May 8, 2009
@ 10:59 PM
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Twitterjecting

Apropos the Blogjecting  Watchdog pattern,  In addition to blogging I recently added to our system the ability to twitter. I am using Tweet# from DimeBrain (thanks Mark Nijhof for the tip via twitter).

Tweet# makes using tweeter really simple (I included the code below in case you find it useful).

The tweeter sender is part of a PostOffice service (I thought that it would be problematic to present it as SpamServer which was its original name :) ).

image Update 11/05 Here it is working on our staging environment :)

A few points about our design in general that are interesting in this regards are

  • The PostOffice is a “Server” type service – we have 3 types of services: server which has one instance per node, channel which has multiple instances per node and algorithmic which has one instance per core
  • The PostOffice implements a pattern I call “Legacy Bridge” – which is basically an SOA version of an adapter+facade in OO terms. The post office supports the events (over WCF) mechanism we have in our system from one side  and connects to external systems (SMS, coupons and twitter) on the other. The PostOffice, basically contains an Edge Component which accepts the requests and funnels them to *Sender classes that interact with the external systems.
  • from contract design perspective – The events I added into the system are StatusEvent and AdminStatusEvent (and not TwitterEvent and DirectMessageEvent). this is better, in my opinion, as it carries the intent of what I want to achieve. It also means that if I choose to change technology or use multiple destinations the events will stay meaningful. For instance, the AdminStatusEvent will be used by our monitoring system to send a notification if the system crashes. I’ll probably want that as an SMS, maybe even a phone call as well as a twit (so the AdminStatusEvent will have a severity to designate how it should be handled) 
   1: using System;
   2: using System.Collections.Generic;
   3: using System.Linq;
   4: using System.Text;
   5: using Dimebrain.TweetSharp.Fluent;
   6:  
   7: namespace xsights.Apps.PostOffice.Server.Twitter
   8: {
   9:     class TwitterSender
  10:     {
  11:         private string account;
  12:         private string password;
  13:         private string admin;
  14:  
  15:         public TwitterSender(string tweetAccount, string twitterPassword,string adminAccount)
  16:         {
  17:             account = tweetAccount;
  18:             password = twitterPassword;
  19:             admin = adminAccount;
  20:         }
  21:         public void Update(string msg)
  22:         {
  23:              foreach (var tweet in BreakToTwitts(msg))
  24:             {
  25:                 var update =
  26:                     FluentTwitter.CreateRequest().AuthenticateAs(account, password).Statuses().Update(tweet).AsJson();
  27:  
  28:                 update.Request();
  29:             }
  30:         }
  31:  
  32:         public void SendAdminMessage(string msg)
  33:         {
  34:             foreach (var twit  in BreakToTwitts(msg))
  35:             {
  36:                 var dm =
  37:                 FluentTwitter.CreateRequest().AuthenticateAs(account, password).DirectMessages().Send(admin, twit).AsJson();
  38:  
  39:                 Retry(2,dm.Request,false);
  40:             }   
  41:             
  42:         }
  43:  
  44:         private IList<string> BreakToTwitts(string originalString)
  45:         {
  46:             var list = new List<string>();
  47:             for (int i = 0; i < originalString.Length; i += 140)
  48:             {
  49:                 var len = 140;
  50:                 if (originalString.Length - i < 140) len = originalString.Length - i;
  51:                 list.Add(originalString.Substring(i, len));
  52:             }
  53:             return list;
  54:         }
  55:  
  56:         private void Retry(int retries, Func<string> call,bool shouldThrow)
  57:         {
  58:            
  59:             try
  60:             {
  61:                 call();
  62:             }
  63:             catch (Exception ex)
  64:             {
  65:  
  66:                 if (retries > 0)
  67:                     Retry(--retries, call,shouldThrow);
  68:                 else
  69:                 {
  70:                     if (shouldThrow)
  71:                         throw;
  72:                 }
  73:             }
  74:           }
  75:           
  76:         }
  77:     }
  78:  
  79: }

 
Tags: .NET | OO | SOA | SOA Patterns

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