diff --git a/context.go b/context.go
index ce6e2c8..b590745 100644
--- a/context.go
+++ b/context.go
@@ -1186,6 +1186,36 @@ func NewContext(db * badger.DB, log Logger) (*Context, error) {
     return nil, err
   }
 
+  err = ctx.RegisterType(reflect.TypeOf(time.Duration(0)), DurationType,
+  func(ctx *Context, ctx_type SerializedType, reflect_type reflect.Type, value *reflect.Value)(SerializedValue,error){
+    var data []byte
+    type_stack := []SerializedType{ctx_type}
+    if value == nil {
+      data = nil
+    } else {
+      data := make([]byte, 8)
+      binary.BigEndian.PutUint64(data, uint64(value.Int()))
+    }
+    return SerializedValue{
+      type_stack,
+      data,
+    }, nil
+  },func(ctx *Context, value SerializedValue)(reflect.Type,*reflect.Value,SerializedValue,error){
+    if value.Data == nil {
+      return reflect.TypeOf(time.Duration(0)), nil, value, nil
+    } else {
+      var bytes []byte
+      var err error 
+      bytes, value, err = value.PopData(8)
+      if err != nil {
+        return nil, nil, value, err
+      }
+      duration := time.Duration(int64(binary.BigEndian.Uint64(bytes)))
+      duration_value := reflect.ValueOf(duration)
+      return duration_value.Type(), &duration_value, value, nil
+    }
+  })
+
   err = ctx.RegisterType(reflect.TypeOf(time.Time{}), TimeType,
   func(ctx *Context, ctx_type SerializedType, reflect_type reflect.Type, value *reflect.Value)(SerializedValue,error) {
     var data []byte
@@ -1321,6 +1351,11 @@ func NewContext(db * badger.DB, log Logger) (*Context, error) {
     return nil, err
   }
 
+  err = ctx.RegisterSignal(reflect.TypeOf(StoppedSignal{}), StoppedSignalType)
+  if err != nil {
+    return nil, err
+  }
+
   err = ctx.RegisterSignal(reflect.TypeOf(AddSubGroupSignal{}), AddSubGroupSignalType)
   if err != nil {
     return nil, err
diff --git a/gql.go b/gql.go
index e26c05b..98d93f9 100644
--- a/gql.go
+++ b/gql.go
@@ -843,6 +843,9 @@ type GQLExtContext struct {
   Query *graphql.Object
   Mutation *graphql.Object
   Subscription *graphql.Object
+
+  TypeMap map[reflect.Type]GQLTypeInfo
+  KindMap map[reflect.Kind]GQLTypeInfo
 }
 
 func (ctx *GQLExtContext) GetACLFields(obj_name string, names []string) (map[ExtType][]string, error) {
@@ -1159,6 +1162,110 @@ func NewGQLExtContext() *GQLExtContext {
     Fields: graphql.Fields{},
   })
 
+  kind_map := map[reflect.Kind]GQLTypeInfo{
+    reflect.String: {
+      func(ctx *GQLExtContext, reflect_type reflect.Type)(graphql.Type, error) {
+        return graphql.String, nil
+      },
+      func(ctx *GQLExtContext, value interface{})(reflect.Value, error) {
+        return reflect.ValueOf(value), nil
+      },
+    },
+    reflect.Bool: {
+      func(ctx *GQLExtContext, reflect_type reflect.Type)(graphql.Type, error) {
+        return graphql.Boolean, nil
+      },
+      func(ctx *GQLExtContext, value interface{})(reflect.Value, error) {
+        return reflect.ValueOf(value), nil
+      },
+    },
+  }
+  type_map := map[reflect.Type]GQLTypeInfo{
+    reflect.TypeOf([2]NodeID{}): {
+      func(ctx *GQLExtContext, reflect_type reflect.Type)(graphql.Type, error) {
+        return graphql.NewList(graphql.String), nil
+      },
+      func(ctx *GQLExtContext, value interface{})(reflect.Value, error) {
+        l, ok := value.([]interface{})
+        if ok == false {
+          return reflect.Value{}, fmt.Errorf("not list: %s", reflect.TypeOf(value))
+        } else if len(l) != 2 {
+          return reflect.Value{}, fmt.Errorf("wrong length: %d/2", len(l))
+        }
+
+        id1_str, ok := l[0].(string)
+        if ok == false {
+          return reflect.Value{}, fmt.Errorf("not strg: %s", reflect.TypeOf(l[0]))
+        }
+        id1, err := ParseID(id1_str)
+        if err != nil {
+          return reflect.Value{}, err
+        }
+        id2_str, ok := l[1].(string)
+        if ok == false {
+          return reflect.Value{}, fmt.Errorf("not strg: %s", reflect.TypeOf(l[1]))
+        }
+        id2, err := ParseID(id2_str)
+        if err != nil {
+          return reflect.Value{}, err
+        }
+        return_value := reflect.New(reflect.TypeOf([2]NodeID{})).Elem()
+        return_value.Index(0).Set(reflect.ValueOf(id1))
+        return_value.Index(1).Set(reflect.ValueOf(id2))
+
+        return return_value, nil
+      },
+    },
+    reflect.TypeOf(time.Time{}): {
+      func(ctx *GQLExtContext, reflect_type reflect.Type) (graphql.Type, error) {
+        return graphql.DateTime, nil
+      },
+      func(ctx *GQLExtContext, value interface{}) (reflect.Value, error) {
+        return reflect.ValueOf(value), nil
+      },
+    },
+    reflect.TypeOf(&NodeID{}): {
+      func(ctx *GQLExtContext, reflect_type reflect.Type) (graphql.Type, error) {
+        return graphql.String, nil
+      },
+      func(ctx *GQLExtContext, value interface{}) (reflect.Value, error) {
+        str, ok := value.(string)
+        if ok == false {
+          return reflect.Value{}, fmt.Errorf("value is not string")
+        }
+  
+        if str == "" {
+          return reflect.New(reflect.TypeOf(&NodeID{})).Elem(), nil
+        }
+  
+        id_parsed, err := ParseID(str)
+        if err != nil {
+          return reflect.Value{}, err
+        }
+  
+        return reflect.ValueOf(&id_parsed), nil
+      },
+    },
+    reflect.TypeOf(NodeID{}): {
+      func(ctx *GQLExtContext, reflect_type reflect.Type)(graphql.Type, error) {
+        return graphql.String, nil
+      },
+      func(ctx *GQLExtContext, value interface{})(reflect.Value, error) {
+        str, ok := value.(string)
+        if ok == false {
+          return reflect.Value{}, fmt.Errorf("value is not string")
+        }
+  
+        id_parsed, err := ParseID(str)
+        if err != nil {
+          return reflect.Value{}, err
+        }
+  
+        return reflect.ValueOf(id_parsed), nil
+      },
+    },
+  }
+
   context := GQLExtContext{
     Schema: graphql.Schema{},
     Types: []graphql.Type{},
@@ -1168,6 +1275,8 @@ func NewGQLExtContext() *GQLExtContext {
     NodeTypes: map[NodeType]*graphql.Object{},
     Interfaces: map[string]*Interface{},
     Fields: map[string]Field{},
+    KindMap: kind_map,
+    TypeMap: type_map,
   }
 
   var err error
diff --git a/gql_signal.go b/gql_signal.go
index a5607f2..8efa43b 100644
--- a/gql_signal.go
+++ b/gql_signal.go
@@ -8,63 +8,25 @@ import (
   "time"
 )
 
+type GQLTypeConverter func(*GQLExtContext, reflect.Type)(graphql.Type, error)
+type GQLValueConverter func(*GQLExtContext, interface{})(reflect.Value, error)
 type GQLTypeInfo struct {
-  graphql.Type
-  FromGQL func(interface{})(reflect.Value, error)
+  Type GQLTypeConverter
+  Value GQLValueConverter
 }
 
-var kind_gql_map = map[reflect.Kind]GQLTypeInfo{
-  reflect.String: {
-    graphql.String,
-    func(value interface{})(reflect.Value, error) {
-      return reflect.ValueOf(value), nil
-    },
-  },
-  reflect.Bool: {
-    graphql.Boolean,
-    func(value interface{})(reflect.Value, error) {
-      return reflect.ValueOf(value), nil
-    },
-  },
-}
-
-var type_gql_map = map[reflect.Type]GQLTypeInfo{
-  reflect.TypeOf(&NodeID{}): {
-    graphql.String,
-    func(value interface{}) (reflect.Value, error) {
-      str, ok := value.(string)
-      if ok == false {
-        return reflect.Value{}, fmt.Errorf("value is not string")
-      }
-
-      if str == "" {
-        return reflect.New(reflect.TypeOf(&NodeID{})).Elem(), nil
-      }
-
-      id_parsed, err := ParseID(str)
-      if err != nil {
-        return reflect.Value{}, err
-      }
-
-      return reflect.ValueOf(&id_parsed), nil
-    },
-  },
-  reflect.TypeOf(NodeID{}): {
-    graphql.String,
-    func(value interface{})(reflect.Value, error) {
-      str, ok := value.(string)
-      if ok == false {
-        return reflect.Value{}, fmt.Errorf("value is not string")
-      }
-
-      id_parsed, err := ParseID(str)
-      if err != nil {
-        return reflect.Value{}, err
-      }
-
-      return reflect.ValueOf(id_parsed), nil
-    },
-  },
+func GetGQLTypeInfo(ctx *GQLExtContext, reflect_type reflect.Type) (*GQLTypeInfo, error) {
+  type_info, type_mapped := ctx.TypeMap[reflect_type]
+  if type_mapped == false {
+    kind_info, kind_mapped := ctx.KindMap[reflect_type.Kind()]
+    if kind_mapped == false {
+      return nil, fmt.Errorf("Signal has unsupported type/kind: %s/%s", reflect_type, reflect_type.Kind())
+    } else {
+      return &kind_info, nil
+    }
+  } else {
+    return &type_info, nil
+  }
 }
 
 type StructFieldInfo struct {
@@ -74,7 +36,7 @@ type StructFieldInfo struct {
   Index []int
 }
 
-func SignalFromArgs(signal_type reflect.Type, fields []StructFieldInfo, args map[string]interface{}, id_index, direction_index []int) (Signal, error) {
+func SignalFromArgs(ctx *GQLExtContext, signal_type reflect.Type, fields []StructFieldInfo, args map[string]interface{}, id_index, direction_index []int) (Signal, error) {
   signal_value := reflect.New(signal_type)
 
   id_field := signal_value.Elem().FieldByIndex(id_index)
@@ -92,7 +54,7 @@ func SignalFromArgs(signal_type reflect.Type, fields []StructFieldInfo, args map
     if field_value.CanConvert(field.Type) == false {
       return nil, fmt.Errorf("Arg %s wrong type %s/%s", field.Name, field_value.Type(), field.Type)
     }
-    value, err := field.GQL.FromGQL(arg)
+    value, err := field.GQL.Value(ctx, arg)
     if err != nil {
       return nil, err
     }
@@ -101,6 +63,25 @@ func SignalFromArgs(signal_type reflect.Type, fields []StructFieldInfo, args map
   return signal_value.Interface().(Signal), nil
 }
 
+func ArgumentInfo(ctx *GQLExtContext, field reflect.StructField, gv_tag string) (*graphql.ArgumentConfig, StructFieldInfo, error) {
+  gql_info, err := GetGQLTypeInfo(ctx, field.Type)
+  if err != nil {
+    return nil, StructFieldInfo{}, err
+  }
+  gql_type, err := gql_info.Type(ctx, field.Type)
+  if err != nil {
+    return nil, StructFieldInfo{}, err
+  }
+  return &graphql.ArgumentConfig{
+    Type: gql_type,
+  }, StructFieldInfo{
+    gv_tag,
+    field.Type,
+    gql_info,
+    field.Index,
+  }, nil
+}
+
 func (ext *GQLExtContext) AddSignalMutation(name string, send_id_key string, signal_type reflect.Type) error {
   args := graphql.FieldConfigArgument{}
   arg_info := []StructFieldInfo{}
@@ -118,27 +99,14 @@ func (ext *GQLExtContext) AddSignalMutation(name string, send_id_key string, sig
         _, exists := args[gv_tag]
         if exists == true {
           return fmt.Errorf("Signal has repeated tag %s", gv_tag)
-        }
-        var gql_info GQLTypeInfo
-        var type_mapped bool
-        gql_info, type_mapped = type_gql_map[field.Type]
-        if type_mapped == false {
-          var kind_mapped bool
-          gql_info, kind_mapped = kind_gql_map[field.Type.Kind()]
-          if kind_mapped == false {
-            return fmt.Errorf("Signal has unsupported type/kind: %s/%s", field.Type, field.Type.Kind())
+        } else {
+          config, info, err := ArgumentInfo(ext, field, gv_tag)
+          if err != nil {
+            return err
           }
+          args[gv_tag] = config
+          arg_info = append(arg_info, info)
         }
-
-        args[gv_tag] = &graphql.ArgumentConfig{
-          Type: gql_info.Type,
-        }
-        arg_info = append(arg_info, StructFieldInfo{
-          gv_tag,
-          field.Type,
-          &gql_info,
-          field.Index,
-        })
       }
     }
   }
@@ -161,7 +129,7 @@ func (ext *GQLExtContext) AddSignalMutation(name string, send_id_key string, sig
       return nil, err
     }
 
-    signal, err := SignalFromArgs(signal_type, arg_info, p.Args, id_index, direction_index)
+    signal, err := SignalFromArgs(ctx.GQLContext, signal_type, arg_info, p.Args, id_index, direction_index)
     if err != nil {
       return nil, err
     }
diff --git a/serialize.go b/serialize.go
index f22002f..1a0f4b1 100644
--- a/serialize.go
+++ b/serialize.go
@@ -106,6 +106,7 @@ var (
   ACLSignalType            = NewSignalType("ACL")
   AddSubGroupSignalType    = NewSignalType("ADD_SUBGROUP")
   RemoveSubGroupSignalType = NewSignalType("REMOVE_SUBGROUP")
+  StoppedSignalType        = NewSignalType("STOPPED")
 
   MemberOfPolicyType      = NewPolicyType("USER_OF")
   RequirementOfPolicyType = NewPolicyType("REQUIEMENT_OF")
@@ -152,6 +153,7 @@ var (
   PendingACLType       = NewSerializedType("PENDING_ACL")
   PendingSignalType    = NewSerializedType("PENDING_SIGNAL")
   TimeType             = NewSerializedType("TIME")
+  DurationType         = NewSerializedType("DURATION")
   ResponseType         = NewSerializedType("RESPONSE")
   StatusType           = NewSerializedType("STATUS")
   TreeType             = NewSerializedType("TREE")