diff --git a/examples/helloworld.yaml b/examples/helloworld.yaml
index 42e2c8cc..34b40e5c 100644
--- a/examples/helloworld.yaml
+++ b/examples/helloworld.yaml
@@ -7,12 +7,9 @@
     - kind: print
       filename: /dev/stdout
   ports:
-    init:
+    begin:
       - name: hello_world
         port: in
-  env:
-    PORT:
-      - data: '{{ .PORT }}'
 
 - kind: step
   name: good_bye
diff --git a/pkg/node/port.go b/pkg/node/port.go
index 48324d88..83fe36ef 100644
--- a/pkg/node/port.go
+++ b/pkg/node/port.go
@@ -9,7 +9,9 @@ import (
 // Commonly used port names.
 const (
 	PortInit  = "init"
+	PortBegin = "begin"
 	PortTerm  = "term"
+	PortFinal = "final"
 	PortIO    = "io"
 	PortIn    = "in"
 	PortOut   = "out"
diff --git a/pkg/symbol/loader.go b/pkg/symbol/loader.go
index 95464a22..d4ab43f9 100644
--- a/pkg/symbol/loader.go
+++ b/pkg/symbol/loader.go
@@ -3,9 +3,9 @@ package symbol
 import (
 	"context"
 	"errors"
-	"github.com/iancoleman/strcase"
 	"reflect"
 
+	"github.com/iancoleman/strcase"
 	"github.com/siyul-park/uniflow/pkg/resource"
 	"github.com/siyul-park/uniflow/pkg/scheme"
 	"github.com/siyul-park/uniflow/pkg/spec"
diff --git a/pkg/symbol/table.go b/pkg/symbol/table.go
index 2c2622fe..786a4ea3 100644
--- a/pkg/symbol/table.go
+++ b/pkg/symbol/table.go
@@ -272,10 +272,13 @@ func (t *Table) load(sb *Symbol) error {
 	linked := t.linked(sb)
 	for _, sb := range linked {
 		if t.active(sb) {
+			if err := t.call(sb, node.PortInit); err != nil {
+				return err
+			}
 			if err := t.loadHooks.Load(sb); err != nil {
 				return err
 			}
-			if err := t.call(sb, node.PortInit); err != nil {
+			if err := t.call(sb, node.PortBegin); err != nil {
 				return err
 			}
 		}
@@ -294,6 +297,9 @@ func (t *Table) unload(sb *Symbol) error {
 			if err := t.unloadHooks.Unload(sb); err != nil {
 				return err
 			}
+			if err := t.call(sb, node.PortFinal); err != nil {
+				return err
+			}
 		}
 	}
 	return nil