Deployment model

Application servers provide enterprise functionality collocated in a JVM, which can be used by multitenant applications. Those applications can share services, be deployed and undeployed in real time, and communicate with each other in a JVM.

In this book, we will concentrate on Swarm-based microservices, but note that this is a valid architecture model with benefits that should be taken into consideration when choosing the right architectural style for the problems that you are solving.

Components of a monolithic application are located in the same JVM, and they can communicate directly within its boundaries. In such an application, you don't have to think about a number of problems inherent to distributed systems. If you decide to distribute your application, you will have to take care of network failures, service discovery, monitoring service availability, and dealing with their failures, just to name a few problems. Also, in a monolithic application, you can use out-of-the-box technologies, such as transactions or security, that have been thoroughly tested and have proven to work well.