C# using asynchronous method to send message back to the other application

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Hi, I developed a POST() method to be called from a third-party application to call this api and now we are tweaking this a bit to copy the datastream and release the call with success message from third-party application and do the downstream processing asynchronously. Could you please guide me through this. Thank you in advance.

What I have tried:

public class DataController : Controller
    {
        private IList<string> errors = new List<string>();

        [HttpPost]
        [Route("data/import", Name = "DataImport")]
        public IActionResult Post()
        {
            var rawdata = ConvertToByteArray(Request.Body); 
            var rdrec = Encoding.UTF8.GetString(content).Split(new string[] { Environment.NewLine, @"\r" }, StringSplitOptions.None).ToList();
            
            Task.Run(() => importdata(rdrec)); //Trying to run asynchronously to send message back to the third party client.
			
            if (errors.Count == 0)
                return Ok("POST");
            else
                return Ok(errors);
        }

        private void importdata(IList<string> lines)
        {
            //string connectionString = @"Data Source=localhost;Initial Catalog=TEST_DB;Integrated Security=True";
			string connectionString = ConfigurationManager.ConnectionStrings["SQLDBCONN"].ConnectionString; // Added this to appsettings.json file and get null reference error in ASP.net core; works fine in ASP.net web api
            var message = "";

            var Data = from line in lines
                        let data = line.Split(',')
                        select new filedata
                        {
                            ID = data[0],
                            Type = data[1],
                            Status = data[2],
                            Description = data[3]
                        };               

            using (SqlConnection sqldbConnection = new SqlConnection(connectionString))
            {
                        sqldbConnection.Open();                       
                            foreach (var i in Data)
                            {
                                try
                                {
                                    using (SqlCommand cmd = new SqlCommand("INSERT INTO [dbo].[testImport] ([ID], [Type], [Status], [Description]) VALUES (@ID, @Type, @Status, @Description)", sqldbConnection))
                                    {
                                        cmd.Parameters.AddWithValue("@ID", i.ID);                                      
                                        cmd.Parameters.AddWithValue("@Type", i.Type);
                                        cmd.Parameters.AddWithValue("@Status", i.Status);
                                        cmd.Parameters.AddWithValue("@Description", i.Description);
                                        cmd.ExecuteNonQuery();
                                    }
                                }
                                catch (Exception ex)
                                {
                                    message = ex.StackTrace;
                                    return (message);
                                }
                            }                     

            }

        }
		
        private byte[] ConvertToByteArray(Stream stream)
        {
            using (MemoryStream ms = new MemoryStream())
            {
                stream.CopyTo(ms);
                return ms.ToArray();
            }
        }		
    }

Posted 23-Aug-19 9:02am

Member 12586110

Updated 27-Aug-19 9:14am

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Afzaal Ahmad Zeeshan 25-Aug-19 12:32pm

What exactly do you mean send the response asynchronously?

Member 12586110 25-Aug-19 13:51pm

Hi Afzaal Ahmad Zeeshan, Thanks very much for your response. I meant instead of waiting for the table insertion to complete, how to send a success response as soon as data stream is copied into memory and table insertion is done asynchronously.

Regards

2 solutions

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Richard Deeming · Answer 1 · 2019-08-27T09:14:00

Start by making your code properly asynchronous, and wrapping the insert commands in a transaction.

ASP.NET Core:

C#

public class DataController : Controller
{
    [HttpPost]
    [Route("data/import", Name = "DataImport")]
    public async Task<IActionResult> Post()
    {
        try
        {
            using (var reader = new StreamReader(Request.Body, Encoding.UTF8))
            {
                await ImportDataAsync(reader);
                return Ok("POST");
            }
        }
        catch (Exception ex)
        {
            return BadRequest(ex.Message);
        }
    }
    
    private async Task ImportData(TextReader input)
    {
        string connectionString = ConfigurationManager.ConnectionStrings["SQLDBCONN"].ConnectionString;
        const string query = "INSERT INTO [dbo].[testImport] ([ID], [Type], [Status], [Description]) VALUES (@ID, @Type, @Status, @Description)";
        
        using (SqlConnection sqldbConnection = new SqlConnection(connectionString))
        {
            await sqldbConnection.OpenAsync();
            
            using (SqlTransaction transaction = sqldbConnection.BeginTransaction())
            using (SqlCommand cmd = new SqlCommand(query, sqldbConnection, transaction))
            {
                // TODO: Set the correct data types and sizes here:
                var pID = cmd.Parameters.Add("@ID", SqlDbType.Int);
                var pType = cmd.Parameters.Add("@Type", SqlDbType.VarChar);
                var pStatus = cmd.Parameters.Add("@Status", SqlDbType.VarChar);
                var pDescription = cmd.Parameters.Add("@Description", SqlDbType.VarChar);
                
                string line = await input.ReadLineAsync();
                while (line != null)
                {
                    string[] parts = line.Split(',');
                    if (parts.Length < 4) throw new InvalidOperationException($"Invalid line: '{line}'");
                    
                    pID.Value = parts[0];
                    pType.Value = parts[1];
                    pStatus.Value = parts[2];
                    pDescription.Value = parts[3];
                    
                    await cmd.ExecuteNonQueryAsync();
                    
                    line = await input.ReadLineAsync();
                }
                
                transaction.Commit();
            }
        }
    }
}

ASP.NET Web API 2:

C#

public class DataController : ApiController
{
    [HttpPost]
    [Route("data/import", Name = "DataImport")]
    public async Task<IHttpActionResult> Post()
    {
        try
        {
            string content = await Request.Content.ReadAsStringAsync();
            string[] lines = content.Split(Environment.NewLine);
            await ImportDataAsync(lines);
            return Ok("POST");
        }
        catch (Exception ex)
        {
            return BadRequest(ex.Message);
        }
    }
    
    private async Task ImportData(IEnumerable<string> lines)
    {
        string connectionString = ConfigurationManager.ConnectionStrings["SQLDBCONN"].ConnectionString;
        const string query = "INSERT INTO [dbo].[testImport] ([ID], [Type], [Status], [Description]) VALUES (@ID, @Type, @Status, @Description)";
        
        using (SqlConnection sqldbConnection = new SqlConnection(connectionString))
        {
            await sqldbConnection.OpenAsync();
            
            using (SqlTransaction transaction = sqldbConnection.BeginTransaction())
            using (SqlCommand cmd = new SqlCommand(query, sqldbConnection, transaction))
            {
                // TODO: Set the correct data types and sizes here:
                var pID = cmd.Parameters.Add("@ID", SqlDbType.Int);
                var pType = cmd.Parameters.Add("@Type", SqlDbType.VarChar);
                var pStatus = cmd.Parameters.Add("@Status", SqlDbType.VarChar);
                var pDescription = cmd.Parameters.Add("@Description", SqlDbType.VarChar);
                
                foreach (string line in lines)
                {
                    string[] parts = line.Split(',');
                    if (parts.Length < 4) throw new InvalidOperationException($"Invalid line: '{line}'");
                    
                    pID.Value = parts[0];
                    pType.Value = parts[1];
                    pStatus.Value = parts[2];
                    pDescription.Value = parts[3];
                    
                    await cmd.ExecuteNonQueryAsync();
                }
                
                transaction.Commit();
            }
        }
    }
}

How you update the calling code to make that asynchronous will depend on which language you're using.

Gerry Schmitz · Answer 2 · 2019-08-25T03:24:00

Solution 1

In your case, the message goes from the "asynch" process to the server, and then to the client; not from the process directly to the client.

Posted 25-Aug-19 3:24am

Gerry Schmitz

Comments

Member 12586110 25-Aug-19 14:01pm

Hi Gerry Schmitz, Thanks very much for your response. Could you please guide how do I make the message go directly from process to the client instead of async process.

Regards