diff --git a/Makefile b/Makefile
index 78462f8f..91c8a993 100644
--- a/Makefile
+++ b/Makefile
@@ -16,4 +16,9 @@ proto:
 generate:
 	go generate ./...
 
+.PHONY: image-push-all
+image-push-all:
+	for dir in $(shell find ./pkg -name 'Makefile' -exec dirname {} \;); do \
+		$(MAKE) -C $$dir image-push TAG=$(TAG); \
+	done
 
diff --git a/pkg/apis/proto/map/v1/map.pb.go b/pkg/apis/proto/map/v1/map.pb.go
index 29d0b37d..7d615a9b 100644
--- a/pkg/apis/proto/map/v1/map.pb.go
+++ b/pkg/apis/proto/map/v1/map.pb.go
@@ -33,6 +33,7 @@ type MapRequest struct {
 	Value     []byte                 `protobuf:"bytes,2,opt,name=value,proto3" json:"value,omitempty"`
 	EventTime *timestamppb.Timestamp `protobuf:"bytes,3,opt,name=event_time,json=eventTime,proto3" json:"event_time,omitempty"`
 	Watermark *timestamppb.Timestamp `protobuf:"bytes,4,opt,name=watermark,proto3" json:"watermark,omitempty"`
+	Headers   map[string]string      `protobuf:"bytes,5,rep,name=headers,proto3" json:"headers,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
 }
 
 func (x *MapRequest) Reset() {
@@ -95,6 +96,13 @@ func (x *MapRequest) GetWatermark() *timestamppb.Timestamp {
 	return nil
 }
 
+func (x *MapRequest) GetHeaders() map[string]string {
+	if x != nil {
+		return x.Headers
+	}
+	return nil
+}
+
 // *
 // MapResponse represents a response element.
 type MapResponse struct {
@@ -206,7 +214,7 @@ type MapResponse_Result struct {
 func (x *MapResponse_Result) Reset() {
 	*x = MapResponse_Result{}
 	if protoimpl.UnsafeEnabled {
-		mi := &file_pkg_apis_proto_map_v1_map_proto_msgTypes[3]
+		mi := &file_pkg_apis_proto_map_v1_map_proto_msgTypes[4]
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		ms.StoreMessageInfo(mi)
 	}
@@ -219,7 +227,7 @@ func (x *MapResponse_Result) String() string {
 func (*MapResponse_Result) ProtoMessage() {}
 
 func (x *MapResponse_Result) ProtoReflect() protoreflect.Message {
-	mi := &file_pkg_apis_proto_map_v1_map_proto_msgTypes[3]
+	mi := &file_pkg_apis_proto_map_v1_map_proto_msgTypes[4]
 	if protoimpl.UnsafeEnabled && x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -265,7 +273,7 @@ var file_pkg_apis_proto_map_v1_map_proto_rawDesc = []byte{
 	0x65, 0x2f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x62, 0x75, 0x66, 0x2f, 0x65, 0x6d, 0x70, 0x74, 0x79,
 	0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x1a, 0x1f, 0x67, 0x6f, 0x6f, 0x67, 0x6c, 0x65, 0x2f, 0x70,
 	0x72, 0x6f, 0x74, 0x6f, 0x62, 0x75, 0x66, 0x2f, 0x74, 0x69, 0x6d, 0x65, 0x73, 0x74, 0x61, 0x6d,
-	0x70, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x22, 0xab, 0x01, 0x0a, 0x0a, 0x4d, 0x61, 0x70, 0x52,
+	0x70, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x22, 0xa2, 0x02, 0x0a, 0x0a, 0x4d, 0x61, 0x70, 0x52,
 	0x65, 0x71, 0x75, 0x65, 0x73, 0x74, 0x12, 0x12, 0x0a, 0x04, 0x6b, 0x65, 0x79, 0x73, 0x18, 0x01,
 	0x20, 0x03, 0x28, 0x09, 0x52, 0x04, 0x6b, 0x65, 0x79, 0x73, 0x12, 0x14, 0x0a, 0x05, 0x76, 0x61,
 	0x6c, 0x75, 0x65, 0x18, 0x02, 0x20, 0x01, 0x28, 0x0c, 0x52, 0x05, 0x76, 0x61, 0x6c, 0x75, 0x65,
@@ -276,29 +284,37 @@ var file_pkg_apis_proto_map_v1_map_proto_rawDesc = []byte{
 	0x61, 0x74, 0x65, 0x72, 0x6d, 0x61, 0x72, 0x6b, 0x18, 0x04, 0x20, 0x01, 0x28, 0x0b, 0x32, 0x1a,
 	0x2e, 0x67, 0x6f, 0x6f, 0x67, 0x6c, 0x65, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x62, 0x75, 0x66,
 	0x2e, 0x54, 0x69, 0x6d, 0x65, 0x73, 0x74, 0x61, 0x6d, 0x70, 0x52, 0x09, 0x77, 0x61, 0x74, 0x65,
-	0x72, 0x6d, 0x61, 0x72, 0x6b, 0x22, 0x8b, 0x01, 0x0a, 0x0b, 0x4d, 0x61, 0x70, 0x52, 0x65, 0x73,
-	0x70, 0x6f, 0x6e, 0x73, 0x65, 0x12, 0x34, 0x0a, 0x07, 0x72, 0x65, 0x73, 0x75, 0x6c, 0x74, 0x73,
-	0x18, 0x01, 0x20, 0x03, 0x28, 0x0b, 0x32, 0x1a, 0x2e, 0x6d, 0x61, 0x70, 0x2e, 0x76, 0x31, 0x2e,
-	0x4d, 0x61, 0x70, 0x52, 0x65, 0x73, 0x70, 0x6f, 0x6e, 0x73, 0x65, 0x2e, 0x52, 0x65, 0x73, 0x75,
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-	0x52, 0x65, 0x61, 0x64, 0x79, 0x52, 0x65, 0x73, 0x70, 0x6f, 0x6e, 0x73, 0x65, 0x42, 0x37, 0x5a,
-	0x35, 0x67, 0x69, 0x74, 0x68, 0x75, 0x62, 0x2e, 0x63, 0x6f, 0x6d, 0x2f, 0x6e, 0x75, 0x6d, 0x61,
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+	0x72, 0x6d, 0x61, 0x72, 0x6b, 0x12, 0x39, 0x0a, 0x07, 0x68, 0x65, 0x61, 0x64, 0x65, 0x72, 0x73,
+	0x18, 0x05, 0x20, 0x03, 0x28, 0x0b, 0x32, 0x1f, 0x2e, 0x6d, 0x61, 0x70, 0x2e, 0x76, 0x31, 0x2e,
+	0x4d, 0x61, 0x70, 0x52, 0x65, 0x71, 0x75, 0x65, 0x73, 0x74, 0x2e, 0x48, 0x65, 0x61, 0x64, 0x65,
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+	0x12, 0x10, 0x0a, 0x03, 0x6b, 0x65, 0x79, 0x18, 0x01, 0x20, 0x01, 0x28, 0x09, 0x52, 0x03, 0x6b,
+	0x65, 0x79, 0x12, 0x14, 0x0a, 0x05, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x18, 0x02, 0x20, 0x01, 0x28,
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+	0x6d, 0x61, 0x70, 0x2e, 0x76, 0x31, 0x2e, 0x4d, 0x61, 0x70, 0x52, 0x65, 0x73, 0x70, 0x6f, 0x6e,
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+	0x74, 0x73, 0x1a, 0x46, 0x0a, 0x06, 0x52, 0x65, 0x73, 0x75, 0x6c, 0x74, 0x12, 0x12, 0x0a, 0x04,
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+	0x12, 0x14, 0x0a, 0x05, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x18, 0x02, 0x20, 0x01, 0x28, 0x0c, 0x52,
+	0x05, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x12, 0x12, 0x0a, 0x04, 0x74, 0x61, 0x67, 0x73, 0x18, 0x03,
+	0x20, 0x03, 0x28, 0x09, 0x52, 0x04, 0x74, 0x61, 0x67, 0x73, 0x22, 0x25, 0x0a, 0x0d, 0x52, 0x65,
+	0x61, 0x64, 0x79, 0x52, 0x65, 0x73, 0x70, 0x6f, 0x6e, 0x73, 0x65, 0x12, 0x14, 0x0a, 0x05, 0x72,
+	0x65, 0x61, 0x64, 0x79, 0x18, 0x01, 0x20, 0x01, 0x28, 0x08, 0x52, 0x05, 0x72, 0x65, 0x61, 0x64,
+	0x79, 0x32, 0x71, 0x0a, 0x03, 0x4d, 0x61, 0x70, 0x12, 0x30, 0x0a, 0x05, 0x4d, 0x61, 0x70, 0x46,
+	0x6e, 0x12, 0x12, 0x2e, 0x6d, 0x61, 0x70, 0x2e, 0x76, 0x31, 0x2e, 0x4d, 0x61, 0x70, 0x52, 0x65,
+	0x71, 0x75, 0x65, 0x73, 0x74, 0x1a, 0x13, 0x2e, 0x6d, 0x61, 0x70, 0x2e, 0x76, 0x31, 0x2e, 0x4d,
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+	0x52, 0x65, 0x61, 0x64, 0x79, 0x12, 0x16, 0x2e, 0x67, 0x6f, 0x6f, 0x67, 0x6c, 0x65, 0x2e, 0x70,
+	0x72, 0x6f, 0x74, 0x6f, 0x62, 0x75, 0x66, 0x2e, 0x45, 0x6d, 0x70, 0x74, 0x79, 0x1a, 0x15, 0x2e,
+	0x6d, 0x61, 0x70, 0x2e, 0x76, 0x31, 0x2e, 0x52, 0x65, 0x61, 0x64, 0x79, 0x52, 0x65, 0x73, 0x70,
+	0x6f, 0x6e, 0x73, 0x65, 0x42, 0x37, 0x5a, 0x35, 0x67, 0x69, 0x74, 0x68, 0x75, 0x62, 0x2e, 0x63,
+	0x6f, 0x6d, 0x2f, 0x6e, 0x75, 0x6d, 0x61, 0x70, 0x72, 0x6f, 0x6a, 0x2f, 0x6e, 0x75, 0x6d, 0x61,
+	0x66, 0x6c, 0x6f, 0x77, 0x2d, 0x67, 0x6f, 0x2f, 0x70, 0x6b, 0x67, 0x2f, 0x61, 0x70, 0x69, 0x73,
+	0x2f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x2f, 0x6d, 0x61, 0x70, 0x2f, 0x76, 0x31, 0x62, 0x06, 0x70,
+	0x72, 0x6f, 0x74, 0x6f, 0x33,
 }
 
 var (
@@ -313,28 +329,30 @@ func file_pkg_apis_proto_map_v1_map_proto_rawDescGZIP() []byte {
 	return file_pkg_apis_proto_map_v1_map_proto_rawDescData
 }
 
-var file_pkg_apis_proto_map_v1_map_proto_msgTypes = make([]protoimpl.MessageInfo, 4)
+var file_pkg_apis_proto_map_v1_map_proto_msgTypes = make([]protoimpl.MessageInfo, 5)
 var file_pkg_apis_proto_map_v1_map_proto_goTypes = []interface{}{
 	(*MapRequest)(nil),            // 0: map.v1.MapRequest
 	(*MapResponse)(nil),           // 1: map.v1.MapResponse
 	(*ReadyResponse)(nil),         // 2: map.v1.ReadyResponse
-	(*MapResponse_Result)(nil),    // 3: map.v1.MapResponse.Result
-	(*timestamppb.Timestamp)(nil), // 4: google.protobuf.Timestamp
-	(*emptypb.Empty)(nil),         // 5: google.protobuf.Empty
+	nil,                           // 3: map.v1.MapRequest.HeadersEntry
+	(*MapResponse_Result)(nil),    // 4: map.v1.MapResponse.Result
+	(*timestamppb.Timestamp)(nil), // 5: google.protobuf.Timestamp
+	(*emptypb.Empty)(nil),         // 6: google.protobuf.Empty
 }
 var file_pkg_apis_proto_map_v1_map_proto_depIdxs = []int32{
-	4, // 0: map.v1.MapRequest.event_time:type_name -> google.protobuf.Timestamp
-	4, // 1: map.v1.MapRequest.watermark:type_name -> google.protobuf.Timestamp
-	3, // 2: map.v1.MapResponse.results:type_name -> map.v1.MapResponse.Result
-	0, // 3: map.v1.Map.MapFn:input_type -> map.v1.MapRequest
-	5, // 4: map.v1.Map.IsReady:input_type -> google.protobuf.Empty
-	1, // 5: map.v1.Map.MapFn:output_type -> map.v1.MapResponse
-	2, // 6: map.v1.Map.IsReady:output_type -> map.v1.ReadyResponse
-	5, // [5:7] is the sub-list for method output_type
-	3, // [3:5] is the sub-list for method input_type
-	3, // [3:3] is the sub-list for extension type_name
-	3, // [3:3] is the sub-list for extension extendee
-	0, // [0:3] is the sub-list for field type_name
+	5, // 0: map.v1.MapRequest.event_time:type_name -> google.protobuf.Timestamp
+	5, // 1: map.v1.MapRequest.watermark:type_name -> google.protobuf.Timestamp
+	3, // 2: map.v1.MapRequest.headers:type_name -> map.v1.MapRequest.HeadersEntry
+	4, // 3: map.v1.MapResponse.results:type_name -> map.v1.MapResponse.Result
+	0, // 4: map.v1.Map.MapFn:input_type -> map.v1.MapRequest
+	6, // 5: map.v1.Map.IsReady:input_type -> google.protobuf.Empty
+	1, // 6: map.v1.Map.MapFn:output_type -> map.v1.MapResponse
+	2, // 7: map.v1.Map.IsReady:output_type -> map.v1.ReadyResponse
+	6, // [6:8] is the sub-list for method output_type
+	4, // [4:6] is the sub-list for method input_type
+	4, // [4:4] is the sub-list for extension type_name
+	4, // [4:4] is the sub-list for extension extendee
+	0, // [0:4] is the sub-list for field type_name
 }
 
 func init() { file_pkg_apis_proto_map_v1_map_proto_init() }
@@ -379,7 +397,7 @@ func file_pkg_apis_proto_map_v1_map_proto_init() {
 				return nil
 			}
 		}
-		file_pkg_apis_proto_map_v1_map_proto_msgTypes[3].Exporter = func(v interface{}, i int) interface{} {
+		file_pkg_apis_proto_map_v1_map_proto_msgTypes[4].Exporter = func(v interface{}, i int) interface{} {
 			switch v := v.(*MapResponse_Result); i {
 			case 0:
 				return &v.state
@@ -398,7 +416,7 @@ func file_pkg_apis_proto_map_v1_map_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_pkg_apis_proto_map_v1_map_proto_rawDesc,
 			NumEnums:      0,
-			NumMessages:   4,
+			NumMessages:   5,
 			NumExtensions: 0,
 			NumServices:   1,
 		},
diff --git a/pkg/apis/proto/map/v1/map.proto b/pkg/apis/proto/map/v1/map.proto
index 89e5dd85..e93a9b01 100644
--- a/pkg/apis/proto/map/v1/map.proto
+++ b/pkg/apis/proto/map/v1/map.proto
@@ -23,6 +23,7 @@ message MapRequest {
   bytes value = 2;
   google.protobuf.Timestamp event_time = 3;
   google.protobuf.Timestamp watermark = 4;
+  map<string, string> headers = 5;
 }
 
 /**
diff --git a/pkg/apis/proto/mapstream/v1/mapstream.pb.go b/pkg/apis/proto/mapstream/v1/mapstream.pb.go
index 23112488..2a2f2bd1 100644
--- a/pkg/apis/proto/mapstream/v1/mapstream.pb.go
+++ b/pkg/apis/proto/mapstream/v1/mapstream.pb.go
@@ -33,6 +33,7 @@ type MapStreamRequest struct {
 	Value     []byte                 `protobuf:"bytes,2,opt,name=value,proto3" json:"value,omitempty"`
 	EventTime *timestamppb.Timestamp `protobuf:"bytes,3,opt,name=event_time,json=eventTime,proto3" json:"event_time,omitempty"`
 	Watermark *timestamppb.Timestamp `protobuf:"bytes,4,opt,name=watermark,proto3" json:"watermark,omitempty"`
+	Headers   map[string]string      `protobuf:"bytes,5,rep,name=headers,proto3" json:"headers,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
 }
 
 func (x *MapStreamRequest) Reset() {
@@ -95,6 +96,13 @@ func (x *MapStreamRequest) GetWatermark() *timestamppb.Timestamp {
 	return nil
 }
 
+func (x *MapStreamRequest) GetHeaders() map[string]string {
+	if x != nil {
+		return x.Headers
+	}
+	return nil
+}
+
 // *
 // MapStreamResponse represents a response element.
 type MapStreamResponse struct {
@@ -206,7 +214,7 @@ type MapStreamResponse_Result struct {
 func (x *MapStreamResponse_Result) Reset() {
 	*x = MapStreamResponse_Result{}
 	if protoimpl.UnsafeEnabled {
-		mi := &file_pkg_apis_proto_mapstream_v1_mapstream_proto_msgTypes[3]
+		mi := &file_pkg_apis_proto_mapstream_v1_mapstream_proto_msgTypes[4]
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		ms.StoreMessageInfo(mi)
 	}
@@ -219,7 +227,7 @@ func (x *MapStreamResponse_Result) String() string {
 func (*MapStreamResponse_Result) ProtoMessage() {}
 
 func (x *MapStreamResponse_Result) ProtoReflect() protoreflect.Message {
-	mi := &file_pkg_apis_proto_mapstream_v1_mapstream_proto_msgTypes[3]
+	mi := &file_pkg_apis_proto_mapstream_v1_mapstream_proto_msgTypes[4]
 	if protoimpl.UnsafeEnabled && x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -266,7 +274,7 @@ var file_pkg_apis_proto_mapstream_v1_mapstream_proto_rawDesc = []byte{
 	0x67, 0x6c, 0x65, 0x2f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x62, 0x75, 0x66, 0x2f, 0x65, 0x6d, 0x70,
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@@ -277,34 +285,42 @@ var file_pkg_apis_proto_mapstream_v1_mapstream_proto_rawDesc = []byte{
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+	0x6d, 0x2f, 0x76, 0x31, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
 }
 
 var (
@@ -319,28 +335,30 @@ func file_pkg_apis_proto_mapstream_v1_mapstream_proto_rawDescGZIP() []byte {
 	return file_pkg_apis_proto_mapstream_v1_mapstream_proto_rawDescData
 }
 
-var file_pkg_apis_proto_mapstream_v1_mapstream_proto_msgTypes = make([]protoimpl.MessageInfo, 4)
+var file_pkg_apis_proto_mapstream_v1_mapstream_proto_msgTypes = make([]protoimpl.MessageInfo, 5)
 var file_pkg_apis_proto_mapstream_v1_mapstream_proto_goTypes = []interface{}{
 	(*MapStreamRequest)(nil),         // 0: mapstream.v1.MapStreamRequest
 	(*MapStreamResponse)(nil),        // 1: mapstream.v1.MapStreamResponse
 	(*ReadyResponse)(nil),            // 2: mapstream.v1.ReadyResponse
-	(*MapStreamResponse_Result)(nil), // 3: mapstream.v1.MapStreamResponse.Result
-	(*timestamppb.Timestamp)(nil),    // 4: google.protobuf.Timestamp
-	(*emptypb.Empty)(nil),            // 5: google.protobuf.Empty
+	nil,                              // 3: mapstream.v1.MapStreamRequest.HeadersEntry
+	(*MapStreamResponse_Result)(nil), // 4: mapstream.v1.MapStreamResponse.Result
+	(*timestamppb.Timestamp)(nil),    // 5: google.protobuf.Timestamp
+	(*emptypb.Empty)(nil),            // 6: google.protobuf.Empty
 }
 var file_pkg_apis_proto_mapstream_v1_mapstream_proto_depIdxs = []int32{
-	4, // 0: mapstream.v1.MapStreamRequest.event_time:type_name -> google.protobuf.Timestamp
-	4, // 1: mapstream.v1.MapStreamRequest.watermark:type_name -> google.protobuf.Timestamp
-	3, // 2: mapstream.v1.MapStreamResponse.result:type_name -> mapstream.v1.MapStreamResponse.Result
-	0, // 3: mapstream.v1.MapStream.MapStreamFn:input_type -> mapstream.v1.MapStreamRequest
-	5, // 4: mapstream.v1.MapStream.IsReady:input_type -> google.protobuf.Empty
-	1, // 5: mapstream.v1.MapStream.MapStreamFn:output_type -> mapstream.v1.MapStreamResponse
-	2, // 6: mapstream.v1.MapStream.IsReady:output_type -> mapstream.v1.ReadyResponse
-	5, // [5:7] is the sub-list for method output_type
-	3, // [3:5] is the sub-list for method input_type
-	3, // [3:3] is the sub-list for extension type_name
-	3, // [3:3] is the sub-list for extension extendee
-	0, // [0:3] is the sub-list for field type_name
+	5, // 0: mapstream.v1.MapStreamRequest.event_time:type_name -> google.protobuf.Timestamp
+	5, // 1: mapstream.v1.MapStreamRequest.watermark:type_name -> google.protobuf.Timestamp
+	3, // 2: mapstream.v1.MapStreamRequest.headers:type_name -> mapstream.v1.MapStreamRequest.HeadersEntry
+	4, // 3: mapstream.v1.MapStreamResponse.result:type_name -> mapstream.v1.MapStreamResponse.Result
+	0, // 4: mapstream.v1.MapStream.MapStreamFn:input_type -> mapstream.v1.MapStreamRequest
+	6, // 5: mapstream.v1.MapStream.IsReady:input_type -> google.protobuf.Empty
+	1, // 6: mapstream.v1.MapStream.MapStreamFn:output_type -> mapstream.v1.MapStreamResponse
+	2, // 7: mapstream.v1.MapStream.IsReady:output_type -> mapstream.v1.ReadyResponse
+	6, // [6:8] is the sub-list for method output_type
+	4, // [4:6] is the sub-list for method input_type
+	4, // [4:4] is the sub-list for extension type_name
+	4, // [4:4] is the sub-list for extension extendee
+	0, // [0:4] is the sub-list for field type_name
 }
 
 func init() { file_pkg_apis_proto_mapstream_v1_mapstream_proto_init() }
@@ -385,7 +403,7 @@ func file_pkg_apis_proto_mapstream_v1_mapstream_proto_init() {
 				return nil
 			}
 		}
-		file_pkg_apis_proto_mapstream_v1_mapstream_proto_msgTypes[3].Exporter = func(v interface{}, i int) interface{} {
+		file_pkg_apis_proto_mapstream_v1_mapstream_proto_msgTypes[4].Exporter = func(v interface{}, i int) interface{} {
 			switch v := v.(*MapStreamResponse_Result); i {
 			case 0:
 				return &v.state
@@ -404,7 +422,7 @@ func file_pkg_apis_proto_mapstream_v1_mapstream_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_pkg_apis_proto_mapstream_v1_mapstream_proto_rawDesc,
 			NumEnums:      0,
-			NumMessages:   4,
+			NumMessages:   5,
 			NumExtensions: 0,
 			NumServices:   1,
 		},
diff --git a/pkg/apis/proto/mapstream/v1/mapstream.proto b/pkg/apis/proto/mapstream/v1/mapstream.proto
index 5d95ff39..43f85f60 100644
--- a/pkg/apis/proto/mapstream/v1/mapstream.proto
+++ b/pkg/apis/proto/mapstream/v1/mapstream.proto
@@ -24,6 +24,7 @@ message MapStreamRequest {
   bytes value = 2;
   google.protobuf.Timestamp event_time = 3;
   google.protobuf.Timestamp watermark = 4;
+  map<string, string> headers = 5;
 }
 
 /**
diff --git a/pkg/apis/proto/reduce/v1/reduce.pb.go b/pkg/apis/proto/reduce/v1/reduce.pb.go
index 2f9b365c..5376e90a 100644
--- a/pkg/apis/proto/reduce/v1/reduce.pb.go
+++ b/pkg/apis/proto/reduce/v1/reduce.pb.go
@@ -376,6 +376,7 @@ type ReduceRequest_Payload struct {
 	Value     []byte                 `protobuf:"bytes,2,opt,name=value,proto3" json:"value,omitempty"`
 	EventTime *timestamppb.Timestamp `protobuf:"bytes,3,opt,name=event_time,json=eventTime,proto3" json:"event_time,omitempty"`
 	Watermark *timestamppb.Timestamp `protobuf:"bytes,4,opt,name=watermark,proto3" json:"watermark,omitempty"`
+	Headers   map[string]string      `protobuf:"bytes,5,rep,name=headers,proto3" json:"headers,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
 }
 
 func (x *ReduceRequest_Payload) Reset() {
@@ -438,6 +439,13 @@ func (x *ReduceRequest_Payload) GetWatermark() *timestamppb.Timestamp {
 	return nil
 }
 
+func (x *ReduceRequest_Payload) GetHeaders() map[string]string {
+	if x != nil {
+		return x.Headers
+	}
+	return nil
+}
+
 // Result represents a result element. It contains the result of the reduce function.
 type ReduceResponse_Result struct {
 	state         protoimpl.MessageState
@@ -452,7 +460,7 @@ type ReduceResponse_Result struct {
 func (x *ReduceResponse_Result) Reset() {
 	*x = ReduceResponse_Result{}
 	if protoimpl.UnsafeEnabled {
-		mi := &file_pkg_apis_proto_reduce_v1_reduce_proto_msgTypes[6]
+		mi := &file_pkg_apis_proto_reduce_v1_reduce_proto_msgTypes[7]
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		ms.StoreMessageInfo(mi)
 	}
@@ -465,7 +473,7 @@ func (x *ReduceResponse_Result) String() string {
 func (*ReduceResponse_Result) ProtoMessage() {}
 
 func (x *ReduceResponse_Result) ProtoReflect() protoreflect.Message {
-	mi := &file_pkg_apis_proto_reduce_v1_reduce_proto_msgTypes[6]
+	mi := &file_pkg_apis_proto_reduce_v1_reduce_proto_msgTypes[7]
 	if protoimpl.UnsafeEnabled && x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -512,7 +520,7 @@ var file_pkg_apis_proto_reduce_v1_reduce_proto_rawDesc = []byte{
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 }
 
 var (
@@ -595,7 +611,7 @@ func file_pkg_apis_proto_reduce_v1_reduce_proto_rawDescGZIP() []byte {
 }
 
 var file_pkg_apis_proto_reduce_v1_reduce_proto_enumTypes = make([]protoimpl.EnumInfo, 1)
-var file_pkg_apis_proto_reduce_v1_reduce_proto_msgTypes = make([]protoimpl.MessageInfo, 7)
+var file_pkg_apis_proto_reduce_v1_reduce_proto_msgTypes = make([]protoimpl.MessageInfo, 8)
 var file_pkg_apis_proto_reduce_v1_reduce_proto_goTypes = []interface{}{
 	(ReduceRequest_WindowOperation_Event)(0), // 0: reduce.v1.ReduceRequest.WindowOperation.Event
 	(*ReduceRequest)(nil),                    // 1: reduce.v1.ReduceRequest
@@ -604,30 +620,32 @@ var file_pkg_apis_proto_reduce_v1_reduce_proto_goTypes = []interface{}{
 	(*ReadyResponse)(nil),                    // 4: reduce.v1.ReadyResponse
 	(*ReduceRequest_WindowOperation)(nil),    // 5: reduce.v1.ReduceRequest.WindowOperation
 	(*ReduceRequest_Payload)(nil),            // 6: reduce.v1.ReduceRequest.Payload
-	(*ReduceResponse_Result)(nil),            // 7: reduce.v1.ReduceResponse.Result
-	(*timestamppb.Timestamp)(nil),            // 8: google.protobuf.Timestamp
-	(*emptypb.Empty)(nil),                    // 9: google.protobuf.Empty
+	nil,                                      // 7: reduce.v1.ReduceRequest.Payload.HeadersEntry
+	(*ReduceResponse_Result)(nil),            // 8: reduce.v1.ReduceResponse.Result
+	(*timestamppb.Timestamp)(nil),            // 9: google.protobuf.Timestamp
+	(*emptypb.Empty)(nil),                    // 10: google.protobuf.Empty
 }
 var file_pkg_apis_proto_reduce_v1_reduce_proto_depIdxs = []int32{
 	6,  // 0: reduce.v1.ReduceRequest.payload:type_name -> reduce.v1.ReduceRequest.Payload
 	5,  // 1: reduce.v1.ReduceRequest.operation:type_name -> reduce.v1.ReduceRequest.WindowOperation
-	8,  // 2: reduce.v1.Window.start:type_name -> google.protobuf.Timestamp
-	8,  // 3: reduce.v1.Window.end:type_name -> google.protobuf.Timestamp
-	7,  // 4: reduce.v1.ReduceResponse.result:type_name -> reduce.v1.ReduceResponse.Result
+	9,  // 2: reduce.v1.Window.start:type_name -> google.protobuf.Timestamp
+	9,  // 3: reduce.v1.Window.end:type_name -> google.protobuf.Timestamp
+	8,  // 4: reduce.v1.ReduceResponse.result:type_name -> reduce.v1.ReduceResponse.Result
 	2,  // 5: reduce.v1.ReduceResponse.window:type_name -> reduce.v1.Window
 	0,  // 6: reduce.v1.ReduceRequest.WindowOperation.event:type_name -> reduce.v1.ReduceRequest.WindowOperation.Event
 	2,  // 7: reduce.v1.ReduceRequest.WindowOperation.windows:type_name -> reduce.v1.Window
-	8,  // 8: reduce.v1.ReduceRequest.Payload.event_time:type_name -> google.protobuf.Timestamp
-	8,  // 9: reduce.v1.ReduceRequest.Payload.watermark:type_name -> google.protobuf.Timestamp
-	1,  // 10: reduce.v1.Reduce.ReduceFn:input_type -> reduce.v1.ReduceRequest
-	9,  // 11: reduce.v1.Reduce.IsReady:input_type -> google.protobuf.Empty
-	3,  // 12: reduce.v1.Reduce.ReduceFn:output_type -> reduce.v1.ReduceResponse
-	4,  // 13: reduce.v1.Reduce.IsReady:output_type -> reduce.v1.ReadyResponse
-	12, // [12:14] is the sub-list for method output_type
-	10, // [10:12] is the sub-list for method input_type
-	10, // [10:10] is the sub-list for extension type_name
-	10, // [10:10] is the sub-list for extension extendee
-	0,  // [0:10] is the sub-list for field type_name
+	9,  // 8: reduce.v1.ReduceRequest.Payload.event_time:type_name -> google.protobuf.Timestamp
+	9,  // 9: reduce.v1.ReduceRequest.Payload.watermark:type_name -> google.protobuf.Timestamp
+	7,  // 10: reduce.v1.ReduceRequest.Payload.headers:type_name -> reduce.v1.ReduceRequest.Payload.HeadersEntry
+	1,  // 11: reduce.v1.Reduce.ReduceFn:input_type -> reduce.v1.ReduceRequest
+	10, // 12: reduce.v1.Reduce.IsReady:input_type -> google.protobuf.Empty
+	3,  // 13: reduce.v1.Reduce.ReduceFn:output_type -> reduce.v1.ReduceResponse
+	4,  // 14: reduce.v1.Reduce.IsReady:output_type -> reduce.v1.ReadyResponse
+	13, // [13:15] is the sub-list for method output_type
+	11, // [11:13] is the sub-list for method input_type
+	11, // [11:11] is the sub-list for extension type_name
+	11, // [11:11] is the sub-list for extension extendee
+	0,  // [0:11] is the sub-list for field type_name
 }
 
 func init() { file_pkg_apis_proto_reduce_v1_reduce_proto_init() }
@@ -708,7 +726,7 @@ func file_pkg_apis_proto_reduce_v1_reduce_proto_init() {
 				return nil
 			}
 		}
-		file_pkg_apis_proto_reduce_v1_reduce_proto_msgTypes[6].Exporter = func(v interface{}, i int) interface{} {
+		file_pkg_apis_proto_reduce_v1_reduce_proto_msgTypes[7].Exporter = func(v interface{}, i int) interface{} {
 			switch v := v.(*ReduceResponse_Result); i {
 			case 0:
 				return &v.state
@@ -727,7 +745,7 @@ func file_pkg_apis_proto_reduce_v1_reduce_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_pkg_apis_proto_reduce_v1_reduce_proto_rawDesc,
 			NumEnums:      1,
-			NumMessages:   7,
+			NumMessages:   8,
 			NumExtensions: 0,
 			NumServices:   1,
 		},
diff --git a/pkg/apis/proto/reduce/v1/reduce.proto b/pkg/apis/proto/reduce/v1/reduce.proto
index 2b2e071d..d807f2d4 100644
--- a/pkg/apis/proto/reduce/v1/reduce.proto
+++ b/pkg/apis/proto/reduce/v1/reduce.proto
@@ -39,6 +39,7 @@ message ReduceRequest {
     bytes value = 2;
     google.protobuf.Timestamp event_time = 3;
     google.protobuf.Timestamp watermark = 4;
+    map<string, string> headers = 5;
   }
 
   Payload payload = 1;
diff --git a/pkg/apis/proto/sessionreduce/v1/sessionreduce.pb.go b/pkg/apis/proto/sessionreduce/v1/sessionreduce.pb.go
index 8a672b83..79cd3f65 100644
--- a/pkg/apis/proto/sessionreduce/v1/sessionreduce.pb.go
+++ b/pkg/apis/proto/sessionreduce/v1/sessionreduce.pb.go
@@ -390,6 +390,7 @@ type SessionReduceRequest_Payload struct {
 	Value     []byte                 `protobuf:"bytes,2,opt,name=value,proto3" json:"value,omitempty"`
 	EventTime *timestamppb.Timestamp `protobuf:"bytes,3,opt,name=event_time,json=eventTime,proto3" json:"event_time,omitempty"`
 	Watermark *timestamppb.Timestamp `protobuf:"bytes,4,opt,name=watermark,proto3" json:"watermark,omitempty"`
+	Headers   map[string]string      `protobuf:"bytes,5,rep,name=headers,proto3" json:"headers,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
 }
 
 func (x *SessionReduceRequest_Payload) Reset() {
@@ -452,6 +453,13 @@ func (x *SessionReduceRequest_Payload) GetWatermark() *timestamppb.Timestamp {
 	return nil
 }
 
+func (x *SessionReduceRequest_Payload) GetHeaders() map[string]string {
+	if x != nil {
+		return x.Headers
+	}
+	return nil
+}
+
 // Result represents a result element. It contains the result of the reduce function.
 type SessionReduceResponse_Result struct {
 	state         protoimpl.MessageState
@@ -466,7 +474,7 @@ type SessionReduceResponse_Result struct {
 func (x *SessionReduceResponse_Result) Reset() {
 	*x = SessionReduceResponse_Result{}
 	if protoimpl.UnsafeEnabled {
-		mi := &file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_msgTypes[6]
+		mi := &file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_msgTypes[7]
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		ms.StoreMessageInfo(mi)
 	}
@@ -479,7 +487,7 @@ func (x *SessionReduceResponse_Result) String() string {
 func (*SessionReduceResponse_Result) ProtoMessage() {}
 
 func (x *SessionReduceResponse_Result) ProtoReflect() protoreflect.Message {
-	mi := &file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_msgTypes[6]
+	mi := &file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_msgTypes[7]
 	if protoimpl.UnsafeEnabled && x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -536,7 +544,7 @@ var file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_rawDesc = []byte{
 	0x6f, 0x74, 0x6f, 0x62, 0x75, 0x66, 0x2e, 0x54, 0x69, 0x6d, 0x65, 0x73, 0x74, 0x61, 0x6d, 0x70,
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@@ -563,7 +571,7 @@ var file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_rawDesc = []byte{
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@@ -573,42 +581,51 @@ var file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_rawDesc = []byte{
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+	0x6d, 0x2f, 0x76, 0x31, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
 }
 
 var (
@@ -624,7 +641,7 @@ func file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_rawDescGZIP() []by
 }
 
 var file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_enumTypes = make([]protoimpl.EnumInfo, 1)
-var file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_msgTypes = make([]protoimpl.MessageInfo, 7)
+var file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_msgTypes = make([]protoimpl.MessageInfo, 8)
 var file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_goTypes = []interface{}{
 	(SessionReduceRequest_WindowOperation_Event)(0), // 0: sessionreduce.v1.SessionReduceRequest.WindowOperation.Event
 	(*KeyedWindow)(nil),                             // 1: sessionreduce.v1.KeyedWindow
@@ -633,30 +650,32 @@ var file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_goTypes = []interfa
 	(*ReadyResponse)(nil),                           // 4: sessionreduce.v1.ReadyResponse
 	(*SessionReduceRequest_WindowOperation)(nil),    // 5: sessionreduce.v1.SessionReduceRequest.WindowOperation
 	(*SessionReduceRequest_Payload)(nil),            // 6: sessionreduce.v1.SessionReduceRequest.Payload
-	(*SessionReduceResponse_Result)(nil),            // 7: sessionreduce.v1.SessionReduceResponse.Result
-	(*timestamppb.Timestamp)(nil),                   // 8: google.protobuf.Timestamp
-	(*emptypb.Empty)(nil),                           // 9: google.protobuf.Empty
+	nil,                                             // 7: sessionreduce.v1.SessionReduceRequest.Payload.HeadersEntry
+	(*SessionReduceResponse_Result)(nil),            // 8: sessionreduce.v1.SessionReduceResponse.Result
+	(*timestamppb.Timestamp)(nil),                   // 9: google.protobuf.Timestamp
+	(*emptypb.Empty)(nil),                           // 10: google.protobuf.Empty
 }
 var file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_depIdxs = []int32{
-	8,  // 0: sessionreduce.v1.KeyedWindow.start:type_name -> google.protobuf.Timestamp
-	8,  // 1: sessionreduce.v1.KeyedWindow.end:type_name -> google.protobuf.Timestamp
+	9,  // 0: sessionreduce.v1.KeyedWindow.start:type_name -> google.protobuf.Timestamp
+	9,  // 1: sessionreduce.v1.KeyedWindow.end:type_name -> google.protobuf.Timestamp
 	6,  // 2: sessionreduce.v1.SessionReduceRequest.payload:type_name -> sessionreduce.v1.SessionReduceRequest.Payload
 	5,  // 3: sessionreduce.v1.SessionReduceRequest.operation:type_name -> sessionreduce.v1.SessionReduceRequest.WindowOperation
-	7,  // 4: sessionreduce.v1.SessionReduceResponse.result:type_name -> sessionreduce.v1.SessionReduceResponse.Result
+	8,  // 4: sessionreduce.v1.SessionReduceResponse.result:type_name -> sessionreduce.v1.SessionReduceResponse.Result
 	1,  // 5: sessionreduce.v1.SessionReduceResponse.keyedWindow:type_name -> sessionreduce.v1.KeyedWindow
 	0,  // 6: sessionreduce.v1.SessionReduceRequest.WindowOperation.event:type_name -> sessionreduce.v1.SessionReduceRequest.WindowOperation.Event
 	1,  // 7: sessionreduce.v1.SessionReduceRequest.WindowOperation.keyedWindows:type_name -> sessionreduce.v1.KeyedWindow
-	8,  // 8: sessionreduce.v1.SessionReduceRequest.Payload.event_time:type_name -> google.protobuf.Timestamp
-	8,  // 9: sessionreduce.v1.SessionReduceRequest.Payload.watermark:type_name -> google.protobuf.Timestamp
-	2,  // 10: sessionreduce.v1.SessionReduce.SessionReduceFn:input_type -> sessionreduce.v1.SessionReduceRequest
-	9,  // 11: sessionreduce.v1.SessionReduce.IsReady:input_type -> google.protobuf.Empty
-	3,  // 12: sessionreduce.v1.SessionReduce.SessionReduceFn:output_type -> sessionreduce.v1.SessionReduceResponse
-	4,  // 13: sessionreduce.v1.SessionReduce.IsReady:output_type -> sessionreduce.v1.ReadyResponse
-	12, // [12:14] is the sub-list for method output_type
-	10, // [10:12] is the sub-list for method input_type
-	10, // [10:10] is the sub-list for extension type_name
-	10, // [10:10] is the sub-list for extension extendee
-	0,  // [0:10] is the sub-list for field type_name
+	9,  // 8: sessionreduce.v1.SessionReduceRequest.Payload.event_time:type_name -> google.protobuf.Timestamp
+	9,  // 9: sessionreduce.v1.SessionReduceRequest.Payload.watermark:type_name -> google.protobuf.Timestamp
+	7,  // 10: sessionreduce.v1.SessionReduceRequest.Payload.headers:type_name -> sessionreduce.v1.SessionReduceRequest.Payload.HeadersEntry
+	2,  // 11: sessionreduce.v1.SessionReduce.SessionReduceFn:input_type -> sessionreduce.v1.SessionReduceRequest
+	10, // 12: sessionreduce.v1.SessionReduce.IsReady:input_type -> google.protobuf.Empty
+	3,  // 13: sessionreduce.v1.SessionReduce.SessionReduceFn:output_type -> sessionreduce.v1.SessionReduceResponse
+	4,  // 14: sessionreduce.v1.SessionReduce.IsReady:output_type -> sessionreduce.v1.ReadyResponse
+	13, // [13:15] is the sub-list for method output_type
+	11, // [11:13] is the sub-list for method input_type
+	11, // [11:11] is the sub-list for extension type_name
+	11, // [11:11] is the sub-list for extension extendee
+	0,  // [0:11] is the sub-list for field type_name
 }
 
 func init() { file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_init() }
@@ -737,7 +756,7 @@ func file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_init() {
 				return nil
 			}
 		}
-		file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_msgTypes[6].Exporter = func(v interface{}, i int) interface{} {
+		file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_msgTypes[7].Exporter = func(v interface{}, i int) interface{} {
 			switch v := v.(*SessionReduceResponse_Result); i {
 			case 0:
 				return &v.state
@@ -756,7 +775,7 @@ func file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_pkg_apis_proto_sessionreduce_v1_sessionreduce_proto_rawDesc,
 			NumEnums:      1,
-			NumMessages:   7,
+			NumMessages:   8,
 			NumExtensions: 0,
 			NumServices:   1,
 		},
diff --git a/pkg/apis/proto/sessionreduce/v1/sessionreduce.proto b/pkg/apis/proto/sessionreduce/v1/sessionreduce.proto
index 07d354e6..22144af1 100644
--- a/pkg/apis/proto/sessionreduce/v1/sessionreduce.proto
+++ b/pkg/apis/proto/sessionreduce/v1/sessionreduce.proto
@@ -50,6 +50,7 @@ message SessionReduceRequest {
     bytes value = 2;
     google.protobuf.Timestamp event_time = 3;
     google.protobuf.Timestamp watermark = 4;
+    map<string, string> headers = 5;
   }
 
   Payload payload = 1;
diff --git a/pkg/apis/proto/sink/v1/sink.pb.go b/pkg/apis/proto/sink/v1/sink.pb.go
index 3da1634b..0bc0a086 100644
--- a/pkg/apis/proto/sink/v1/sink.pb.go
+++ b/pkg/apis/proto/sink/v1/sink.pb.go
@@ -34,6 +34,7 @@ type SinkRequest struct {
 	EventTime *timestamppb.Timestamp `protobuf:"bytes,3,opt,name=event_time,json=eventTime,proto3" json:"event_time,omitempty"`
 	Watermark *timestamppb.Timestamp `protobuf:"bytes,4,opt,name=watermark,proto3" json:"watermark,omitempty"`
 	Id        string                 `protobuf:"bytes,5,opt,name=id,proto3" json:"id,omitempty"`
+	Headers   map[string]string      `protobuf:"bytes,6,rep,name=headers,proto3" json:"headers,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
 }
 
 func (x *SinkRequest) Reset() {
@@ -103,6 +104,13 @@ func (x *SinkRequest) GetId() string {
 	return ""
 }
 
+func (x *SinkRequest) GetHeaders() map[string]string {
+	if x != nil {
+		return x.Headers
+	}
+	return nil
+}
+
 // *
 // ReadyResponse is the health check result.
 type ReadyResponse struct {
@@ -217,7 +225,7 @@ type SinkResponse_Result struct {
 func (x *SinkResponse_Result) Reset() {
 	*x = SinkResponse_Result{}
 	if protoimpl.UnsafeEnabled {
-		mi := &file_pkg_apis_proto_sink_v1_sink_proto_msgTypes[3]
+		mi := &file_pkg_apis_proto_sink_v1_sink_proto_msgTypes[4]
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		ms.StoreMessageInfo(mi)
 	}
@@ -230,7 +238,7 @@ func (x *SinkResponse_Result) String() string {
 func (*SinkResponse_Result) ProtoMessage() {}
 
 func (x *SinkResponse_Result) ProtoReflect() protoreflect.Message {
-	mi := &file_pkg_apis_proto_sink_v1_sink_proto_msgTypes[3]
+	mi := &file_pkg_apis_proto_sink_v1_sink_proto_msgTypes[4]
 	if protoimpl.UnsafeEnabled && x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -276,7 +284,7 @@ var file_pkg_apis_proto_sink_v1_sink_proto_rawDesc = []byte{
 	0x6f, 0x67, 0x6c, 0x65, 0x2f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x62, 0x75, 0x66, 0x2f, 0x65, 0x6d,
 	0x70, 0x74, 0x79, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x1a, 0x1f, 0x67, 0x6f, 0x6f, 0x67, 0x6c,
 	0x65, 0x2f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x62, 0x75, 0x66, 0x2f, 0x74, 0x69, 0x6d, 0x65, 0x73,
-	0x74, 0x61, 0x6d, 0x70, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x22, 0xbc, 0x01, 0x0a, 0x0b, 0x53,
+	0x74, 0x61, 0x6d, 0x70, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x22, 0xb5, 0x02, 0x0a, 0x0b, 0x53,
 	0x69, 0x6e, 0x6b, 0x52, 0x65, 0x71, 0x75, 0x65, 0x73, 0x74, 0x12, 0x12, 0x0a, 0x04, 0x6b, 0x65,
 	0x79, 0x73, 0x18, 0x01, 0x20, 0x03, 0x28, 0x09, 0x52, 0x04, 0x6b, 0x65, 0x79, 0x73, 0x12, 0x14,
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@@ -288,31 +296,38 @@ var file_pkg_apis_proto_sink_v1_sink_proto_rawDesc = []byte{
 	0x28, 0x0b, 0x32, 0x1a, 0x2e, 0x67, 0x6f, 0x6f, 0x67, 0x6c, 0x65, 0x2e, 0x70, 0x72, 0x6f, 0x74,
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+	0x6e, 0x6b, 0x2f, 0x76, 0x31, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
 }
 
 var (
@@ -327,28 +342,30 @@ func file_pkg_apis_proto_sink_v1_sink_proto_rawDescGZIP() []byte {
 	return file_pkg_apis_proto_sink_v1_sink_proto_rawDescData
 }
 
-var file_pkg_apis_proto_sink_v1_sink_proto_msgTypes = make([]protoimpl.MessageInfo, 4)
+var file_pkg_apis_proto_sink_v1_sink_proto_msgTypes = make([]protoimpl.MessageInfo, 5)
 var file_pkg_apis_proto_sink_v1_sink_proto_goTypes = []interface{}{
 	(*SinkRequest)(nil),           // 0: sink.v1.SinkRequest
 	(*ReadyResponse)(nil),         // 1: sink.v1.ReadyResponse
 	(*SinkResponse)(nil),          // 2: sink.v1.SinkResponse
-	(*SinkResponse_Result)(nil),   // 3: sink.v1.SinkResponse.Result
-	(*timestamppb.Timestamp)(nil), // 4: google.protobuf.Timestamp
-	(*emptypb.Empty)(nil),         // 5: google.protobuf.Empty
+	nil,                           // 3: sink.v1.SinkRequest.HeadersEntry
+	(*SinkResponse_Result)(nil),   // 4: sink.v1.SinkResponse.Result
+	(*timestamppb.Timestamp)(nil), // 5: google.protobuf.Timestamp
+	(*emptypb.Empty)(nil),         // 6: google.protobuf.Empty
 }
 var file_pkg_apis_proto_sink_v1_sink_proto_depIdxs = []int32{
-	4, // 0: sink.v1.SinkRequest.event_time:type_name -> google.protobuf.Timestamp
-	4, // 1: sink.v1.SinkRequest.watermark:type_name -> google.protobuf.Timestamp
-	3, // 2: sink.v1.SinkResponse.results:type_name -> sink.v1.SinkResponse.Result
-	0, // 3: sink.v1.Sink.SinkFn:input_type -> sink.v1.SinkRequest
-	5, // 4: sink.v1.Sink.IsReady:input_type -> google.protobuf.Empty
-	2, // 5: sink.v1.Sink.SinkFn:output_type -> sink.v1.SinkResponse
-	1, // 6: sink.v1.Sink.IsReady:output_type -> sink.v1.ReadyResponse
-	5, // [5:7] is the sub-list for method output_type
-	3, // [3:5] is the sub-list for method input_type
-	3, // [3:3] is the sub-list for extension type_name
-	3, // [3:3] is the sub-list for extension extendee
-	0, // [0:3] is the sub-list for field type_name
+	5, // 0: sink.v1.SinkRequest.event_time:type_name -> google.protobuf.Timestamp
+	5, // 1: sink.v1.SinkRequest.watermark:type_name -> google.protobuf.Timestamp
+	3, // 2: sink.v1.SinkRequest.headers:type_name -> sink.v1.SinkRequest.HeadersEntry
+	4, // 3: sink.v1.SinkResponse.results:type_name -> sink.v1.SinkResponse.Result
+	0, // 4: sink.v1.Sink.SinkFn:input_type -> sink.v1.SinkRequest
+	6, // 5: sink.v1.Sink.IsReady:input_type -> google.protobuf.Empty
+	2, // 6: sink.v1.Sink.SinkFn:output_type -> sink.v1.SinkResponse
+	1, // 7: sink.v1.Sink.IsReady:output_type -> sink.v1.ReadyResponse
+	6, // [6:8] is the sub-list for method output_type
+	4, // [4:6] is the sub-list for method input_type
+	4, // [4:4] is the sub-list for extension type_name
+	4, // [4:4] is the sub-list for extension extendee
+	0, // [0:4] is the sub-list for field type_name
 }
 
 func init() { file_pkg_apis_proto_sink_v1_sink_proto_init() }
@@ -393,7 +410,7 @@ func file_pkg_apis_proto_sink_v1_sink_proto_init() {
 				return nil
 			}
 		}
-		file_pkg_apis_proto_sink_v1_sink_proto_msgTypes[3].Exporter = func(v interface{}, i int) interface{} {
+		file_pkg_apis_proto_sink_v1_sink_proto_msgTypes[4].Exporter = func(v interface{}, i int) interface{} {
 			switch v := v.(*SinkResponse_Result); i {
 			case 0:
 				return &v.state
@@ -412,7 +429,7 @@ func file_pkg_apis_proto_sink_v1_sink_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_pkg_apis_proto_sink_v1_sink_proto_rawDesc,
 			NumEnums:      0,
-			NumMessages:   4,
+			NumMessages:   5,
 			NumExtensions: 0,
 			NumServices:   1,
 		},
diff --git a/pkg/apis/proto/sink/v1/sink.proto b/pkg/apis/proto/sink/v1/sink.proto
index 1c97077a..5e47fe4c 100644
--- a/pkg/apis/proto/sink/v1/sink.proto
+++ b/pkg/apis/proto/sink/v1/sink.proto
@@ -25,6 +25,7 @@ message SinkRequest {
   google.protobuf.Timestamp event_time = 3;
   google.protobuf.Timestamp watermark = 4;
   string id = 5;
+  map<string, string> headers = 6;
 }
 
 /**
diff --git a/pkg/apis/proto/source/v1/source.pb.go b/pkg/apis/proto/source/v1/source.pb.go
index 60903e31..1304f4ee 100644
--- a/pkg/apis/proto/source/v1/source.pb.go
+++ b/pkg/apis/proto/source/v1/source.pb.go
@@ -511,6 +511,10 @@ type ReadResponse_Result struct {
 	// We add this optional field to support the use case where the user defined source can provide keys for the datum.
 	// e.g. Kafka and Redis Stream message usually include information about the keys.
 	Keys []string `protobuf:"bytes,4,rep,name=keys,proto3" json:"keys,omitempty"`
+	// Optional list of headers associated with the datum.
+	// Headers are the metadata associated with the datum.
+	// e.g. Kafka and Redis Stream message usually include information about the headers.
+	Headers map[string]string `protobuf:"bytes,5,rep,name=headers,proto3" json:"headers,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
 }
 
 func (x *ReadResponse_Result) Reset() {
@@ -573,6 +577,13 @@ func (x *ReadResponse_Result) GetKeys() []string {
 	return nil
 }
 
+func (x *ReadResponse_Result) GetHeaders() map[string]string {
+	if x != nil {
+		return x.Headers
+	}
+	return nil
+}
+
 type AckRequest_Request struct {
 	state         protoimpl.MessageState
 	sizeCache     protoimpl.SizeCache
@@ -588,7 +599,7 @@ type AckRequest_Request struct {
 func (x *AckRequest_Request) Reset() {
 	*x = AckRequest_Request{}
 	if protoimpl.UnsafeEnabled {
-		mi := &file_pkg_apis_proto_source_v1_source_proto_msgTypes[10]
+		mi := &file_pkg_apis_proto_source_v1_source_proto_msgTypes[11]
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		ms.StoreMessageInfo(mi)
 	}
@@ -601,7 +612,7 @@ func (x *AckRequest_Request) String() string {
 func (*AckRequest_Request) ProtoMessage() {}
 
 func (x *AckRequest_Request) ProtoReflect() protoreflect.Message {
-	mi := &file_pkg_apis_proto_source_v1_source_proto_msgTypes[10]
+	mi := &file_pkg_apis_proto_source_v1_source_proto_msgTypes[11]
 	if protoimpl.UnsafeEnabled && x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -636,7 +647,7 @@ type AckResponse_Result struct {
 func (x *AckResponse_Result) Reset() {
 	*x = AckResponse_Result{}
 	if protoimpl.UnsafeEnabled {
-		mi := &file_pkg_apis_proto_source_v1_source_proto_msgTypes[11]
+		mi := &file_pkg_apis_proto_source_v1_source_proto_msgTypes[12]
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		ms.StoreMessageInfo(mi)
 	}
@@ -649,7 +660,7 @@ func (x *AckResponse_Result) String() string {
 func (*AckResponse_Result) ProtoMessage() {}
 
 func (x *AckResponse_Result) ProtoReflect() protoreflect.Message {
-	mi := &file_pkg_apis_proto_source_v1_source_proto_msgTypes[11]
+	mi := &file_pkg_apis_proto_source_v1_source_proto_msgTypes[12]
 	if protoimpl.UnsafeEnabled && x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -685,7 +696,7 @@ type PendingResponse_Result struct {
 func (x *PendingResponse_Result) Reset() {
 	*x = PendingResponse_Result{}
 	if protoimpl.UnsafeEnabled {
-		mi := &file_pkg_apis_proto_source_v1_source_proto_msgTypes[12]
+		mi := &file_pkg_apis_proto_source_v1_source_proto_msgTypes[13]
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		ms.StoreMessageInfo(mi)
 	}
@@ -698,7 +709,7 @@ func (x *PendingResponse_Result) String() string {
 func (*PendingResponse_Result) ProtoMessage() {}
 
 func (x *PendingResponse_Result) ProtoReflect() protoreflect.Message {
-	mi := &file_pkg_apis_proto_source_v1_source_proto_msgTypes[12]
+	mi := &file_pkg_apis_proto_source_v1_source_proto_msgTypes[13]
 	if protoimpl.UnsafeEnabled && x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -733,7 +744,7 @@ type PartitionsResponse_Result struct {
 func (x *PartitionsResponse_Result) Reset() {
 	*x = PartitionsResponse_Result{}
 	if protoimpl.UnsafeEnabled {
-		mi := &file_pkg_apis_proto_source_v1_source_proto_msgTypes[13]
+		mi := &file_pkg_apis_proto_source_v1_source_proto_msgTypes[14]
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		ms.StoreMessageInfo(mi)
 	}
@@ -746,7 +757,7 @@ func (x *PartitionsResponse_Result) String() string {
 func (*PartitionsResponse_Result) ProtoMessage() {}
 
 func (x *PartitionsResponse_Result) ProtoReflect() protoreflect.Message {
-	mi := &file_pkg_apis_proto_source_v1_source_proto_msgTypes[13]
+	mi := &file_pkg_apis_proto_source_v1_source_proto_msgTypes[14]
 	if protoimpl.UnsafeEnabled && x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -788,12 +799,12 @@ var file_pkg_apis_proto_source_v1_source_proto_rawDesc = []byte{
 	0x6f, 0x72, 0x64, 0x73, 0x18, 0x01, 0x20, 0x01, 0x28, 0x04, 0x52, 0x0a, 0x6e, 0x75, 0x6d, 0x52,
 	0x65, 0x63, 0x6f, 0x72, 0x64, 0x73, 0x12, 0x22, 0x0a, 0x0d, 0x74, 0x69, 0x6d, 0x65, 0x6f, 0x75,
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+	0x69, 0x6d, 0x65, 0x6f, 0x75, 0x74, 0x49, 0x6e, 0x4d, 0x73, 0x22, 0xe8, 0x02, 0x0a, 0x0c, 0x52,
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-	0x75, 0x6c, 0x74, 0x1a, 0x9c, 0x01, 0x0a, 0x06, 0x52, 0x65, 0x73, 0x75, 0x6c, 0x74, 0x12, 0x18,
+	0x75, 0x6c, 0x74, 0x1a, 0x9f, 0x02, 0x0a, 0x06, 0x52, 0x65, 0x73, 0x75, 0x6c, 0x74, 0x12, 0x18,
 	0x0a, 0x07, 0x70, 0x61, 0x79, 0x6c, 0x6f, 0x61, 0x64, 0x18, 0x01, 0x20, 0x01, 0x28, 0x0c, 0x52,
 	0x07, 0x70, 0x61, 0x79, 0x6c, 0x6f, 0x61, 0x64, 0x12, 0x29, 0x0a, 0x06, 0x6f, 0x66, 0x66, 0x73,
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@@ -803,69 +814,77 @@ var file_pkg_apis_proto_source_v1_source_proto_rawDesc = []byte{
 	0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x62, 0x75, 0x66, 0x2e, 0x54, 0x69, 0x6d, 0x65, 0x73, 0x74,
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 }
 
 var (
@@ -880,7 +899,7 @@ func file_pkg_apis_proto_source_v1_source_proto_rawDescGZIP() []byte {
 	return file_pkg_apis_proto_source_v1_source_proto_rawDescData
 }
 
-var file_pkg_apis_proto_source_v1_source_proto_msgTypes = make([]protoimpl.MessageInfo, 14)
+var file_pkg_apis_proto_source_v1_source_proto_msgTypes = make([]protoimpl.MessageInfo, 15)
 var file_pkg_apis_proto_source_v1_source_proto_goTypes = []interface{}{
 	(*ReadRequest)(nil),               // 0: source.v1.ReadRequest
 	(*ReadResponse)(nil),              // 1: source.v1.ReadResponse
@@ -892,39 +911,41 @@ var file_pkg_apis_proto_source_v1_source_proto_goTypes = []interface{}{
 	(*Offset)(nil),                    // 7: source.v1.Offset
 	(*ReadRequest_Request)(nil),       // 8: source.v1.ReadRequest.Request
 	(*ReadResponse_Result)(nil),       // 9: source.v1.ReadResponse.Result
-	(*AckRequest_Request)(nil),        // 10: source.v1.AckRequest.Request
-	(*AckResponse_Result)(nil),        // 11: source.v1.AckResponse.Result
-	(*PendingResponse_Result)(nil),    // 12: source.v1.PendingResponse.Result
-	(*PartitionsResponse_Result)(nil), // 13: source.v1.PartitionsResponse.Result
-	(*timestamppb.Timestamp)(nil),     // 14: google.protobuf.Timestamp
-	(*emptypb.Empty)(nil),             // 15: google.protobuf.Empty
+	nil,                               // 10: source.v1.ReadResponse.Result.HeadersEntry
+	(*AckRequest_Request)(nil),        // 11: source.v1.AckRequest.Request
+	(*AckResponse_Result)(nil),        // 12: source.v1.AckResponse.Result
+	(*PendingResponse_Result)(nil),    // 13: source.v1.PendingResponse.Result
+	(*PartitionsResponse_Result)(nil), // 14: source.v1.PartitionsResponse.Result
+	(*timestamppb.Timestamp)(nil),     // 15: google.protobuf.Timestamp
+	(*emptypb.Empty)(nil),             // 16: google.protobuf.Empty
 }
 var file_pkg_apis_proto_source_v1_source_proto_depIdxs = []int32{
 	8,  // 0: source.v1.ReadRequest.request:type_name -> source.v1.ReadRequest.Request
 	9,  // 1: source.v1.ReadResponse.result:type_name -> source.v1.ReadResponse.Result
-	10, // 2: source.v1.AckRequest.request:type_name -> source.v1.AckRequest.Request
-	11, // 3: source.v1.AckResponse.result:type_name -> source.v1.AckResponse.Result
-	12, // 4: source.v1.PendingResponse.result:type_name -> source.v1.PendingResponse.Result
-	13, // 5: source.v1.PartitionsResponse.result:type_name -> source.v1.PartitionsResponse.Result
+	11, // 2: source.v1.AckRequest.request:type_name -> source.v1.AckRequest.Request
+	12, // 3: source.v1.AckResponse.result:type_name -> source.v1.AckResponse.Result
+	13, // 4: source.v1.PendingResponse.result:type_name -> source.v1.PendingResponse.Result
+	14, // 5: source.v1.PartitionsResponse.result:type_name -> source.v1.PartitionsResponse.Result
 	7,  // 6: source.v1.ReadResponse.Result.offset:type_name -> source.v1.Offset
-	14, // 7: source.v1.ReadResponse.Result.event_time:type_name -> google.protobuf.Timestamp
-	7,  // 8: source.v1.AckRequest.Request.offsets:type_name -> source.v1.Offset
-	15, // 9: source.v1.AckResponse.Result.success:type_name -> google.protobuf.Empty
-	0,  // 10: source.v1.Source.ReadFn:input_type -> source.v1.ReadRequest
-	2,  // 11: source.v1.Source.AckFn:input_type -> source.v1.AckRequest
-	15, // 12: source.v1.Source.PendingFn:input_type -> google.protobuf.Empty
-	15, // 13: source.v1.Source.PartitionsFn:input_type -> google.protobuf.Empty
-	15, // 14: source.v1.Source.IsReady:input_type -> google.protobuf.Empty
-	1,  // 15: source.v1.Source.ReadFn:output_type -> source.v1.ReadResponse
-	3,  // 16: source.v1.Source.AckFn:output_type -> source.v1.AckResponse
-	5,  // 17: source.v1.Source.PendingFn:output_type -> source.v1.PendingResponse
-	6,  // 18: source.v1.Source.PartitionsFn:output_type -> source.v1.PartitionsResponse
-	4,  // 19: source.v1.Source.IsReady:output_type -> source.v1.ReadyResponse
-	15, // [15:20] is the sub-list for method output_type
-	10, // [10:15] is the sub-list for method input_type
-	10, // [10:10] is the sub-list for extension type_name
-	10, // [10:10] is the sub-list for extension extendee
-	0,  // [0:10] is the sub-list for field type_name
+	15, // 7: source.v1.ReadResponse.Result.event_time:type_name -> google.protobuf.Timestamp
+	10, // 8: source.v1.ReadResponse.Result.headers:type_name -> source.v1.ReadResponse.Result.HeadersEntry
+	7,  // 9: source.v1.AckRequest.Request.offsets:type_name -> source.v1.Offset
+	16, // 10: source.v1.AckResponse.Result.success:type_name -> google.protobuf.Empty
+	0,  // 11: source.v1.Source.ReadFn:input_type -> source.v1.ReadRequest
+	2,  // 12: source.v1.Source.AckFn:input_type -> source.v1.AckRequest
+	16, // 13: source.v1.Source.PendingFn:input_type -> google.protobuf.Empty
+	16, // 14: source.v1.Source.PartitionsFn:input_type -> google.protobuf.Empty
+	16, // 15: source.v1.Source.IsReady:input_type -> google.protobuf.Empty
+	1,  // 16: source.v1.Source.ReadFn:output_type -> source.v1.ReadResponse
+	3,  // 17: source.v1.Source.AckFn:output_type -> source.v1.AckResponse
+	5,  // 18: source.v1.Source.PendingFn:output_type -> source.v1.PendingResponse
+	6,  // 19: source.v1.Source.PartitionsFn:output_type -> source.v1.PartitionsResponse
+	4,  // 20: source.v1.Source.IsReady:output_type -> source.v1.ReadyResponse
+	16, // [16:21] is the sub-list for method output_type
+	11, // [11:16] is the sub-list for method input_type
+	11, // [11:11] is the sub-list for extension type_name
+	11, // [11:11] is the sub-list for extension extendee
+	0,  // [0:11] is the sub-list for field type_name
 }
 
 func init() { file_pkg_apis_proto_source_v1_source_proto_init() }
@@ -1053,7 +1074,7 @@ func file_pkg_apis_proto_source_v1_source_proto_init() {
 				return nil
 			}
 		}
-		file_pkg_apis_proto_source_v1_source_proto_msgTypes[10].Exporter = func(v interface{}, i int) interface{} {
+		file_pkg_apis_proto_source_v1_source_proto_msgTypes[11].Exporter = func(v interface{}, i int) interface{} {
 			switch v := v.(*AckRequest_Request); i {
 			case 0:
 				return &v.state
@@ -1065,7 +1086,7 @@ func file_pkg_apis_proto_source_v1_source_proto_init() {
 				return nil
 			}
 		}
-		file_pkg_apis_proto_source_v1_source_proto_msgTypes[11].Exporter = func(v interface{}, i int) interface{} {
+		file_pkg_apis_proto_source_v1_source_proto_msgTypes[12].Exporter = func(v interface{}, i int) interface{} {
 			switch v := v.(*AckResponse_Result); i {
 			case 0:
 				return &v.state
@@ -1077,7 +1098,7 @@ func file_pkg_apis_proto_source_v1_source_proto_init() {
 				return nil
 			}
 		}
-		file_pkg_apis_proto_source_v1_source_proto_msgTypes[12].Exporter = func(v interface{}, i int) interface{} {
+		file_pkg_apis_proto_source_v1_source_proto_msgTypes[13].Exporter = func(v interface{}, i int) interface{} {
 			switch v := v.(*PendingResponse_Result); i {
 			case 0:
 				return &v.state
@@ -1089,7 +1110,7 @@ func file_pkg_apis_proto_source_v1_source_proto_init() {
 				return nil
 			}
 		}
-		file_pkg_apis_proto_source_v1_source_proto_msgTypes[13].Exporter = func(v interface{}, i int) interface{} {
+		file_pkg_apis_proto_source_v1_source_proto_msgTypes[14].Exporter = func(v interface{}, i int) interface{} {
 			switch v := v.(*PartitionsResponse_Result); i {
 			case 0:
 				return &v.state
@@ -1108,7 +1129,7 @@ func file_pkg_apis_proto_source_v1_source_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_pkg_apis_proto_source_v1_source_proto_rawDesc,
 			NumEnums:      0,
-			NumMessages:   14,
+			NumMessages:   15,
 			NumExtensions: 0,
 			NumServices:   1,
 		},
diff --git a/pkg/apis/proto/source/v1/source.proto b/pkg/apis/proto/source/v1/source.proto
index a0778dfe..9ee6f688 100644
--- a/pkg/apis/proto/source/v1/source.proto
+++ b/pkg/apis/proto/source/v1/source.proto
@@ -62,6 +62,10 @@ message ReadResponse {
     // We add this optional field to support the use case where the user defined source can provide keys for the datum.
     // e.g. Kafka and Redis Stream message usually include information about the keys.
     repeated string keys = 4;
+    // Optional list of headers associated with the datum.
+    // Headers are the metadata associated with the datum.
+    // e.g. Kafka and Redis Stream message usually include information about the headers.
+    map<string, string> headers = 5;
   }
   // Required field holding the result.
   Result result = 1;
diff --git a/pkg/apis/proto/sourcetransform/v1/transform.pb.go b/pkg/apis/proto/sourcetransform/v1/transform.pb.go
index 6aff9fb6..3a34e351 100644
--- a/pkg/apis/proto/sourcetransform/v1/transform.pb.go
+++ b/pkg/apis/proto/sourcetransform/v1/transform.pb.go
@@ -33,6 +33,7 @@ type SourceTransformRequest struct {
 	Value     []byte                 `protobuf:"bytes,2,opt,name=value,proto3" json:"value,omitempty"`
 	EventTime *timestamppb.Timestamp `protobuf:"bytes,3,opt,name=event_time,json=eventTime,proto3" json:"event_time,omitempty"`
 	Watermark *timestamppb.Timestamp `protobuf:"bytes,4,opt,name=watermark,proto3" json:"watermark,omitempty"`
+	Headers   map[string]string      `protobuf:"bytes,5,rep,name=headers,proto3" json:"headers,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
 }
 
 func (x *SourceTransformRequest) Reset() {
@@ -95,6 +96,13 @@ func (x *SourceTransformRequest) GetWatermark() *timestamppb.Timestamp {
 	return nil
 }
 
+func (x *SourceTransformRequest) GetHeaders() map[string]string {
+	if x != nil {
+		return x.Headers
+	}
+	return nil
+}
+
 // *
 // SourceTransformerResponse represents a response element.
 type SourceTransformResponse struct {
@@ -207,7 +215,7 @@ type SourceTransformResponse_Result struct {
 func (x *SourceTransformResponse_Result) Reset() {
 	*x = SourceTransformResponse_Result{}
 	if protoimpl.UnsafeEnabled {
-		mi := &file_pkg_apis_proto_sourcetransform_v1_transform_proto_msgTypes[3]
+		mi := &file_pkg_apis_proto_sourcetransform_v1_transform_proto_msgTypes[4]
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		ms.StoreMessageInfo(mi)
 	}
@@ -220,7 +228,7 @@ func (x *SourceTransformResponse_Result) String() string {
 func (*SourceTransformResponse_Result) ProtoMessage() {}
 
 func (x *SourceTransformResponse_Result) ProtoReflect() protoreflect.Message {
-	mi := &file_pkg_apis_proto_sourcetransform_v1_transform_proto_msgTypes[3]
+	mi := &file_pkg_apis_proto_sourcetransform_v1_transform_proto_msgTypes[4]
 	if protoimpl.UnsafeEnabled && x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -275,7 +283,7 @@ var file_pkg_apis_proto_sourcetransform_v1_transform_proto_rawDesc = []byte{
 	0x65, 0x2f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x62, 0x75, 0x66, 0x2f, 0x74, 0x69, 0x6d, 0x65, 0x73,
 	0x74, 0x61, 0x6d, 0x70, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x1a, 0x1b, 0x67, 0x6f, 0x6f, 0x67,
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+	0x79, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x22, 0xc8, 0x02, 0x0a, 0x16, 0x53, 0x6f, 0x75, 0x72,
 	0x63, 0x65, 0x54, 0x72, 0x61, 0x6e, 0x73, 0x66, 0x6f, 0x72, 0x6d, 0x52, 0x65, 0x71, 0x75, 0x65,
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@@ -287,42 +295,51 @@ var file_pkg_apis_proto_sourcetransform_v1_transform_proto_rawDesc = []byte{
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+	0x6c, 0x75, 0x65, 0x12, 0x39, 0x0a, 0x0a, 0x65, 0x76, 0x65, 0x6e, 0x74, 0x5f, 0x74, 0x69, 0x6d,
+	0x65, 0x18, 0x03, 0x20, 0x01, 0x28, 0x0b, 0x32, 0x1a, 0x2e, 0x67, 0x6f, 0x6f, 0x67, 0x6c, 0x65,
+	0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x62, 0x75, 0x66, 0x2e, 0x54, 0x69, 0x6d, 0x65, 0x73, 0x74,
+	0x61, 0x6d, 0x70, 0x52, 0x09, 0x65, 0x76, 0x65, 0x6e, 0x74, 0x54, 0x69, 0x6d, 0x65, 0x12, 0x12,
+	0x0a, 0x04, 0x74, 0x61, 0x67, 0x73, 0x18, 0x04, 0x20, 0x03, 0x28, 0x09, 0x52, 0x04, 0x74, 0x61,
+	0x67, 0x73, 0x22, 0x25, 0x0a, 0x0d, 0x52, 0x65, 0x61, 0x64, 0x79, 0x52, 0x65, 0x73, 0x70, 0x6f,
+	0x6e, 0x73, 0x65, 0x12, 0x14, 0x0a, 0x05, 0x72, 0x65, 0x61, 0x64, 0x79, 0x18, 0x01, 0x20, 0x01,
+	0x28, 0x08, 0x52, 0x05, 0x72, 0x65, 0x61, 0x64, 0x79, 0x32, 0xcb, 0x01, 0x0a, 0x0f, 0x53, 0x6f,
+	0x75, 0x72, 0x63, 0x65, 0x54, 0x72, 0x61, 0x6e, 0x73, 0x66, 0x6f, 0x72, 0x6d, 0x12, 0x70, 0x0a,
+	0x11, 0x53, 0x6f, 0x75, 0x72, 0x63, 0x65, 0x54, 0x72, 0x61, 0x6e, 0x73, 0x66, 0x6f, 0x72, 0x6d,
+	0x46, 0x6e, 0x12, 0x2c, 0x2e, 0x73, 0x6f, 0x75, 0x72, 0x63, 0x65, 0x74, 0x72, 0x61, 0x6e, 0x73,
+	0x66, 0x6f, 0x72, 0x6d, 0x65, 0x72, 0x2e, 0x76, 0x31, 0x2e, 0x53, 0x6f, 0x75, 0x72, 0x63, 0x65,
+	0x54, 0x72, 0x61, 0x6e, 0x73, 0x66, 0x6f, 0x72, 0x6d, 0x52, 0x65, 0x71, 0x75, 0x65, 0x73, 0x74,
+	0x1a, 0x2d, 0x2e, 0x73, 0x6f, 0x75, 0x72, 0x63, 0x65, 0x74, 0x72, 0x61, 0x6e, 0x73, 0x66, 0x6f,
+	0x72, 0x6d, 0x65, 0x72, 0x2e, 0x76, 0x31, 0x2e, 0x53, 0x6f, 0x75, 0x72, 0x63, 0x65, 0x54, 0x72,
+	0x61, 0x6e, 0x73, 0x66, 0x6f, 0x72, 0x6d, 0x52, 0x65, 0x73, 0x70, 0x6f, 0x6e, 0x73, 0x65, 0x12,
+	0x46, 0x0a, 0x07, 0x49, 0x73, 0x52, 0x65, 0x61, 0x64, 0x79, 0x12, 0x16, 0x2e, 0x67, 0x6f, 0x6f,
+	0x67, 0x6c, 0x65, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x62, 0x75, 0x66, 0x2e, 0x45, 0x6d, 0x70,
+	0x74, 0x79, 0x1a, 0x23, 0x2e, 0x73, 0x6f, 0x75, 0x72, 0x63, 0x65, 0x74, 0x72, 0x61, 0x6e, 0x73,
+	0x66, 0x6f, 0x72, 0x6d, 0x65, 0x72, 0x2e, 0x76, 0x31, 0x2e, 0x52, 0x65, 0x61, 0x64, 0x79, 0x52,
+	0x65, 0x73, 0x70, 0x6f, 0x6e, 0x73, 0x65, 0x42, 0x43, 0x5a, 0x41, 0x67, 0x69, 0x74, 0x68, 0x75,
+	0x62, 0x2e, 0x63, 0x6f, 0x6d, 0x2f, 0x6e, 0x75, 0x6d, 0x61, 0x70, 0x72, 0x6f, 0x6a, 0x2f, 0x6e,
+	0x75, 0x6d, 0x61, 0x66, 0x6c, 0x6f, 0x77, 0x2d, 0x67, 0x6f, 0x2f, 0x70, 0x6b, 0x67, 0x2f, 0x61,
+	0x70, 0x69, 0x73, 0x2f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x2f, 0x73, 0x6f, 0x75, 0x72, 0x63, 0x65,
+	0x74, 0x72, 0x61, 0x6e, 0x73, 0x66, 0x6f, 0x72, 0x6d, 0x2f, 0x76, 0x31, 0x62, 0x06, 0x70, 0x72,
+	0x6f, 0x74, 0x6f, 0x33,
 }
 
 var (
@@ -337,29 +354,31 @@ func file_pkg_apis_proto_sourcetransform_v1_transform_proto_rawDescGZIP() []byte
 	return file_pkg_apis_proto_sourcetransform_v1_transform_proto_rawDescData
 }
 
-var file_pkg_apis_proto_sourcetransform_v1_transform_proto_msgTypes = make([]protoimpl.MessageInfo, 4)
+var file_pkg_apis_proto_sourcetransform_v1_transform_proto_msgTypes = make([]protoimpl.MessageInfo, 5)
 var file_pkg_apis_proto_sourcetransform_v1_transform_proto_goTypes = []interface{}{
 	(*SourceTransformRequest)(nil),         // 0: sourcetransformer.v1.SourceTransformRequest
 	(*SourceTransformResponse)(nil),        // 1: sourcetransformer.v1.SourceTransformResponse
 	(*ReadyResponse)(nil),                  // 2: sourcetransformer.v1.ReadyResponse
-	(*SourceTransformResponse_Result)(nil), // 3: sourcetransformer.v1.SourceTransformResponse.Result
-	(*timestamppb.Timestamp)(nil),          // 4: google.protobuf.Timestamp
-	(*emptypb.Empty)(nil),                  // 5: google.protobuf.Empty
+	nil,                                    // 3: sourcetransformer.v1.SourceTransformRequest.HeadersEntry
+	(*SourceTransformResponse_Result)(nil), // 4: sourcetransformer.v1.SourceTransformResponse.Result
+	(*timestamppb.Timestamp)(nil),          // 5: google.protobuf.Timestamp
+	(*emptypb.Empty)(nil),                  // 6: google.protobuf.Empty
 }
 var file_pkg_apis_proto_sourcetransform_v1_transform_proto_depIdxs = []int32{
-	4, // 0: sourcetransformer.v1.SourceTransformRequest.event_time:type_name -> google.protobuf.Timestamp
-	4, // 1: sourcetransformer.v1.SourceTransformRequest.watermark:type_name -> google.protobuf.Timestamp
-	3, // 2: sourcetransformer.v1.SourceTransformResponse.results:type_name -> sourcetransformer.v1.SourceTransformResponse.Result
-	4, // 3: sourcetransformer.v1.SourceTransformResponse.Result.event_time:type_name -> google.protobuf.Timestamp
-	0, // 4: sourcetransformer.v1.SourceTransform.SourceTransformFn:input_type -> sourcetransformer.v1.SourceTransformRequest
-	5, // 5: sourcetransformer.v1.SourceTransform.IsReady:input_type -> google.protobuf.Empty
-	1, // 6: sourcetransformer.v1.SourceTransform.SourceTransformFn:output_type -> sourcetransformer.v1.SourceTransformResponse
-	2, // 7: sourcetransformer.v1.SourceTransform.IsReady:output_type -> sourcetransformer.v1.ReadyResponse
-	6, // [6:8] is the sub-list for method output_type
-	4, // [4:6] is the sub-list for method input_type
-	4, // [4:4] is the sub-list for extension type_name
-	4, // [4:4] is the sub-list for extension extendee
-	0, // [0:4] is the sub-list for field type_name
+	5, // 0: sourcetransformer.v1.SourceTransformRequest.event_time:type_name -> google.protobuf.Timestamp
+	5, // 1: sourcetransformer.v1.SourceTransformRequest.watermark:type_name -> google.protobuf.Timestamp
+	3, // 2: sourcetransformer.v1.SourceTransformRequest.headers:type_name -> sourcetransformer.v1.SourceTransformRequest.HeadersEntry
+	4, // 3: sourcetransformer.v1.SourceTransformResponse.results:type_name -> sourcetransformer.v1.SourceTransformResponse.Result
+	5, // 4: sourcetransformer.v1.SourceTransformResponse.Result.event_time:type_name -> google.protobuf.Timestamp
+	0, // 5: sourcetransformer.v1.SourceTransform.SourceTransformFn:input_type -> sourcetransformer.v1.SourceTransformRequest
+	6, // 6: sourcetransformer.v1.SourceTransform.IsReady:input_type -> google.protobuf.Empty
+	1, // 7: sourcetransformer.v1.SourceTransform.SourceTransformFn:output_type -> sourcetransformer.v1.SourceTransformResponse
+	2, // 8: sourcetransformer.v1.SourceTransform.IsReady:output_type -> sourcetransformer.v1.ReadyResponse
+	7, // [7:9] is the sub-list for method output_type
+	5, // [5:7] is the sub-list for method input_type
+	5, // [5:5] is the sub-list for extension type_name
+	5, // [5:5] is the sub-list for extension extendee
+	0, // [0:5] is the sub-list for field type_name
 }
 
 func init() { file_pkg_apis_proto_sourcetransform_v1_transform_proto_init() }
@@ -404,7 +423,7 @@ func file_pkg_apis_proto_sourcetransform_v1_transform_proto_init() {
 				return nil
 			}
 		}
-		file_pkg_apis_proto_sourcetransform_v1_transform_proto_msgTypes[3].Exporter = func(v interface{}, i int) interface{} {
+		file_pkg_apis_proto_sourcetransform_v1_transform_proto_msgTypes[4].Exporter = func(v interface{}, i int) interface{} {
 			switch v := v.(*SourceTransformResponse_Result); i {
 			case 0:
 				return &v.state
@@ -423,7 +442,7 @@ func file_pkg_apis_proto_sourcetransform_v1_transform_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_pkg_apis_proto_sourcetransform_v1_transform_proto_rawDesc,
 			NumEnums:      0,
-			NumMessages:   4,
+			NumMessages:   5,
 			NumExtensions: 0,
 			NumServices:   1,
 		},
diff --git a/pkg/apis/proto/sourcetransform/v1/transform.proto b/pkg/apis/proto/sourcetransform/v1/transform.proto
index 1267bb02..8885db08 100644
--- a/pkg/apis/proto/sourcetransform/v1/transform.proto
+++ b/pkg/apis/proto/sourcetransform/v1/transform.proto
@@ -25,6 +25,7 @@ message SourceTransformRequest {
   bytes value = 2;
   google.protobuf.Timestamp event_time = 3;
   google.protobuf.Timestamp watermark = 4;
+  map<string, string> headers = 5;
 }
 
 /**
diff --git a/pkg/mapper/interface.go b/pkg/mapper/interface.go
index 12700009..e4f8355f 100644
--- a/pkg/mapper/interface.go
+++ b/pkg/mapper/interface.go
@@ -7,9 +7,14 @@ import (
 
 // Datum contains methods to get the payload information.
 type Datum interface {
+	// Value returns the payload of the message.
 	Value() []byte
+	// EventTime returns the event time of the message.
 	EventTime() time.Time
+	// Watermark returns the watermark of the message.
 	Watermark() time.Time
+	// Headers returns the headers of the message.
+	Headers() map[string]string
 }
 
 // Mapper is the interface of map function implementation.
diff --git a/pkg/mapper/service.go b/pkg/mapper/service.go
index 16aab8a0..636f494e 100644
--- a/pkg/mapper/service.go
+++ b/pkg/mapper/service.go
@@ -29,7 +29,7 @@ func (fs *Service) IsReady(context.Context, *emptypb.Empty) (*mappb.ReadyRespons
 
 // MapFn applies a user defined function to each request element and returns a list of results.
 func (fs *Service) MapFn(ctx context.Context, d *mappb.MapRequest) (*mappb.MapResponse, error) {
-	var hd = NewHandlerDatum(d.GetValue(), d.GetEventTime().AsTime(), d.GetWatermark().AsTime())
+	var hd = NewHandlerDatum(d.GetValue(), d.GetEventTime().AsTime(), d.GetWatermark().AsTime(), d.GetHeaders())
 	messages := fs.Mapper.Map(ctx, d.GetKeys(), hd)
 	var elements []*mappb.MapResponse_Result
 	for _, m := range messages.Items() {
diff --git a/pkg/mapper/types.go b/pkg/mapper/types.go
index e924b926..fd18c024 100644
--- a/pkg/mapper/types.go
+++ b/pkg/mapper/types.go
@@ -7,13 +7,15 @@ type handlerDatum struct {
 	value     []byte
 	eventTime time.Time
 	watermark time.Time
+	headers   map[string]string
 }
 
-func NewHandlerDatum(value []byte, eventTime time.Time, watermark time.Time) Datum {
+func NewHandlerDatum(value []byte, eventTime time.Time, watermark time.Time, headers map[string]string) Datum {
 	return &handlerDatum{
 		value:     value,
 		eventTime: eventTime,
 		watermark: watermark,
+		headers:   headers,
 	}
 }
 
@@ -28,3 +30,7 @@ func (h *handlerDatum) EventTime() time.Time {
 func (h *handlerDatum) Watermark() time.Time {
 	return h.watermark
 }
+
+func (h *handlerDatum) Headers() map[string]string {
+	return h.headers
+}
diff --git a/pkg/mapstreamer/interface.go b/pkg/mapstreamer/interface.go
index 8a14ffe3..57487914 100644
--- a/pkg/mapstreamer/interface.go
+++ b/pkg/mapstreamer/interface.go
@@ -7,9 +7,14 @@ import (
 
 // Datum contains methods to get the payload information.
 type Datum interface {
+	// Value returns the payload of the message.
 	Value() []byte
+	// EventTime returns the event time of the message.
 	EventTime() time.Time
+	// Watermark returns the watermark of the message.
 	Watermark() time.Time
+	// Headers returns the headers of the message.
+	Headers() map[string]string
 }
 
 // MapStreamer is the interface of map stream function implementation.
diff --git a/pkg/mapstreamer/service.go b/pkg/mapstreamer/service.go
index 2e9022e0..c272b7ce 100644
--- a/pkg/mapstreamer/service.go
+++ b/pkg/mapstreamer/service.go
@@ -30,7 +30,7 @@ func (fs *Service) IsReady(context.Context, *emptypb.Empty) (*mapstreampb.ReadyR
 
 // MapStreamFn applies a function to each request element and streams the results back.
 func (fs *Service) MapStreamFn(d *mapstreampb.MapStreamRequest, stream mapstreampb.MapStream_MapStreamFnServer) error {
-	var hd = NewHandlerDatum(d.GetValue(), d.EventTime.AsTime(), d.Watermark.AsTime())
+	var hd = NewHandlerDatum(d.GetValue(), d.GetEventTime().AsTime(), d.GetWatermark().AsTime(), d.GetHeaders())
 	ctx := stream.Context()
 	messageCh := make(chan Message)
 
diff --git a/pkg/mapstreamer/types.go b/pkg/mapstreamer/types.go
index 72038a6c..e7f95d0a 100644
--- a/pkg/mapstreamer/types.go
+++ b/pkg/mapstreamer/types.go
@@ -7,13 +7,15 @@ type handlerDatum struct {
 	value     []byte
 	eventTime time.Time
 	watermark time.Time
+	headers   map[string]string
 }
 
-func NewHandlerDatum(value []byte, eventTime time.Time, watermark time.Time) Datum {
+func NewHandlerDatum(value []byte, eventTime time.Time, watermark time.Time, headers map[string]string) Datum {
 	return &handlerDatum{
 		value:     value,
 		eventTime: eventTime,
 		watermark: watermark,
+		headers:   headers,
 	}
 }
 
@@ -28,3 +30,7 @@ func (h *handlerDatum) EventTime() time.Time {
 func (h *handlerDatum) Watermark() time.Time {
 	return h.watermark
 }
+
+func (h *handlerDatum) Headers() map[string]string {
+	return h.headers
+}
diff --git a/pkg/reducer/interface.go b/pkg/reducer/interface.go
index e49d858a..08d6dd31 100644
--- a/pkg/reducer/interface.go
+++ b/pkg/reducer/interface.go
@@ -7,9 +7,14 @@ import (
 
 // Datum contains methods to get the payload information.
 type Datum interface {
+	// Value returns the payload of the message.
 	Value() []byte
+	// EventTime returns the event time of the message.
 	EventTime() time.Time
+	// Watermark returns the watermark of the message.
 	Watermark() time.Time
+	// Headers returns the headers of the message.
+	Headers() map[string]string
 }
 
 // Metadata contains methods to get the metadata for the reduce operation.
diff --git a/pkg/reducer/task_manager.go b/pkg/reducer/task_manager.go
index 53e37503..a722eba3 100644
--- a/pkg/reducer/task_manager.go
+++ b/pkg/reducer/task_manager.go
@@ -166,5 +166,10 @@ func generateKey(window *v1.Window, keys []string) string {
 }
 
 func buildDatum(request *v1.ReduceRequest) Datum {
-	return NewHandlerDatum(request.Payload.GetValue(), request.Payload.EventTime.AsTime(), request.Payload.Watermark.AsTime())
+	return NewHandlerDatum(
+		request.GetPayload().GetValue(),
+		request.GetPayload().GetEventTime().AsTime(),
+		request.GetPayload().GetWatermark().AsTime(),
+		request.GetPayload().GetHeaders(),
+	)
 }
diff --git a/pkg/reducer/types.go b/pkg/reducer/types.go
index 3210a5a4..b17f690d 100644
--- a/pkg/reducer/types.go
+++ b/pkg/reducer/types.go
@@ -7,13 +7,15 @@ type handlerDatum struct {
 	value     []byte
 	eventTime time.Time
 	watermark time.Time
+	headers   map[string]string
 }
 
-func NewHandlerDatum(value []byte, eventTime time.Time, watermark time.Time) Datum {
+func NewHandlerDatum(value []byte, eventTime time.Time, watermark time.Time, headers map[string]string) Datum {
 	return &handlerDatum{
 		value:     value,
 		eventTime: eventTime,
 		watermark: watermark,
+		headers:   headers,
 	}
 }
 
@@ -29,6 +31,10 @@ func (h *handlerDatum) Watermark() time.Time {
 	return h.watermark
 }
 
+func (h *handlerDatum) Headers() map[string]string {
+	return h.headers
+}
+
 // intervalWindow implements IntervalWindow interface which will be passed as metadata
 // to reduce handlers
 type intervalWindow struct {
diff --git a/pkg/reducestreamer/interface.go b/pkg/reducestreamer/interface.go
index 40dd4faa..c0730570 100644
--- a/pkg/reducestreamer/interface.go
+++ b/pkg/reducestreamer/interface.go
@@ -7,9 +7,14 @@ import (
 
 // Datum contains methods to get the payload information.
 type Datum interface {
+	// Value returns the payload of the message.
 	Value() []byte
+	// EventTime returns the event time of the message.
 	EventTime() time.Time
+	// Watermark returns the watermark of the message.
 	Watermark() time.Time
+	// Headers returns the headers of the message.
+	Headers() map[string]string
 }
 
 // Metadata contains methods to get the metadata for the reduceStream operation.
diff --git a/pkg/reducestreamer/task_manager.go b/pkg/reducestreamer/task_manager.go
index a6d5feee..ae04f096 100644
--- a/pkg/reducestreamer/task_manager.go
+++ b/pkg/reducestreamer/task_manager.go
@@ -173,5 +173,10 @@ func generateKey(window *v1.Window, keys []string) string {
 }
 
 func buildDatum(request *v1.ReduceRequest) Datum {
-	return NewHandlerDatum(request.Payload.GetValue(), request.Payload.EventTime.AsTime(), request.Payload.Watermark.AsTime())
+	return NewHandlerDatum(
+		request.GetPayload().GetValue(),
+		request.GetPayload().GetEventTime().AsTime(),
+		request.GetPayload().GetWatermark().AsTime(),
+		request.GetPayload().GetHeaders(),
+	)
 }
diff --git a/pkg/reducestreamer/types.go b/pkg/reducestreamer/types.go
index 1f19c27a..0e22917c 100644
--- a/pkg/reducestreamer/types.go
+++ b/pkg/reducestreamer/types.go
@@ -7,13 +7,15 @@ type handlerDatum struct {
 	value     []byte
 	eventTime time.Time
 	watermark time.Time
+	headers   map[string]string
 }
 
-func NewHandlerDatum(value []byte, eventTime time.Time, watermark time.Time) Datum {
+func NewHandlerDatum(value []byte, eventTime time.Time, watermark time.Time, headers map[string]string) Datum {
 	return &handlerDatum{
 		value:     value,
 		eventTime: eventTime,
 		watermark: watermark,
+		headers:   headers,
 	}
 }
 
@@ -29,6 +31,10 @@ func (h *handlerDatum) Watermark() time.Time {
 	return h.watermark
 }
 
+func (h *handlerDatum) Headers() map[string]string {
+	return h.headers
+}
+
 // intervalWindow implements IntervalWindow interface which will be passed as metadata
 // to reduce handlers
 type intervalWindow struct {
diff --git a/pkg/sessionreducer/interface.go b/pkg/sessionreducer/interface.go
index 905ae380..7dac50cd 100644
--- a/pkg/sessionreducer/interface.go
+++ b/pkg/sessionreducer/interface.go
@@ -7,9 +7,14 @@ import (
 
 // Datum contains methods to get the payload information.
 type Datum interface {
+	// Value returns the payload of the message.
 	Value() []byte
+	// EventTime returns the event time of the message.
 	EventTime() time.Time
+	// Watermark returns the watermark of the message.
 	Watermark() time.Time
+	// Headers returns the headers of the message.
+	Headers() map[string]string
 }
 
 // SessionReducer is the interface which can be used to implement a session reduce operation.
diff --git a/pkg/sessionreducer/service_test.go b/pkg/sessionreducer/service_test.go
index b001bd3a..a0c55531 100644
--- a/pkg/sessionreducer/service_test.go
+++ b/pkg/sessionreducer/service_test.go
@@ -109,6 +109,7 @@ func TestService_SessionReduceFn(t *testing.T) {
 						Value:     []byte(strconv.Itoa(10)),
 						EventTime: timestamppb.New(time.Time{}),
 						Watermark: timestamppb.New(time.Time{}),
+						Headers:   map[string]string{"x-txn-id": "test-txn-1"},
 					},
 					Operation: &sessionreducepb.SessionReduceRequest_WindowOperation{
 						Event: sessionreducepb.SessionReduceRequest_WindowOperation_OPEN,
diff --git a/pkg/sessionreducer/task_manager.go b/pkg/sessionreducer/task_manager.go
index 3bfaa050..49500eef 100644
--- a/pkg/sessionreducer/task_manager.go
+++ b/pkg/sessionreducer/task_manager.go
@@ -320,5 +320,10 @@ func generateKey(keyedWindow *v1.KeyedWindow) string {
 }
 
 func buildDatum(payload *v1.SessionReduceRequest_Payload) Datum {
-	return NewHandlerDatum(payload.GetValue(), payload.EventTime.AsTime(), payload.Watermark.AsTime())
+	return NewHandlerDatum(
+		payload.GetValue(),
+		payload.GetEventTime().AsTime(),
+		payload.GetWatermark().AsTime(),
+		payload.GetHeaders(),
+	)
 }
diff --git a/pkg/sessionreducer/types.go b/pkg/sessionreducer/types.go
index ee5c4966..490b377b 100644
--- a/pkg/sessionreducer/types.go
+++ b/pkg/sessionreducer/types.go
@@ -7,13 +7,15 @@ type handlerDatum struct {
 	value     []byte
 	eventTime time.Time
 	watermark time.Time
+	headers   map[string]string
 }
 
-func NewHandlerDatum(value []byte, eventTime time.Time, watermark time.Time) Datum {
+func NewHandlerDatum(value []byte, eventTime time.Time, watermark time.Time, headers map[string]string) Datum {
 	return &handlerDatum{
 		value:     value,
 		eventTime: eventTime,
 		watermark: watermark,
+		headers:   headers,
 	}
 }
 
@@ -28,3 +30,7 @@ func (h *handlerDatum) EventTime() time.Time {
 func (h *handlerDatum) Watermark() time.Time {
 	return h.watermark
 }
+
+func (h *handlerDatum) Headers() map[string]string {
+	return h.headers
+}
diff --git a/pkg/sinker/interface.go b/pkg/sinker/interface.go
index 9118a102..9d00a933 100644
--- a/pkg/sinker/interface.go
+++ b/pkg/sinker/interface.go
@@ -7,11 +7,18 @@ import (
 
 // Datum is the interface of incoming message payload for sink function.
 type Datum interface {
+	// Keys returns the keys of the message.
 	Keys() []string
+	// Value returns the payload of the message.
 	Value() []byte
+	// EventTime returns the event time of the message.
 	EventTime() time.Time
+	// Watermark returns the watermark of the message.
 	Watermark() time.Time
+	// ID returns the ID of the message.
 	ID() string
+	// Headers returns the headers of the message.
+	Headers() map[string]string
 }
 
 // Sinker is the interface of sink function implementation.
diff --git a/pkg/sinker/service.go b/pkg/sinker/service.go
index d008c1a3..4ac48c15 100644
--- a/pkg/sinker/service.go
+++ b/pkg/sinker/service.go
@@ -25,6 +25,7 @@ type handlerDatum struct {
 	value     []byte
 	eventTime time.Time
 	watermark time.Time
+	headers   map[string]string
 }
 
 func (h *handlerDatum) Keys() []string {
@@ -47,6 +48,10 @@ func (h *handlerDatum) Watermark() time.Time {
 	return h.watermark
 }
 
+func (h *handlerDatum) Headers() map[string]string {
+	return h.headers
+}
+
 // Service implements the proto gen server interface and contains the sinkfn operation handler.
 type Service struct {
 	sinkpb.UnimplementedSinkServer
@@ -98,6 +103,7 @@ func (fs *Service) SinkFn(stream sinkpb.Sink_SinkFnServer) error {
 			keys:      d.GetKeys(),
 			eventTime: d.GetEventTime().AsTime(),
 			watermark: d.GetWatermark().AsTime(),
+			headers:   d.GetHeaders(),
 		}
 		datumStreamCh <- hd
 	}
diff --git a/pkg/sinker/service_test.go b/pkg/sinker/service_test.go
index 5b88a0d2..176499a6 100644
--- a/pkg/sinker/service_test.go
+++ b/pkg/sinker/service_test.go
@@ -57,6 +57,7 @@ func TestService_SinkFn(t *testing.T) {
 					Value:     []byte(strconv.Itoa(10)),
 					EventTime: timestamppb.New(time.Time{}),
 					Watermark: timestamppb.New(time.Time{}),
+					Headers:   map[string]string{"x-txn-id": "test-txn-1"},
 				},
 				{
 					Id:        "two-processed",
@@ -64,6 +65,7 @@ func TestService_SinkFn(t *testing.T) {
 					Value:     []byte(strconv.Itoa(20)),
 					EventTime: timestamppb.New(time.Time{}),
 					Watermark: timestamppb.New(time.Time{}),
+					Headers:   map[string]string{"x-txn-id": "test-txn-2"},
 				},
 				{
 					Id:        "three-processed",
@@ -71,6 +73,7 @@ func TestService_SinkFn(t *testing.T) {
 					Value:     []byte(strconv.Itoa(30)),
 					EventTime: timestamppb.New(time.Time{}),
 					Watermark: timestamppb.New(time.Time{}),
+					Headers:   map[string]string{"x-txn-id": "test-txn-3"},
 				},
 			},
 			sh: SinkerFunc(func(ctx context.Context, rch <-chan Datum) Responses {
@@ -109,6 +112,7 @@ func TestService_SinkFn(t *testing.T) {
 					Value:     []byte(strconv.Itoa(10)),
 					EventTime: timestamppb.New(time.Time{}),
 					Watermark: timestamppb.New(time.Time{}),
+					Headers:   map[string]string{"x-txn-id": "test-txn-1"},
 				},
 				{
 					Id:        "two-processed",
@@ -123,6 +127,7 @@ func TestService_SinkFn(t *testing.T) {
 					Value:     []byte(strconv.Itoa(30)),
 					EventTime: timestamppb.New(time.Time{}),
 					Watermark: timestamppb.New(time.Time{}),
+					Headers:   map[string]string{"x-txn-id": "test-txn-2"},
 				},
 			},
 			sh: SinkerFunc(func(ctx context.Context, rch <-chan Datum) Responses {
diff --git a/pkg/sourcer/examples/simple_source/go.mod b/pkg/sourcer/examples/simple_source/go.mod
index 5eb180a0..c46157e5 100644
--- a/pkg/sourcer/examples/simple_source/go.mod
+++ b/pkg/sourcer/examples/simple_source/go.mod
@@ -5,6 +5,7 @@ go 1.20
 replace github.com/numaproj/numaflow-go => ../../../..
 
 require (
+	github.com/google/uuid v1.3.0
 	github.com/numaproj/numaflow-go v0.6.1-0.20240221033908-7c1198bc89f1
 	github.com/stretchr/testify v1.8.1
 )
diff --git a/pkg/sourcer/examples/simple_source/go.sum b/pkg/sourcer/examples/simple_source/go.sum
index 0eb6ac02..7e7e9a2c 100644
--- a/pkg/sourcer/examples/simple_source/go.sum
+++ b/pkg/sourcer/examples/simple_source/go.sum
@@ -7,6 +7,8 @@ github.com/golang/protobuf v1.5.3 h1:KhyjKVUg7Usr/dYsdSqoFveMYd5ko72D+zANwlG1mmg
 github.com/golang/protobuf v1.5.3/go.mod h1:XVQd3VNwM+JqD3oG2Ue2ip4fOMUkwXdXDdiuN0vRsmY=
 github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
+github.com/google/uuid v1.3.0 h1:t6JiXgmwXMjEs8VusXIJk2BXHsn+wx8BZdTaoZ5fu7I=
+github.com/google/uuid v1.3.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
diff --git a/pkg/sourcer/examples/simple_source/impl/simple_source.go b/pkg/sourcer/examples/simple_source/impl/simple_source.go
index bd8c783c..b294850d 100644
--- a/pkg/sourcer/examples/simple_source/impl/simple_source.go
+++ b/pkg/sourcer/examples/simple_source/impl/simple_source.go
@@ -6,6 +6,8 @@ import (
 	"sync"
 	"time"
 
+	"github.com/google/uuid"
+
 	sourcesdk "github.com/numaproj/numaflow-go/pkg/sourcer"
 )
 
@@ -52,12 +54,15 @@ func (s *SimpleSource) Read(_ context.Context, readRequest sourcesdk.ReadRequest
 			return
 		default:
 			s.lock.Lock()
+			headers := map[string]string{
+				"x-txn-id": uuid.NewString(),
+			}
 			// Otherwise, we read the data from the source and send the data to the message channel.
 			offsetValue := serializeOffset(s.readIdx)
 			messageCh <- sourcesdk.NewMessage(
 				[]byte(strconv.FormatInt(s.readIdx, 10)),
 				sourcesdk.NewOffsetWithDefaultPartitionId(offsetValue),
-				time.Now())
+				time.Now()).WithHeaders(headers)
 			// Mark the offset as to be acked, and increment the read index.
 			s.toAckSet[s.readIdx] = struct{}{}
 			s.readIdx++
diff --git a/pkg/sourcer/message.go b/pkg/sourcer/message.go
index 7bdb26a7..2ea4ea58 100644
--- a/pkg/sourcer/message.go
+++ b/pkg/sourcer/message.go
@@ -15,6 +15,7 @@ type Message struct {
 	offset    Offset
 	eventTime time.Time
 	keys      []string
+	headers   map[string]string
 }
 
 // NewMessage creates a Message with value
@@ -28,11 +29,22 @@ func (m Message) WithKeys(keys []string) Message {
 	return m
 }
 
+// WithHeaders is used to assign the headers to the message
+func (m Message) WithHeaders(headers map[string]string) Message {
+	m.headers = headers
+	return m
+}
+
 // Keys returns message keys
 func (m Message) Keys() []string {
 	return m.keys
 }
 
+// Headers returns message headers
+func (m Message) Headers() map[string]string {
+	return m.headers
+}
+
 // Value returns message value
 func (m Message) Value() []byte {
 	return m.value
@@ -67,7 +79,7 @@ func NewOffsetWithDefaultPartitionId(value []byte) Offset {
 }
 
 // DefaultPartitions returns default partitions for the source.
-// It can be used in the Partitions() function of the Sourcer interface only 
+// It can be used in the Partitions() function of the Sourcer interface only
 // if the source doesn't have partitions. DefaultPartition will be the pod replica
 // index of the source.
 func DefaultPartitions() []int32 {
diff --git a/pkg/sourcer/service.go b/pkg/sourcer/service.go
index 33d82743..185c0e8f 100644
--- a/pkg/sourcer/service.go
+++ b/pkg/sourcer/service.go
@@ -76,6 +76,7 @@ func (fs *Service) ReadFn(d *sourcepb.ReadRequest, stream sourcepb.Source_ReadFn
 				Offset:    offset,
 				EventTime: timestamppb.New(msg.EventTime()),
 				Keys:      msg.Keys(),
+				Headers:   msg.Headers(),
 			},
 		}
 		// The error here is returned by the stream, which is already a gRPC error
diff --git a/pkg/sourcer/service_test.go b/pkg/sourcer/service_test.go
index 1f340777..fe6643c8 100644
--- a/pkg/sourcer/service_test.go
+++ b/pkg/sourcer/service_test.go
@@ -24,7 +24,7 @@ var testPartitions = []int32{1, 3, 5}
 type TestSource struct{}
 
 func (ts TestSource) Read(_ context.Context, _ ReadRequest, messageCh chan<- Message) {
-	msg := NewMessage([]byte(`test`), Offset{}, testEventTime)
+	msg := NewMessage([]byte(`test`), Offset{}, testEventTime).WithHeaders(map[string]string{"x-txn-id": "test-txn-id"})
 	messageCh <- msg.WithKeys([]string{testKey})
 }
 
@@ -120,6 +120,7 @@ func TestService_ReadFn(t *testing.T) {
 						Offset:    &sourcepb.Offset{},
 						EventTime: timestamppb.New(testEventTime),
 						Keys:      []string{testKey},
+						Headers:   map[string]string{"x-txn-id": "test-txn-id"},
 					},
 				},
 			},
@@ -140,6 +141,7 @@ func TestService_ReadFn(t *testing.T) {
 						Offset:    &sourcepb.Offset{},
 						EventTime: timestamppb.New(testEventTime),
 						Keys:      []string{testKey},
+						Headers:   map[string]string{"x-txn-id": "test-txn-id"},
 					},
 				},
 			},
diff --git a/pkg/sourcetransformer/interface.go b/pkg/sourcetransformer/interface.go
index 4b1fd609..131e100c 100644
--- a/pkg/sourcetransformer/interface.go
+++ b/pkg/sourcetransformer/interface.go
@@ -7,9 +7,14 @@ import (
 
 // Datum contains methods to get the payload information.
 type Datum interface {
+	// Value returns the payload of the message.
 	Value() []byte
+	// EventTime returns the event time of the message.
 	EventTime() time.Time
+	// Watermark returns the watermark of the message.
 	Watermark() time.Time
+	// Headers returns the headers of the message.
+	Headers() map[string]string
 }
 
 // SourceTransformer is the interface of SourceTransformer function implementation.
diff --git a/pkg/sourcetransformer/service.go b/pkg/sourcetransformer/service.go
index 327c7fdd..004e13dc 100644
--- a/pkg/sourcetransformer/service.go
+++ b/pkg/sourcetransformer/service.go
@@ -32,7 +32,7 @@ func (fs *Service) IsReady(context.Context, *emptypb.Empty) (*v1.ReadyResponse,
 // In addition to map function, SourceTransformFn also supports assigning a new event time to response.
 // SourceTransformFn can be used only at source vertex by source data transformer.
 func (fs *Service) SourceTransformFn(ctx context.Context, d *v1.SourceTransformRequest) (*v1.SourceTransformResponse, error) {
-	var hd = NewHandlerDatum(d.GetValue(), d.EventTime.AsTime(), d.Watermark.AsTime())
+	var hd = NewHandlerDatum(d.GetValue(), d.EventTime.AsTime(), d.Watermark.AsTime(), d.Headers)
 	messageTs := fs.Transformer.Transform(ctx, d.GetKeys(), hd)
 	var results []*v1.SourceTransformResponse_Result
 	for _, m := range messageTs.Items() {
diff --git a/pkg/sourcetransformer/types.go b/pkg/sourcetransformer/types.go
index 472d0f26..ad1a2290 100644
--- a/pkg/sourcetransformer/types.go
+++ b/pkg/sourcetransformer/types.go
@@ -9,13 +9,15 @@ type handlerDatum struct {
 	value     []byte
 	eventTime time.Time
 	watermark time.Time
+	headers   map[string]string
 }
 
-func NewHandlerDatum(value []byte, eventTime time.Time, watermark time.Time) Datum {
+func NewHandlerDatum(value []byte, eventTime time.Time, watermark time.Time, headers map[string]string) Datum {
 	return &handlerDatum{
 		value:     value,
 		eventTime: eventTime,
 		watermark: watermark,
+		headers:   headers,
 	}
 }
 
@@ -30,3 +32,7 @@ func (h *handlerDatum) EventTime() time.Time {
 func (h *handlerDatum) Watermark() time.Time {
 	return h.watermark
 }
+
+func (h *handlerDatum) Headers() map[string]string {
+	return h.headers
+}