At the end of the first phase, we get a number of microservices with their own data-storage facilities. These microservices are modular in nature and interoperable, and they are intrinsically capable of interacting with one another through the APIs. The widely-recommended design approach is to design and develop microservices for different domains. The widely-used aspect is domain-driven design (DDD). For example, take an e-commerce application. The domains include the shopping cart, payment, shipping, notifications, credit verification, and analytics. Every domain is looked at as a business functionality and hence implemented as a microservice. There can be multiple methods within a microservice. There can be intra- as well as inter-microservice communication and collaboration. 

The microservices within a domain are supposed to interact frequently. There are situations where microservices in a domain have to connect and correspond with microservices in other domains in order to fulfill different business processes and activities. Thus, an e-business and e-commerce application is bound to have several domains and hundreds of microservices. With containers emerging as the best fit for hosting and running microservices in a fault-tolerant manner, there can be thousands of containers to run microservices-centric applications.