PDC – Day 3 – Boku, .NET services and more on Azure queues

Posted on October 30, 2008 by yoelarnon

Day 3 keynotes were about Microsoft research, presented by Rick Rashid. Rick’s presentation was probably the most impressing presentation in PDC – even I did not know how large the Microsoft research team is (850 researchers – larger than most universities), and the breath of projects they are involved in – from software proofing, to weather control, health research (yes!) and surface programming. However to me as a father (and as a former LOGO instructor) the most impressing project presented is Boku – a programming environment for children. If you have children (and / or you are still, like me, a little bit of a child yourself) go see it.

After Boku, returning to the technical stuff was a bit hard…

I went to see Clemens Vasters‘ presentation on .NET services. Clemens showed how you can connect two applications through the cloud – even if they run on public Internet connections, corporate environments, NATS etc. To enable that, Microsoft is delivering a whole bunch of new bindings for WCF – the "relay" bindings – each corresponding to an existing "normal" binding (for example, BasicHttpRelayBinding corresponds to BasicHttpBinding. There is no MsmqRelayBinding yet – it may be a good exercise to develop one… According to Clemens, one of the reasons that Microsoft did not come up with such binding is the difficulty of keeping end-to-end transactional messages protocol through the cloud. However, I think it is a good idea anyway to avoid transactional messages.

Later in the day, I went to see Sriram Krishnan’s talk on best practices of programming on the Cloud. Sriram is an excellent presenter and I highly recommend that you go see his talk (should be available online on the PDC site in a few days) – especially if you are distributed applications architects  – not only those developing for the cloud. Sriram preaches for stateless, loosely coupled and simple solutions (did I tell you I hate transactions?). He strengthened my conclusion that cloud programming to the enterprise programmers is what VB.NET is to VB6 programmers – it looks the same, but it is actually quite different – and it will take time to adjust and think "the cloud way". You can see more in his site.

I learned a little more today about Azure queues. The interface to these queues is HTTP REST interface (which implies that duplications are part of life and there are no real transactions – but you know that already). Here are the APIs:

Queues:

Similar to get properties in MSMQ, except it also returns the message count (do I hear you clap?) and the other properties are free form name / value pairs.

Messages:

In the URI, you can also ask for the number of messages you want, and also specify a timeout. If you do not delete the message within the timeout, it will be returned to the queue.

Same as GET, but the message remains visible in the queue (you knew that already, didn’t you?)

"lightweight commit" You have to call that after GET – otherwise the message will be put back in the queue

Deletes all the messages in the queue (purge).

The Azure samples (provided with the SDK) wrap the REST methods with a .NET class, RestQueue, which itself is wrapped with a class called… Ahm… MessageQueue! Isn’t that fun? You already know that when programming with System.Messaging on a widows form you have to explicitly put the namespace for Message, now you also have MessageQueue in a different namespace. Should be fun.

That’s all folks… four queue methods, five message methods. Is that all we need? I guess that in most cases, the answer is surprisingly YES. I would love to hear your views.

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