## 3 Theoretical Framework
### Containers
Similarly, the Best Buy architecture became a bottleneck for deployments. Its downtime was far too long to keep business online. At Cloud Elements, the transition also arose out of necessity, as it was a company experiencing exponential growth. A microservices design would help iterate continuously to meet new demands [47; 48]. Wix.com had to invent new patterns of integration, analysis, and fostering a new internal culture among the constraints or obstacles encountered along with the development. In Cloud Elements, its modern design generated debate and conflict. For Best Buy, one of the significant challenges was creating trust. Cultural resistance to the way software is developed and implemented is challenging changes the way people do their jobs. For these companies, almost no support tools existed when they set out on this path. The migration process was not easy. However, in a view towards the past, it has been fortunately a wise decision. However, migrating to a microservices design does not guarantee benefits for all companies. A monolithic codebase may be more efficient and with less overhead for smaller-scale applications. Although implemented, microservices can provide a backbone upon which innovation can thrive. However, the benefits of microservices must outweigh the time spent migratingand maintaining new issues. Staying with a monolithic architecture is probably a much easier task than managing a distributed system, which allows us to deduce that a progressive migration should be generated [47; 48]. A Critical Review of the Evolution from Monolithic to Microservices Architectures in Terms of Their Applications, Efficiency and Development Complexity  
There exist some of the companies such as Walmart, Spotify, Netflix, Amazon, and eBay, among others [52; 53; 54], and many other large-scale websites and applications that have evolved from a monolithic architecture to microservices. The following describes some of the success stories and how their design scheme might be. Walmart needs to handle some six million page views per minute, with currently approximately some four billion people connected and more than 25 million applications available. Spotify, which built a microservice architecture with autonomous equipment, provides services to more than 75 million active users per month, with an average session duration of 23 min. Netflix receives an average of one billion calls to its different services. It is capable of adapting to more than 800 types of devices through its video streaming API. To offer a more stable service, for each given request, it performs five requests to different servers to avoid the loss of the continuity of the transmission [55]. Amazon, which migrated three years ago to the microservice architecture, is one of the first of the large companies that implemented it in production. There is no approximation of the number of applications they can receive daily [56]. The company, eBay, is one of the corporations with the most optimal vision for the future, being a pioneer in the adoption of technologies such as Docker. Its main application includes several autonomous services, and each one is executing the logic of each functional area that is offered to customers. For a critical analysis, the design of a microservice oriented application, according to Microsoft [57], is here described as more detailed. A crucial app that may meet the requirements of the analyzed success stories should be able to control requests by executing business logic, accessing databases, and returning HTML, JSON, or XML responses [58]. The application needs to support a variety of clients, including desktop browsers running single-page applications (SPA), traditional web applications, mobile web applications, and native mobile applications. It is also possible that the application exposes an API for third-party consumption. Furthermore, it should be able to integrate the external microservices or applications asynchronously. Thus, this approach allows the resistance of the microservices in case of partial errors.