Having an Internet Service Bus up in the cloud is not very entertaining unless there are services in the bus. Therefore, I built one (and already showed some of the code basics) that’s hopefully fun to play with and will soon share the first version with you after some scrubbing and pending a few updates to the ISB that will optimize the authentication process. It’s a 0.1 version and an experiment. The code download should be ready in the next two weeks, including those adjustments. But you can actually play with parts of it today without compiling or installing anything. The info is at the bottom of this post.

To make matters really interesting, this sample not only shows how to plug a service into the cloud and call it from some Console app, but is a combo of two rather unusual hosts for WCF services: A Windows Live Messenger Add-In that acts as the server, and a Windows Vista Sidebar gadget that acts as the client.

Since the Silicon Valley scene is currently all over Twitter and clones of Twitter are apparently popping up somewhere every day, I thought I could easily provide fodder to the proponents of the alleged Microsoft tradition of purely relying on copying other’s ideas and clone them as well ;-)  Well, no, maybe not. This is a bit different.

TweetieBot is an example of a simple personal service. If you choose to host it, you own it, you run it, you control it. The data is held nowhere but on your personal machine and it’s using the BizTalk Services ISB to stick its head up into the cloud and at a stable endpoint so that its easily reachable for a circle of friends, bridging the common obstacles of dynamic IPs, firewalls and NAT. No need to use UPnP or open up ports on your router. If you choose to do so, you can encrypt traffic so that there’s no chance that anyone looking at our ISB nor anyone else can see the what’s actually going across the wire.

Right now, lots of the Web 2.0 world lives on the assumption that everything needs to live at central places and that community forms around ad-driven hubs. The mainframe folks had a similar stance in the 70s and 80s and then Personal Computers came along. The pendulum is always swinging and I have little doubt that it will swing back to “personal” once more and that the federation of personal services will seriously challenge the hub model once more.

So what does the sample do? As indicated, TweetieBot is a bot that plugs into a Windows Live Messenger using a simple Add-In. Bart De Smet has a brilliant summary for how to build such Add-Ins. When the Add-In is active and someone chats the bot, it answers politely and remembers the chat line, time and sender. The bird has a leaky long term memory, though. It forgets everything past the last 40 lines.

Where it gets interesting is that the Add-In can stick three endpoints into the BizTalk Services ISB:

• A Request/Response Web Service that allows retrieving the list of the last 40 (or less) “tweets” and also allows client to submit tweets programmatically.
• An RSS service that allows (right now) anyone to peek in to the chat log of the last 40 tweets.
• An Event service that allows subscribers to get real-time notifications whenever a new tweet is recorded.

The accompanying Sidebar Gadget, which is implemented using WPF, is a client for two of these services.

 When you drop the Gadget on the Sidebar, it will prompt for the IM address of the TweetieBot service you’d like to subscribe to. Once you’ve authenticated at the relay using your registered Information Card, the gadget will pull and show the current list of Tweets and subscribe to the Events service for real-time updates. And whenever someone chats the bot, the Sidebar gadget will immediately show the new entry. So even though the Gadget lives on some client machine that’s hidden between several layers of firewalls and behind NAT, it can actually get push-style event notifications through the cloud!

“How do I send events to clients?” must be one of the most frequent questions that I’ve been asked about Web Services in the past several years. Well, this is your answer right here.

While I’m still toying around with the code and the guys on the 1st floor in my building are doing some tweaks on the ISB infrastructure to make multi-endpoint authentication simpler, you can already play with the bot and help me a bit:

Using Windows Live Messenger you can chat (click here) tweetiebot@hotmail.comnow. Drop a few lines. If the bot is online (which means that I’m not tinkering with it) it will reply. Then look at this RSS feed [1] and you can see what you and everyone else have been telling the bot recently. Enjoy.

[1] http://connect.biztalk.net/services/tweetiebot/tweetiebot%40hotmail.com/rss

Steve Maine explains what's in the newest revision of the BizTalk Services SDK, including quite a few (standalone-) surprises for WCF and WF developers. In case you haven't noticed, we've dropped a new and substantially expanded build of the SDK just a week after we published the first SDK.

Stop. Don't leave yet. Before you say "What do I care about BizTalk?", you should know that while BizTalk has been more or less associated with the BizTalk Server 200x product line in the past few years, (Codename-) BizTalk Services is a complementary set of functionality that's not only interesting to BizTalk Server customers, but really to all .NET developers.

Weird? Flip flopping? Confusing? No. The fact that BizTalk is not only BizTalk Server isn't really new. When BizTalk came out back in 2000 and I was very closely looking at what's going on (get it used for $2), the definition read like this in the press release:

The BizTalk Initiative represents the collective set of investments that Microsoft is making to facilitate business process integration within and between organizations using Internet-standard protocols and formats. It includes the BizTalk Framework, the BizTalk.org community and business document library, as well as BizTalk Server 2000, a business process orchestration server and tools for developing, executing and managing distributed business processes. These investments are being made in conjunction with industry standards groups, technology and service providers, as well as key global organizations.

While the envisioned schema exchange BizTalk.org fell flat since industry-wide message-level-schema standardization for "everything" more or less didn't happen in the way people initially expected, what came out of this initiative as a significant element was that the set of specifications then known as the BizTalk Framework 2.0 that acted as a foundation for quite a few of the WS-* specifications and the BizTalk Server product which evolved into a very successful and leading SOA/BPM suite that's soon seeing its next release, BizTalk Server 2006 R2. Fast forward, read Steven Martin's blog entry where he writes:

[...] We see BizTalk Services as a complement to "traditional" BizTalk Server uses on premise. As you need to coordinate SOA on a broader scale beyond the organization, we see the introduction of hosted services as one way to help support federation of business process, messaging, and identity across boundaries. Over time, we want to ensure that BizTalk Server customers will be able to easily use the cloud services in conjunction with their premise technology. [...]

So all in all, a very sane way to think about BizTalk is that the software and services we publish under that name are providing functionality for messaging, process management and connectivity that go beyond the capability of the core .NET Framework.

I wrote a slightly Twitter-inspired, fun app over the weekend that's using the BizTalk Services Connectivity service and relay. In the spirit of Software+Services I'm going to give you half of it [for now] ;-)   You must have the BizTalk Services SDK installed to run the sample.

The server app, which I'm keeping to myself for the next few days as part of the experiment, is an extension (add-in) to Windows Live Messenger. The Messenger add-in monitors all chats with tweetiebot@hotmail.com and keeps circular buffer with the last 40 incoming messages. Using the client (which is in the attached archive), you can get a list of "Tweets" and add a new one (same as chatting)

[ServiceContract(Name = "TweetieBot", Namespace = http://samples.vasters.com/2007/05/tweetiebot)]
publicinterfaceITweetieBot
{
  [OperationContract]
  IList<Tweet> GetTweets(DateTime? since);
  [OperationContract]
  void Tweet(string nickname, string text);
}

or you can subscribe to new tweets and get them as they arrive

[ServiceContract(Name = "TweetieEvents", Namespace = http://samples.vasters.com/2007/05/tweetiebot)]
publicinterfaceITweetieEvents
{
  [OperationContract(IsOneWay=true)]
  void OnTweet(Tweet tweet);
}

The client application hooks up to the client (that lives right on my desktop machine) through the BizTalk Services ISB and the server fires events back through the ISB relay into the client as new tweets arrive. So when you run the attached client app, you'll find that it starts with a dump of the current log of the bot and then keeps spitting out events as they arrive.

The client is actually pretty simple. The EventsClient is the subscriber for the pub/sub service (ConnectionMode.RelayMulticast) that writes out the received events to the console. The rest all happens in Main (parsing an validating the command line argument) and in Run.

    class Program
    {
        class EventsClient : ITweetieEvents
        {
            public void OnTweet( Tweet tweet)
            {
                Console .WriteLine( "[{0}] {1}:{2}" , tweet.Time, tweet.User, tweet.Text);
            }
        }

        static void Main( string [] args)
        {
            string usageMessage = "Usage: IMBotClient <messenger-email-address>" ;
            if (args.Length == 0)
            {
                Console .WriteLine(usageMessage);
            }
            else
            {
                if (! Regex .IsMatch(args[0], @"^([\w\-\.]+)@((\[([0-9]{1,3}\.){3}[0-9]{1,3}\])|(([\w\-]+\.)+)([a-zA-Z]{2,4}))$" ))
                {
                    Console .WriteLine(usageMessage);
                    Console .WriteLine( "'{0}' is not a valid email address" );
                }
                else
                {
                    Run(args[0]);
                }
            }
        }

        private static void Run( string emailAddress)
        {
            EndpointAddress serviceAddress =
                new EndpointAddress ( String .Format( String .Format( "sb://{0}/services/tweetiebot/{1}/service" , 
                                     RelayBinding .DefaultRelayHostName, Uri .EscapeDataString(emailAddress))));
            EndpointAddress eventsAddress =
                new EndpointAddress ( String .Format( String .Format( "sb://{0}/services/tweetiebot/{1}/events" ,
                                    RelayBinding .DefaultRelayHostName, Uri .EscapeDataString(emailAddress))));

The URI scheme for services that hook into the ISB is "sb:" and the default address of the relay is encoded in the SDK assemblies. We set up two endpoints here. One for the client channel to fetch the initial list and one for the event subscriber. 

            RelayBinding relayBinding = new RelayBinding ();
     
              ServiceHost eventsHost = new ServiceHost ( typeof ( EventsClient ));
            RelayBinding eventBinding = new RelayBinding ( RelayConnectionMode .RelayedMulticast);
            eventsHost.AddServiceEndpoint( typeof ( ITweetieEvents ), eventBinding, eventsAddress.ToString());
            eventsHost.Open();

            ChannelFactory < TweetieBotChannel > channelFactory = new ChannelFactory < TweetieBotChannel >(relayBinding, serviceAddress);
            TweetieBotChannel channel = channelFactory.CreateChannel();
            channel.Open();

The two *.Open() calls will each prompt for a CardSpace authentication, so you will have to be registered to run the sample. Once you have opened the channels (and my service is running), you'll be able to pull the list of current tweets. Meanwhile, whenever a new event pops up, the EventsClient above will write out a new line.

            IList < Tweet > tweets = channel.GetTweets(lastTime);
            foreach ( Tweet tweet in tweets)
            {
                Console .WriteLine( "[{0}] {1}:{2}" , tweet.Time, tweet.User, tweet.Text);
            }

            Console .WriteLine( "Press ENTER to quit at any time" );
            Console .ReadLine();

            eventsHost.Close();
            channel.Close();
            channelFactory.Close();
        }        

Christian Weyer shows off the few lines of pretty straightforward WCF code & config he needed to figure out in order to set up a duplex conversation through BizTalk Services.

Steve has a great analysis of what BizTalk Services means for Corzen and how he views it in the broader industry context.