        }
-        TypeUtils.outputVal("\n}\n", buf, "");
+        handler.output(s, buf, prefix);
     }
 }

src/main/java/org/apache/metadata/types/TypedStructHandler.java

+/**
+ * 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.metadata.types;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+import org.apache.metadata.IStruct;
+import org.apache.metadata.ITypedStruct;
+import org.apache.metadata.MetadataException;
+import org.apache.metadata.Struct;
+import org.apache.metadata.storage.StructInstance;
+
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.util.Date;
+import java.util.Map;
+
+public class TypedStructHandler {
+
+    private final IConstructableType<IStruct, ITypedStruct> structType;
+    private final FieldMapping fieldMapping;
+
+    public TypedStructHandler(IConstructableType<IStruct, ITypedStruct> structType) {
+        this.structType = structType;
+        fieldMapping = structType.fieldMapping();
+    }
+
+    public ITypedStruct convert(Object val, Multiplicity m) throws MetadataException {
+        if ( val != null ) {
+            if ( val instanceof Struct) {
+                Struct s = (Struct) val;
+                if ( s.typeName != structType.getName() ) {
+                    throw new ValueConversionException(structType, val);
+                }
+                ITypedStruct ts = createInstance();
+                for(Map.Entry<String,AttributeInfo> e : fieldMapping.fields.entrySet() ) {
+                    String attrKey = e.getKey();
+                    AttributeInfo i = e.getValue();
+                    Object aVal = s.get(attrKey);
+                    try {
+                        ts.set(attrKey, aVal);
+                    } catch(ValueConversionException ve) {
+                        throw new ValueConversionException(structType, val, ve);
+                    }
+                }
+                return ts;
+            } else if ( val instanceof StructInstance && ((StructInstance)val).getTypeName() == structType.getName() ) {
+                return (StructInstance) val;
+            } else {
+                throw new ValueConversionException(structType, val);
+            }
+        }
+        if (!m.nullAllowed() ) {
+            throw new ValueConversionException.NullConversionException(m);
+        }
+        return null;
+    }
+
+    public DataTypes.TypeCategory getTypeCategory() {
+        return DataTypes.TypeCategory.STRUCT;
+    }
+
+    public ITypedStruct createInstance() {
+        return new StructInstance(structType.getName(),
+                fieldMapping,
+                new boolean[fieldMapping.fields.size()],
+                fieldMapping.numBools == 0 ? null : new boolean[fieldMapping.numBools],
+                fieldMapping.numBytes == 0 ? null : new byte[fieldMapping.numBytes],
+                fieldMapping.numShorts == 0 ? null : new short[fieldMapping.numShorts],
+                fieldMapping.numInts == 0 ? null : new int[fieldMapping.numInts],
+                fieldMapping.numLongs == 0 ? null : new long[fieldMapping.numLongs],
+                fieldMapping.numFloats == 0 ? null : new float[fieldMapping.numFloats],
+                fieldMapping.numDoubles == 0 ? null : new double[fieldMapping.numDoubles],
+                fieldMapping.numBigDecimals == 0 ? null : new BigDecimal[fieldMapping.numBigDecimals],
+                fieldMapping.numBigInts == 0 ? null : new BigInteger[fieldMapping.numBigInts],
+                fieldMapping.numDates == 0 ? null : new Date[fieldMapping.numDates],
+                fieldMapping.numStrings == 0 ? null : new String[fieldMapping.numStrings],
+                fieldMapping.numArrays == 0 ? null : new ImmutableList[fieldMapping.numArrays],
+                fieldMapping.numMaps == 0 ? null : new ImmutableMap[fieldMapping.numMaps],
+                fieldMapping.numStructs == 0 ? null : new StructInstance[fieldMapping.numStructs]);
+    }
+
+    public void output(IStruct s, Appendable buf, String prefix) throws MetadataException {
+        TypeUtils.outputVal("{", buf, prefix);
+        if ( s == null ) {
+            TypeUtils.outputVal("<null>\n", buf, "");
+            return;
+        }
+        TypeUtils.outputVal("\n", buf, "");
+        String fieldPrefix = prefix + "\t";
+        for(AttributeInfo i : fieldMapping.fields.values()) {
+            Object aVal = s.get(i.name);
+            TypeUtils.outputVal(i.name + " : ", buf, fieldPrefix);
+            i.dataType().output(aVal, buf, "");
+            TypeUtils.outputVal("\n", buf, "");
+        }
+        TypeUtils.outputVal("\n}\n", buf, "");
+    }
+
+}

src/main/scala/org/apache/metadata/dsl/DynamicTypedStruct.scala

@@ -18,12 +18,12 @@
 
 package org.apache.metadata.dsl
 
-import org.apache.metadata.MetadataService
+import org.apache.metadata.{ITypedStruct, MetadataService}
 import org.apache.metadata.storage.StructInstance
 import org.apache.metadata.types.TypeSystem
 import scala.language.dynamics
 
-class DynamicTypedStruct(val ts : StructInstance) extends Dynamic {
+class DynamicTypedStruct(val ts : ITypedStruct) extends Dynamic {
   def selectDynamic(name: String) = ts.get(name)
   def updateDynamic(name: String)(value: Any) {
     var value1 = value

src/main/scala/org/apache/metadata/dsl/package.scala

@@ -82,7 +82,7 @@ package object dsl {
 
   def createInstance(typeName : String) = {
     new DynamicTypedStruct(
-      ts.getDataType(typeName).asInstanceOf[StructType].createInstance())
+      ts.getDataType(typeName).asInstanceOf[IConstructableType[IStruct, ITypedStruct]].createInstance())
   }
 
   implicit def dynTypedStructToTypedStruct(s : DynamicTypedStruct) = s.ts

src/main/scala/org/apache/metadata/json/Serialization.scala

@@ -19,7 +19,7 @@
 package org.apache.metadata.json
 
 import org.apache.metadata.types.DataTypes.{MapType, TypeCategory, ArrayType}
-import org.apache.metadata.{MetadataException, MetadataService}
+import org.apache.metadata.{ITypedStruct, IStruct, MetadataException, MetadataService}
 import org.apache.metadata.types._
 import org.json4s.JsonAST.JInt
 import org.json4s._
@@ -27,7 +27,6 @@ import org.json4s.native.Serialization.{read, write => swrite}
 import org.json4s.reflect.{ScalaType, Reflector}
 import java.util.regex.Pattern
 import java.util.Date
-import org.apache.metadata.storage.StructInstance
 import collection.JavaConversions._
 import scala.collection.JavaConverters._
 
@@ -45,7 +44,7 @@ class BigIntegerSerializer extends CustomSerializer[java.math.BigInteger](format
 }
   ))
 
-class TypedStructSerializer extends Serializer[StructInstance] {
+class TypedStructSerializer extends Serializer[ITypedStruct] {
 
   def extractList(lT : ArrayType, value : JArray)(implicit format: Formats) : Any = {
     val dT = lT.getElemType
@@ -69,15 +68,15 @@ class TypedStructSerializer extends Serializer[StructInstance] {
     case value : JObject if dT.getTypeCategory eq TypeCategory.MAP =>
       extractMap(dT.asInstanceOf[MapType], value.asInstanceOf[JObject])
     case value : JObject  =>
-      Extraction.extract[StructInstance](value)
+      Extraction.extract[ITypedStruct](value)
   }
 
   def deserialize(implicit format: Formats) = {
-    case (TypeInfo(clazz, ptype), json) if classOf[StructInstance].isAssignableFrom(clazz) => json match {
+    case (TypeInfo(clazz, ptype), json) if classOf[ITypedStruct].isAssignableFrom(clazz) => json match {
       case JObject(fs) =>
         val(typ, fields) = fs.partition(f => f._1 == Serialization.STRUCT_TYPE_FIELD_NAME)
         val typName = typ(0)._2.asInstanceOf[JString].s
-        val sT = MetadataService.getCurrentTypeSystem().getDataType(typName).asInstanceOf[StructType]
+        val sT = MetadataService.getCurrentTypeSystem().getDataType(typName).asInstanceOf[IConstructableType[IStruct, ITypedStruct]]
         val s = sT.createInstance()
         fields.foreach { f =>
           val fName = f._1
@@ -85,7 +84,8 @@ class TypedStructSerializer extends Serializer[StructInstance] {
           if ( fInfo != null ) {
             //println(fName)
             var v = f._2
-            if ( fInfo.dataType().isInstanceOf[StructType] ) {
+            if ( fInfo.dataType().getTypeCategory == TypeCategory.TRAIT ||
+              fInfo.dataType().getTypeCategory == TypeCategory.STRUCT) {
               v = v match {
                 case JObject(sFields) =>
                   JObject(JField(Serialization.STRUCT_TYPE_FIELD_NAME, JString(fInfo.dataType.getName)) :: sFields)
@@ -109,7 +109,7 @@ class TypedStructSerializer extends Serializer[StructInstance] {
   //implicit def javaBigInteger2bigInt(x: java.math.BigInteger): BigInt = new BigInt(x)
 
   def serialize(implicit format: Formats) = {
-    case e: StructInstance =>
+    case e: ITypedStruct =>
       val fields  = e.fieldMapping.fields.map {
         case (fName, info) => {
           var v = e.get(fName)
@@ -119,7 +119,7 @@ class TypedStructSerializer extends Serializer[StructInstance] {
           JField(fName, Extraction.decompose(v))
         }
       }.toList.map(_.asInstanceOf[JField])
-      JObject(JField(Serialization.STRUCT_TYPE_FIELD_NAME, JString(e.dataTypeName)) :: fields)
+      JObject(JField(Serialization.STRUCT_TYPE_FIELD_NAME, JString(e.getTypeName)) :: fields)
   }
 }
 

src/test/java/org/apache/metadata/StructTest.java

@@ -38,7 +38,7 @@ public class StructTest extends BaseTest {
     @Test
     public void test1() throws MetadataException {
         Struct s = createStruct(ms);
-        StructInstance ts = structType.convert(s, Multiplicity.REQUIRED);
+        ITypedStruct ts = structType.convert(s, Multiplicity.REQUIRED);
         System.out.println(ts);
     }
 
@@ -49,7 +49,7 @@ public class StructTest extends BaseTest {
         Struct s2 = new Struct(recursiveStructType.getName());
         s2.set("a", 1);
         s2.set("s", s1);
-        StructInstance ts = recursiveStructType.convert(s2, Multiplicity.REQUIRED);
+        ITypedStruct ts = recursiveStructType.convert(s2, Multiplicity.REQUIRED);
         System.out.println(ts);
     }
 

src/test/java/org/apache/metadata/TraitTest.java

@@ -64,7 +64,7 @@ public class TraitTest extends BaseTest {
         s1.set("A.C.D.d", 3);
 
 
-        StructInstance ts = DType.convert(s1, Multiplicity.REQUIRED);
+        ITypedStruct ts = DType.convert(s1, Multiplicity.REQUIRED);
         System.out.println(ts);
 
         /*

src/test/scala/org/apache/metadata/json/SerializationTest.scala

@@ -19,11 +19,10 @@
 package org.apache.metadata.json
 
 import com.google.common.collect.ImmutableList
-import org.apache.metadata.Struct
+import org.apache.metadata.{ITypedStruct, Struct, BaseTest}
 import org.apache.metadata.storage.StructInstance
 import org.apache.metadata.storage.StructInstance
 import org.apache.metadata.types._
-import org.apache.metadata.{Struct, BaseTest}
 import org.json4s.NoTypeHints
 import org.junit.Before
 import org.junit.Test
@@ -46,7 +45,7 @@ class SerializationTest extends BaseTest {
 
   @Test def test1 {
     val s: Struct = BaseTest.createStruct(ms)
-    val ts: StructInstance = structType.convert(s, Multiplicity.REQUIRED)
+    val ts: ITypedStruct = structType.convert(s, Multiplicity.REQUIRED)
 
     println("Typed Struct :")
     println(ts)
@@ -65,7 +64,7 @@ class SerializationTest extends BaseTest {
 
   @Test def test2 {
     val s: Struct = BaseTest.createStruct(ms)
-    val ts: StructInstance = structType.convert(s, Multiplicity.REQUIRED)
+    val ts: ITypedStruct = structType.convert(s, Multiplicity.REQUIRED)
 
     implicit val formats = org.json4s.native.Serialization.formats(NoTypeHints) + new TypedStructSerializer +
       new BigDecimalSerializer + new BigIntegerSerializer
@@ -108,7 +107,7 @@ class SerializationTest extends BaseTest {
     s1.set("A.C.D.d", 3)
 
     val s: Struct = BaseTest.createStruct(ms)
-    val ts: StructInstance = DType.convert(s1, Multiplicity.REQUIRED)
+    val ts: ITypedStruct = DType.convert(s1, Multiplicity.REQUIRED)
 
     implicit val formats = org.json4s.native.Serialization.formats(NoTypeHints) + new TypedStructSerializer +
       new BigDecimalSerializer + new BigIntegerSerializer