Introduction
The article is about creating the
SMS messaging framework to allow user to send SMS to their application
subscribers using Twilio REST Api. It provides a lot boilerplate code for
someone to quickly get the task done.
Background
I got a task to develop a SMS
messaging framework using TWILIO api. Most of the things at my end were quite
easy to write however things related to TWILIO were missing in most of the
forums I searched and there were days of interaction with TWILIO support member
to get the resolutions. That is why I thought to write this article in order to
save time for others.
Prerequisites
This article requires knowledge
about VS 2010, WCF REST Service and MSMQ.
Let us start developing the SMS
inbound and outbound messaging framework using the TWILIO API. First of all you
need to buy an account with TWILIO or use Trial account. They will give you a
number which will be used for sending and receiving the messages. Also, you
will receive the AccountId and Auth token to be used to access the TWILIO
API.
OK, now so this framework contains
the following components:
- Outbound Message queue to persist the messages sent from you application.
- Windows service to poll the message queue and send the SMS to the interested parties.
- REST API to collect the response received to the SMS send from your application.
- Inbound Message queue to collect the response messages.
- Windows service to process the inbound messages.
Creating
Queues
I am assuming you have the queues
installed on your machine otherwise you can install it from Windows Components.
Create a queue in the following manner (on Windows 7 OS):
Go to Administrative Tools -> Computer Management ->
Services and Applications -> Message Queuing -> Private Queues:
If we enabled the Journaling then we can audit the
messages.
[Serializable]
public class MessageDTO
{
public MessageDTO(){}
public Guid MessageGUID{ set; get; }
public string To { set; get; } //Phone number to whom message need to send
public string Subject { set; get; }
public string Body { set; get; }
public string From { set; get; } //Phone number from whom message need to send
public DateTime CreatedOn { set; get; }
public DateTime SentOn { set; get; }
}
Utility.cs
Now you need the function that will push the messages in the outbound SMS
queue (smsoutq). This function which can be put in Utility.cs class to be
reusable, is quite easy and can be used for pushing both inbound and outbound
messages in their respective queues as follows: public class Utility
{
private static string smsOutQueuePath = ".\private$\smsoutq";
private static string smsInQueuePath = ".\private$\smsinq";
private static Message SetMessageProperties(Message objMsg)
{
objMsg.Recoverable = true;
objMsg.UseDeadLetterQueue = true;
objMsg.UseJournalQueue = true;
objMsg.Formatter = new BinaryMessageFormatter();
return objMsg;
}
public static MessageQueue GetMessageQueue(string queuePath)
{
MessageQueue msgQ = null;
try
{
if(!MessageQueue.Exists(queuePath))
{
msgQ = MessageQueue.Create(queuePath);
}
msgQ = new MessageQueue(queuePath, QueueAccessMode.SendAndReceive);
msgQ.Formatter = new BinaryMessageFormatter();
msgQ.DefaultPropertiesToSend.UseJournalQueue = true;
msgQ.DefaultPropertiesToSend.Recoverable = true; //Messages remain if server goes down
msgQ.DefaultPropertiesToSend.UseDeadLetterQueue = true;
msgQ.MessageReadPropertyFilter.SetAll();
}
catch (Exception ex)
{
//your exception logging code
}
return msgQ;
}
public static bool PostToSMSQueue(MessageDTO objMsg, string direction = Constants.MESSAGE_DIRECTION_OUT)
{
bool success = false;
try
{
Message objMessage = new Message();
objMessage = SetMessageProperties(objMessage);
objMessage.Body = objMsg;
MessageQueue msgQ = null;
if(direction == Constants.MESSAGE_DIRECTION_OUT)
msgQ = GetMessageQueue(smsOutQueuePath);
else
msgQ = GetMessageQueue(smsInQueuePath);
msgQ.Send(objMessage);
success = true;
}
catch (Exception ex)
{
//your exception logging code
}
return success;
}
public static NameValueCollection ConvertUrlStringToNSCollection(string strUri)
{
NameValueCollection nsCol = new NameValueCollection();
if(!String.IsNullOrEmpty(strUri))
{
try
{
int endPos = 0;
string[] messageArray = null;
messageArray = strUri.Split('&');
for(int count = 0; count < messageArray.Length; count++)
{
endPos = messageArray[count].LastIndexOf('=');
nsCol.Add(messageArray[count].Substring(0, endPos),
messageArray[count].Substring(endPos + 1, messageArray[count].Length - (endPos + 1)));
}
}
catch(Exception ex)
{
throw ex;
}
}
return nsCol;
}
}
Creating
OutboundMsgPoller Service to Send Message to TWILIO
Now
you have to write the windows service (OutboundMsgPoller) which will read the
messages to the desired parties at some defined time interval and pick the
messages and sent them to TWILO using their API to be sent further. Note the
code will be same for the ReponseProcessor (Windows service to process the
received responses, read inline comments below), so you can reuse it.
public partial class OutboundMsgPoller : ServiceBase
{
private static string smsOutQueuePath = ".\private$\smsoutq";
private static string accountSID = string.Empty;
private static string authToken = string.Empty;
private static string callbackURL = string.Empty;
private Thread m_oPollingThread = null;
private bool shallRun = false;
protected override void OnStart(string[] args)
{
try
{
this.EventLog.WriteEntry("OutboundMessagePoller service started successfully", EventLogEntryType.Information);
shallRun = true;
if (m_oPollingThread == null)
m_oPollingThread = new Thread(SendMessage);
m_oPollingThread.IsBackground = false;
m_oPollingThread.Start();
}
catch (Exception ex)
{
//your logging code
}
}
protected override void OnStop()
{
this.EventLog.WriteEntry("OutboundMessagePoller service is OnStop.", EventLogEntryType.Information);
}
private void SendMessage()
{
IList lstMsg = new List();
int pollInterval = 0;
MessageQueue queue = new MessageQueue(smsOutQueuePath, QueueAccessMode.SendAndReceive);
accountSID = "Your Account ID";
authToken = "Your Auth Token";
callbackURL = string.Empty;//in case you want to collect the message status then you can specify a url for your application where TWILIO can POST the status.
do
{
try
{
using (MessageEnumerator messageEnumerator = queue.GetMessageEnumerator2())
{
while (messageEnumerator.MoveNext(new TimeSpan(0, 0, 1)))
{
Message msg = queue.ReceiveById(messageEnumerator.Current.Id, new TimeSpan(0, 0, 1));
lstMsg.Add(msg);
}
}
queue.Close();
if (lstMsg != null && lstMsg.Count > 0)
{
//for OutboundMsgPoller service
this.SendMessageToTwilio(lstMsg, accountSID, authToken, callbackURL);
//for ReponseProcessor service, you have to write your own method
YourMethod(lstMsg);
}
lstMsg.Clear();
//Wait...
{
pollInterval = 30000; //time in milliseconds, can be made configurable
}
Thread.Sleep(pollInterval);
}
catch (Exception ex)
{
shallRun = false;
//your logging code
}
} while (shallRun);
}
private void SendMessageToTwilio(IList objMessage, string accountSID, string authToken, string callbackURL)
{
try
{
if (objMessage != null && objMessage.Count > 0)
{
// instantiate a new Twilio Rest Client
var client = new TwilioRestClient(accountSID, authToken);
// iterate over message
foreach (Message ms in objMessage)
{
ms.Formatter = new BinaryMessageFormatter();//this is important
if (ms.Body != null)
{
var objTw = client.SendSmsMessage(((MessageDTO)ms.Body).From, ((MessageDTO)ms.Body).To, ((MessageDTO)ms.Body).Body, callbackURL);
if (objTw.RestException != null)// this is important
{
throw new Exception("SendMessageToTwilio - Twilio Error Code - " + objTw.RestException.Code + "|| Error Message - " + objTw.RestException.Message);
}
else
{
//Update the SMSID received from TWILIO in your DB or other appropriate repository.
}
}
}
}
}
catch (Exception ex)
{
//your logging code
}
}
}
Creating
REST Service to Collect TWILIO Responses
In
case you don’t have please install the install the WCF REST template from given
link: http://visualstudiogallery.msdn.microsoft.com/fbc7e5c1-a0d2-41bd-9d7b-e54c845394cd
Once
you install it, create a new project using this template as follows:
TWILIO
Response Class
You
will be needing to create a Twilio Response class as follows:
[Serializable]// this is important
public class TwilioRespDTO
{
public TwilioRespDTO(){}
public string SmsSid { get; set; }
public string AccountSid { get; set; }
public string From { get; set; }
public string To { get; set; }
public string Body { get; set; }
}
Response
Collection REST API
[ServiceContract]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall)]
// NOTE: If the service is renamed, remember to update the global.asax.cs file
public class Responder
{
[WebInvoke(UriTemplate = "response/sms", Method = "POST")]
//IMPORTANT: response/sms is the part of the uri you will register with Twilio account for getting responses.
public void GetTwilioSMSResponse(Stream sr)
{
if (sr != null)
{
try
{
string postData = string.Empty;
NameValueCollection nsCol = new NameValueCollection();
using (StreamReader srt = new StreamReader(sr))
{
postData = srt.ReadToEnd();
}
nsCol = Utility.ConvertUrlStringToNSCollection(postData);
if (nsCol != null && nsCol.Count > 0)
{
TwilioResponseDTO objTw = new TwilioResponseDTO();
objTw = CreateTwilioResponseObject(nsCol);
Utility.PostToSMSQueue(objResp, Constants.MESSAGE_DIRECTION_IN);
}
}
catch (Exception ex)
{
//your error handling code here
}
}
}
private TwilioResponseDTO CreateTwilioResponseObject(NameValueCollection nsCol)
{
MethodInfo objMethod = (MethodInfo)MethodBase.GetCurrentMethod();
TwilioResponseDTO objTw = new TwilioResponseDTO();
objTw.SmsSid = nsCol.Get("SmsId");
objTw.AccountSid = nsCol.Get("AccountId");
objTw.From = HttpUtility.UrlDecode(nsCol.Get("From"));
objTw.To = HttpUtility.UrlDecode(nsCol.Get("To"));
objTw.Body = nsCol.Get("Body");
return objTw;
}
}
Conclusion
I hope you enjoyed reading about this article as much as I enjoyed writing it.
I also hope that it will relieve you from writing boilerplate code and allow
you to concentrate on the task at hand instead. Feel free to borrow the code
and use it for your needs.
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