diff --git a/src/brayns/core/engine/Camera.h b/src/brayns/core/engine/Camera.h
index 818091ede..a480ac974 100644
--- a/src/brayns/core/engine/Camera.h
+++ b/src/brayns/core/engine/Camera.h
@@ -72,9 +72,9 @@ struct PerspectiveCameraSettings
 {
     float fovy = radians(60.0F);
     float aspect = 1.0F;
-    std::optional<DepthOfField> depthOfField = std::nullopt;
+    std::optional<DepthOfField> depthOfField = {};
     bool architectural = false;
-    std::optional<Stereo> stereo = std::nullopt;
+    std::optional<Stereo> stereo = {};
 };
 
 class PerspectiveCamera : public Camera
diff --git a/src/brayns/core/engine/Framebuffer.h b/src/brayns/core/engine/Framebuffer.h
index 3bd0a896c..0c6884901 100644
--- a/src/brayns/core/engine/Framebuffer.h
+++ b/src/brayns/core/engine/Framebuffer.h
@@ -60,8 +60,8 @@ struct FramebufferSettings
     Size2 resolution;
     FramebufferFormat format = FramebufferFormat::Srgba8;
     std::set<FramebufferChannel> channels = {FramebufferChannel::Color};
-    std::optional<Accumulation> accumulation = std::nullopt;
-    std::optional<Data<ImageOperation>> operations = std::nullopt;
+    std::optional<Accumulation> accumulation = {};
+    std::optional<Data<ImageOperation>> operations = {};
 };
 
 class FramebufferData
diff --git a/src/brayns/core/engine/GeometricModel.h b/src/brayns/core/engine/GeometricModel.h
index 5811f89d0..f7ff00b1a 100644
--- a/src/brayns/core/engine/GeometricModel.h
+++ b/src/brayns/core/engine/GeometricModel.h
@@ -37,7 +37,7 @@ struct Materials
 {
     std::variant<IndexInRenderer, Data<IndexInRenderer>> values;
     std::variant<std::monostate, Color4, Data<Color4>> colors = {};
-    std::optional<Data<std::uint8_t>> indices = std::nullopt;
+    std::optional<Data<std::uint8_t>> indices = {};
 };
 
 struct GeometricModelSettings
diff --git a/src/brayns/core/engine/Geometry.h b/src/brayns/core/engine/Geometry.h
index 63f19f8ff..9adbbf719 100644
--- a/src/brayns/core/engine/Geometry.h
+++ b/src/brayns/core/engine/Geometry.h
@@ -40,9 +40,9 @@ class Geometry : public Managed<OSPGeometry>
 struct MeshSettings
 {
     Data<Vector3> positions;
-    std::optional<Data<Vector3>> normals = std::nullopt;
-    std::optional<Data<Color4>> colors = std::nullopt;
-    std::optional<Data<Vector2>> uvs = std::nullopt;
+    std::optional<Data<Vector3>> normals = {};
+    std::optional<Data<Color4>> colors = {};
+    std::optional<Data<Vector2>> uvs = {};
 };
 
 class Mesh : public Geometry
@@ -56,7 +56,7 @@ class Mesh : public Geometry
 struct TriangleMeshSettings
 {
     MeshSettings base;
-    std::optional<Data<Index3>> indices = std::nullopt;
+    std::optional<Data<Index3>> indices = {};
 };
 
 class TriangleMesh : public Mesh
@@ -70,7 +70,7 @@ TriangleMesh createTriangleMesh(Device &device, const TriangleMeshSettings &sett
 struct QuadMeshSettings
 {
     MeshSettings base;
-    std::optional<Data<Index4>> indices = std::nullopt;
+    std::optional<Data<Index4>> indices = {};
 };
 
 class QuadMesh : public Mesh
@@ -84,7 +84,7 @@ QuadMesh createQuadMesh(Device &device, const QuadMeshSettings &settings);
 struct SphereSettings
 {
     Data<Vector4> spheres;
-    std::optional<Data<Vector2>> uvs = std::nullopt;
+    std::optional<Data<Vector2>> uvs = {};
 };
 
 class Spheres : public Geometry
@@ -98,8 +98,8 @@ Spheres createSpheres(Device &device, const SphereSettings &settings);
 struct DiscSettings
 {
     Data<Vector4> spheres;
-    std::optional<Data<Vector3>> normals = std::nullopt;
-    std::optional<Data<Vector2>> uvs = std::nullopt;
+    std::optional<Data<Vector3>> normals = {};
+    std::optional<Data<Vector2>> uvs = {};
 };
 
 class Discs : public Geometry
@@ -114,8 +114,8 @@ struct CylinderSettings
 {
     Data<Vector4> spheres;
     Data<std::uint32_t> indices;
-    std::optional<Data<Color4>> colors = std::nullopt;
-    std::optional<Data<Vector2>> uvs = std::nullopt;
+    std::optional<Data<Color4>> colors = {};
+    std::optional<Data<Vector2>> uvs = {};
 };
 
 class Cylinders : public Geometry
@@ -170,8 +170,8 @@ struct CurveSettings
 {
     Data<Vector4> spheres;
     Data<std::uint32_t> indices;
-    std::optional<Data<Color4>> colors = std::nullopt;
-    std::optional<Data<Vector2>> uvs = std::nullopt;
+    std::optional<Data<Color4>> colors = {};
+    std::optional<Data<Vector2>> uvs = {};
     CurveType type = RoundCurve();
     CurveBasis basis = LinearCurve();
 };
@@ -200,7 +200,7 @@ Boxes createBoxes(Device &device, const BoxSettings &settings);
 struct PlaneSettings
 {
     Data<Vector4> coefficients;
-    std::optional<Data<Box3>> bounds = std::nullopt;
+    std::optional<Data<Box3>> bounds = {};
 };
 
 class Planes : public Geometry
diff --git a/src/brayns/core/engine/Renderer.h b/src/brayns/core/engine/Renderer.h
index 6bce100d8..01d284e2f 100644
--- a/src/brayns/core/engine/Renderer.h
+++ b/src/brayns/core/engine/Renderer.h
@@ -51,7 +51,7 @@ struct RendererSettings
     float minContribution = 0.001F;
     float varianceThreshold = 0.0F;
     Background background = Color4(0.0F, 0.0F, 0.0F, 0.0F);
-    std::optional<Texture2D> maxDepth = std::nullopt;
+    std::optional<Texture2D> maxDepth = {};
     PixelFilter pixelFilter = PixelFilter::Gauss;
 };
 
diff --git a/src/brayns/core/engine/Volume.h b/src/brayns/core/engine/Volume.h
index f30c79a13..b8c539905 100644
--- a/src/brayns/core/engine/Volume.h
+++ b/src/brayns/core/engine/Volume.h
@@ -56,7 +56,7 @@ struct RegularVolumeSettings
     Vector3 spacing = {1.0F, 1.0F, 1.0F};
     VolumeType type = VolumeType::VertexCentered;
     VolumeFilter filter = VolumeFilter::Linear;
-    std::optional<float> background = std::nullopt;
+    std::optional<float> background = {};
 };
 
 class RegularVolume : public Volume
diff --git a/src/brayns/core/engine/World.h b/src/brayns/core/engine/World.h
index da85caba9..ad1872138 100644
--- a/src/brayns/core/engine/World.h
+++ b/src/brayns/core/engine/World.h
@@ -32,10 +32,10 @@ namespace brayns
 {
 struct GroupSettings
 {
-    std::optional<Data<GeometricModel>> geometries = std::nullopt;
-    std::optional<Data<GeometricModel>> clippingGeometries = std::nullopt;
-    std::optional<Data<VolumetricModel>> volumes = std::nullopt;
-    std::optional<Data<Light>> lights = std::nullopt;
+    std::optional<Data<GeometricModel>> geometries = {};
+    std::optional<Data<GeometricModel>> clippingGeometries = {};
+    std::optional<Data<VolumetricModel>> volumes = {};
+    std::optional<Data<Light>> lights = {};
 };
 
 class Group : public Managed<OSPGroup>
@@ -67,7 +67,7 @@ Instance createInstance(Device &device, const InstanceSettings &settings);
 
 struct WorldSettings
 {
-    std::optional<Data<Instance>> instances = std::nullopt;
+    std::optional<Data<Instance>> instances = {};
 };
 
 class World : public Managed<OSPWorld>
diff --git a/src/brayns/core/json/Json.h b/src/brayns/core/json/Json.h
index 7f4723883..60ab94cc5 100644
--- a/src/brayns/core/json/Json.h
+++ b/src/brayns/core/json/Json.h
@@ -27,6 +27,7 @@
 #include "JsonValue.h"
 
 #include "types/Arrays.h"
+#include "types/Buffer.h"
 #include "types/Consts.h"
 #include "types/Enums.h"
 #include "types/Maps.h"
@@ -35,5 +36,6 @@
 #include "types/Primitives.h"
 #include "types/Schema.h"
 #include "types/Sets.h"
+#include "types/Update.h"
 #include "types/Variants.h"
 #include "types/Vectors.h"
diff --git a/src/brayns/core/json/JsonSchema.h b/src/brayns/core/json/JsonSchema.h
index 4a7ab1919..afe3167f3 100644
--- a/src/brayns/core/json/JsonSchema.h
+++ b/src/brayns/core/json/JsonSchema.h
@@ -161,16 +161,16 @@ struct JsonSchema
 {
     std::string description = {};
     bool required = true;
-    std::optional<JsonValue> defaultValue = std::nullopt;
+    std::optional<JsonValue> defaultValue = {};
     std::vector<JsonSchema> oneOf = {};
     JsonType type = JsonType::Undefined;
     JsonValue constant = {};
-    std::optional<double> minimum = std::nullopt;
-    std::optional<double> maximum = std::nullopt;
+    std::optional<double> minimum = {};
+    std::optional<double> maximum = {};
     std::vector<JsonSchema> items = {};
     bool uniqueItems = false;
-    std::optional<std::size_t> minItems = std::nullopt;
-    std::optional<std::size_t> maxItems = std::nullopt;
+    std::optional<std::size_t> minItems = {};
+    std::optional<std::size_t> maxItems = {};
     std::map<std::string, JsonSchema> properties = {};
 
     bool operator==(const JsonSchema &) const = default;
diff --git a/src/brayns/core/json/types/Buffer.h b/src/brayns/core/json/types/Buffer.h
new file mode 100644
index 000000000..ad38da8c8
--- /dev/null
+++ b/src/brayns/core/json/types/Buffer.h
@@ -0,0 +1,69 @@
+/* Copyright (c) 2015-2024 EPFL/Blue Brain Project
+ * All rights reserved. Do not distribute without permission.
+ *
+ * Responsible Author: adrien.fleury@epfl.ch
+ *
+ * This file is part of Brayns <https://github.com/BlueBrain/Brayns>
+ *
+ * This library is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU Lesser General Public License version 3.0 as published
+ * by the Free Software Foundation.
+ *
+ * This library is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#pragma once
+
+#include <brayns/core/json/JsonReflector.h>
+
+namespace brayns
+{
+template<ReflectedJson T>
+class JsonBuffer
+{
+public:
+    const JsonValue &get() const
+    {
+        return _json;
+    }
+
+    void store(const JsonValue &json)
+    {
+        _json = json;
+    }
+
+    void extract(T &value) const
+    {
+        deserializeJson(_json, value);
+    }
+
+private:
+    JsonValue _json;
+};
+
+template<ReflectedJson T>
+struct JsonReflector<JsonBuffer<T>>
+{
+    static JsonSchema getSchema()
+    {
+        return getJsonSchema<T>();
+    }
+
+    static void serialize(const JsonBuffer<T> &value, JsonValue &json)
+    {
+        json = value.get();
+    }
+
+    static void deserialize(const JsonValue &json, JsonBuffer<T> &value)
+    {
+        value.store(json);
+    }
+};
+}
diff --git a/src/brayns/core/json/types/Objects.h b/src/brayns/core/json/types/Objects.h
index cde5b5317..6f391689e 100644
--- a/src/brayns/core/json/types/Objects.h
+++ b/src/brayns/core/json/types/Objects.h
@@ -217,15 +217,6 @@ JsonField<Parent> convertJsonField(const JsonField<Child> &child, JsonChildGette
     };
 }
 
-inline void removeJsonObjectDefaults(std::map<std::string, JsonSchema> &properties)
-{
-    for (auto &[key, field] : properties)
-    {
-        field.defaultValue = std::nullopt;
-        removeJsonObjectDefaults(field.properties);
-    }
-}
-
 class JsonFieldBuilder
 {
 public:
@@ -328,15 +319,6 @@ class JsonBuilder
         }
     }
 
-    void removeDefaultValues()
-    {
-        for (auto &field : _info.fields)
-        {
-            field.schema.defaultValue = std::nullopt;
-            removeJsonObjectDefaults(field.schema.properties);
-        }
-    }
-
     JsonObjectInfo<T> build()
     {
         return std::exchange(_info, {});
diff --git a/src/brayns/core/json/types/Update.h b/src/brayns/core/json/types/Update.h
new file mode 100644
index 000000000..a812ec4e2
--- /dev/null
+++ b/src/brayns/core/json/types/Update.h
@@ -0,0 +1,53 @@
+/* Copyright (c) 2015-2024 EPFL/Blue Brain Project
+ * All rights reserved. Do not distribute without permission.
+ *
+ * Responsible Author: adrien.fleury@epfl.ch
+ *
+ * This file is part of Brayns <https://github.com/BlueBrain/Brayns>
+ *
+ * This library is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU Lesser General Public License version 3.0 as published
+ * by the Free Software Foundation.
+ *
+ * This library is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#pragma once
+
+#include "Objects.h"
+
+namespace brayns
+{
+template<ReflectedJsonObject T>
+struct JsonUpdate
+{
+    T value;
+};
+
+template<ReflectedJsonObject T>
+struct JsonObjectReflector<JsonUpdate<T>>
+{
+    static auto reflect()
+    {
+        auto builder = JsonBuilder<JsonUpdate<T>>();
+        builder.extend([](auto &object) { return &object.value; });
+
+        auto info = builder.build();
+
+        for (auto &field : info.fields)
+        {
+            field.schema.required = false;
+            field.schema.defaultValue.reset();
+        }
+
+        return info;
+    }
+};
+}
diff --git a/src/brayns/core/json/types/Variants.h b/src/brayns/core/json/types/Variants.h
index 1542c22c2..6d118c1c2 100644
--- a/src/brayns/core/json/types/Variants.h
+++ b/src/brayns/core/json/types/Variants.h
@@ -53,7 +53,7 @@ struct JsonReflector<std::optional<T>>
     {
         if (json.isEmpty())
         {
-            value = std::nullopt;
+            value.reset();
             return;
         }
 
diff --git a/src/brayns/core/jsonrpc/Parser.h b/src/brayns/core/jsonrpc/Parser.h
index f55f8c9b0..971ce2fb5 100644
--- a/src/brayns/core/jsonrpc/Parser.h
+++ b/src/brayns/core/jsonrpc/Parser.h
@@ -34,5 +34,5 @@ std::string composeAsText(const JsonRpcSuccessResponse &response);
 std::string composeAsText(const JsonRpcErrorResponse &response);
 std::string composeAsBinary(const JsonRpcSuccessResponse &response);
 JsonRpcError composeError(const JsonRpcException &e);
-JsonRpcErrorResponse composeErrorResponse(const JsonRpcException &e, std::optional<JsonRpcId> id = std::nullopt);
+JsonRpcErrorResponse composeErrorResponse(const JsonRpcException &e, std::optional<JsonRpcId> id = {});
 }
diff --git a/src/brayns/core/websocket/WebSocketServer.h b/src/brayns/core/websocket/WebSocketServer.h
index c70581cb6..8a997ed26 100644
--- a/src/brayns/core/websocket/WebSocketServer.h
+++ b/src/brayns/core/websocket/WebSocketServer.h
@@ -49,7 +49,7 @@ struct WebSocketServerSettings
     std::size_t maxThreadCount = 1;
     std::size_t maxQueueSize = 64;
     std::size_t maxFrameSize = std::numeric_limits<int>::max();
-    std::optional<SslSettings> ssl = std::nullopt;
+    std::optional<SslSettings> ssl = {};
 };
 
 class WebSocketServer
diff --git a/tests/core/json/TestJsonReflection.cpp b/tests/core/json/TestJsonReflection.cpp
index fde6dad45..748d96808 100644
--- a/tests/core/json/TestJsonReflection.cpp
+++ b/tests/core/json/TestJsonReflection.cpp
@@ -92,37 +92,36 @@ struct JsonObjectReflector<SomeObject>
     }
 };
 
-struct Updatable
+struct Extended
 {
-    int value;
+    Internal child;
+    std::string additional;
 };
 
 template<>
-struct JsonObjectReflector<Updatable>
+struct JsonObjectReflector<Extended>
 {
     static auto reflect()
     {
-        auto builder = JsonBuilder<Updatable>();
-        builder.field("value", [](auto &object) { return &object.value; }).defaultValue(0);
-        builder.removeDefaultValues();
+        auto builder = JsonBuilder<Extended>();
+        builder.extend([](auto &object) { return &object.child; });
+        builder.field("additional", [](auto &object) { return &object.additional; });
         return builder.build();
     }
 };
 
-struct Extended
+struct Update
 {
-    Updatable child;
-    std::string additional;
+    int test;
 };
 
 template<>
-struct JsonObjectReflector<Extended>
+struct JsonObjectReflector<Update>
 {
     static auto reflect()
     {
-        auto builder = JsonBuilder<Extended>();
-        builder.extend([](auto &object) { return &object.child; });
-        builder.field("additional", [](auto &object) { return &object.additional; });
+        auto builder = JsonBuilder<Update>();
+        builder.field("test", [](auto &object) { return &object.test; }).defaultValue(2);
         return builder.build();
     }
 };
@@ -384,15 +383,32 @@ TEST_CASE("Object")
     CHECK_EQ(stringifyToJson(test), stringifyToJson(json));
 }
 
-TEST_CASE("Empty field")
+TEST_CASE("Update")
 {
-    auto object = Updatable{1};
+    using T = JsonUpdate<Update>;
+    using Buffer = JsonBuffer<T>;
+
+    auto schema = getJsonSchema<Buffer>();
+    auto child = getJsonSchema<int>();
+    child.required = false;
+
+    CHECK_EQ(schema.type, JsonType::Object);
+    CHECK_EQ(schema.properties.size(), 1);
+    CHECK_EQ(schema.properties.at("test"), child);
+
+    auto json = R"({"test":1})";
 
-    auto json = JsonValue(createJsonObject());
+    auto buffer = parseJsonAs<Buffer>(json);
+    auto update = T{};
 
-    deserializeJson(json, object);
+    buffer.extract(update);
+    CHECK_EQ(update.value.test, 1);
 
-    CHECK_EQ(object.value, 1);
+    CHECK_EQ(stringifyToJson(buffer), json);
+
+    buffer = parseJsonAs<Buffer>("{}");
+    buffer.extract(update);
+    CHECK_EQ(update.value.test, 1);
 }
 
 TEST_CASE("Extension")
@@ -400,4 +416,15 @@ TEST_CASE("Extension")
     auto schema = getJsonSchema<Extended>();
 
     CHECK_EQ(schema.properties.size(), 2);
+    CHECK_EQ(schema.properties.at("value"), getJsonSchema<int>());
+    CHECK_EQ(schema.properties.at("additional"), getJsonSchema<std::string>());
+
+    auto json = R"({"additional":"test","value":1})";
+
+    auto value = parseJsonAs<Extended>(json);
+
+    CHECK_EQ(value.child.value, 1);
+    CHECK_EQ(value.additional, "test");
+
+    CHECK_EQ(stringifyToJson(value), json);
 }