Azure: Will it work for my App?

Question

I'm creating an application that I want to put into the cloud. This application has one main function.

It hosts socket CLIENT sessions on behalf of other users (think of Beejive IM for the iPhone, where it hosts IM sessions for clients to maintain state on those IM networks, allowing the client to connect/disconnect at will, without breaking the IM network connection).

Now, the way I've planned it now, is that one 'worker instance' can likely only handle a finite number of client sessions (let's say 50,000 for argument sake). Those sessions will be very long lived worker tasks.

The issue I'm trying to get my head around is that I will sometimes need to perform tasks to specific client sessions (eg: If I need to disconnect a client session). With Azure, would I be able to queue up a smaller task that only the instance hosting that specific client session would be able to dequeue?

Right now I'm contemplating GoGrid as my provider, and I solve this issue by using Apache's Active Messaging Queue software. My web app enqueues 'disconnect' tasks that are assigned to a specific instance Id. Each client session is therefore assigned to a specific instance id. The instance then only dequeues 'disconnect' tasks that are assigned to it.

I'm wondering if it's feasible to do something similar on Azure, and how I would generally do it. I like the idea of not having to setup many different VM's to scale, but instead just deploying a single package. Also, it would be nice to make use of Azure's Queues instead of integrating a third party product such as Apache ActiveMQ, or even MSMQ.

Answer 1

I think you can absolutely use Windows Azure for this. My recommendation would be to create a queue for each session you're tracking. Then enqueue the disconnect message (for example) on the queue for that session. The worker instance that's handling that connection should be the only one polling that queue, so it should handle performing the task on that connection.

Answer 2

I'd be very concerned about building a production application on Azure until the feature set, pricing, and licensing terms are finalized. For starters, you can't even do a cost comparison between it and e.g. GoGrid or EC2 or Mosso. So I don't see how it could possibly end up a front-runner. Also, we know that all of these systems will have glitches as they mature. Amazon's services are in much wider use than any of the others, and have been publicly available for much years. IMHO choosing Azure is a recipe for pain as they stabilize.

Have you considered Amazon's Simple Queue Service for queueing?

Answer 3

Regarding the application hosting socket connections for clients to connect to, I'd double-check on what's allowed as I think only HTTP and HTTPS connections are allowed to be made with Azure.