diff --git a/src/config/address.go b/src/config/address.go
index ada521245d0427895bff646cffd036314869bae2..13baf5520c2f20a199d3b386f2c6b4415eae1175 100644
--- a/src/config/address.go
+++ b/src/config/address.go
@@ -32,14 +32,16 @@ type ServerUrl struct {
 }
 
 const (
-	MEP_AUTH_APIGW_URL              string = "https://${MEP_IP}:${MEP_APIGW_PORT}/mep/token"
-	MEP_SER_REGISTER_APIGW_URL      string = "https://${MEP_IP}:${MEP_APIGW_PORT}/mep/mec_service_mgmt/v1/applications/${appInstanceId}/services"
-	MEP_SER_QUERY_BY_NAME_APIGW_URL string = "https://${MEP_IP}:${MEP_APIGW_PORT}/mep/mec_service_mgmt/v1/services?ser_name="
-	MEP_HEART_BEAT_APIGW_URL        string = "https://${MEP_IP}:${MEP_APIGW_PORT}"
-	MEP_IP                          string = "${MEP_IP}"
-	MEP_APIGW_PORT                  string = "${MEP_APIGW_PORT}"
+	MepAuthApigwUrl           string = "https://${MEP_IP}:${MEP_APIGW_PORT}/mep/token"
+	MepSerRegisterApigwUrl    string = "https://${MEP_IP}:${MEP_APIGW_PORT}/mep/mec_service_mgmt/v1/applications/${appInstanceId}/services"
+	MepSerQueryByNameApigwUrl string = "https://${MEP_IP}:${MEP_APIGW_PORT}/mep/mec_service_mgmt/v1/services?ser_name="
+	MepHeartBeatApigwUrl      string = "https://${MEP_IP}:${MEP_APIGW_PORT}"
+	MepIp                     string = "${MEP_IP}"
+	MepApigwPort              string = "${MEP_APIGW_PORT}"
 )
 
+var ServerUrlConfig ServerUrl
+
 // Returns server URL
 func GetServerUrl() (ServerUrl, error) {
 
@@ -55,19 +57,19 @@ func GetServerUrl() (ServerUrl, error) {
 	}
 
 	serverUrl.MepServerRegisterUrl = strings.Replace(
-		strings.Replace(MEP_SER_REGISTER_APIGW_URL, MEP_IP, mepIp, 1),
-		MEP_APIGW_PORT, mepApiGwPort, 1)
+		strings.Replace(MepSerRegisterApigwUrl, MepIp, mepIp, 1),
+		MepApigwPort, mepApiGwPort, 1)
 
 	serverUrl.MepAuthUrl = strings.Replace(
-		strings.Replace(MEP_AUTH_APIGW_URL, MEP_IP, mepIp, 1),
-		MEP_APIGW_PORT, mepApiGwPort, 1)
+		strings.Replace(MepAuthApigwUrl, MepIp, mepIp, 1),
+		MepApigwPort, mepApiGwPort, 1)
 
 	serverUrl.MepHeartBeatUrl = strings.Replace(
-		strings.Replace(MEP_HEART_BEAT_APIGW_URL, MEP_IP, mepIp, 1),
-		MEP_APIGW_PORT, mepApiGwPort, 1)
+		strings.Replace(MepHeartBeatApigwUrl, MepIp, mepIp, 1),
+		MepApigwPort, mepApiGwPort, 1)
 
 	serverUrl.MepServiceDiscoveryUrl = strings.Replace(
-		strings.Replace(MEP_SER_QUERY_BY_NAME_APIGW_URL, MEP_IP, mepIp, 1),
-		MEP_APIGW_PORT, mepApiGwPort, 1)
+		strings.Replace(MepSerQueryByNameApigwUrl, MepIp, mepIp, 1),
+		MepApigwPort, mepApiGwPort, 1)
 	return serverUrl, nil
 }
diff --git a/src/controllers/endpointcontroller.go b/src/controllers/endpointcontroller.go
index 2071e170c36d2dea5e2471cdcbc328552dca76b2..b2e5b8740916b64d3141f3b34e16cc418a03b0b7 100644
--- a/src/controllers/endpointcontroller.go
+++ b/src/controllers/endpointcontroller.go
@@ -34,6 +34,7 @@ type Service struct {
 	TransportInfo TransportInfo `yaml:"transportInfo" json:"transportInfo"`
 }
 
+// Transport information of the service.
 type TransportInfo struct {
 	Id          string       `yaml:"id" json:"id"`
 	Name        string       `yaml:"name" json:"name"`
@@ -43,6 +44,7 @@ type TransportInfo struct {
 	Endpoint    EndPointInfo `yaml:"endpoint" json:"endpoint"`
 }
 
+// End point of the service.
 type EndPointInfo struct {
 	Uris        []string              `json:"uris" validate:"omitempty,dive,uri"`
 	Addresses   []EndPointInfoAddress `json:"addresses" validate:"omitempty,dive"`
@@ -58,12 +60,7 @@ func (c *EndpointController) Get() {
 	log.Info("received get endpoint request from app")
 	serName := c.Ctx.Input.Param(":serName")
 
-	server, errGetServer := config.GetServerUrl()
-	if errGetServer != nil {
-		log.Error("Failed to get serviceUrl")
-	}
-
-	url := server.MepServiceDiscoveryUrl + serName
+	url := config.ServerUrlConfig.MepServiceDiscoveryUrl + serName
 
 	requestData := service.RequestData{Data: "", Url: url, Token: &util.MepToken}
 	resBody, errPostRequest := service.SendQueryRequest(requestData)
diff --git a/src/main/main.go b/src/main/main.go
index 8ce7fb8bc609eda224ea02452afd343110032562..0cb0ffd4928157bafc540f387e661d2d1105be7f 100644
--- a/src/main/main.go
+++ b/src/main/main.go
@@ -19,6 +19,7 @@ package main
 import (
 	"github.com/astaxie/beego"
 	log "github.com/sirupsen/logrus"
+	"mep-agent/src/config"
 	"mep-agent/src/controllers"
 	_ "mep-agent/src/router"
 	"mep-agent/src/service"
@@ -35,8 +36,16 @@ func main() {
 		os.Exit(1)
 	}
 
-	if err := util.ValidateAkSk(string(*util.AppConfig["ACCESS_KEY"]), util.AppConfig["SECRET_KEY"]); err != nil {
-		log.Error("the input param of ak or sk do not pass the validation")
+	service.TlsConf, err = service.TlsConfig()
+	if err != nil {
+		log.Error("Failed to set TLS Configurations")
+		util.ClearMap()
+		os.Exit(1)
+	}
+
+	config.ServerUrlConfig, err = config.GetServerUrl()
+	if err != nil {
+		log.Error("Failed to get server url Configurations")
 		util.ClearMap()
 		os.Exit(1)
 	}
diff --git a/src/model/instance.go b/src/model/instance.go
index 0729b5ae68135abf95bdd0e7d6924a7644b3888c..c897ac9f4680e1f861cba33b7a413eea6a7fc980 100644
--- a/src/model/instance.go
+++ b/src/model/instance.go
@@ -22,6 +22,7 @@ type AppInstanceInfo struct {
 	SerAvailabilityNotificationSubscriptions []SerAvailabilityNotificationSubscription `yaml:"serAvailabilityNotificationSubscriptions" json:"serAvailabilityNotificationSubscriptions"`
 }
 
+// Service Information to be registered.
 type ServiceInfoPost struct {
 	SerName           string         `yaml:"serName" json:"serName"`
 	SerCategory       CategoryRef    `yaml:"serCategory" json:"serCategory"`
@@ -53,6 +54,7 @@ type CategoryRef struct {
 
 type ServiceState string
 
+// Transport Information of the service to be registered.
 type TransportInfo struct {
 	Id               string           `yaml:"id" json:"id"`
 	Name             string           `yaml:"name" json:"name"`
@@ -67,6 +69,7 @@ type TransportInfo struct {
 
 type TransportType string
 
+// Endpoint of the service to be registered.
 type EndPointInfo struct {
 	Addresses   []EndPointInfoAddress `yaml:"addresses" json:"addresses"`
 }
diff --git a/src/service/heart.go b/src/service/heart.go
index b949fc901ef193baf5b73868915ad1929ba44734..b5d6fb25178cb46d51506de213414f2f93a1c159 100644
--- a/src/service/heart.go
+++ b/src/service/heart.go
@@ -22,7 +22,6 @@ import (
 	log "github.com/sirupsen/logrus"
 	"mep-agent/src/config"
 	"mep-agent/src/model"
-	"time"
 	"mep-agent/src/util"
 )
 
@@ -36,11 +35,6 @@ type ServiceLivenessUpdate struct {
 	State string `json:"state"`
 }
 
-// Sleeps for an hour
-func Heart() {
-	time.Sleep(time.Hour)
-}
-
 // Send service heartbeat to MEP
 func HeartBeatRequestToMep(serviceInfo model.ServiceInfoPost) {
 
@@ -48,14 +42,10 @@ func HeartBeatRequestToMep(serviceInfo model.ServiceInfoPost) {
 	data, errJsonMarshal := json.Marshal(heartBeatRequest)
 	if errJsonMarshal != nil {
 		log.Error("Failed to marshal service info to object")
+		return
 	}
 
-	server, errGetServer := config.GetServerUrl()
-	if errGetServer != nil {
-		log.Error("Failed to get serviceUrl")
-	}
-
-	url := server.MepHeartBeatUrl + serviceInfo.Links.Self.Liveness
+	url := config.ServerUrlConfig.MepHeartBeatUrl + serviceInfo.Links.Self.Liveness
 	var heartBeatData = HeartBeatData{data: string(data), url: url, token: &util.MepToken}
 	_, errPostRequest := SendHeartBeatRequest(heartBeatData)
 	if errPostRequest != nil {
diff --git a/src/service/register.go b/src/service/register.go
index ff2affc0c5c7f46f1aa183e05ead3473ae177591..8f5ef92d0c80106f4cc5da997aee836ac0e4d3af 100644
--- a/src/service/register.go
+++ b/src/service/register.go
@@ -56,16 +56,12 @@ func RegisterToMep(conf model.AppInstanceInfo, wg *sync.WaitGroup) ([]model.Serv
 		return nil, errors.New("Registration of service failed, cannot contain more than " +
 			strconv.Itoa(MAX_SERVICE_COUNT) + " services in a single request")
 	}
-	server, errGetServer := config.GetServerUrl()
-	if errGetServer != nil {
-		return nil, errGetServer
-	}
 
 	if util.ValidateUUID(appInstanceId) != nil {
 		return nil, errors.New("validate appInstanceId failed")
 	}
 
-	url := strings.Replace(server.MepServerRegisterUrl, "${appInstanceId}", appInstanceId, 1)
+	url := strings.Replace(config.ServerUrlConfig.MepServerRegisterUrl, "${appInstanceId}", appInstanceId, 1)
 
 	for _, serviceInfo := range serviceInfos {
 		data, errJsonMarshal := json.Marshal(serviceInfo)
diff --git a/src/service/request.go b/src/service/request.go
index 8bf9e85320d588b268da9c361a164ace12b3ff4e..cb9b1db4615d6f8cab7310dc7a1262a58254ca4c 100644
--- a/src/service/request.go
+++ b/src/service/request.go
@@ -35,6 +35,8 @@ import (
 
 const AUTHORIZATION = "Authorization"
 
+var TlsConf *tls.Config
+
 type RequestData struct {
 	Token *model.TokenModel
 	Data  string
@@ -148,14 +150,9 @@ func PostTokenRequest(param string, url string, auth model.Auth) (string, error)
 
 // do request
 func DoRequest(req *http.Request) (*http.Response, error) {
-	config, err := TlsConfig()
-	if err != nil {
-		log.Error("Unable to send request")
-		return nil, err
-	}
 
 	tr := &http.Transport{
-		TLSClientConfig: config,
+		TLSClientConfig: TlsConf,
 	}
 	client := &http.Client{Transport: tr}
 
@@ -181,6 +178,7 @@ func TlsConfig() (*tls.Config, error) {
 	if util.ValidateDomainName(domainName) != nil {
 		return nil, errors.New("Domain name validation failed")
 	}
+
 	return &tls.Config{
 		ServerName:         domainName,
 		MinVersion:         tls.VersionTLS12,
diff --git a/src/service/token.go b/src/service/token.go
index 2a12d4e219aef5cc79f6df950bd339bfee50e0ce..a5e1c14543331765a1903e9a186da175de3d13f7 100644
--- a/src/service/token.go
+++ b/src/service/token.go
@@ -29,14 +29,9 @@ import (
 
 // Request token from mep_auth
 func GetMepToken(auth model.Auth) error {
-	// get request url
-	server, errGetServer := config.GetServerUrl()
-	if errGetServer != nil {
-		return errGetServer
-	}
 
 	// construct http request and send
-	resp, errPostRequest := PostTokenRequest("", server.MepAuthUrl, auth)
+	resp, errPostRequest := PostTokenRequest("", config.ServerUrlConfig.MepAuthUrl, auth)
 	if errPostRequest != nil {
 		return errPostRequest
 	}
diff --git a/src/util/util.go b/src/util/util.go
index 50e95755b6bbf237f2b66579dbcbd364dfcc3fd7..469764fd8862f8830f25ffba2902187d7e1dd89c 100644
--- a/src/util/util.go
+++ b/src/util/util.go
@@ -75,29 +75,31 @@ func ReadTokenFromEnvironment() error {
 	defer os.Unsetenv(AK)
 	defer os.Unsetenv(SK)
 
-	if len(os.Getenv(AK)) == 0 || len(os.Getenv(SK)) == 0 {
+	ak := os.Getenv(AK)
+	sk := os.Getenv(SK)
+
+	if len(ak) == 0 || len(sk) == 0 {
 		err := errors.New("ak and sk keys should be set in env variable")
 		log.Error("Keys should not be empty")
 		return err
 	}
-	ak := []byte(os.Getenv(AK))
-	AppConfig["ACCESS_KEY"] = &ak
-	sk := []byte(os.Getenv(SK))
-	AppConfig["SECRET_KEY"] = &sk
-	log.Infof("Ak: %s", ak)
+	akByte := []byte(ak)
+	AppConfig["ACCESS_KEY"] = &akByte
+	skByte := []byte(sk)
+	AppConfig["SECRET_KEY"] = &skByte
+	log.Infof("Ak: %s", akByte)
 	return nil
 }
 
 //Read application instanceId
 func GetAppInstanceId() (string, error) {
 	defer os.Unsetenv(APPINSTID)
-	if len(os.Getenv(APPINSTID)) == 0 {
+	instId := os.Getenv(APPINSTID)
+	if len(instId) == 0 {
 		err := errors.New("appInstanceId should be set in env variable")
 		log.Error("appInstanceId must be set")
 		return "", err
 	}
 
-	instId := os.Getenv(APPINSTID)
-	AppInstanceId = instId
-	return AppInstanceId, nil
+	return instId, nil
 }
diff --git a/src/util/validation.go b/src/util/validation.go
index a7853bb376111985dde25fb4ac828cce106ac5c9..a0a104e3853cfcb579eddd84eac45d9b7b99f50c 100644
--- a/src/util/validation.go
+++ b/src/util/validation.go
@@ -25,10 +25,10 @@ import (
 )
 
 const (
-	IP_PATTERN   string = `^[a-z][a-z-]{0,126}[a-z]$`
+	//IP_PATTERN   string = `^[a-z][a-z-]{0,126}[a-z]$`
 	PORT_PATTERN string = `^([1-9]|[1-9]\d{1,3}|[1-5]\d{4}|6[0-4]\d{3}|65[0-4]\d{2}|655[0-2]\d|6553[0-5])$`
-	AK_PATTERN   string = `^\w{20}$`
-	SK_PATTERN   string = `^\w{64}$`
+	//AK_PATTERN   string = `^\w{20}$`
+	//SK_PATTERN   string = `^\w{64}$`
 	DOMAIN_PATTERN string = `^([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])(\.([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\-]{0,61}[a-zA-Z0-9]))*$`
 	DNS_PATTERN string = `^(([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\-]*[a-zA-Z0-9])\.)*([A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9\-]*[A-Za-z0-9])$`
 	maxHostNameLen = 253
@@ -37,15 +37,20 @@ const (
 // Validates Ip address
 func ValidateDns(ip string) error {
 	ipv := net.ParseIP(ip)
+	if ipv != nil && (ipv.IsMulticast() || ipv.Equal(net.IPv4bcast)) {
+		return errors.New("invalid dns ip")
+	}
+
 	if ipv != nil {
 		return nil
 	}
+
 	return ValidateByPattern(DNS_PATTERN, ip)
 }
 
 // Validates domain name
 func ValidateDomainName(name string) error {
-	if len(name) > maxHostNameLen {
+	if len(name) == 0 || len(name) > maxHostNameLen {
 		return errors.New("validate domain name failed")
 	}
 	return ValidateByPattern(DOMAIN_PATTERN, name)
@@ -77,29 +82,3 @@ func ValidateUUID(id string) error {
 	return nil
 }
 
-// Validates SK
-func ValidateSkByPattern(pattern string, param *[]byte) error {
-	res, errMatch := regexp.Match(pattern, *param)
-	if errMatch != nil {
-		return errMatch
-	}
-	if !res {
-		return errors.New("validate failed")
-	}
-	return nil
-}
-
-// Validates AK and SK
-func ValidateAkSk(ak string, sk *[]byte) error {
-	_ = ak
-	_ = sk
-	/*
-	err := ValidateByPattern(AK_PATTERN, ak)
-	if err != nil {
-	    return err
-	}
-	err = ValidateSkByPattern(SK_PATTERN, sk)
-	return err
-	*/
-	return nil
-}