Caller interface applies to both units and chains

core/chain.go

@@ -0,0 +1,34 @@
+package core
+
+type (
+	Chain struct {
+		Flow  Flow
+		Links []Caller
+	}
+	Caller interface {
+		Call([]byte) ([]byte, error)
+		Units() []string
+	}
+)
+
+func (c *Chain) Call(data []byte) (resp []byte, err error) {
+	return data, nil
+}
+
+func (c *Chain) Units() []string {
+	// Collecting unique unit names using map
+	units := map[string]*struct{}{}
+	for _, caller := range c.Links {
+		for _, unit := range caller.Units() {
+			units[unit] = nil
+		}
+	}
+
+	// Extracting names to a slice
+	uniq := []string{}
+	for unit, _ := range units {
+		uniq = append(uniq, unit)
+	}
+
+	return uniq
+}

unit/unit.go

@@ -19,9 +19,14 @@ func New(name string) *Unit {
 	}
 }
 
-func (u *Unit) Send(data []byte) (resp []byte, err error) {
-	conn, err := net.DialUnix("unix", nil, &net.UnixAddr{u.socketPath(), "unix"})
-	if err != nil {
+func (u *Unit) Call(data []byte) (resp []byte, err error) {
+	var (
+		addr = &net.UnixAddr{u.socketPath(), "unix"}
+		conn *net.UnixConn
+		buf  bytes.Buffer
+	)
+
+	if conn, err = net.DialUnix("unix", nil, addr); err != nil {
 		fmt.Println("Failed opening socket:", err.Error())
 		return
 	}
@@ -36,14 +41,16 @@ func (u *Unit) Send(data []byte) (resp []byte, err error) {
 		return
 	}
 
-	var respBuf bytes.Buffer
-	if _, err = respBuf.ReadFrom(conn); err != nil {
+	if _, err = buf.ReadFrom(conn); err != nil {
 		fmt.Println("Failed read data from socket:", err.Error())
 		return
 	}
-	resp = respBuf.Bytes()
 
-	return
+	return buf.Bytes(), nil
+}
+
+func (u *Unit) Units() []string {
+	return []string{u.Name}
 }
 
 func (u *Unit) socketPath() string {