/// <summary>
/// Opens the session with the remote endpoint.
/// </summary>
/// <param name="cancellationToken">A cancellation token.</param>
/// <returns>A task.</returns>
private async Task OpenSessionAsync(CancellationToken cancellationToken = default(CancellationToken))
{
await this.semaphore.WaitAsync(cancellationToken).ConfigureAwait(false);
try
{
if (this.RemoteEndpoint == null)
{
// If specific endpoint is not provided, use discovery to select endpoint with highest
// security level.
try
{
Log.Info($"Discovering endpoints of '{this.discoveryUrl}'.");
var getEndpointsRequest = new GetEndpointsRequest
{
EndpointUrl = this.discoveryUrl,
ProfileUris = new[] { TransportProfileUris.UaTcpTransport }
};
var getEndpointsResponse = await UaTcpDiscoveryClient.GetEndpointsAsync(getEndpointsRequest);
if (getEndpointsResponse.Endpoints == null || getEndpointsResponse.Endpoints.Length == 0)
{
throw new InvalidOperationException($"'{this.discoveryUrl}' returned no endpoints.");
}
this.RemoteEndpoint = getEndpointsResponse.Endpoints.OrderBy(e => e.SecurityLevel).Last();
}
catch (Exception ex)
{
Log.Warn($"Error discovering endpoints of '{this.discoveryUrl}'. {ex.Message}");
throw;
}
}
// throw here to exit state machine.
cancellationToken.ThrowIfCancellationRequested();
try
{
Log.Info($"Opening UaTcpSessionChannel with endpoint '{this.RemoteEndpoint.EndpointUrl}'.");
this.innerChannel = new UaTcpSessionChannel(this.LocalDescription, this.LocalCertificate, this.UserIdentity, this.RemoteEndpoint)
{
SessionTimeout = this.SessionTimeout,
TimeoutHint = this.TimeoutHint,
DiagnosticsHint = this.DiagnosticsHint,
LocalSendBufferSize = this.LocalSendBufferSize,
LocalReceiveBufferSize = this.LocalReceiveBufferSize,
LocalMaxMessageSize = this.LocalMaxMessageSize,
LocalMaxChunkCount = this.LocalMaxChunkCount,
};
await this.innerChannel.OpenAsync(cancellationToken);
}
catch (Exception ex)
{
Log.Warn($"Error opening UaTcpSessionChannel with endpoint '{this.RemoteEndpoint.EndpointUrl}'. {ex.Message}");
throw;
}
}
finally
{
this.semaphore.Release();
}
}
/// <summary>
/// Initializes a new instance of the <see cref="UaTcpSessionClient"/> class.
/// </summary>
/// <param name="localDescription">The <see cref="ApplicationDescription"/> of the local application.</param>
/// <param name="localCertificate">The <see cref="X509Certificate2"/> of the local application.</param>
/// <param name="userIdentity">The user identity or null if anonymous. Supports <see cref="AnonymousIdentity"/>, <see cref="UserNameIdentity"/>, <see cref="IssuedIdentity"/> and <see cref="X509Identity"/>.</param>
/// <param name="remoteEndpoint">The <see cref="EndpointDescription"/> of the remote application. Obtained from a prior call to UaTcpDiscoveryClient.GetEndpoints.</param>
public UaTcpSessionClient(ApplicationDescription localDescription, X509Certificate2 localCertificate, IUserIdentity userIdentity, EndpointDescription remoteEndpoint)
{
this.innerChannel = new UaTcpSessionChannel(localDescription, localCertificate, userIdentity, remoteEndpoint);
this.semaphore = new SemaphoreSlim(1);
}