subscription: add ModifySubscription functionality

closes #713 Signed-off-by: Jack Chen <jack@iotechsys.com>
gopcua · Jan 7, 2025 · 0b636c4 · 0b636c4
1 parent a958e31
commit 0b636c4
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Showing 3 changed files with 44 additions and 1 deletion.
diff --git a/README.md b/README.md
@@ -241,7 +241,7 @@ Here is the current set of supported services. For low-level access use the clie
 |                             | SetMonitoringMode             | Yes    | Yes    |              |
 |                             | SetTriggering                 |        |        |              |
 | Subscription Service Set    | CreateSubscription            | Yes    | Yes    |              |
-|                             | ModifySubscription            |        |        |              |
+|                             | ModifySubscription            | Yes    |        |              |
 |                             | SetPublishingMode             |        |        |              |
 |                             | Publish                       | Yes    | Yes    |              |
 |                             | Republish                     |        |        |              |

diff --git a/examples/subscribe/subscribe.go b/examples/subscribe/subscribe.go
@@ -97,6 +97,14 @@ func main() {
 		log.Fatal(err)
 	}
 
+	// Uncomment the following to try modifying the subscription
+	//var params opcua.SubscriptionParameters
+	//params.Interval = time.Millisecond * 2000
+	//_, err = sub.ModifySubscription(ctx, params)
+	//if err != nil {
+	//	log.Fatal(err)
+	//}
+
 	// read from subscription's notification channel until ctx is cancelled
 	for {
 		select {

diff --git a/subscription.go b/subscription.go
@@ -31,6 +31,7 @@ type Subscription struct {
 	RevisedMaxKeepAliveCount  uint32
 	Notifs                    chan<- *PublishNotificationData
 	params                    *SubscriptionParameters
+	paramsMu                  sync.Mutex
 	items                     map[uint32]*monitoredItem
 	itemsMu                   sync.Mutex
 	lastSeq                   uint32
@@ -111,6 +112,40 @@ func (s *Subscription) delete(ctx context.Context) error {
 	}
 }
 
+func (s *Subscription) ModifySubscription(ctx context.Context, params SubscriptionParameters) (*ua.ModifySubscriptionResponse, error) {
+	stats.Subscription().Add("ModifySubscription", 1)
+
+	params.setDefaults()
+	req := &ua.ModifySubscriptionRequest{
+		SubscriptionID:              s.SubscriptionID,
+		RequestedPublishingInterval: float64(params.Interval.Milliseconds()),
+		RequestedLifetimeCount:      params.LifetimeCount,
+		RequestedMaxKeepAliveCount:  params.MaxKeepAliveCount,
+		MaxNotificationsPerPublish:  params.MaxNotificationsPerPublish,
+		Priority:                    params.Priority,
+	}
+
+	var res *ua.ModifySubscriptionResponse
+	err := s.c.Send(ctx, req, func(v ua.Response) error {
+		return safeAssign(v, &res)
+	})
+
+	if err != nil {
+		return nil, err
+	}
+
+	// update subscription parameters
+	s.paramsMu.Lock()
+	s.params = &params
+	s.paramsMu.Unlock()
+	// update revised subscription parameters
+	s.RevisedPublishingInterval = time.Duration(res.RevisedPublishingInterval) * time.Millisecond
+	s.RevisedLifetimeCount = res.RevisedLifetimeCount
+	s.RevisedMaxKeepAliveCount = res.RevisedMaxKeepAliveCount
+
+	return res, nil
+}
+
 func (s *Subscription) Monitor(ctx context.Context, ts ua.TimestampsToReturn, items ...*ua.MonitoredItemCreateRequest) (*ua.CreateMonitoredItemsResponse, error) {
 	stats.Subscription().Add("Monitor", 1)
 	stats.Subscription().Add("MonitoredItems", int64(len(items)))