Horizontal Scaling of Tomcat in Microsoft Azure

I am working on this quiet a while, but still no conclustion.

I want to do horizontal scaling of Tomcat instances in Microsoft Azure (1,2,3,... Tomcat instances for one service). I read lots of articles about session replication, clustering,... with Tomcat. Since Azure does not support Multicasts, there is no easy way to cluster Tomcat. Also sticky sess开发者_开发问答ions is no options, because Azure does round robin load balancing. Setting up two services - one with Terracotta or Apache mod_jk - and the other with Tomcat instances seems overkill for me (if even doable)...

Is this even possible?

Thanks in advance for reading and answering my question. Every comment/idea is highly appreciated.

There is the new appFabric caching service you could use, or there are examples of using Memcache on Azure, would that help?

http://code.msdn.microsoft.com/winazurememcached

Why do you feel that running 2 services is overkill, exactly? If you have no issue with scaling out to n Tomcat instances, adding another service for load distribution is a perfectly acceptable solution in my book. By running that service on a minimum of 2 instances, that service itself meets the Azure SLA requirements: your uptime will be as good as it is going to get on Azure, and you avoid a SPoF (single point of failure).

You could go with a product like terracotta, but it is also pretty straightforward to write a simple socket server to route HTTP sessions back to a particular instance running in Windows Azure. You would have to be aware of node recyles, but that is quite doable.

Be aware that memcached requires an additional Azure service as well (web roles), the appFabric caching service does not (but also has cost associated with it). I do not know Tomcat, but for IIS you can easily move session state from in memory to persisted (either SQL Azure or Azure Storage). Something to be aware of: for high volume sites, the transaction cost to Azure Storage can actually become a cost driver for your deployment if you store session info there. SQL Azure could well be the more cost-effective solution, but on the other hand might not be supported out-of-the-box for your solution.

I do not think that you can run Tomcat on Azure. Even if you could (using the virtual machine role) it is probably cheaper to run it on a Linux VM on Amazon EC2.

Edit

I see that this is possible using the Tomcat Solution Accelerator. But look at the disclaimer:

This solution accelerator is provided for informational purposes only and Microsoft or Infosys makes no warranties, either express or implied

This is an unsupported solution. I know that it is often difficult to question management decisions. But using unsupported software for production systems, when a cheaper supported alternative is available, is generally not a good idea.