How can we make asynchronous call to edge hub trigger from a C# edge module ?

Question

The iot edge solution is having 2 modules, first module is a C# module and second is Edgehub trigger module. First module is sending data in a loop to second module. I want the edge hub module to execute asynchronously

        static async Task Main(string[] args)  
                {  
                    _logger = Logger.Factory.CreateLogger

Answer 1

Hi @Satyam Chauhan , there are couple of different issues you are pointing here

1. Make an asynchronous call to IoT Edge Hub trigger module -- We have already achieved this by removing the await key word before making the call to the "SendEventAsync". We
   noticed this evidently when we add a delay in the function, the Edge Hub trigger function gets invoked without waiting for the entire list to iterate. Please note that the C# module function
   does not wait any longer for the Edge Hub trigger function to return the Task and proceeds with iterating the list which indicates that the call is made asynchronously.
2. Can the order of execution be changed on IoT Edge Hub trigger-- Please note that when we send out an event through SendEventAsyc method, the messages will be queued and
   passed along to the receiving end point. Please refer the below image that points to how SendEventAsyc function behaves.
   
   Here is the Code Sample where you can find the above explanation of how the code behaves. Since the events are queued from the C# code module, the processing on the Edge Hub
   trigger will always be sequential.

Hope this clarifies your question. Please let me know if you still have any doubts with regards to this issue.

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Answer 2

static async Task SendMessageToEdgeHubModule(ModuleClient ioTHubModuleClient, List<String> items)

{  

       await Parallel.ForEachAsync(items.ToList(), async (item, token) =>  

       {  

                var messageOut = new Message(Encoding.ASCII.GetBytes(item));  

                await ioTHubModuleClient.SendEventAsync("output1", messageOut);  

       }          

}