In the previous chapters, we have examined approaches and steps for transforming from a monolithic application to microservices. It is important to understand that it is not necessary to migrate all modules to the new microservices architecture, unless it is really required. A major reason is that these migrations incur cost.

We will review a few such scenarios here. BrownField has already taken a decision to use an external revenue management system in place of the PSS revenue management function. BrownField is also in the process of centralizing their accounting functions, and therefore, need not migrate the accounting function from the legacy system. Migration of CRM does not add much value at this point to the business. Therefore, it is decided to keep the CRM in the legacy system itself. The business has plans to move to a SaaS-based CRM solution as part of their cloud strategy. Also note that stalling the migration halfway through could seriously impact the complexity of the system.