Gone are the days when software development was about building monolithic applications. Such traditional applications that were built as single units are fast becoming obsolete as more applications are deployed to the cloud. Any change made to a small part of one of these traditional apps required the entire monolithic app to be rebuilt and deployed.
It has become nearly impossible to maintain a good modular structure for these apps so that changes in one module do not impact other modules. Scaling is required for the entire application, rather than only the parts of it that require resources. Enterprise applications were often built in three main parts: a client-side user interface, a database and a server-side application. The server-side application would handle requests, execute the domain logic, retrieve and update data from/to the database and select and populate views to be sent to the browser. This server-side application would be a monolith – a single logical executable. Any changes to the system would involve building and deploying a new version of the server-side application.
Companies that expect to survive in the digital age have to be innovative, agile and fast. To this end, they should use the microservice architecture to develop and deploy future applications.
The microservice architecture is used to design software applications as independently deployable and scalable services. Microservices offer a divide-and-conquer approach to application development.
Services can be used as components rather than libraries because services can be deployed independently. Any change to a specific service means that service alone has to be redeployed, not the entire application. Some changes may require modifications to the service interface that may result in some coordination between services to be updated. But this can be minimized through cohesive service boundaries and evolution mechanisms in the service contracts.
Amazon, Apple and Netflix pioneered this architectural style. Netflix began to move a monolithic architecture to a cloud-based microservices architecture as early as in 2009. At this time, the term microservices didn’t even exist. Amazon started working towards achieving microservices architecture style prior to 2015.
They decided to build small services—as self-contained services with a well-defined interface—that could handle discrete business functions instead of having all aspects of their service in one ginormous deployment. The boundaries between these units are functional APIs that expose the core capabilities of each service. The advantage of this technique is that separate teams can work on each service. So, if there’s a team responsible for billing, or inventory management and shopping cart, they are responsible for everything. This includes writing the code, testing it, pushing it to production, handling failures and anything else that may happen with that service. This is better for continuous delivery, as small units are easier to manage test and deploy.
Microservices are becoming increasingly popular especially as more applications are being deployed to the cloud. Docker is arguably the most influential platform today for getting businesses to adopt microservices. Docker containers are a natural fit for microservices because they match the desire for lightweight components that can be easily managed, dynamically replaced. Also, Docker isolates containers to one process or service. We could also take advantage of container orchestration capabilities to monitor, manage and scale the different services dynamically.
Solutions can be provided in the form of containerized microservices. For example, applications that earlier had an Element Management System (EMS) and the actual application as a single deployment can be now be categorized as two separate microservices and deployed in separate Docker containers. So, when a change needs to be made to the actual application, only the container image for the app is built and redeployed, and the EMS node is unaffected.
In the future, companies will move to microservices because they offer the opportunity to iterate more quickly; in fact, many times a week. Microservices are well-documented and easy-to-use and allow greater flexibility in deployment and more tightly focused applications since they are developed as independent products that deliver a single business capability. Based on documented evidence from companies using the microservices architecture, there is no downside to embracing the change.