[OLINGO-832] Merge branch 'OLINGO-832_StreamSerializerPoC'

fit/src/test/java/org/apache/olingo/fit/tecsvc/http/BasicStreamITCase.java

@@ -0,0 +1,66 @@
+/*
+ * 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.olingo.fit.tecsvc.http;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import java.net.HttpURLConnection;
+import java.net.URL;
+
+import org.apache.commons.io.IOUtils;
+import org.apache.olingo.client.api.ODataClient;
+import org.apache.olingo.commons.api.format.ContentType;
+import org.apache.olingo.commons.api.http.HttpHeader;
+import org.apache.olingo.commons.api.http.HttpMethod;
+import org.apache.olingo.commons.api.http.HttpStatusCode;
+import org.apache.olingo.fit.AbstractBaseTestITCase;
+import org.apache.olingo.fit.tecsvc.TecSvcConst;
+import org.junit.Test;
+
+public class BasicStreamITCase extends AbstractBaseTestITCase {
+
+  private static final String SERVICE_URI = TecSvcConst.BASE_URI + "/";
+
+  @Test
+  public void streamAllPrim() throws Exception {
+    URL url = new URL(SERVICE_URI + "ESAllPrim?$format=json");
+
+    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
+    connection.setRequestMethod(HttpMethod.GET.name());
+    connection.setRequestProperty("odata.streaming", "true");
+    connection.connect();
+
+    assertEquals(HttpStatusCode.OK.getStatusCode(), connection.getResponseCode());
+    assertEquals(ContentType.JSON, ContentType.create(connection.getHeaderField(HttpHeader.CONTENT_TYPE)));
+
+    final String content = IOUtils.toString(connection.getInputStream());
+
+    assertTrue(content.contains("\"PropertyString\":\"First Resource - positive values->streamed\""));
+    assertTrue(content.contains("\"PropertyString\":\"Second Resource - negative values->streamed\""));
+    assertTrue(content.contains("\"PropertyString\":\"->streamed\""));
+  }
+
+
+  @Override
+  protected ODataClient getClient() {
+    return null;
+  }
+
+}

lib/client-core/src/main/java/org/apache/olingo/client/core/serialization/AtomSerializer.java

@@ -525,7 +525,7 @@ public class AtomSerializer extends AbstractAtomDealer implements ODataSerialize
 
     common(writer, entitySet);
 
-    for (Entity entity : entitySet.getEntities()) {
+    for (Entity entity : entitySet) {
       if (entity.getType() == null && entity.getProperties().isEmpty()) {
         entityRef(writer, entity);
       } else {

lib/commons-api/src/main/java/org/apache/olingo/commons/api/data/AbstractEntityCollection.java

@@ -0,0 +1,30 @@
+/*
+ * 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.olingo.commons.api.data;
+
+import java.net.URI;
+import java.util.Iterator;
+
+public abstract class AbstractEntityCollection extends AbstractODataObject implements Iterable<Entity> {
+  public abstract Integer getCount();
+
+  public abstract URI getNext();
+
+  public abstract URI getDeltaLink();
+}

lib/commons-api/src/main/java/org/apache/olingo/commons/api/data/EntityCollection.java

@@ -20,12 +20,13 @@ package org.apache.olingo.commons.api.data;
 
 import java.net.URI;
 import java.util.ArrayList;
+import java.util.Iterator;
 import java.util.List;
 
 /**
  * Data representation for a collection of single entities.
  */
-public class EntityCollection extends AbstractODataObject {
+public class EntityCollection extends AbstractEntityCollection {
 
   private final List<Entity> entities = new ArrayList<Entity>();
   private Integer count;
@@ -46,6 +47,7 @@ public class EntityCollection extends AbstractODataObject {
    *
    * @return number of entries into the entity set.
    */
+  @Override
   public Integer getCount() {
     return count;
   }
@@ -73,6 +75,7 @@ public class EntityCollection extends AbstractODataObject {
    *
    * @return next link if exists; null otherwise.
    */
+  @Override
   public URI getNext() {
     return next;
   }
@@ -82,6 +85,7 @@ public class EntityCollection extends AbstractODataObject {
    *
    * @return delta link if exists; null otherwise.
    */
+  @Override
   public URI getDeltaLink() {
     return deltaLink;
   }
@@ -95,6 +99,11 @@ public class EntityCollection extends AbstractODataObject {
     this.deltaLink = deltaLink;
   }
 
+  @Override
+  public Iterator<Entity> iterator() {
+    return this.entities.iterator();
+  }
+
   @Override
   public boolean equals(final Object o) {
     if (!super.equals(o)) {

lib/commons-api/src/main/java/org/apache/olingo/commons/api/data/EntityIterator.java

@@ -0,0 +1,58 @@
+/*
+ * 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.olingo.commons.api.data;
+
+import org.apache.olingo.commons.api.ex.ODataNotSupportedException;
+import org.apache.olingo.commons.api.ex.ODataRuntimeException;
+import sun.reflect.generics.reflectiveObjects.NotImplementedException;
+
+import java.net.URI;
+import java.util.Iterator;
+
+/**
+ * Data representation for a collection of single entities.
+ */
+public abstract class EntityIterator extends AbstractEntityCollection implements Iterator<Entity> {
+
+  public abstract boolean hasNext();
+  public abstract Entity next();
+
+  @Override
+  public void remove() {
+    //"Remove is not supported for iteration over Entities."
+    throw new ODataNotSupportedException("Entity Iterator does not support remove()");
+  }
+
+  @Override
+  public Iterator<Entity> iterator() {
+    return this;
+  }
+
+  public Integer getCount() {
+    throw new ODataNotSupportedException("Entity Iterator does not support getCount()");
+  }
+
+  public URI getNext() {
+    throw new ODataNotSupportedException("Entity Iterator does not support getNext()");
+  }
+
+  public URI getDeltaLink() {
+    throw new ODataNotSupportedException("Entity Iterator does not support getDeltaLink()");
+  }
+}

lib/commons-api/src/main/java/org/apache/olingo/commons/api/ex/ODataNotSupportedException.java

@@ -0,0 +1,56 @@
+/*
+ * 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.olingo.commons.api.ex;
+
+/**
+ * Core runtime exception for OData.
+ */
+public class ODataNotSupportedException extends ODataRuntimeException {
+
+  private static final long serialVersionUID = 42L;
+
+  /**
+   * Create with <code>message</code>.
+   *
+   * @param msg message text for exception
+   */
+  public ODataNotSupportedException(final String msg) {
+    super(msg);
+  }
+
+  /**
+   * Create with <code>message</code> for and <code>cause</code> of exception.
+   *
+   * @param msg message text for exception
+   * @param cause cause of exception
+   */
+  public ODataNotSupportedException(final String msg, final Exception cause) {
+    super(msg, cause);
+  }
+
+  /**
+   * Create with <code>cause</code> of exception.
+   *
+   * @param cause cause of exception
+   */
+  public ODataNotSupportedException(final Exception cause) {
+    super(cause);
+  }
+
+}

lib/server-api/src/main/java/org/apache/olingo/server/api/ODataContent.java

@@ -0,0 +1,28 @@
+/*
+ * 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.olingo.server.api;
+
+import java.io.OutputStream;
+import java.nio.channels.WritableByteChannel;
+
+public interface ODataContent {
+  void write(WritableByteChannel channel);
+
+  void write(OutputStream stream);
+}

lib/server-api/src/main/java/org/apache/olingo/server/api/ODataResponse.java

@@ -18,12 +18,12 @@
  */
 package org.apache.olingo.server.api;
 
+import org.apache.olingo.commons.api.http.HttpStatusCode;
+
 import java.io.InputStream;
 import java.util.List;
 import java.util.Map;
 
-import org.apache.olingo.commons.api.http.HttpStatusCode;
-
 /**
  * Response object to carry OData-relevant HTTP information (status code, response headers, and content).
  */
@@ -131,4 +131,13 @@ public class ODataResponse {
     return content;
   }
 
+  private ODataContent odataContent;
+
+  public void setODataContent(ODataContent result) {
+    odataContent = result;
+  }
+
+  public ODataContent getODataContent() {
+    return odataContent;
+  }
 }

lib/server-api/src/main/java/org/apache/olingo/server/api/WriteContentErrorCallback.java

@@ -0,0 +1,30 @@
+/*
+ * 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.olingo.server.api;
+
+import java.io.OutputStream;
+import java.nio.channels.WritableByteChannel;
+
+/**
+ * The WriteContentErrorCallback is called when during the {@link ODataContent#write(OutputStream)}
+ * or the {@link ODataContent#write(WritableByteChannel)} an error occurs.
+ */
+public interface WriteContentErrorCallback {
+  void handleError(WriteContentErrorContext context, WritableByteChannel channel);
+}

lib/server-api/src/main/java/org/apache/olingo/server/api/WriteContentErrorContext.java

@@ -0,0 +1,27 @@
+/*
+ * 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.olingo.server.api;
+
+/**
+ * The WriteContentErrorErrorContext is the parameter for the WriteContentErrorCallback.
+ */
+public interface WriteContentErrorContext {
+  Exception getException();
+  ODataLibraryException getODataLibraryException();
+}

lib/server-api/src/main/java/org/apache/olingo/server/api/serializer/EntityCollectionSerializerOptions.java

@@ -19,6 +19,7 @@
 package org.apache.olingo.server.api.serializer;
 
 import org.apache.olingo.commons.api.data.ContextURL;
+import org.apache.olingo.server.api.WriteContentErrorCallback;
 import org.apache.olingo.server.api.uri.queryoption.CountOption;
 import org.apache.olingo.server.api.uri.queryoption.ExpandOption;
 import org.apache.olingo.server.api.uri.queryoption.SelectOption;
@@ -32,6 +33,7 @@ public class EntityCollectionSerializerOptions {
   private SelectOption select;
   private boolean writeOnlyReferences;
   private String id;
+  private WriteContentErrorCallback writeContentErrorCallback;
   private String xml10InvalidCharReplacement;
 
   /** Gets the {@link ContextURL}. */
@@ -64,6 +66,17 @@ public class EntityCollectionSerializerOptions {
     return id;
   }
 
+  /**
+   * Gets the callback which is used in case of an exception during
+   * write of the content (in case the content will be written/streamed
+   * in the future)
+   * @return callback which is used in case of an exception during
+   * write of the content
+   *
+   */
+  public WriteContentErrorCallback getWriteContentErrorCallback() {
+    return writeContentErrorCallback;
+  }
   /** Gets the replacement string for unicode characters, that is not allowed in XML 1.0 */
   public String xml10InvalidCharReplacement() {
     return xml10InvalidCharReplacement;
@@ -119,6 +132,18 @@ public class EntityCollectionSerializerOptions {
       return this;
     }
 
+    /**
+     * Set the callback which is used in case of an exception during
+     * write of the content.
+     *
+     * @param writeContentErrorCallback the callback
+     * @return the builder
+     */
+    public Builder writeContentErrorCallback(WriteContentErrorCallback writeContentErrorCallback) {
+      options.writeContentErrorCallback = writeContentErrorCallback;
+      return this;
+    }
+
     /** set the replacement String for xml 1.0 unicode controlled characters that are not allowed */
     public Builder xml10InvalidCharReplacement(final String replacement) {
       options.xml10InvalidCharReplacement = replacement;

lib/server-api/src/main/java/org/apache/olingo/server/api/serializer/ODataSerializer.java

@@ -19,7 +19,8 @@
 package org.apache.olingo.server.api.serializer;
 
 import org.apache.olingo.commons.api.data.Entity;
-import org.apache.olingo.commons.api.data.EntityCollection;
+import org.apache.olingo.commons.api.data.AbstractEntityCollection;
+import org.apache.olingo.commons.api.data.EntityIterator;
 import org.apache.olingo.commons.api.data.Property;
 import org.apache.olingo.commons.api.edm.EdmComplexType;
 import org.apache.olingo.commons.api.edm.EdmEntitySet;
@@ -61,7 +62,17 @@ public interface ODataSerializer {
    * @param options options for the serializer
    */
   SerializerResult entityCollection(ServiceMetadata metadata, EdmEntityType entityType,
-      EntityCollection entitySet, EntityCollectionSerializerOptions options) throws SerializerException;
+      AbstractEntityCollection entitySet, EntityCollectionSerializerOptions options) throws SerializerException;
+
+  /**
+   * Writes entity-collection data into an InputStream.
+   * @param metadata metadata for the service
+   * @param entityType the {@link EdmEntityType}
+   * @param entities the data of the entity set
+   * @param options options for the serializer
+   */
+  SerializerStreamResult entityCollectionStreamed(ServiceMetadata metadata, EdmEntityType entityType,
+      EntityIterator entities, EntityCollectionSerializerOptions options) throws SerializerException;
 
   /**
    * Writes entity data into an InputStream.
@@ -128,8 +139,9 @@ public interface ODataSerializer {
    * @param metadata metadata for the service
    * @param edmEntitySet {@link EdmEntitySet}
    * @param entityCollection data of the entity collection
-   * @param ReferenceCollectionSerializerOptions {@link ReferenceCollectionSerializerOptions}
+   * @param options {@link ReferenceCollectionSerializerOptions}
    */
   SerializerResult referenceCollection(ServiceMetadata metadata, EdmEntitySet edmEntitySet,
-      EntityCollection entityCollection, ReferenceCollectionSerializerOptions options) throws SerializerException;
+      AbstractEntityCollection entityCollection, ReferenceCollectionSerializerOptions options)
+      throws SerializerException;
 }

lib/server-api/src/main/java/org/apache/olingo/server/api/serializer/SerializerStreamResult.java

@@ -0,0 +1,33 @@
+/*
+ * 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.olingo.server.api.serializer;
+
+import org.apache.olingo.server.api.ODataContent;
+
+/**
+ * Result type for {@link ODataSerializer} methods
+ * which supports stream/write in the future
+ */
+public interface SerializerStreamResult {
+  /**
+   * Returns the content as ODataContent
+   * @return content
+   */
+  ODataContent getODataContent();
+}

lib/server-core/src/main/java/org/apache/olingo/server/core/ODataHttpHandlerImpl.java

@@ -19,6 +19,7 @@
 package org.apache.olingo.server.core;
 
 import java.io.IOException;
+import java.io.InputStream;
 import java.nio.ByteBuffer;
 import java.nio.channels.Channel;
 import java.nio.channels.Channels;
@@ -38,6 +39,7 @@ import org.apache.olingo.commons.api.ex.ODataRuntimeException;
 import org.apache.olingo.commons.api.http.HttpHeader;
 import org.apache.olingo.commons.api.http.HttpMethod;
 import org.apache.olingo.server.api.OData;
+import org.apache.olingo.server.api.ODataContent;
 import org.apache.olingo.server.api.ODataHttpHandler;
 import org.apache.olingo.server.api.ODataLibraryException;
 import org.apache.olingo.server.api.ODataRequest;
@@ -149,22 +151,35 @@ public class ODataHttpHandlerImpl implements ODataHttpHandler {
       }
     }
 
-    if (odResponse.getContent() != null) {
+    if (odResponse.getContent() != null ) {
-      copyContent(odResponse, response);
+      copyContent(odResponse.getContent(), response);
+    } else if(odResponse.getODataContent() != null) {
+      writeContent(odResponse, response);
     }
   }
 
-  static void copyContent(final ODataResponse odataResponse, final HttpServletResponse servletResponse) {
+  static void writeContent(final ODataResponse odataResponse, final HttpServletResponse servletResponse) {
-    ReadableByteChannel input = null;
+    try {
+      ODataContent res = odataResponse.getODataContent();
+      res.write(Channels.newChannel(servletResponse.getOutputStream()));
+    } catch (IOException e) {
+      throw new ODataRuntimeException("Error on reading request content", e);
+    }
+  }
+
+  static void copyContent(final InputStream inputStream, final HttpServletResponse servletResponse) {
+    copyContent(Channels.newChannel(inputStream), servletResponse);
+  }
+
+  static void copyContent(final ReadableByteChannel input, final HttpServletResponse servletResponse) {
     WritableByteChannel output = null;
     try {
       ByteBuffer inBuffer = ByteBuffer.allocate(COPY_BUFFER_SIZE);
       output = Channels.newChannel(servletResponse.getOutputStream());
-      input = Channels.newChannel(odataResponse.getContent());
       while (input.read(inBuffer) > 0) {
         inBuffer.flip();
         output.write(inBuffer);
-        inBuffer.rewind();
+        inBuffer.clear();
       }
     } catch (IOException e) {
       throw new ODataRuntimeException("Error on reading request content", e);

lib/server-core/src/main/java/org/apache/olingo/server/core/ODataWritableContent.java

@@ -0,0 +1,188 @@
+/*
+ * 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.olingo.server.core;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.nio.channels.Channels;
+import java.nio.channels.WritableByteChannel;
+
+import org.apache.olingo.commons.api.data.EntityIterator;
+import org.apache.olingo.commons.api.edm.EdmEntityType;
+import org.apache.olingo.commons.api.ex.ODataRuntimeException;
+import org.apache.olingo.server.api.ODataContent;
+import org.apache.olingo.server.api.ODataLibraryException;
+import org.apache.olingo.server.api.ServiceMetadata;
+import org.apache.olingo.server.api.WriteContentErrorCallback;
+import org.apache.olingo.server.api.WriteContentErrorContext;
+import org.apache.olingo.server.api.serializer.EntityCollectionSerializerOptions;
+import org.apache.olingo.server.api.serializer.ODataSerializer;
+import org.apache.olingo.server.api.serializer.SerializerException;
+import org.apache.olingo.server.api.serializer.SerializerStreamResult;
+import org.apache.olingo.server.core.serializer.SerializerStreamResultImpl;
+import org.apache.olingo.server.core.serializer.json.ODataJsonSerializer;
+import org.apache.olingo.server.core.serializer.xml.ODataXmlSerializer;
+
+public class ODataWritableContent implements ODataContent {
+  private StreamContent streamContent;
+
+  private static abstract class StreamContent {
+    protected ODataSerializer serializer;
+    protected EntityIterator iterator;
+    protected ServiceMetadata metadata;
+    protected EdmEntityType entityType;
+    protected EntityCollectionSerializerOptions options;
+
+    public StreamContent(EntityIterator iterator, EdmEntityType entityType,
+                         ODataSerializer serializer, ServiceMetadata metadata,
+                         EntityCollectionSerializerOptions options) {
+      this.iterator = iterator;
+      this.entityType = entityType;
+      this.serializer = serializer;
+      this.metadata = metadata;
+      this.options = options;
+    }
+
+    protected abstract void writeEntity(EntityIterator entity, OutputStream outputStream) throws SerializerException;
+
+    public void write(OutputStream out) {
+      try {
+        writeEntity(iterator, out);
+      } catch (SerializerException e) {
+        final WriteContentErrorCallback errorCallback = options.getWriteContentErrorCallback();
+        if(errorCallback != null) {
+          final ErrorContext errorContext = new ErrorContext(e);
+          errorCallback.handleError(errorContext, Channels.newChannel(out));
+        }
+      }
+    }
+  }
+
+  private static class StreamContentForJson extends StreamContent {
+    private ODataJsonSerializer jsonSerializer;
+
+    public StreamContentForJson(EntityIterator iterator, EdmEntityType entityType,
+        ODataJsonSerializer jsonSerializer, ServiceMetadata metadata,
+        EntityCollectionSerializerOptions options) {
+      super(iterator, entityType, jsonSerializer, metadata, options);
+
+      this.jsonSerializer = jsonSerializer;
+    }
+
+    protected void writeEntity(EntityIterator entity, OutputStream outputStream) throws SerializerException {
+      try {
+        jsonSerializer.entityCollectionIntoStream(metadata, entityType, entity, options, outputStream);
+        outputStream.flush();
+      } catch (final IOException e) {
+        throw new ODataRuntimeException("Failed entity serialization");
+      }
+    }
+  }
+
+  private static class StreamContentForXml extends StreamContent {
+    private ODataXmlSerializer xmlSerializer;
+
+    public StreamContentForXml(EntityIterator iterator, EdmEntityType entityType,
+        ODataXmlSerializer xmlSerializer, ServiceMetadata metadata,
+        EntityCollectionSerializerOptions options) {
+      super(iterator, entityType, xmlSerializer, metadata, options);
+
+      this.xmlSerializer = xmlSerializer;
+    }
+
+    protected void writeEntity(EntityIterator entity, OutputStream outputStream) throws SerializerException {
+      try {
+        xmlSerializer.entityCollectionIntoStream(metadata, entityType, entity, options, outputStream);
+        outputStream.flush();
+      } catch (final IOException e) {
+        throw new ODataRuntimeException("Failed entity serialization");
+      }
+    }
+  }
+
+  @Override
+  public void write(WritableByteChannel writeChannel) {
+    this.streamContent.write(Channels.newOutputStream(writeChannel));
+  }
+
+  @Override
+  public void write(OutputStream stream) {
+    write(Channels.newChannel(stream));
+  }
+
+  private ODataWritableContent(StreamContent streamContent) {
+    this.streamContent = streamContent;
+  }
+
+  public static ODataWritableContentBuilder with(EntityIterator iterator, EdmEntityType entityType,
+                                             ODataSerializer serializer, ServiceMetadata metadata,
+      EntityCollectionSerializerOptions options) {
+    return new ODataWritableContentBuilder(iterator, entityType, serializer, metadata, options);
+  }
+
+  public static class ErrorContext implements WriteContentErrorContext {
+    private ODataLibraryException exception;
+    public ErrorContext(ODataLibraryException exception) {
+      this.exception = exception;
+    }
+
+    @Override
+    public Exception getException() {
+      return exception;
+    }
+    @Override
+    public ODataLibraryException getODataLibraryException() {
+      return exception;
+    }
+  }
+
+  public static class ODataWritableContentBuilder {
+    private ODataSerializer serializer;
+    private EntityIterator entities;
+    private ServiceMetadata metadata;
+    private EdmEntityType entityType;
+    private EntityCollectionSerializerOptions options;
+
+    public ODataWritableContentBuilder(EntityIterator entities, EdmEntityType entityType,
+                                    ODataSerializer serializer,
+                                   ServiceMetadata metadata, EntityCollectionSerializerOptions options) {
+      this.entities = entities;
+      this.entityType = entityType;
+      this.serializer = serializer;
+      this.metadata = metadata;
+      this.options = options;
+    }
+
+    public ODataContent buildContent() {
+      if(serializer instanceof ODataJsonSerializer) {
+        StreamContent input = new StreamContentForJson(entities, entityType,
+            (ODataJsonSerializer) serializer, metadata, options);
+        return new ODataWritableContent(input);
+      } else if(serializer instanceof ODataXmlSerializer) {
+        StreamContentForXml input = new StreamContentForXml(entities, entityType,
+            (ODataXmlSerializer) serializer, metadata, options);
+        return new ODataWritableContent(input);
+      }
+      throw new ODataRuntimeException("No suitable serializer found");
+    }
+    public SerializerStreamResult build() {
+      return SerializerStreamResultImpl.with().content(buildContent()).build();
+    }
+  }
+}

lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/SerializerResultImpl.java

@@ -20,6 +20,7 @@ package org.apache.olingo.server.core.serializer;
 
 import java.io.InputStream;
 
+import org.apache.olingo.server.api.ODataContent;
 import org.apache.olingo.server.api.serializer.SerializerResult;
 
 public class SerializerResultImpl implements SerializerResult {
@@ -30,23 +31,34 @@ public class SerializerResultImpl implements SerializerResult {
     return content;
   }
 
+  //  @Override
+//  public ReadableByteChannel getChannel() {
+//    return Channels.newChannel(getContent());
+//  }
+//
+//  @Override
+//  public void write(WritableByteChannel channel) {
+//    ResultHelper.copy(Channels.newChannel(content), channel);
+//  }
+//
+//  @Override
+//  public boolean isWriteSupported() {
+//    return false;
+//  }
+
   public static SerializerResultBuilder with() {
     return new SerializerResultBuilder();
   }
 
   public static class SerializerResultBuilder {
-    private InputStream content;
+    private SerializerResultImpl result = new SerializerResultImpl();
 
     public SerializerResultBuilder content(final InputStream input) {
-      content = input;
+      result.content = input;
-
       return this;
     }
 
     public SerializerResult build() {
-      SerializerResultImpl result = new SerializerResultImpl();
-      result.content = content;
-
       return result;
     }
   }

lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/SerializerStreamResultImpl.java

@@ -0,0 +1,48 @@
+/*
+ * 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.olingo.server.core.serializer;
+
+import org.apache.olingo.server.api.ODataContent;
+import org.apache.olingo.server.api.serializer.SerializerStreamResult;
+
+public class SerializerStreamResultImpl implements SerializerStreamResult {
+  private ODataContent oDataContent;
+
+  @Override
+  public ODataContent getODataContent() {
+    return oDataContent;
+  }
+
+  public static SerializerResultBuilder with() {
+    return new SerializerResultBuilder();
+  }
+
+  public static class SerializerResultBuilder {
+    private SerializerStreamResultImpl result = new SerializerStreamResultImpl();
+
+    public SerializerResultBuilder content(final ODataContent content) {
+      result.oDataContent = content;
+      return this;
+    }
+
+    public SerializerStreamResult build() {
+      return result;
+    }
+  }
+}

lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/json/ODataJsonSerializer.java

@@ -29,7 +29,8 @@ import org.apache.olingo.commons.api.Constants;
 import org.apache.olingo.commons.api.data.ComplexValue;
 import org.apache.olingo.commons.api.data.ContextURL;
 import org.apache.olingo.commons.api.data.Entity;
-import org.apache.olingo.commons.api.data.EntityCollection;
+import org.apache.olingo.commons.api.data.AbstractEntityCollection;
+import org.apache.olingo.commons.api.data.EntityIterator;
 import org.apache.olingo.commons.api.data.Link;
 import org.apache.olingo.commons.api.data.Linked;
 import org.apache.olingo.commons.api.data.Property;
@@ -57,11 +58,13 @@ import org.apache.olingo.server.api.serializer.ReferenceCollectionSerializerOpti
 import org.apache.olingo.server.api.serializer.ReferenceSerializerOptions;
 import org.apache.olingo.server.api.serializer.SerializerException;
 import org.apache.olingo.server.api.serializer.SerializerResult;
+import org.apache.olingo.server.api.serializer.SerializerStreamResult;
 import org.apache.olingo.server.api.uri.UriHelper;
 import org.apache.olingo.server.api.uri.queryoption.ExpandItem;
 import org.apache.olingo.server.api.uri.queryoption.ExpandOption;
 import org.apache.olingo.server.api.uri.queryoption.SelectOption;
 import org.apache.olingo.server.core.serializer.AbstractODataSerializer;
+import org.apache.olingo.server.core.ODataWritableContent;
 import org.apache.olingo.server.core.serializer.SerializerResultImpl;
 import org.apache.olingo.server.core.serializer.utils.CircleStreamBuffer;
 import org.apache.olingo.server.core.serializer.utils.ContentTypeHelper;
@@ -136,7 +139,7 @@ public class ODataJsonSerializer extends AbstractODataSerializer {
 
   @Override
   public SerializerResult entityCollection(final ServiceMetadata metadata,
-      final EdmEntityType entityType, final EntityCollection entitySet,
+      final EdmEntityType entityType, final AbstractEntityCollection entitySet,
       final EntityCollectionSerializerOptions options) throws SerializerException {
     OutputStream outputStream = null;
     SerializerException cachedException = null;
@@ -175,6 +178,50 @@ public class ODataJsonSerializer extends AbstractODataSerializer {
     }
   }
 
+  @Override
+  public SerializerStreamResult entityCollectionStreamed(ServiceMetadata metadata, EdmEntityType entityType,
+      EntityIterator entities, EntityCollectionSerializerOptions options) throws SerializerException {
+
+    return ODataWritableContent.with(entities, entityType, this, metadata, options).build();
+  }
+
+
+  public void entityCollectionIntoStream(final ServiceMetadata metadata,
+      final EdmEntityType entityType, final EntityIterator entitySet,
+      final EntityCollectionSerializerOptions options, final OutputStream outputStream)
+        throws SerializerException {
+
+    SerializerException cachedException;
+    try {
+      JsonGenerator json = new JsonFactory().createGenerator(outputStream);
+      json.writeStartObject();
+
+      final ContextURL contextURL = checkContextURL(options == null ? null : options.getContextURL());
+      writeContextURL(contextURL, json);
+
+      writeMetadataETag(metadata, json);
+
+      if (options != null && options.getCount() != null && options.getCount().getValue()) {
+        writeCount(entitySet, json);
+      }
+      json.writeFieldName(Constants.VALUE);
+      if (options == null) {
+        writeEntitySet(metadata, entityType, entitySet, null, null, false, json);
+      } else {
+        writeEntitySet(metadata, entityType, entitySet,
+            options.getExpand(), options.getSelect(), options.getWriteOnlyReferences(), json);
+      }
+      // next link not supported by default for streaming results
+//      writeNextLink(entitySet, json);
+
+      json.close();
+    } catch (final IOException e) {
+      cachedException =
+          new SerializerException(IO_EXCEPTION_TEXT, e, SerializerException.MessageKeys.IO_EXCEPTION);
+      throw cachedException;
+    }
+  }
+
   @Override
   public SerializerResult entity(final ServiceMetadata metadata, final EdmEntityType entityType,
       final Entity entity, final EntitySerializerOptions options) throws SerializerException {
@@ -203,7 +250,7 @@ public class ODataJsonSerializer extends AbstractODataSerializer {
     }
   }
 
-  private ContextURL checkContextURL(final ContextURL contextURL) throws SerializerException {
+  ContextURL checkContextURL(final ContextURL contextURL) throws SerializerException {
     if (isODataMetadataNone) {
       return null;
     } else if (contextURL == null) {
@@ -213,11 +260,11 @@ public class ODataJsonSerializer extends AbstractODataSerializer {
   }
 
   protected void writeEntitySet(final ServiceMetadata metadata, final EdmEntityType entityType,
-      final EntityCollection entitySet, final ExpandOption expand, final SelectOption select,
+      final AbstractEntityCollection entitySet, final ExpandOption expand, final SelectOption select,
       final boolean onlyReference, final JsonGenerator json) throws IOException,
       SerializerException {
     json.writeStartArray();
-    for (final Entity entity : entitySet.getEntities()) {
+    for (final Entity entity : entitySet) {
       if (onlyReference) {
         json.writeStartObject();
         json.writeStringField(Constants.JSON_ID, entity.getId().toASCIIString());
@@ -229,9 +276,9 @@ public class ODataJsonSerializer extends AbstractODataSerializer {
     json.writeEndArray();
   }
 
-  protected void writeEntity(final ServiceMetadata metadata, final EdmEntityType entityType,
+  public void writeEntity(final ServiceMetadata metadata, final EdmEntityType entityType, final Entity entity,
-      final Entity entity, final ContextURL contextURL, final ExpandOption expand,
+      final ContextURL contextURL, final ExpandOption expand, final SelectOption select, final boolean onlyReference,
-      final SelectOption select, final boolean onlyReference, final JsonGenerator json)
+      final JsonGenerator json)
           throws IOException, SerializerException {
     json.writeStartObject();
     if (!isODataMetadataNone) {
@@ -736,7 +783,7 @@ public class ODataJsonSerializer extends AbstractODataSerializer {
 
   @Override
   public SerializerResult referenceCollection(final ServiceMetadata metadata, final EdmEntitySet edmEntitySet,
-      final EntityCollection entityCollection, final ReferenceCollectionSerializerOptions options)
+      final AbstractEntityCollection entityCollection, final ReferenceCollectionSerializerOptions options)
           throws SerializerException {
     OutputStream outputStream = null;
     SerializerException cachedException = null;
@@ -755,7 +802,7 @@ public class ODataJsonSerializer extends AbstractODataSerializer {
       }
 
       json.writeArrayFieldStart(Constants.VALUE);
-      for (final Entity entity : entityCollection.getEntities()) {
+      for (final Entity entity : entityCollection) {
         json.writeStartObject();
         json.writeStringField(Constants.JSON_ID, uriHelper.buildCanonicalURL(edmEntitySet, entity));
         json.writeEndObject();
@@ -779,13 +826,13 @@ public class ODataJsonSerializer extends AbstractODataSerializer {
 
   }
 
-  private void writeContextURL(final ContextURL contextURL, final JsonGenerator json) throws IOException {
+  void writeContextURL(final ContextURL contextURL, final JsonGenerator json) throws IOException {
     if (!isODataMetadataNone && contextURL != null) {
       json.writeStringField(Constants.JSON_CONTEXT, ContextURLBuilder.create(contextURL).toASCIIString());
     }
   }
 
-  private void writeMetadataETag(final ServiceMetadata metadata, final JsonGenerator json) throws IOException {
+  void writeMetadataETag(final ServiceMetadata metadata, final JsonGenerator json) throws IOException {
     if (!isODataMetadataNone
         && metadata != null
         && metadata.getServiceMetadataETagSupport() != null
@@ -795,7 +842,7 @@ public class ODataJsonSerializer extends AbstractODataSerializer {
     }
   }
 
-  private void writeCount(final EntityCollection entityCollection, final JsonGenerator json) throws IOException {
+  void writeCount(final AbstractEntityCollection entityCollection, final JsonGenerator json) throws IOException {
     if (entityCollection.getCount() != null) {
       if (isIEEE754Compatible) {
         json.writeStringField(Constants.JSON_COUNT, entityCollection.getCount().toString());
@@ -805,7 +852,7 @@ public class ODataJsonSerializer extends AbstractODataSerializer {
     }
   }
 
-  private void writeNextLink(final EntityCollection entitySet, final JsonGenerator json) throws IOException {
+  void writeNextLink(final AbstractEntityCollection entitySet, final JsonGenerator json) throws IOException {
     if (entitySet.getNext() != null) {
       json.writeStringField(Constants.JSON_NEXT_LINK, entitySet.getNext().toASCIIString());
     }

lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/utils/CircleStreamBuffer.java

@@ -193,6 +193,25 @@ public class CircleStreamBuffer {
     return readBuffer.get();
   }
 
+  public ByteBuffer getBuffer() throws IOException {
+    if (readClosed) {
+      throw new IOException("Tried to read from closed stream.");
+    }
+    writeMode = false;
+
+    // FIXME: mibo_160108: This is not efficient and only for test/poc reasons
+    int reqSize = 0;
+    for (ByteBuffer byteBuffer : bufferQueue) {
+      reqSize += byteBuffer.position();
+    }
+    ByteBuffer tmp = ByteBuffer.allocateDirect(reqSize);
+    for (ByteBuffer byteBuffer : bufferQueue) {
+      byteBuffer.flip();
+      tmp.put(byteBuffer);
+    }
+    return tmp;
+  }
+
   // #############################################
   // #
   // # Writing parts

lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/utils/ResultHelper.java

@@ -0,0 +1,65 @@
+/*
+ * 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.olingo.server.core.serializer.utils;
+
+import org.apache.olingo.commons.api.ex.ODataRuntimeException;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.nio.ByteBuffer;
+import java.nio.channels.Channel;
+import java.nio.channels.Channels;
+import java.nio.channels.ReadableByteChannel;
+import java.nio.channels.WritableByteChannel;
+
+public class ResultHelper {
+
+  public static final int COPY_BUFFER_SIZE = 8192;
+
+  public static void copy(InputStream input, OutputStream output) {
+    copy(Channels.newChannel(input), Channels.newChannel(output));
+  }
+
+  public static void copy(ReadableByteChannel input, WritableByteChannel output) {
+    try {
+      ByteBuffer inBuffer = ByteBuffer.allocate(COPY_BUFFER_SIZE);
+      while (input.read(inBuffer) > 0) {
+        inBuffer.flip();
+        output.write(inBuffer);
+        inBuffer.clear();
+      }
+    } catch (IOException e) {
+      throw new ODataRuntimeException("Error on reading request content", e);
+    } finally {
+      closeStream(input);
+      closeStream(output);
+    }
+  }
+
+  private static void closeStream(final Channel closeable) {
+    if (closeable != null) {
+      try {
+        closeable.close();
+      } catch (IOException e) {
+        // ignore
+      }
+    }
+  }
+}

lib/server-core/src/main/java/org/apache/olingo/server/core/serializer/xml/ODataXmlSerializer.java

@@ -35,6 +35,8 @@ import org.apache.olingo.commons.api.data.ComplexValue;
 import org.apache.olingo.commons.api.data.ContextURL;
 import org.apache.olingo.commons.api.data.Entity;
 import org.apache.olingo.commons.api.data.EntityCollection;
+import org.apache.olingo.commons.api.data.AbstractEntityCollection;
+import org.apache.olingo.commons.api.data.EntityIterator;
 import org.apache.olingo.commons.api.data.Link;
 import org.apache.olingo.commons.api.data.Linked;
 import org.apache.olingo.commons.api.data.Property;
@@ -51,6 +53,7 @@ import org.apache.olingo.commons.api.edm.EdmType;
 import org.apache.olingo.commons.api.edm.FullQualifiedName;
 import org.apache.olingo.commons.api.edm.constants.EdmTypeKind;
 import org.apache.olingo.commons.api.ex.ODataErrorDetail;
+import org.apache.olingo.commons.api.ex.ODataRuntimeException;
 import org.apache.olingo.commons.core.edm.primitivetype.EdmPrimitiveTypeFactory;
 import org.apache.olingo.commons.core.edm.primitivetype.EdmString;
 import org.apache.olingo.server.api.ODataServerError;
@@ -63,9 +66,11 @@ import org.apache.olingo.server.api.serializer.ReferenceCollectionSerializerOpti
 import org.apache.olingo.server.api.serializer.ReferenceSerializerOptions;
 import org.apache.olingo.server.api.serializer.SerializerException;
 import org.apache.olingo.server.api.serializer.SerializerResult;
+import org.apache.olingo.server.api.serializer.SerializerStreamResult;
 import org.apache.olingo.server.api.uri.queryoption.ExpandItem;
 import org.apache.olingo.server.api.uri.queryoption.ExpandOption;
 import org.apache.olingo.server.api.uri.queryoption.SelectOption;
+import org.apache.olingo.server.core.ODataWritableContent;
 import org.apache.olingo.server.core.serializer.AbstractODataSerializer;
 import org.apache.olingo.server.core.serializer.SerializerResultImpl;
 import org.apache.olingo.server.core.serializer.utils.CircleStreamBuffer;
@@ -210,7 +215,7 @@ public class ODataXmlSerializer extends AbstractODataSerializer {
 
   @Override
   public SerializerResult entityCollection(final ServiceMetadata metadata,
-      final EdmEntityType entityType, final EntityCollection entitySet,
+      final EdmEntityType entityType, final AbstractEntityCollection entitySet,
       final EntityCollectionSerializerOptions options) throws SerializerException {
 
     final ContextURL contextURL = checkContextURL(options == null ? null : options.getContextURL());
@@ -278,6 +283,69 @@ public class ODataXmlSerializer extends AbstractODataSerializer {
     }
   }
 
+  public void entityCollectionIntoStream(ServiceMetadata metadata, EdmEntityType entityType, EntityIterator entitySet,
+      EntityCollectionSerializerOptions options, OutputStream outputStream) throws SerializerException {
+
+    final ContextURL contextURL = checkContextURL(options == null ? null : options.getContextURL());
+//    if (options != null && options.getWriteOnlyReferences()) {
+//      ReferenceCollectionSerializerOptions rso = ReferenceCollectionSerializerOptions.with()
+//          .contextURL(contextURL).build();
+//      return entityReferenceCollection(entitySet, rso);
+//    }
+
+    SerializerException cachedException = null;
+    try {
+      CircleStreamBuffer buffer = new CircleStreamBuffer();
+      outputStream = buffer.getOutputStream();
+      XMLStreamWriter writer = XMLOutputFactory.newInstance().createXMLStreamWriter(outputStream, DEFAULT_CHARSET);
+      writer.writeStartDocument(DEFAULT_CHARSET, "1.0");
+      writer.writeStartElement(ATOM, Constants.ATOM_ELEM_FEED, NS_ATOM);
+      writer.writeNamespace(ATOM, NS_ATOM);
+      writer.writeNamespace(METADATA, NS_METADATA);
+      writer.writeNamespace(DATA, NS_DATA);
+
+      writer.writeAttribute(METADATA, NS_METADATA, Constants.CONTEXT,
+          ContextURLBuilder.create(contextURL).toASCIIString());
+      writeMetadataETag(metadata, writer);
+
+      if (options != null && options.getId() != null) {
+        writer.writeStartElement(ATOM, Constants.ATOM_ELEM_ID, NS_ATOM);
+        writer.writeCharacters(options.getId());
+        writer.writeEndElement();
+      }
+
+      if (options != null && options.getCount() != null && options.getCount().getValue()
+          && entitySet.getCount() != null) {
+        writeCount(entitySet, writer);
+      }
+      if (entitySet.getNext() != null) {
+        writeNextLink(entitySet, writer);
+      }
+
+      if (options == null) {
+        writeEntitySet(metadata, entityType, entitySet, null, null, null, writer);
+      } else {
+        writeEntitySet(metadata, entityType, entitySet,
+            options.getExpand(), options.getSelect(), options.xml10InvalidCharReplacement(), writer);
+      }
+
+      writer.writeEndElement();
+      writer.writeEndDocument();
+
+      writer.flush();
+    } catch (final XMLStreamException e) {
+      cachedException =
+          new SerializerException(IO_EXCEPTION_TEXT, e, SerializerException.MessageKeys.IO_EXCEPTION);
+      throw cachedException;
+    }
+  }
+
+  @Override
+  public SerializerStreamResult entityCollectionStreamed(ServiceMetadata metadata, EdmEntityType entityType,
+      EntityIterator entities, EntityCollectionSerializerOptions options) throws SerializerException {
+      return ODataWritableContent.with(entities, entityType, this, metadata, options).build();
+  }
+
   @Override
   public SerializerResult entity(final ServiceMetadata metadata, final EdmEntityType entityType,
       final Entity entity, final EntitySerializerOptions options) throws SerializerException {
@@ -338,10 +406,10 @@ public class ODataXmlSerializer extends AbstractODataSerializer {
   }
 
   protected void writeEntitySet(final ServiceMetadata metadata, final EdmEntityType entityType,
-      final EntityCollection entitySet, final ExpandOption expand, final SelectOption select,
+      final AbstractEntityCollection entitySet, final ExpandOption expand, final SelectOption select,
       final String xml10InvalidCharReplacement,final XMLStreamWriter writer) 
           throws XMLStreamException, SerializerException {
-    for (final Entity entity : entitySet.getEntities()) {
+    for (final Entity entity : entitySet) {
       writeEntity(metadata, entityType, entity, null, expand, select, xml10InvalidCharReplacement, writer, false);
     }
   }
@@ -1063,12 +1131,12 @@ public class ODataXmlSerializer extends AbstractODataSerializer {
 
   @Override
   public SerializerResult referenceCollection(final ServiceMetadata metadata, final EdmEntitySet edmEntitySet,
-      final EntityCollection entityCollection, final ReferenceCollectionSerializerOptions options)
+      final AbstractEntityCollection entityCollection, final ReferenceCollectionSerializerOptions options)
       throws SerializerException {
     return entityReferenceCollection(entityCollection, options);
   }
 
-  protected SerializerResult entityReferenceCollection(final EntityCollection entitySet,
+  protected SerializerResult entityReferenceCollection(final AbstractEntityCollection entitySet,
       final ReferenceCollectionSerializerOptions options) throws SerializerException {
     OutputStream outputStream = null;
     SerializerException cachedException = null;
@@ -1091,7 +1159,7 @@ public class ODataXmlSerializer extends AbstractODataSerializer {
       if (entitySet.getNext() != null) {
         writeNextLink(entitySet, writer);
       }
-      for (final Entity entity : entitySet.getEntities()) {
+      for (final Entity entity : entitySet) {
         writeReference(entity, options == null ? null : options.getContextURL(), writer, false);
       }
       writer.writeEndElement();
@@ -1114,14 +1182,14 @@ public class ODataXmlSerializer extends AbstractODataSerializer {
     }
   }
 
-  private void writeCount(final EntityCollection entitySet, final XMLStreamWriter writer)
+  private void writeCount(final AbstractEntityCollection entitySet, final XMLStreamWriter writer)
       throws XMLStreamException {
     writer.writeStartElement(METADATA, Constants.ATOM_ELEM_COUNT, NS_METADATA);
     writer.writeCharacters(String.valueOf(entitySet.getCount()));
     writer.writeEndElement();
   }
 
-  private void writeNextLink(final EntityCollection entitySet, final XMLStreamWriter writer)
+  private void writeNextLink(final AbstractEntityCollection entitySet, final XMLStreamWriter writer)
       throws XMLStreamException {
     writer.writeStartElement(ATOM, Constants.ATOM_ELEM_LINK, NS_ATOM);
     writer.writeAttribute(Constants.ATTR_REL, Constants.NEXT_LINK_REL);

lib/server-core/src/test/java/org/apache/olingo/server/core/uri/parser/search/SearchTokenizerTest.java

@@ -18,6 +18,13 @@
  */
 package org.apache.olingo.server.core.uri.parser.search;
 
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
 import static org.apache.olingo.server.core.uri.parser.search.SearchQueryToken.Token.AND;
 import static org.apache.olingo.server.core.uri.parser.search.SearchQueryToken.Token.CLOSE;
 import static org.apache.olingo.server.core.uri.parser.search.SearchQueryToken.Token.NOT;
@@ -26,13 +33,6 @@ import static org.apache.olingo.server.core.uri.parser.search.SearchQueryToken.T
 import static org.apache.olingo.server.core.uri.parser.search.SearchQueryToken.Token.PHRASE;
 import static org.apache.olingo.server.core.uri.parser.search.SearchQueryToken.Token.WORD;
 
-import java.util.ArrayList;
-import java.util.Iterator;
-import java.util.List;
-
-import org.junit.Assert;
-import org.junit.Test;
-
 public class SearchTokenizerTest {
 
   @Test

lib/server-tecsvc/src/main/java/org/apache/olingo/server/tecsvc/processor/TechnicalEntityProcessor.java

@@ -18,6 +18,8 @@
  */
 package org.apache.olingo.server.tecsvc.processor;
 
+import java.util.Iterator;
+import java.util.List;
 import java.util.Locale;
 
 import org.apache.olingo.commons.api.data.ContextURL;
@@ -25,6 +27,9 @@ import org.apache.olingo.commons.api.data.ContextURL.Builder;
 import org.apache.olingo.commons.api.data.ContextURL.Suffix;
 import org.apache.olingo.commons.api.data.Entity;
 import org.apache.olingo.commons.api.data.EntityCollection;
+import org.apache.olingo.commons.api.data.EntityIterator;
+import org.apache.olingo.commons.api.data.Property;
+import org.apache.olingo.commons.api.data.ValueType;
 import org.apache.olingo.commons.api.edm.EdmEntitySet;
 import org.apache.olingo.commons.api.edm.EdmEntityType;
 import org.apache.olingo.commons.api.format.ContentType;
@@ -51,6 +56,7 @@ import org.apache.olingo.server.api.serializer.EntitySerializerOptions;
 import org.apache.olingo.server.api.serializer.ReferenceCollectionSerializerOptions;
 import org.apache.olingo.server.api.serializer.ReferenceSerializerOptions;
 import org.apache.olingo.server.api.serializer.SerializerResult;
+import org.apache.olingo.server.api.serializer.SerializerStreamResult;
 import org.apache.olingo.server.api.uri.UriInfo;
 import org.apache.olingo.server.api.uri.UriResourceEntitySet;
 import org.apache.olingo.server.api.uri.UriResourceNavigation;
@@ -519,12 +525,26 @@ public class TechnicalEntityProcessor extends TechnicalProcessor
       id = request.getRawBaseUri() + edmEntitySet.getName();
     }
 
-    // Serialize
+    if(isReference) {
-    final SerializerResult serializerResult = (isReference) ?
+      final SerializerResult serializerResult =
-        serializeReferenceCollection(entitySetSerialization, edmEntitySet, requestedContentType, countOption) :
+          serializeReferenceCollection(entitySetSerialization, edmEntitySet, requestedContentType, countOption);
-        serializeEntityCollection(request, entitySetSerialization, edmEntitySet, edmEntityType, requestedContentType,
+      response.setContent(serializerResult.getContent());
-            expand, select, countOption, id);
+    } else if(isOdataStreaming(request)) {
-    response.setContent(serializerResult.getContent());
+      final SerializerStreamResult serializerResult =
+          serializeEntityCollectionStreamed(request,
+              entitySetSerialization, edmEntitySet, edmEntityType, requestedContentType,
+              expand, select, countOption, id);
+
+      response.setODataContent(serializerResult.getODataContent());
+    } else {
+      final SerializerResult serializerResult =
+          serializeEntityCollection(request,
+              entitySetSerialization, edmEntitySet, edmEntityType, requestedContentType,
+              expand, select, countOption, id);
+      response.setContent(serializerResult.getContent());
+    }
+
+    //
     response.setStatusCode(HttpStatusCode.OK.getStatusCode());
     response.setHeader(HttpHeader.CONTENT_TYPE, requestedContentType.toContentTypeString());
     if (pageSize != null) {
@@ -533,6 +553,11 @@ public class TechnicalEntityProcessor extends TechnicalProcessor
     }
   }
 
+  private boolean isOdataStreaming(ODataRequest request) {
+    String odataStreaming = request.getHeader("odata.streaming");
+    return Boolean.parseBoolean(odataStreaming);
+  }
+
   private SerializerResult serializeEntityCollection(final ODataRequest request, final EntityCollection
       entityCollection, final EdmEntitySet edmEntitySet, final EdmEntityType edmEntityType,
       final ContentType requestedFormat, final ExpandOption expand, final SelectOption select,
@@ -551,6 +576,56 @@ public class TechnicalEntityProcessor extends TechnicalProcessor
             .build());
   }
 
+  // serialise as streamed collection
+  private SerializerStreamResult serializeEntityCollectionStreamed(final ODataRequest request,
+      final EntityCollection entityCollection, final EdmEntitySet edmEntitySet,
+      final EdmEntityType edmEntityType,
+      final ContentType requestedFormat, final ExpandOption expand, final SelectOption select,
+      final CountOption countOption, final String id) throws ODataLibraryException {
+
+    EntityIterator streamCollection = new EntityIterator() {
+      Iterator<Entity> entityIterator = entityCollection.iterator();
+
+      @Override
+      public boolean hasNext() {
+        return entityIterator.hasNext();
+      }
+
+      @Override
+      public Entity next() {
+        return addToPrimitiveProperty(entityIterator.next(), "PropertyString", "->streamed");
+      }
+
+      private Entity addToPrimitiveProperty(Entity entity, String name, Object data) {
+        List<Property> properties = entity.getProperties();
+        int pos = 0;
+        for (Property property : properties) {
+          if(name.equals(property.getName())) {
+            properties.remove(pos);
+            final String old = property.getValue().toString();
+            String newValue = (old == null ? "": old) + data.toString();
+            entity.addProperty(new Property(null, name, ValueType.PRIMITIVE, newValue));
+            break;
+          }
+          pos++;
+        }
+        return entity;
+      }
+    };
+
+    return odata.createSerializer(requestedFormat).entityCollectionStreamed(
+        serviceMetadata,
+        edmEntityType,
+        streamCollection,
+        EntityCollectionSerializerOptions.with()
+            .contextURL(isODataMetadataNone(requestedFormat) ? null :
+                getContextUrl(request.getRawODataPath(), edmEntitySet, edmEntityType, false, expand, select))
+            .count(countOption)
+            .expand(expand).select(select)
+            .id(id)
+            .build());
+  }
+
   private SerializerResult serializeReferenceCollection(final EntityCollection entityCollection,
       final EdmEntitySet edmEntitySet, final ContentType requestedFormat, final CountOption countOption)
       throws ODataLibraryException {

lib/server-test/src/test/java/org/apache/olingo/server/core/serializer/json/ODataJsonSerializerTest.java

@@ -18,18 +18,25 @@
  */
 package org.apache.olingo.server.core.serializer.json;
 
+import java.io.IOException;
 import java.io.InputStream;
 import java.net.URI;
+import java.nio.ByteBuffer;
+import java.nio.channels.WritableByteChannel;
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.Iterator;
+import java.util.Locale;
 import java.util.TimeZone;
 
 import org.apache.commons.io.IOUtils;
+import org.apache.commons.io.output.ByteArrayOutputStream;
 import org.apache.olingo.commons.api.data.ComplexValue;
 import org.apache.olingo.commons.api.data.ContextURL;
 import org.apache.olingo.commons.api.data.ContextURL.Suffix;
 import org.apache.olingo.commons.api.data.Entity;
 import org.apache.olingo.commons.api.data.EntityCollection;
+import org.apache.olingo.commons.api.data.EntityIterator;
 import org.apache.olingo.commons.api.data.Property;
 import org.apache.olingo.commons.api.data.ValueType;
 import org.apache.olingo.commons.api.edm.EdmComplexType;
@@ -40,7 +47,10 @@ import org.apache.olingo.commons.api.edm.EdmPrimitiveType;
 import org.apache.olingo.commons.api.edm.EdmProperty;
 import org.apache.olingo.commons.api.format.ContentType;
 import org.apache.olingo.server.api.OData;
+import org.apache.olingo.server.api.ODataContent;
 import org.apache.olingo.server.api.ServiceMetadata;
+import org.apache.olingo.server.api.WriteContentErrorCallback;
+import org.apache.olingo.server.api.WriteContentErrorContext;
 import org.apache.olingo.server.api.edmx.EdmxReference;
 import org.apache.olingo.server.api.serializer.ComplexSerializerOptions;
 import org.apache.olingo.server.api.serializer.EntityCollectionSerializerOptions;
@@ -207,6 +217,90 @@ public class ODataJsonSerializerTest {
     Assert.assertEquals(8, count);
   }
 
+  @Test
+  public void entityCollectionStreamed() throws Exception {
+    final EdmEntitySet edmEntitySet = entityContainer.getEntitySet("ESAllPrim");
+    final EntityIterator entityIterator = new EntityIterator() {
+      Iterator<Entity> innerIterator = data.readAll(edmEntitySet).iterator();
+      @Override
+      public boolean hasNext() {
+        return innerIterator.hasNext();
+      }
+      @Override
+      public Entity next() {
+        return innerIterator.next();
+      }
+    };
+    CountOption countOption = Mockito.mock(CountOption.class);
+    Mockito.when(countOption.getValue()).thenReturn(true);
+
+    ODataContent result = serializer.entityCollectionStreamed(
+        metadata, edmEntitySet.getEntityType(), entityIterator,
+        EntityCollectionSerializerOptions.with()
+            .contextURL(ContextURL.with().entitySet(edmEntitySet).build())
+            .build()).getODataContent();
+    ByteArrayOutputStream bout = new ByteArrayOutputStream();
+    result.write(bout);
+    final String resultString = new String(bout.toByteArray(), "UTF-8");
+
+    Assert.assertThat(resultString, CoreMatchers.startsWith("{"
+        + "\"@odata.context\":\"$metadata#ESAllPrim\","
+        + "\"@odata.metadataEtag\":\"W/\\\"metadataETag\\\"\","
+        + "\"value\":[{\"PropertyInt16\":32767,\"PropertyString\""));
+    Assert.assertThat(resultString, CoreMatchers.endsWith(
+        "\"PropertyTimeOfDay\":\"00:01:01\"}]}"));
+
+    int count = 0;
+    int index = -1;
+    while ((index = resultString.indexOf("PropertyInt16\":", ++index)) > 0) {
+      count++;
+    }
+    Assert.assertEquals(3, count);
+  }
+
+  @Test
+  public void entityCollectionStreamedWithError() throws Exception {
+    final EdmEntitySet edmEntitySet = entityContainer.getEntitySet("ESAllPrim");
+    final EntityIterator entityIterator = new EntityIterator() {
+      Iterator<Entity> innerIterator = data.readAll(edmEntitySet).iterator();
+      @Override
+      public boolean hasNext() {
+        return innerIterator.hasNext();
+      }
+      @Override
+      public Entity next() {
+        return new Entity();
+      }
+    };
+    CountOption countOption = Mockito.mock(CountOption.class);
+    Mockito.when(countOption.getValue()).thenReturn(true);
+
+    WriteContentErrorCallback errorCallback = new WriteContentErrorCallback() {
+      @Override
+      public void handleError(WriteContentErrorContext context, WritableByteChannel channel) {
+        try {
+          String msgKey = context.getODataLibraryException().getMessageKey().getKey();
+          String toChannel = "ERROR: " + msgKey;
+          channel.write(ByteBuffer.wrap(toChannel.getBytes("UTF-8")));
+        } catch (IOException e) {
+          throw new RuntimeException("Error in error.");
+        }
+      }
+    };
+
+    ODataContent result = serializer.entityCollectionStreamed(
+        metadata, edmEntitySet.getEntityType(), entityIterator,
+        EntityCollectionSerializerOptions.with()
+            .writeContentErrorCallback(errorCallback)
+            .contextURL(ContextURL.with().entitySet(edmEntitySet).build())
+            .build()).getODataContent();
+    ByteArrayOutputStream bout = new ByteArrayOutputStream();
+    result.write(bout);
+    final String resultString = new String(bout.toByteArray(), "UTF-8");
+    Assert.assertEquals(resultString, "ERROR: MISSING_PROPERTY");
+  }
+
+
   @Test
   public void entityCollAllPrim() throws Exception {
     final EdmEntitySet edmEntitySet = entityContainer.getEntitySet("ESCollAllPrim");