Chapter 5 Designing the integration Layer • Microservices architecture: In this architecture, the application is split into multiple microservice processes, and each process holds the business logic of that particular module. Each microservice needs to be authenticated and authorized; hence, the logic of authentication and authorization wouldn’t be implemented in every microservice. To overcome this issue, a client application such as an Angular application can access the services through an API gateway where each of the services are registered and controlled. Authentication and authorization modules would be implemented in the API gateway, and all the microservices are registered with the API gateway. The API gateway is exposed to the client application and is responsible for routing requests to the appropriate microservices after verifying the user details. • Legacy modernization: You need to check whether the system has to interact with the legacy system, because the integration method and interface will differ and should be considered while designing the application. Data Formats Data formats the integration layer. There are mainly three types of data format, flat, relational, and hierarchal, but it is recommended to use the hierarchal data format because of its efficient structure. • Flat: It has one record per row, but there is a chance of duplicate entry in these things. The flat data format is not recommended in an integration system, but it is used in file systems and databases because it contains additional payload. In the following example, Account ID and Name are redundant in every row for a particular account ID, hence increasing the payload while transporting data in the network and therefore increasing the bandwidth. Account ID Account Name Transaction Type Transaction Amount Currency aBCBanK1234 sourabhhsethii neFt 1250 inr aBCBanK1234 sourabhhsethii rtgs 850 UsD 153