With refactor, your applications require minimal to no code changes. With this method, we can exploit a mix of IaaS and PaaS features. Migrating a three-tier web application into a managed middleware and into a managed database is a perfect example of this migration model.
With a managed database or managed middleware, we don't have to worry about things such as OS management, database engine installation and administration, framework updates, security patches, and even configuring additional instances for load balancing, as it is all taken care of for us. We just need to upload our code and select the framework that we need for it to run. We still can run monolithic applications, and very little code changes are required; the main purpose of this method is to migrate by taking things such as management and configuration off our shoulders, thus increasing the agility of our workloads.