diff --git a/src/projects/base/ovlibrary/AMS.mk b/src/projects/base/ovlibrary/AMS.mk
index 843a3a44b..2bd636db9 100644
--- a/src/projects/base/ovlibrary/AMS.mk
+++ b/src/projects/base/ovlibrary/AMS.mk
@@ -3,9 +3,17 @@ include $(DEFAULT_VARIABLES)
 
 LOCAL_TARGET := ovlibrary
 
-LOCAL_HEADER_FILES := $(LOCAL_HEADER_FILES)
-LOCAL_SOURCE_FILES := $(LOCAL_SOURCE_FILES)
+LOCAL_HEADER_FILES := $(LOCAL_HEADER_FILES) \
+    $(call get_sub_header_list,logger) \
+	$(call get_sub_header_list,logger/formatters) \
+	$(call get_sub_header_list,logger/pattern_flags)
+
+LOCAL_SOURCE_FILES := $(LOCAL_SOURCE_FILES) \
+	$(call get_sub_source_list,logger) \
+	$(call get_sub_source_list,logger/formatters) \
+	$(call get_sub_source_list,logger/pattern_flags)
 
 $(call add_pkg_config,libpcre2-8)
+$(call add_pkg_config,spdlog)
 
 include $(BUILD_STATIC_LIBRARY)
diff --git a/src/projects/base/ovlibrary/json.cpp b/src/projects/base/ovlibrary/json.cpp
index 03b84a8a3..6759f9520 100644
--- a/src/projects/base/ovlibrary/json.cpp
+++ b/src/projects/base/ovlibrary/json.cpp
@@ -12,6 +12,36 @@
 
 namespace ov
 {
+	constexpr const char *StringFromJsonValueType(::Json::ValueType value_type)
+	{
+		switch (value_type)
+		{
+			case ::Json::ValueType::nullValue:
+				return "null";
+			case ::Json::ValueType::intValue:
+				return "int";
+			case ::Json::ValueType::uintValue:
+				return "uint";
+			case ::Json::ValueType::realValue:
+				return "real";
+			case ::Json::ValueType::stringValue:
+				return "string";
+			case ::Json::ValueType::booleanValue:
+				return "boolean";
+			case ::Json::ValueType::arrayValue:
+				return "array";
+			case ::Json::ValueType::objectValue:
+				return "object";
+		}
+
+		return "unknown";
+	}
+
+	const char *StringFromJsonValueType(const ::Json::Value &value)
+	{
+		return StringFromJsonValueType(value.type());
+	}
+
 	ov::String Json::Stringify(const JsonObject &object)
 	{
 		return Stringify(object._value);
@@ -74,35 +104,4 @@ namespace ov
 
 		return JsonObject::NullObject();
 	}
-
-	const char *StringFromJsonValueType(::Json::ValueType value_type)
-	{
-		switch (value_type)
-		{
-			case ::Json::ValueType::nullValue:
-				return "null";
-			case ::Json::ValueType::intValue:
-				return "int";
-			case ::Json::ValueType::uintValue:
-				return "uint";
-			case ::Json::ValueType::realValue:
-				return "real";
-			case ::Json::ValueType::stringValue:
-				return "string";
-			case ::Json::ValueType::booleanValue:
-				return "boolean";
-			case ::Json::ValueType::arrayValue:
-				return "array";
-			case ::Json::ValueType::objectValue:
-				return "object";
-		}
-
-		return "unknown";
-	}
-
-	const char *StringFromJsonValueType(const ::Json::Value &value)
-	{
-		return StringFromJsonValueType(value.type());
-	}
-
 }  // namespace ov
diff --git a/src/projects/base/ovlibrary/json.h b/src/projects/base/ovlibrary/json.h
index 7fb157632..39fb65cb3 100644
--- a/src/projects/base/ovlibrary/json.h
+++ b/src/projects/base/ovlibrary/json.h
@@ -8,11 +8,13 @@
 //==============================================================================
 #pragma once
 
-#include "./json_object.h"
-#include "./string.h"
+#include "./json_builder.h"
 
 namespace ov
 {
+	constexpr const char *StringFromJsonValueType(::Json::ValueType value_type);
+	const char *StringFromJsonValueType(const ::Json::Value &value);
+
 	class Json
 	{
 	public:
@@ -26,7 +28,4 @@ namespace ov
 		static JsonObject Parse(const ov::String &str);
 		static JsonObject Parse(const std::shared_ptr<const Data> &data);
 	};
-
-	const char *StringFromJsonValueType(::Json::ValueType value_type);
-	const char *StringFromJsonValueType(const ::Json::Value &value);
 }  // namespace ov
diff --git a/src/projects/base/ovlibrary/json_builder.cpp b/src/projects/base/ovlibrary/json_builder.cpp
new file mode 100644
index 000000000..afece732f
--- /dev/null
+++ b/src/projects/base/ovlibrary/json_builder.cpp
@@ -0,0 +1,258 @@
+//==============================================================================
+//
+//  OvenMediaEngine
+//
+//  Created by Hyunjun Jang
+//  Copyright (c) 2025 AirenSoft. All rights reserved.
+//
+//==============================================================================
+#include "./json_builder.h"
+
+#include "./json.h"
+
+namespace ov
+{
+	JsonBuilder::JsonBuilder(const PrivateToken &token)
+	{
+	}
+
+	std::shared_ptr<JsonBuilder> JsonBuilder::Builder(JsonBuilderModifier modifier)
+	{
+		auto builder = std::make_shared<JsonBuilder>(PrivateToken());
+
+		auto modified_builder = (modifier != nullptr) ? modifier(builder.get()) : builder.get();
+
+		if (modified_builder != nullptr)
+		{
+			return modified_builder->GetSharedPtrAs<JsonBuilder>();
+		}
+
+		return nullptr;
+	}
+
+	void JsonBuilder::PushBackInternal(const char *key, JsonValueType value)
+	{
+		if (_value_type == ::Json::ValueType::nullValue)
+		{
+			_value_type = ::Json::ValueType::objectValue;
+		}
+
+		if (_value_type != ::Json::ValueType::objectValue)
+		{
+			OV_ASSERT(false, "The current JSON value is not an object");
+			return;
+		}
+
+		_value_map.PushBack(key, std::move(value));
+	}
+
+	JsonBuilder *JsonBuilder::PushBack(const char *key, ::Json::Value value)
+	{
+		PushBackInternal(key, std::move(value));
+
+		return this;
+	}
+
+	JsonBuilder *JsonBuilder::PushBack(const char *key, std::shared_ptr<JsonBuilder> builder)
+	{
+		if (builder == nullptr)
+		{
+			PushBackInternal(key, ::Json::Value::null);
+		}
+		else
+		{
+			PushBackInternal(key, builder);
+		}
+
+		return this;
+	}
+
+	JsonBuilder *JsonBuilder::PushBack(const char *key, JsonBuilderModifier modifier)
+	{
+		if (modifier == nullptr)
+		{
+			PushBackInternal(key, ::Json::Value::null);
+		}
+		else
+		{
+			PushBackInternal(key, Builder(modifier));
+		}
+
+		return this;
+	}
+
+	void JsonBuilder::PushBackInternal(JsonValueType item)
+	{
+		if (_value_type == ::Json::ValueType::nullValue)
+		{
+			_value_type = ::Json::ValueType::arrayValue;
+		}
+
+		if (_value_type != ::Json::ValueType::arrayValue)
+		{
+			OV_ASSERT(false, "The current JSON value is not an array");
+			return;
+		}
+
+		_value_list.push_back(std::move(item));
+	}
+
+	JsonBuilder *JsonBuilder::PushBack(::Json::Value value)
+	{
+		PushBackInternal(std::move(value));
+
+		return this;
+	}
+
+	JsonBuilder *JsonBuilder::PushBack(std::shared_ptr<JsonBuilder> builder)
+	{
+		if (builder == nullptr)
+		{
+			PushBackInternal(::Json::Value::null);
+		}
+		else
+		{
+			PushBackInternal(builder);
+		}
+
+		return this;
+	}
+
+	JsonBuilder *JsonBuilder::PushBack(JsonBuilderModifier modifier)
+	{
+		if (modifier == nullptr)
+		{
+			PushBackInternal(::Json::Value::null);
+		}
+		else
+		{
+			PushBackInternal(Builder(modifier));
+		}
+
+		return this;
+	}
+
+	ov::String JsonBuilder::Stringify() const
+	{
+		ov::String output;
+		return Stringify(output);
+	}
+
+	ov::String &JsonBuilder::Stringify(ov::String &output) const
+	{
+		switch (_value_type)
+		{
+			case ::Json::ValueType::nullValue:
+				output = "";
+				break;
+
+			case ::Json::ValueType::objectValue:
+				StringifyObject(output);
+				break;
+
+			case ::Json::ValueType::arrayValue:
+				StringifyArray(output);
+				break;
+
+			default:
+				OV_ASSERT(false, "Invalid JSON value type");
+				break;
+		}
+
+		return output;
+	}
+
+	static std::string EscapeString(ov::String &output, const ov::String &value)
+	{
+		::Json::StreamWriterBuilder builder;
+
+		return ::Json::writeString(builder, value.CStr()).c_str();
+	}
+
+	ov::String &JsonBuilder::StringifyObject(ov::String &output) const
+	{
+		auto end = _value_map.end();
+
+		output.Append('{');
+
+		for (auto it = _value_map.begin(); it != end; ++it)
+		{
+			if (it != _value_map.begin())
+			{
+				output.Append(',');
+			}
+
+			auto &key = it->first;
+			auto &value = it->second;
+
+			// Print key
+			output.AppendFormat("%s:", EscapeString(output, key).c_str());
+
+			// Print value
+			if (std::holds_alternative<::Json::Value>(value))
+			{
+				auto json = std::get<::Json::Value>(value);
+
+				output.Append(Json::Stringify(json, false));
+			}
+			else if (std::holds_alternative<std::shared_ptr<JsonBuilder>>(value))
+			{
+				auto builder = std::get<std::shared_ptr<JsonBuilder>>(value);
+
+				builder->Stringify(output);
+			}
+			else
+			{
+				OV_ASSERT(false, "Invalid JSON value type: %d", value.index());
+			}
+		}
+
+		output.Append('}');
+
+		return output;
+	}
+
+	ov::String &JsonBuilder::StringifyArray(ov::String &output) const
+	{
+		auto end = _value_list.end();
+
+		output.Append('[');
+
+		for (auto it = _value_list.begin(); it != end; ++it)
+		{
+			if (it != _value_list.begin())
+			{
+				output.Append(',');
+			}
+
+			auto &value = *it;
+
+			// Print value
+			if (std::holds_alternative<::Json::Value>(value))
+			{
+				auto json = std::get<::Json::Value>(value);
+
+				output.Append(Json::Stringify(json, false));
+			}
+			else if (std::holds_alternative<std::shared_ptr<JsonBuilder>>(value))
+			{
+				auto builder = std::get<std::shared_ptr<JsonBuilder>>(value);
+
+				builder->Stringify(output);
+			}
+			else
+			{
+				OV_ASSERT(false, "Invalid JSON value type: %d", value.index());
+			}
+		}
+
+		output.Append(']');
+
+		return output;
+	}
+
+	::Json::Value JsonBuilder::ToJsonValue() const
+	{
+		return ::Json::Value();
+	}
+}  // namespace ov
diff --git a/src/projects/base/ovlibrary/json_builder.h b/src/projects/base/ovlibrary/json_builder.h
new file mode 100644
index 000000000..fc24bb65e
--- /dev/null
+++ b/src/projects/base/ovlibrary/json_builder.h
@@ -0,0 +1,109 @@
+//==============================================================================
+//
+//  OvenMediaEngine
+//
+//  Created by Hyunjun Jang
+//  Copyright (c) 2025 AirenSoft. All rights reserved.
+//
+//==============================================================================
+#pragma once
+
+#include <variant>
+
+#include "./enable_shared_from_this.h"
+#include "./json_object.h"
+#include "./sequencial_map.h"
+
+namespace ov
+{
+	class JsonBuilder;
+
+	using JsonBuilderModifier = std::function<JsonBuilder *(JsonBuilder *builder)>;
+
+	// According to the specification, JSON works regardless of order, but when visualizing it as a JSON format
+	// such as outputting logs, the order may be important, so we provide a JsonBuilder class that guarantees the order.
+	//
+	// Usage:
+	//
+	// ov::String json = ov::JsonBuilder::Builder()
+	//     ->PushBack("key1", 100)
+	//     ->PushBack("key2", "value")
+	//     // If you don't need additional operations when set nested values, you can create a new builder and use it
+	//     ->PushBack("sub_object",
+	//                 ov::JsonBuilder::Builder()
+	//                     ->PushBack("sub_key1", "sub_value1")
+	//                     ->PushBack("sub_key2", "sub_value2")
+	//                     ->PushBack("sub_key3", [](auto builder) -> auto {
+	//                         return builder
+	//                             ->PushBack("sub_sub_key1", "sub_sub_value1")
+	//                             ->PushBack("sub_sub_key2", "sub_sub_value2");
+	//                     }))
+	//     // If you need additional operations when set nested values, you can use the modifier function
+	//     ->PushBack("sub_array", [obj](auto builder) -> auto {
+	//         ov::String s = "some complex value";
+	//         s += "!";
+	//
+	//         return builder
+	//             ->PushBack(s.CStr())
+	//             ->PushBack("sub_array")
+	//             ->PushBack([](auto builder) -> auto {
+	//                 return builder
+	//                     ->PushBack("sub_sub_key1", "sub_array1")
+	//                     ->PushBack("sub_sub_key2", "sub_array2");
+	//             });
+	//     })
+	//     ->Stringify();
+	//
+	// This will output:
+	// {"key1":100,"key2":"value","sub_object":true,"sub_array":["some complex value!","sub_array",{"sub_sub_key1":"sub_array1","sub_sub_key2":"sub_array2"}]}
+	class JsonBuilder : public ov::EnableSharedFromThis<JsonBuilder>
+	{
+	private:
+		struct PrivateToken
+		{
+		};
+
+		using JsonValueType = std::variant<
+			::Json::Value,
+			std::shared_ptr<JsonBuilder>>;
+
+	public:
+		// To ensure that the JsonBuilder object always uses shared_ptr
+		JsonBuilder() = delete;
+		JsonBuilder(const PrivateToken &token);
+		~JsonBuilder() = default;
+
+		// Create a new JsonBuilder object
+		static std::shared_ptr<JsonBuilder> Builder(JsonBuilderModifier modifier = nullptr);
+
+		// These APIs can be used when the JSON value currently being created is an object
+		JsonBuilder *PushBack(const char *key, ::Json::Value value);
+		JsonBuilder *PushBack(const char *key, std::shared_ptr<JsonBuilder> builder);
+		JsonBuilder *PushBack(const char *key, JsonBuilderModifier modifier);
+
+		// These APIs can be used when the JSON value currently being created is an array
+		JsonBuilder *PushBack(::Json::Value value);
+		JsonBuilder *PushBack(std::shared_ptr<JsonBuilder> builder);
+		JsonBuilder *PushBack(JsonBuilderModifier modifier);
+
+		// To JSON string
+		ov::String Stringify() const;
+
+		// To JSON object/array
+		::Json::Value ToJsonValue() const;
+
+	protected:
+		void PushBackInternal(const char *key, JsonValueType item);
+		void PushBackInternal(JsonValueType item);
+
+		ov::String &Stringify(ov::String &output) const;
+		ov::String &StringifyObject(ov::String &output) const;
+		ov::String &StringifyArray(ov::String &output) const;
+
+	protected:
+		::Json::ValueType _value_type = ::Json::ValueType::nullValue;
+
+		SequencialMap<ov::String, JsonValueType> _value_map;
+		std::vector<JsonValueType> _value_list;
+	};
+}  // namespace ov
diff --git a/src/projects/base/ovlibrary/json_object.h b/src/projects/base/ovlibrary/json_object.h
index a5652fe9e..0f60b711e 100644
--- a/src/projects/base/ovlibrary/json_object.h
+++ b/src/projects/base/ovlibrary/json_object.h
@@ -102,10 +102,10 @@ namespace ov
 
 			if (value.isString())
 			{
-				return ov::String( value.asString().c_str() );
+				return ov::String(value.asString().c_str());
 			}
 
-			return nullptr;			
+			return nullptr;
 		}
 
 		bool GetBoolValue(const ov::String &key) const
diff --git a/src/projects/base/ovlibrary/logger/formatters/common.h b/src/projects/base/ovlibrary/logger/formatters/common.h
new file mode 100644
index 000000000..8f8ad4a78
--- /dev/null
+++ b/src/projects/base/ovlibrary/logger/formatters/common.h
@@ -0,0 +1,133 @@
+//==============================================================================
+//
+//  OvenMediaEngine
+//
+//  Created by Hyunjun Jang
+//  Copyright (c) 2025 AirenSoft. All rights reserved.
+//
+//==============================================================================
+#pragma once
+
+#include <spdlog/fmt/bundled/format.h>
+
+#include <functional>
+#include <iostream>
+
+namespace ov
+{
+	namespace logger
+	{
+		// The following code is to delegate processing to `MyFormatter.Parse()` when `fmt::formatter::parse()` is called.
+		// If `MyFormatter` has a `Parse()` function, it calls `MyFormatter.Parse()`, otherwise it returns `ctx.begin()`.
+		using ParseContext = fmt::format_parse_context;
+		using ParseResult = ParseContext::iterator;
+		using Parser = std::function<ParseResult(ParseContext &)>;
+
+		template <typename Tformatter>
+		constexpr auto HasParse(int) -> decltype(std::declval<Tformatter>().Parse(std::declval<ParseContext &>()), std::true_type())
+		{
+			return std::true_type();
+		}
+
+		template <typename Tformatter>
+		constexpr auto HasParse(...) -> std::false_type
+		{
+			return std::false_type();
+		}
+
+		template <typename Tformatter, std::enable_if_t<decltype(HasParse<Tformatter>(0))::value, int> = 0>
+		constexpr ParseResult CallParse(Tformatter &formatter, ParseContext &ctx)
+		{
+			return formatter.Parse(ctx);
+		}
+
+		template <typename Tformatter, std::enable_if_t<!decltype(HasParse<Tformatter>(0))::value, int> = 0>
+		constexpr ParseResult CallParse(Tformatter const &formatter, ParseContext &ctx)
+		{
+			return ctx.begin();
+		}
+
+		// The following code is to delegate processing to `MyFormatter.Format()` when `fmt::formatter::format()` is called.
+		// If `MyFormatter` has a `Format()` function, it calls `MyFormatter.Format()`, otherwise it prints in the form of `<MyClass: 0x{:x}>`.
+		using FormatContext = fmt::format_context;
+		using FormatResult = FormatContext::iterator;
+		template <typename Tinstance>
+		using Formatter = std::function<FormatResult(Tinstance const &instance, FormatContext &)>;
+
+		template <typename Tformatter, typename Tinstance>
+		constexpr auto HasFormat(int) -> decltype(std::declval<Tformatter>().Format(
+													  std::declval<Tinstance &>(),
+													  std::declval<FormatContext &>()),
+												  std::true_type())
+		{
+			return std::true_type();
+		}
+
+		template <typename Tformatter, typename Tinstance>
+		constexpr auto HasFormat(...) -> std::false_type
+		{
+			return std::false_type();
+		}
+
+		template <typename Tformatter, typename Tinstance, std::enable_if_t<decltype(HasFormat<Tformatter, Tinstance>(0))::value, int> = 0>
+		constexpr FormatResult CallFormat(
+			const char *instance_name,
+			Tformatter const &formatter,
+			Tinstance const &instance,
+			FormatContext &ctx)
+		{
+			return formatter.Format(instance, ctx);
+		}
+
+		template <typename Tformatter, typename Tinstance, std::enable_if_t<!decltype(HasFormat<Tformatter, Tinstance>(0))::value, int> = 0>
+		constexpr FormatResult CallFormat(
+			const char *instance_name,
+			Tformatter const &formatter,
+			Tinstance const &instance,
+			FormatContext &ctx)
+		{
+			// Split by '::' and get the last element as the class name to exclude the namespace
+			auto class_name = instance_name;
+
+			for (auto i = instance_name; *i; ++i)
+			{
+				if (*i == ':')
+				{
+					class_name = i + 1;
+				}
+			}
+
+			if (class_name[0] == '\0')
+			{
+				class_name = instance_name;
+			}
+
+			return fmt::format_to(ctx.out(), "<{}: 0x{:x}>", class_name, reinterpret_cast<uintptr_t>(&instance));
+		}
+	}  // namespace logger
+}  // namespace ov
+
+// To support custom class for logging
+// https://github.com/gabime/spdlog/wiki/1.-QuickStart#log-user-defined-objects
+
+// If `DECLARE_FORMATTER(MyFormatter, MyClass)` is declared, when `MyClass` is output to the log,
+// `MyFormatter`'s `Parse()` and `Format()` functions are called.
+// If `MyFormatter` does not have `Parse()` and `Format()` functions, the default behavior is performed.
+#define DECLARE_CUSTOM_FORMATTER(formatter_name, for_class)                                       \
+	template <>                                                                                   \
+	class fmt::formatter<for_class>                                                               \
+	{                                                                                             \
+	public:                                                                                       \
+		constexpr auto parse(format_parse_context &ctx)                                           \
+		{                                                                                         \
+			return ov::logger::CallParse<formatter_name>(_formatter, ctx);                        \
+		}                                                                                         \
+                                                                                                  \
+		template <typename FmtContext>                                                            \
+		constexpr auto format(for_class const &instance, FmtContext &ctx) const                   \
+		{                                                                                         \
+			return ov::logger::CallFormat<formatter_name>(#for_class, _formatter, instance, ctx); \
+		}                                                                                         \
+                                                                                                  \
+		formatter_name _formatter;                                                                \
+	}
diff --git a/src/projects/base/ovlibrary/logger/formatters/formatters.h b/src/projects/base/ovlibrary/logger/formatters/formatters.h
new file mode 100644
index 000000000..665039748
--- /dev/null
+++ b/src/projects/base/ovlibrary/logger/formatters/formatters.h
@@ -0,0 +1,13 @@
+//==============================================================================
+//
+//  OvenMediaEngine
+//
+//  Created by Hyunjun Jang
+//  Copyright (c) 2025 AirenSoft. All rights reserved.
+//
+//==============================================================================
+#pragma once
+
+#include "./common.h"
+#include "./json_formatter.h"
+#include "./string_formatter.h"
diff --git a/src/projects/base/ovlibrary/logger/formatters/json_formatter.cpp b/src/projects/base/ovlibrary/logger/formatters/json_formatter.cpp
new file mode 100644
index 000000000..59deb1e93
--- /dev/null
+++ b/src/projects/base/ovlibrary/logger/formatters/json_formatter.cpp
@@ -0,0 +1,23 @@
+//==============================================================================
+//
+//  OvenMediaEngine
+//
+//  Created by Hyunjun Jang
+//  Copyright (c) 2025 AirenSoft. All rights reserved.
+//
+//==============================================================================
+#include "./json_formatter.h"
+
+namespace ov
+{
+	namespace logger
+	{
+		FormatResult JsonFormatter::Format(::Json::Value const &instance, FormatContext &ctx) const
+		{
+			auto json_str = ov::Json::Stringify(instance);
+
+			return fmt::formatter<std::string_view>::format(
+				std::string_view(json_str.CStr(), json_str.GetLength()), ctx);
+		}
+	}  // namespace logger
+}  // namespace ov
diff --git a/src/projects/base/ovlibrary/logger/formatters/json_formatter.h b/src/projects/base/ovlibrary/logger/formatters/json_formatter.h
new file mode 100644
index 000000000..b5355edc5
--- /dev/null
+++ b/src/projects/base/ovlibrary/logger/formatters/json_formatter.h
@@ -0,0 +1,31 @@
+//==============================================================================
+//
+//  OvenMediaEngine
+//
+//  Created by Hyunjun Jang
+//  Copyright (c) 2025 AirenSoft. All rights reserved.
+//
+//==============================================================================
+#pragma once
+
+#include "../../json.h"
+#include "./common.h"
+
+namespace ov
+{
+	namespace logger
+	{
+		class JsonFormatter : protected fmt::formatter<std::string_view>
+		{
+		public:
+			constexpr ParseResult Parse(ParseContext &ctx)
+			{
+				return fmt::formatter<std::string_view>::parse(ctx);
+			}
+
+			FormatResult Format(::Json::Value const &instance, FormatContext &ctx) const;
+		};
+	}  // namespace logger
+}  // namespace ov
+
+DECLARE_CUSTOM_FORMATTER(ov::logger::JsonFormatter, ::Json::Value);
diff --git a/src/projects/base/ovlibrary/logger/formatters/string_formatter.cpp b/src/projects/base/ovlibrary/logger/formatters/string_formatter.cpp
new file mode 100644
index 000000000..af9a2d117
--- /dev/null
+++ b/src/projects/base/ovlibrary/logger/formatters/string_formatter.cpp
@@ -0,0 +1,21 @@
+//==============================================================================
+//
+//  OvenMediaEngine
+//
+//  Created by Hyunjun Jang
+//  Copyright (c) 2025 AirenSoft. All rights reserved.
+//
+//==============================================================================
+#include "./string_formatter.h"
+
+namespace ov
+{
+	namespace logger
+	{
+		FormatResult StringFormatter::Format(String const &instance, FormatContext &ctx) const
+		{
+			return fmt::formatter<std::string_view>::format(
+				std::string_view(instance.CStr(), instance.GetLength()), ctx);
+		}
+	}  // namespace logger
+}  // namespace ov
diff --git a/src/projects/base/ovlibrary/logger/formatters/string_formatter.h b/src/projects/base/ovlibrary/logger/formatters/string_formatter.h
new file mode 100644
index 000000000..f5f2969e9
--- /dev/null
+++ b/src/projects/base/ovlibrary/logger/formatters/string_formatter.h
@@ -0,0 +1,31 @@
+//==============================================================================
+//
+//  OvenMediaEngine
+//
+//  Created by Hyunjun Jang
+//  Copyright (c) 2025 AirenSoft. All rights reserved.
+//
+//==============================================================================
+#pragma once
+
+#include "../../string.h"
+#include "./common.h"
+
+namespace ov
+{
+	namespace logger
+	{
+		class StringFormatter : protected fmt::formatter<std::string_view>
+		{
+		public:
+			constexpr ParseResult Parse(ParseContext &ctx)
+			{
+				return fmt::formatter<std::string_view>::parse(ctx);
+			}
+
+			FormatResult Format(String const &instance, FormatContext &ctx) const;
+		};
+	}  // namespace logger
+}  // namespace ov
+
+DECLARE_CUSTOM_FORMATTER(ov::logger::StringFormatter, ov::String);
diff --git a/src/projects/base/ovlibrary/logger/logger.cpp b/src/projects/base/ovlibrary/logger/logger.cpp
new file mode 100644
index 000000000..6c0c0476d
--- /dev/null
+++ b/src/projects/base/ovlibrary/logger/logger.cpp
@@ -0,0 +1,140 @@
+//==============================================================================
+//
+//  OvenMediaEngine
+//
+//  Created by Hyunjun Jang
+//  Copyright (c) 2025 AirenSoft. All rights reserved.
+//
+//==============================================================================
+#include "logger.h"
+
+#include <spdlog/sinks/stdout_color_sinks.h>
+#include <spdlog/spdlog.h>
+
+#include <memory>
+
+#define OV_LOG_COLOR_RESET "\x1B[0m"
+
+#define OV_LOG_COLOR_FG_BLACK "\x1B[30m"
+#define OV_LOG_COLOR_FG_RED "\x1B[31m"
+#define OV_LOG_COLOR_FG_GREEN "\x1B[32m"
+#define OV_LOG_COLOR_FG_YELLOW "\x1B[33m"
+#define OV_LOG_COLOR_FG_BLUE "\x1B[34m"
+#define OV_LOG_COLOR_FG_MAGENTA "\x1B[35m"
+#define OV_LOG_COLOR_FG_CYAN "\x1B[36m"
+#define OV_LOG_COLOR_FG_WHITE "\x1B[37m"
+
+#define OV_LOG_COLOR_FG_BR_BLACK "\x1B[90m"
+#define OV_LOG_COLOR_FG_BR_RED "\x1B[91m"
+#define OV_LOG_COLOR_FG_BR_GREEN "\x1B[92m"
+#define OV_LOG_COLOR_FG_BR_YELLOW "\x1B[93m"
+#define OV_LOG_COLOR_FG_BR_BLUE "\x1B[94m"
+#define OV_LOG_COLOR_FG_BR_MAGENTA "\x1B[95m"
+#define OV_LOG_COLOR_FG_BR_CYAN "\x1B[96m"
+#define OV_LOG_COLOR_FG_BR_WHITE "\x1B[97m"
+
+#define OV_LOG_COLOR_BG_BLACK "\x1B[40m"
+#define OV_LOG_COLOR_BG_RED "\x1B[41m"
+#define OV_LOG_COLOR_BG_GREEN "\x1B[42m"
+#define OV_LOG_COLOR_BG_YELLOW "\x1B[43m"
+#define OV_LOG_COLOR_BG_BLUE "\x1B[44m"
+#define OV_LOG_COLOR_BG_MAGENTA "\x1B[45m"
+#define OV_LOG_COLOR_BG_CYAN "\x1B[46m"
+#define OV_LOG_COLOR_BG_WHITE "\x1B[47m"
+
+#define OV_LOG_COLOR_BG_BR_BLACK "\x1B[100m"
+#define OV_LOG_COLOR_BG_BR_RED "\x1B[101m"
+#define OV_LOG_COLOR_BG_BR_GREEN "\x1B[102m"
+#define OV_LOG_COLOR_BG_BR_YELLOW "\x1B[103m"
+#define OV_LOG_COLOR_BG_BR_BLUE "\x1B[104m"
+#define OV_LOG_COLOR_BG_BR_MAGENTA "\x1B[105m"
+#define OV_LOG_COLOR_BG_BR_CYAN "\x1B[106m"
+#define OV_LOG_COLOR_BG_BR_WHITE "\x1B[107m"
+
+namespace ov
+{
+	namespace logger
+	{
+		constexpr spdlog::level::level_enum LogLevelToSpdlogLevel(LogLevel level)
+		{
+			switch (level)
+			{
+				case LogLevel::Trace:
+					return spdlog::level::trace;
+
+				case LogLevel::Debug:
+					return spdlog::level::debug;
+
+				case LogLevel::Info:
+					return spdlog::level::info;
+
+				case LogLevel::Warn:
+					return spdlog::level::warn;
+
+				case LogLevel::Error:
+					return spdlog::level::err;
+
+				case LogLevel::Critical:
+					return spdlog::level::critical;
+			}
+
+			return spdlog::level::off;
+		}
+
+		std::shared_ptr<Logger> GetLogger(const char *tag)
+		{
+			static std::mutex logger_map_mutex;
+			static std::map<std::string, std::shared_ptr<Logger>> logger_map;
+
+			std::lock_guard lock_guard(logger_map_mutex);
+
+			{
+				auto logger = logger_map.find(tag);
+
+				if (logger != logger_map.end())
+				{
+					return logger->second;
+				}
+			}
+
+			// TODO(dimiden): Need to initialize logger according to the contents of Logger.xml here
+			auto internal_logger = spdlog::stdout_color_mt(tag);
+
+			auto &sinks = internal_logger->sinks();
+			auto sink = std::dynamic_pointer_cast<spdlog::sinks::stdout_color_sink_mt>(sinks[0]);
+
+			sink->set_color(spdlog::level::trace, OV_LOG_COLOR_FG_CYAN);
+			sink->set_color(spdlog::level::debug, OV_LOG_COLOR_FG_CYAN);
+			sink->set_color(spdlog::level::info, OV_LOG_COLOR_FG_WHITE);
+			sink->set_color(spdlog::level::warn, OV_LOG_COLOR_FG_YELLOW);
+			sink->set_color(spdlog::level::err, OV_LOG_COLOR_FG_RED);
+			sink->set_color(spdlog::level::critical, OV_LOG_COLOR_FG_BR_WHITE OV_LOG_COLOR_BG_RED);
+
+			// [2025-02-12 17:54:01.445] I [SPRTMP-t41935:423153] Publisher | stream.cpp:294  | [stream(1423176515)] LLHLS Publisher Application - All StreamWorker has been stopped
+
+			// https://github.com/gabime/spdlog/wiki/3.-Custom-formatting#pattern-flags
+			auto formatter = std::make_unique<spdlog::pattern_formatter>();
+			formatter
+				->add_flag<ThreadNamePatternFlag>(ThreadNamePatternFlag::FLAG)
+				.set_pattern("%^[%Y-%m-%d %H:%M:%S.%e%z] %L [%N:%t] %n | %s:%-4# | %v%$");
+
+			internal_logger->set_formatter(std::move(formatter));
+
+			auto logger = std::make_shared<Logger>(internal_logger);
+
+			logger_map[tag] = logger;
+
+			return logger;
+		}
+
+		void Logger::SetLogPattern(const char *pattern)
+		{
+			_logger->set_pattern(pattern);
+		}
+
+		void Logger::Log(LogLevel level, const char *file, int line, const char *function, const std::string &message)
+		{
+			_logger->log(spdlog::source_loc{file, line, function}, LogLevelToSpdlogLevel(level), message);
+		}
+	}  // namespace logger
+}  // namespace ov
diff --git a/src/projects/base/ovlibrary/logger/logger.h b/src/projects/base/ovlibrary/logger/logger.h
new file mode 100644
index 000000000..3782f77e0
--- /dev/null
+++ b/src/projects/base/ovlibrary/logger/logger.h
@@ -0,0 +1,145 @@
+//==============================================================================
+//
+//  OvenMediaEngine
+//
+//  Created by Hyunjun Jang
+//  Copyright (c) 2025 AirenSoft. All rights reserved.
+//
+//==============================================================================
+#pragma once
+
+#include <spdlog/fmt/bundled/format.h>
+
+#include <cstdarg>
+#include <map>
+#include <memory>
+
+#include "./pattern_flags/pattern_flags.h"
+#include "formatters/formatters.h"
+
+// Forward declaration of spdlog::logger
+namespace spdlog
+{
+	class logger;
+}  // namespace spdlog
+
+namespace ov
+{
+	namespace logger
+	{
+		enum class LogLevel
+		{
+			Trace,
+			Debug,
+			Info,
+			Warn,
+			Error,
+			Critical,
+		};
+
+		class Logger
+		{
+		public:
+			Logger(std::shared_ptr<spdlog::logger> logger)
+				: _logger(logger)
+			{
+			}
+
+			// Since the Logger is configured with spdlog, please refer to spdlog's pattern flags for more details.
+			//
+			// https://github.com/gabime/spdlog/wiki/3.-Custom-formatting#pattern-flags
+			//
+			// | flag     | meaning                                                                                    | example                                                    |
+			// +----------+--------------------------------------------------------------------------------------------+------------------------------------------------------------+
+			// | %v       | The actual text to log                                                                     | some user text"                                            |
+			// | %t       | Thread id                                                                                  | 1232"                                                      |
+			// | %P       | Process id                                                                                 | 3456"                                                      |
+			// | %n       | Logger's name                                                                              | some logger name"                                          |
+			// | %l       | The log level of the message                                                               | debug", "info", etc                                        |
+			// | %L       | Short log level of the message                                                             | D", "I", etc                                               |
+			// | %a       | Abbreviated weekday name                                                                   | Thu"                                                       |
+			// | %A       | Full weekday name                                                                          | Thursday"                                                  |
+			// | %b       | Abbreviated month name                                                                     | Aug"                                                       |
+			// | %B       | Full month name                                                                            | August"                                                    |
+			// | %c       | Date and time representation                                                               | Thu Aug 23 15:35:46 2014"                                  |
+			// | %C       | Year in 2 digits                                                                           | 14"                                                        |
+			// | %Y       | Year in 4 digits                                                                           | 2014"                                                      |
+			// | %D or %x | Short MM/DD/YY date                                                                        | 08/23/14"                                                  |
+			// | %m       | Month 01-12                                                                                | 11"                                                        |
+			// | %d       | Day of month 01-31                                                                         | 29"                                                        |
+			// | %H       | Hours in 24 format 00-23                                                                   | 23"                                                        |
+			// | %I       | Hours in 12 format 01-12                                                                   | 11"                                                        |
+			// | %M       | Minutes 00-59                                                                              | 59"                                                        |
+			// | %S       | Seconds 00-59                                                                              | 58"                                                        |
+			// | %e       | Millisecond part of the current second 000-999                                             | 678"                                                       |
+			// | %f       | Microsecond part of the current second 000000-999999                                       | 056789"                                                    |
+			// | %F       | Nanosecond part of the current second 000000000-999999999                                  | 256789123"                                                 |
+			// | %p       | AM/PM                                                                                      | AM"                                                        |
+			// | %r       | 12 hour clock                                                                              | 02:55:02 PM"                                               |
+			// | %R       | 24-hour HH:MM time, equivalent to %H:%M                                                    | 23:55"                                                     |
+			// | %T or %X | ISO 8601 time format (HH:MM:SS), equivalent to %H:%M:%S                                    | 23:55:59"                                                  |
+			// | %z       | ISO 8601 offset from UTC in timezone ([+/-]HH:MM)                                          | "+02:00"                                                   |
+			// | %E       | Seconds since the epoch                                                                    | 1528834770"                                                |
+			// | %%       | The % sign                                                                                 | "%"                                                        |
+			// | %+       | spdlog's default format                                                                    | "[2014-10-31 23:46:59.678] [mylogger] [info] Some message" |
+			// | %^       | start color range (can be used only once)                                                  | "[mylogger] [info(green)] Some message"                    |
+			// | %$       | end color range (for example %^[+++]%$ %v) (can be used only once)                         | [+++] Some message                                         |
+			// | %@       | Source file and line (use SPDLOG_TRACE(..),                                                | some/dir/my_file.cpp:123                                   |
+			// |          | SPDLOG_INFO(...) etc. instead of spdlog::trace(...)) Same as %g:%#                         |                                                            |
+			// | %s       | Basename of the source file (use SPDLOG_TRACE(..), SPDLOG_INFO(...) etc.)                  | my_file.cpp                                                |
+			// | %g       | Full or relative path of the source file as appears in                                     | some/dir/my_file.cpp                                       |
+			// |          | spdlog::source_loc (use SPDLOG_TRACE(..), SPDLOG_INFO(...) etc.)                           |                                                            |
+			// | %#       | Source line (use SPDLOG_TRACE(..), SPDLOG_INFO(...) etc.)                                  | 123                                                        |
+			// | %!       | Source function (use SPDLOG_TRACE(..), SPDLOG_INFO(...) etc. see tweakme for pretty-print) | my_func                                                    |
+			// | %o       | Elapsed time in milliseconds since previous message                                        | 456                                                        |
+			// | %i       | Elapsed time in microseconds since previous message                                        | 456                                                        |
+			// | %u       | Elapsed time in nanoseconds since previous message                                         | 11456                                                      |
+			// | %O       | Elapsed time in seconds since previous message                                             | 4                                                          |
+			void SetLogPattern(const char *pattern);
+
+			template <typename... Targs>
+			inline void Trace(const char *file, int line, const char *function, const char *format, Targs &&...args)
+			{
+				return Log(LogLevel::Trace, file, line, function, fmt::vformat(format, fmt::make_format_args(args...)));
+			}
+
+			template <typename... Targs>
+			inline void Debug(const char *file, int line, const char *function, const char *format, Targs &&...args)
+			{
+				return Log(LogLevel::Debug, file, line, function, fmt::vformat(format, fmt::make_format_args(args...)));
+			}
+
+			template <typename... Targs>
+			inline void Info(const char *file, int line, const char *function, const char *format, Targs &&...args)
+			{
+				return Log(LogLevel::Info, file, line, function, fmt::vformat(format, fmt::make_format_args(args...)));
+			}
+
+			template <typename... Targs>
+			inline void Warn(const char *file, int line, const char *function, const char *format, Targs &&...args)
+			{
+				return Log(LogLevel::Warn, file, line, function, fmt::vformat(format, fmt::make_format_args(args...)));
+			}
+
+			template <typename... Targs>
+			inline void Error(const char *file, int line, const char *function, const char *format, Targs &&...args)
+			{
+				return Log(LogLevel::Error, file, line, function, fmt::vformat(format, fmt::make_format_args(args...)));
+			}
+
+			template <typename... Targs>
+			inline void Critical(const char *file, int line, const char *function, const char *format, Targs &&...args)
+			{
+				return Log(LogLevel::Critical, file, line, function, fmt::vformat(format, fmt::make_format_args(args...)));
+			}
+
+		protected:
+			void Log(LogLevel level, const char *file, int line, const char *function, const std::string &message);
+
+		private:
+			std::shared_ptr<spdlog::logger> _logger;
+		};
+
+		std::shared_ptr<Logger> GetLogger(const char *tag);
+	}  // namespace logger
+}  // namespace ov
diff --git a/src/projects/base/ovlibrary/logger/pattern_flags/pattern_flags.h b/src/projects/base/ovlibrary/logger/pattern_flags/pattern_flags.h
new file mode 100644
index 000000000..e8ed41f40
--- /dev/null
+++ b/src/projects/base/ovlibrary/logger/pattern_flags/pattern_flags.h
@@ -0,0 +1,11 @@
+//==============================================================================
+//
+//  OvenMediaEngine
+//
+//  Created by Hyunjun Jang
+//  Copyright (c) 2025 AirenSoft. All rights reserved.
+//
+//==============================================================================
+#pragma once
+
+#include "./thread_name_pattern_flag.h"
diff --git a/src/projects/base/ovlibrary/logger/pattern_flags/thread_name_pattern_flag.h b/src/projects/base/ovlibrary/logger/pattern_flags/thread_name_pattern_flag.h
new file mode 100644
index 000000000..2b8ae50e1
--- /dev/null
+++ b/src/projects/base/ovlibrary/logger/pattern_flags/thread_name_pattern_flag.h
@@ -0,0 +1,47 @@
+//==============================================================================
+//
+//  OvenMediaEngine
+//
+//  Created by Hyunjun Jang
+//  Copyright (c) 2025 AirenSoft. All rights reserved.
+//
+//==============================================================================
+#include <spdlog/pattern_formatter.h>
+
+namespace ov
+{
+	namespace logger
+	{
+		// https://github.com/gabime/spdlog/wiki/3.-Custom-formatting#extending-spdlog-with-your-own-flags
+		class ThreadNamePatternFlag : public spdlog::custom_flag_formatter
+		{
+		public:
+			constexpr static const char FLAG = 'N';
+
+			//--------------------------------------------------------------------
+			// Overriding of spdlog::custom_flag_formatter
+			//--------------------------------------------------------------------
+			void format(const spdlog::details::log_msg &msg, const std::tm &, spdlog::memory_buf_t &dest) override
+			{
+				AppendThreadName(msg.pthread_id, dest);
+			}
+
+			std::unique_ptr<custom_flag_formatter> clone() const override
+			{
+				return spdlog::details::make_unique<ThreadNamePatternFlag>();
+			}
+
+		protected:
+			void AppendThreadName(pthread_t thread_id, spdlog::memory_buf_t &dest)
+			{
+				char name[16]{0};
+				size_t length = 0;
+
+				::pthread_getname_np(thread_id, name, 16);
+				length = ::strlen(name);
+
+				dest.append(name, name + length);
+			}
+		};
+	}  // namespace logger
+}  // namespace ov
\ No newline at end of file
diff --git a/src/projects/base/ovlibrary/ovlibrary.h b/src/projects/base/ovlibrary/ovlibrary.h
index 4e54e90f4..51b418a61 100644
--- a/src/projects/base/ovlibrary/ovlibrary.h
+++ b/src/projects/base/ovlibrary/ovlibrary.h
@@ -45,3 +45,6 @@
 #include "./url.h"
 #include "./precise_timer.h"
 #include "./files.h"
+#include "./sequencial_map.h"
+
+#include "./logger/logger.h"
diff --git a/src/projects/base/ovlibrary/sequencial_map.h b/src/projects/base/ovlibrary/sequencial_map.h
new file mode 100644
index 000000000..c5098cb57
--- /dev/null
+++ b/src/projects/base/ovlibrary/sequencial_map.h
@@ -0,0 +1,290 @@
+//==============================================================================
+//
+//  OvenMediaEngine
+//
+//  Created by Hyunjun Jang
+//  Copyright (c) 2025 AirenSoft. All rights reserved.
+//
+//==============================================================================
+#pragma once
+
+#include <unordered_map>
+#include <vector>
+
+#include "./assert.h"
+
+namespace ov
+{
+	// This is a map that maintains the order in which `PushBack()` or `EmplaceBack()` was called
+	template <typename Tkey, typename Tvalue>
+	class SequencialMap
+	{
+	private:
+		using KeyRefList = std::vector<std::reference_wrapper<const Tkey>>;
+
+	public:
+		using SizeType = typename KeyRefList::size_type;
+
+		template <typename Titerator, typename Tvalue_map>
+		class IteratorBase
+		{
+		public:
+			IteratorBase(
+				Titerator current,
+				Tvalue_map &value_map)
+				: _current(current),
+				  _value_map(value_map)
+			{
+			}
+
+			auto &operator*()
+			{
+				return *(_value_map.find(*_current));
+			}
+
+			auto operator->()
+			{
+				return _value_map.find(*_current).operator->();
+			}
+
+			IteratorBase<Titerator, Tvalue_map> &operator++()
+			{
+				++_current;
+				return *this;
+			}
+
+			bool operator!=(const IteratorBase<Titerator, Tvalue_map> &other) const
+			{
+				return _current != other._current;
+			}
+
+		private:
+			Titerator _current;
+
+			Tvalue_map &_value_map;
+		};
+
+		using Iterator = IteratorBase<typename KeyRefList::iterator, std::unordered_map<Tkey, Tvalue>>;
+		using ConstIterator = IteratorBase<typename KeyRefList::const_iterator, const std::unordered_map<Tkey, Tvalue>>;
+
+	public:
+		void PushBack(const Tkey &key, const Tvalue &value)
+		{
+			auto it = _value_map.find(key);
+
+			if (it == _value_map.end())
+			{
+				_value_map[key] = value;
+				it = _value_map.find(key);
+				_key_ref_list.emplace_back(std::ref(it->first));
+			}
+			else
+			{
+				// Update
+				it->second = value;
+			}
+		}
+
+		template <typename... Targs>
+		std::pair<Iterator, bool> EmplaceBack(Tkey &&key, Targs &&...args)
+		{
+			auto it = _value_map.find(key);
+			bool inserted = false;
+
+			if (it == _value_map.end())
+			{
+				auto new_it = _value_map.emplace(
+					std::piecewise_construct,
+					std::forward_as_tuple(std::forward<Tkey>(key)),
+					std::forward_as_tuple(std::forward<Targs>(args)...));
+				it = new_it.first;
+				_key_ref_list.emplace_back(std::ref(it->first));
+
+				inserted = true;
+			}
+			else
+			{
+				// Update value if key exists
+				it->second = Tvalue(std::forward<Targs>(args)...);
+			}
+
+			return std::make_pair(Iterator(_key_ref_list.begin(), _value_map), inserted);
+		}
+
+		// Throws std::out_of_range if key does not exist
+		const Tvalue &At(const Tkey &key) const
+		{
+			auto it = _value_map.find(key);
+
+			if (it != _value_map.end())
+			{
+				return it->second;
+			}
+
+			throw std::out_of_range("Key does not exist");
+		}
+
+		// Throws std::out_of_range if key does not exist
+		Tvalue &At(const Tkey &key)
+		{
+			return const_cast<Tvalue &>(std::as_const(*this).At(key));
+		}
+
+		SizeType Size() const
+		{
+			return _key_ref_list.size();
+		}
+
+		bool Empty() const
+		{
+			return _key_ref_list.empty();
+		}
+
+		void Clear()
+		{
+			_key_ref_list.clear();
+			_value_map.clear();
+		}
+
+		bool Contains(const Tkey &key) const
+		{
+			return _value_map.find(key) != _value_map.end();
+		}
+
+		void Erase(const Tkey &key)
+		{
+			auto it = _value_map.find(key);
+
+			if (it == _value_map.end())
+			{
+				return;
+			}
+
+			auto key_it = std::find(_key_ref_list.begin(), _key_ref_list.end(), key);
+			if (key_it != _key_ref_list.end())
+			{
+				_key_ref_list.erase(key_it);
+			}
+			else
+			{
+				// If the key exists in _value_map, it must also exist in _key_list
+				OV_ASSERT(false, "Key does not exist in _key_list");
+			}
+
+			_value_map.erase(it);
+		}
+
+		Tvalue &operator[](const Tkey &key)
+		{
+			auto it = _value_map.find(key);
+
+			if (it != _value_map.end())
+			{
+				return it->second;
+			}
+
+			return
+				// EmplaceBack() returns std::pair<Iterator, bool>,
+				EmplaceBack(key).first->
+				// and Iterator.second is the value
+				second;
+		}
+
+		Tvalue &operator[](Tkey &&key)
+		{
+			auto it = _value_map.find(key);
+
+			if (it != _value_map.end())
+			{
+				return it->second;
+			}
+
+			return
+				// EmplaceBack() returns std::pair<Iterator, bool>,
+				EmplaceBack(std::move(key)).first->
+				// and Iterator.second is the value
+				second;
+		}
+
+		ConstIterator CBegin() const
+		{
+			return ConstIterator(_key_ref_list.cbegin(), _value_map);
+		}
+
+		ConstIterator CEnd() const
+		{
+			return ConstIterator(_key_ref_list.cend(), _value_map);
+		}
+
+		Iterator Begin()
+		{
+			return Iterator(_key_ref_list.begin(), _value_map);
+		}
+
+		Iterator End()
+		{
+			return Iterator(_key_ref_list.end(), _value_map);
+		}
+
+		ConstIterator Begin() const
+		{
+			return CBegin();
+		}
+
+		ConstIterator End() const
+		{
+			return CEnd();
+		}
+
+		// For STL
+		inline ConstIterator cbegin() const
+		{
+			return CBegin();
+		}
+
+		inline ConstIterator cend() const
+		{
+			return CEnd();
+		}
+
+		inline Iterator begin()
+		{
+			return Begin();
+		}
+
+		inline Iterator end()
+		{
+			return End();
+		}
+
+		inline ConstIterator begin() const
+		{
+			return Begin();
+		}
+
+		inline ConstIterator end() const
+		{
+			return End();
+		}
+
+	private:
+		template <typename... Targs>
+		typename std::unordered_map<Tkey, Tvalue>::iterator EmplaceBackInternal(const Tkey &key, Targs &&...args)
+		{
+			auto it = _value_map.find(key);
+
+			if (it == _value_map.end())
+			{
+				_value_map.emplace(key, Tvalue());
+				it = _value_map.find(key);
+				_key_ref_list.emplace_back(std::ref(it->first));
+			}
+
+			return it;
+		}
+
+	private:
+		KeyRefList _key_ref_list;
+		std::unordered_map<Tkey, Tvalue> _value_map;
+	};
+}  // namespace ov