property EventsCallMode: TScEventCallMode; default ecAsynchronous;
The EventsCallMode property determines how the OnAsyncReceiveData and OnAsyncError event handlers will be called. The thing is that data coming from the client is processed in a separate thread of the TLS connection. And the event handlers call can occur in a different way to synchronize with the main application thread.
The default value is the ecAsynchronous mode when events are added to a queue and then asynchronously synchronized from this queue with the main thread. This allows not slowing down the thread in which events occur and at the same time calling the event handlers in the main thread.
When setting the property to the ecSynchronous value, the event call be immediately synchronized with the main thread.
When setting the property to the ecDirectly value, there is no synchronization with the main thread.