I need to build Identity server like Microsoft's http://login.live.com.
To handle failover I will have multiple web servers nodes. The plan is that all database write operations are done by sending messages to the database server. Database will be mirrored or replicated. The idea is that database subscribes to the write operations but that other nodes subscribe also. That way other nodes do not need to read from database and can update their caches.
I am just starting to learn the service bus architecture and what is not clear to me is how to handle failover scenario for the service bus.
Question:
- If database server is not available, what will happen with the published messages ?
- Will they be stored somewhere and where ?
- Do I need additional machine or a cluster to handle failover of the service bus?
- I read that SQL Server can be used as a message store but can I use durable MSMQ? I am queuing messages to be able to write them to the database so why would I store them to the DB first just to take them and write them again? OR, I am getting this wrong and DB is only used for the list of subscriptions and not for the Messages?