Question

I have the following code which send out SMS to the subscribers. However, some SMS were rejected from the SMSGateway because I’m sending too many SMS at one time. So I’m thinking to make a delay in between.

Sending out the SMS like this –

            foreach (DataRow row in dt.Rows)
            {
                //Gets Subscriber number
                smsSender.destinationNum = Convert.ToInt64(row["callerID"]);
                foreach (DataRow articleRow in dtArticle.Rows)
                {
                    //Gets SMS content
                    smsSender.smsMessage = articleRow["news"].ToString();
                    //Then send out the SMS
                    smsSendder.sendSMS();
                }
            }

Please advice because I have no experience with the threads and timers

Answer 1

It would depend on the architecture of the application.

Assuming this is a service-style app, with no user interface, that simply gets data out of the database and sends it to SMS, then Thread.Sleep(…) is fine.

If this app has a user interface, and you’re running this SMS sending code on the UI thread, then Thread.Sleep(…) will block your UI. Actually, smsSender.sendSMS is probably already blocking your UI in this case!

Refactoring so that this code is off the UI thread is the answer. And you can do that simply by using a timer, although you will have to refactor the code so that the result set is cached in a local object and the timer iterates through the set sending one SMS out at a time.

In either case, I hope you don’t have a lock on the database while you’re sending SMSes.