/// <summary>
/// Creates and adds one or more MonitoredItems to a Subscription.
/// </summary>
/// <param name="client">A instance of <see cref="ISessionClient"/>.</param>
/// <param name="request">A <see cref="CreateMonitoredItemsRequest"/>.</param>
/// <returns>A <see cref="Task"/> representing the asynchronous operation that returns a <see cref="CreateMonitoredItemsResponse"/>.</returns>
public static async Task<CreateMonitoredItemsResponse> CreateMonitoredItemsAsync(this ISessionClient client, CreateMonitoredItemsRequest request)
{
if (request == null)
{
throw new ArgumentNullException("request");
}
return (CreateMonitoredItemsResponse)await client.RequestAsync(request).ConfigureAwait(false);
}
/// <summary>
/// Creates new subscriptions on the server.
/// </summary>
/// <param name="cancellationToken">A cancellation token. </param>
/// <returns>A task.</returns>
private async Task CreateNewSubscriptionsAsync(CancellationToken cancellationToken = default(CancellationToken))
{
var subscriptionsChanged = new AsyncAutoResetEvent();
var handler = new NotifyCollectionChangedEventHandler((s, e) => subscriptionsChanged.Set());
this.Subscriptions.CollectionChanged += handler;
try
{
while (!cancellationToken.IsCancellationRequested)
{
foreach (var subscription in this.Subscriptions)
{
if (subscription.Id == 0)
{
try
{
// create the subscription.
var subscriptionRequest = new CreateSubscriptionRequest
{
RequestedPublishingInterval = subscription.PublishingInterval,
RequestedMaxKeepAliveCount = subscription.KeepAliveCount,
RequestedLifetimeCount = subscription.LifetimeCount > 0 ? subscription.LifetimeCount : (uint)(this.SessionTimeout / subscription.PublishingInterval),
PublishingEnabled = false, // initially
Priority = subscription.Priority
};
var subscriptionResponse = await this.CreateSubscriptionAsync(subscriptionRequest);
var id = subscription.Id = subscriptionResponse.SubscriptionId;
// add the items.
if (subscription.MonitoredItems.Count > 0)
{
var items = subscription.MonitoredItems.ToList();
var requests = items.Select(m => new MonitoredItemCreateRequest { ItemToMonitor = new ReadValueId { NodeId = m.NodeId, AttributeId = m.AttributeId, IndexRange = m.IndexRange }, MonitoringMode = m.MonitoringMode, RequestedParameters = new MonitoringParameters { ClientHandle = m.ClientId, DiscardOldest = m.DiscardOldest, QueueSize = m.QueueSize, SamplingInterval = m.SamplingInterval, Filter = m.Filter } }).ToArray();
var itemsRequest = new CreateMonitoredItemsRequest
{
SubscriptionId = id,
ItemsToCreate = requests,
};
var itemsResponse = await this.CreateMonitoredItemsAsync(itemsRequest);
for (int i = 0; i < itemsResponse.Results.Length; i++)
{
var item = items[i];
var result = itemsResponse.Results[i];
item.ServerId = result.MonitoredItemId;
if (StatusCode.IsBad(result.StatusCode))
{
Log.Warn($"Error response from MonitoredItemCreateRequest for {item.NodeId}. {result.StatusCode}");
}
}
}
// start publishing.
if (subscription.PublishingEnabled)
{
var modeRequest = new SetPublishingModeRequest
{
SubscriptionIds = new[] { id },
PublishingEnabled = true,
};
var modeResponse = await this.SetPublishingModeAsync(modeRequest);
}
}
catch (ServiceResultException ex)
{
Log.Warn($"Error creating subscription '{subscription.GetType().Name}'. {ex.Message}");
}
}
}
await subscriptionsChanged.WaitAsync().WithCancellation(cancellationToken);
}
}
catch (OperationCanceledException)
{
}
finally
{
this.Subscriptions.CollectionChanged -= handler;
}
}