Azure Service Bus cost is minimal for AX Companion Apps

As customers and partners are planning to add the companion apps to their implementation, there have been numerous questions about the cost of the Windows Azure Service Bus. The companion apps leverage Service Bus to relay messages between devices (not on corpnet) and the on-premises instances of AX. So what is the cost of using Service Bus? In order to answer this question, we did some measurement and calculations this week. Following are the results.

Scenario

We tested the use of the Windows Store Dynamics AX 2012 Expenses app since it is the most message and data intensive of the apps. We used the app to create an expense report which had 9 expenses with 4 typical receipts. The receipts were captured with the Windows Phone Dynamics AX app. We then extrapolated that usage over 40,000 expense reports in a month (for example 20,000 employees with 2 expense reports per month).

Cost

The resulting monthly charge from Azure for Service Bus for 40,000 typical expense reports per month is approximately $21.97. That’s it – the cost is measured in 10s of dollars per month for a fairly high transaction volume. This is consistent with the numbers we are seeing inside Microsoft for use of the companion apps for our internal deployment of Dynamics AX 2012 Expense Management. If you’d like to understand the details behind this number, then please read on. Otherwise rest assured that the cost of using Service Bus is minimal compared to the value provided by using the AX companion apps. Its worth noting that most of the MSDN subscriptions include an Azure monthly credit which can apply to Service Bus usage. 

Chargeable Usage

Azure charges are based on the following measures for usage of the Service Bus (pricing details):

1. Relay hours: The total number of hours during which an app or service was listening to an address. In the case of companion apps this includes the on-premises connector which is typically listening 24/7 for requests from the apps and the apps which connect for very small intervals while interacting with the on-premises connector. The price is $.10 for every 100 relay hours.
2. Number of Messages: Each request and each response which is relayed across the service bus is considered a message. The price is $.01 for every 10,000 messages
3. Data Transfers through the Azure service: Data going out of the Azure service is priced at $.12 for per GB (for Zone 1 – US, Europe) or $.19 for per GB (for Zone 2 – other locations). The first 5 GB/Month is free.

Note: these reflect the current measures and rates as of this blog post

 Measured Usage

For the scenario described above, the following were measured.

For a single expense report:

Extrapolating for monthly volume of 40,000 expense reports:

 Note: We assumed the on-premises connector was running 24/7 during the month and had 3 addresses (1. W8 Expenses app, 2. phone expense capture app, 3. address to provide config info to the apps). We also assumed 2 connectors for redundancy.

Calculated Costs

The calculated costs based on those measures are:

Note: We used the higher Data Transfer rate of $.19 per GB.  

Azure provides a pricing calculator that can be used to replicate these calculations.

Conclusions

1. The cost is minimal for a relatively high transaction volume.
2. For the Expenses app costs are likely to be most sensitive to the size and quantity of receipts which will drive the data transfer costs.
3. Adding the other companion apps will cause an increased fixed-cost based on the on-premises connector. With all apps deployed (for the existing set of apps) the connector is listening on 8 total addresses.
4. The Time and Approvals apps are likely to be less message and data intensive than the Expenses app.

We hope this helps clear the perceived hurdle of the cost of using Service Bus. We’d love to hear from customers and partners as you deploy the companion apps get more actual transaction volume and associated service bus costs.