diff --git a/pkgs/ioswitch/plan/ops/var.go b/pkgs/ioswitch/plan/ops/var.go
index 962ec4c..973cc59 100644
--- a/pkgs/ioswitch/plan/ops/var.go
+++ b/pkgs/ioswitch/plan/ops/var.go
@@ -1,6 +1,7 @@
 package ops
 
 import (
+	"gitlink.org.cn/cloudream/common/pkgs/ioswitch/dag"
 	"gitlink.org.cn/cloudream/common/pkgs/ioswitch/exec"
 )
 
@@ -21,3 +22,31 @@ func (o *ConstVar) Execute(ctx *exec.ExecContext, e *exec.Executor) error {
 func (o *ConstVar) String() string {
 	return "ConstVar"
 }
+
+type ConstNode struct {
+	dag.NodeBase
+	Value exec.VarValue
+}
+
+func (b *GraphNodeBuilder) NewConst(val exec.VarValue) *ConstNode {
+	node := &ConstNode{
+		Value: val,
+	}
+	b.AddNode(node)
+
+	node.OutputValues().Init(node, 1)
+	return node
+}
+
+func (t *ConstNode) Output() dag.ValueOutputSlot {
+	return dag.ValueOutputSlot{
+		Node:  t,
+		Index: 0,
+	}
+}
+
+func (t *ConstNode) GenerateOp() (exec.Op, error) {
+	return &DropStream{
+		Input: t.Output().Var().VarID,
+	}, nil
+}