DDD and CQRS are not necessary for all types of applications; it might not even be for all bounded contexts of your application. However, I highly recommend looking deeper into this. It's probably a good idea to go down the path of looking at the SOLID principles, if you haven't already done this before. Also, it's worth looking at Behavior Driven Design, as it's close in mindset. Bifrost has been created to provide a full experience when implementing on top of these concepts and principles. It should give you a great opportunity for productivity and help you stay on the narrow path of being SOLID.
Note
You can find the entire sample code at https://github.com/dolittle/SignalR_Blueprints/tree/master/Source/Chapter6.
In the next chapter, we will move on to how we can hook a Windows Phone client into this bank.