I’m trying to determine how best to accomplish the following scenario using the Azure Service Bus. I have millions of devices (desktop software, mobile phone apps, etc) that need to have messages sent to them based on subscriptions. This in and of itself is pretty easy. However, the Service Bus has limits on the number of subscriptions per topic, filters per subscription, etc. (listed below). So, that being said, I was wondering if someone has solved this problem before or if there are best practices or whatever.

Assumptions

• 20,000 customers
• each with 1-* appliances
• each appliance with one customerId, applianceId
• each appliance manages 1-* devices
• each device with a deviceId

Requirements

• discover appliances by customerId (filter by customerId)

  • When a customer logs in we need to “ping” all appliances belonging to that customer.

• commands to specific appliance (filter by applianceId)

  • Once we know all of the appliances used by the customer, we can execute commands against specific appliances.

• commands to a specific device (filter by deviceId)

  • We can also provide commands against a specific appliance for a specific device

Now, none if this is very difficult. I’m really just bumping up against some of the Service Bus quotas as seen here: http://msdn.microsoft.com/en-us/library/azure/ee732538.aspx

• 2000 filters/topic
• 2000 subscriptions/topic
• 10,000 total topics and queus per namespace

So my first inclination was to have a single SB Namespace with a single a single Topic and a single Subscription. Each appliance could then simply add or utilize the following SqlFilters:

1. Appliance by CustomerId – this would allow for messaging with all appliances that belong to a specific customer.
2. Appliance by applianceId – this would allow for messaging with a specific appliance.
3. Appliance by deviceId – this would allow for messaging with a specific appliance for a specific device.

Using the assumptions stated above that would be 20k filters for #1, a filter per appliance (lets assume it’s a million) for #2, and potentially millions of filters for #3.

Obviously that wouldn’t work. I could even go so far as to disregard #3 which would then still leave me with over a million filters. This is the specific quota that I’m bumping up against.

The most important two things here are that I can send messages to all appliances owned by a customer and the second is that I can send messages to a single appliance. Appliances and devices communicating back is not an issue.

Queues may figure into this equation but simply replacing topics with queues in certain scenarios will only relieve part of the problem.

Anyhow, let me know if anyone has any ideas!