Architectural Elements and Principles of Microservices
Microservices made a loud and clear entry into the world of IT a couple of years ago. They announced their ability to split the monolithic applications and transformed the system into independently managed components to claim the significance they enjoy today.
It didn’t take much time for organisations to jump the bandwagon of microservices with all their architectural needs.
However, this revolutionary application didn’t give us much time to lay down a foundation of principles for you. Thus, in this article we will go back to the basics of microservices and demystify the elements and principles of its architecture.
Elements of Microservices
These five elements are a prerequisite for your microservice before it takes its place in the ecosystem.
Functionality and Flexibility
As the primary goal of microservices is to break the monotony of monolithic structures, the ease of new processes helps in approaching the systems with agility and flexibility. The shorter life cycles lead to frequent releases and incremental improvements that ultimately deliver better products. The users are able to run applications on a reduced cost yet achieve higher density by leveraging the shared infrastructure of the microservices. Focused on a single capability, each container is managed within a separate environment. This accelerates the functionality, time to market and infrastructure utilisation.
For the distributed services to be connected with each other, the REST web services API is put to use. This mechanism involves API exposing the fine grained data to the customers. Therefore, a common interface is required that commands the APIs about the functions of each service. It is of high importance for the API to be treated with care when defining the SLA between the client and the service. It becomes a necessity to automate the design, documentation and development of the concerned API to deliver at a speed.
Though the microservices are stateless but there are other operations that run on a separate network requiring data services. When you choose a platform to hold these services, there are certain factors to be called in. For starters, the run time or the response time of the server during heavy traffic situations.
The support for such conditions requires management that reposts the status and coordinates the load variations. One way to handle this is via the process of auto-scaling. It is a management system that tracks service loads and adds or removes service instances as per the need.
Offloading The Data
In continuation of the data traffic, the base infrastructure also comes under the scrutiny of services. The unreliability of the infrastructure is a reality that leads to crash and failure of response to high-load status of the services. The microservices require steady operating system for pushing out consistent results. In order to achieve this, the user-specific data can be offloaded from the service instance and shared into a storage system that’s accessible from all service instance. In case the session fails, the data can be migrated to ensure that the crash doesn’t stop the user interactions.
You can insert a shared memory-based cache system that will allow for a quick data access and thus improve the performance of the application. The insertion of the cache system might complicate the architecture further for the microservices but the sheer satisfaction of data offloading is a necessity in such critical situations.
With an additional offloaded data layer and traffic variations adding complexities too, monitoring becomes inevitable. For obvious reasons, traditional monitoring approaches do not comply with the environments of microservices. The scale and dynamic nature demands an ongoing resource that captures data in a central location and reflects the changes of the application in the monitoring system. It is also important to track each service instance data and capture application-created log information. This kind of real time service monitoring gives a holistic stand of your microservices to proactively processes and deploy services that produce resilient and scalable solutions for business continuity.
The digital entertainment giant, Netflix is a prime example of optimising the design and implementation of microservices in use. Netflix started using the open source NGINX software in 2011 as its delivery infrastructure which offers a high quality digital experience with the ability to push millions of requests per second every day. Adrian Cockcroft, the Director of Web Engineering back then visualised the division of teams into smaller groups working on the end-to-end development of the platform for a smooth streaming experience. Cockcroft as a Cloud Architect focused on discovering and formalising the architecture as Netflix engineers established several best practices for designing and implementing the microservices.
Following are the key principles to remember while designing a microservices-based enterprise application.
Implement Domain Driven Design
For the different domains of the microservices to work in accordance with each other, the architecture provides a domain driven design. In this strategy, the focus shifts to the core domain that minimises any possibility of the application getting out of hand. As a team, you should list your Entities, Repositories, Value Objects, and Services that defines a bounded context of your model. This helps in setting the limits around decisions like who uses it, how they use it and where it applies within a larger application context.
Hide Away Implementation Details
Database holds a secretive value when it comes to running independent cycles within a microservice. A good contract requires to hide away the service implementation details in order to reduce the tight coupling between services and consumers. This ensures that each service gets to retain its autonomous nature. It is crucial to manage a segregated control over the intent of the service and its implementation. The contract can facilitate the use of REST protocol over HTTP for this through which the internal and external details can be maintained.
The DevOps team work in sync with the microservices’ architecture.
Another aspect of the monolithic architecture is the single logical database for all applications in use. The aim of microservices on the other hand is to decentralise this decision making authority and give a faster pace to teams to work independently. However, there are some key questions that needs to be addressed for the process of decentralisation. For instance, who serves on which team, what are the tools, languages and architectures that will be used inside each service, when do you create or retire services and so on. Addressing these allows innovation to thrive and reduces the risks that hold impact on the system.
Building boundaries that separate services do reduce the risks of failure at large within the microservices architecture. However, it does not completely eliminates the failure issues. Within the services, the risk of failing systems, network, hardware or the application isn’t isolated.
In cases like these, how do you ensure that the failure doesn’t have a domino effect and spirals into the central system?
The discipline of chaos engineering is put to work for solving this dilemma of attaining reliable distributed systems. The primary objective of chaos engineering is to inject issues that the system might encounter in the real world. For instance, crash of an application, network failure or no availability zone. Here, the architecture is put to test whether it can handle these expected and unexpected situations and is thus prepared to be more resilient.
The DevOps team work in sync with the microservices’ architecture. The automation of building and deploying the processes is maintained by the DevOps system whereas the microservices divides the services for enabling it. Both practices are designed to offer greater agility and efficiency for the operations of the enterprise to run without hiccups.
The most unique principle of microservices is their nature of reuse. Here, building a microservices architecture for non-project specific purpose is the key. Developers can simply set new configurations and add new project’s logic along with cloning a repository to reuse the application. This improves productivity and builds a culture of sharing the work, ultimately bringing innovation to the limelight.
Microservices have emerged with trendsetting abilities in the IT departments across the globe.
Organisations can implement these principles of microservices when installing the operations for the ease of deployment and agility of projects.
A Content Associate at OpenSense Labs, Jayati Kataria is a social media aficionado. When not scrolling down her Instagram feed, she can be found reading classics on her way to new adventures around the world. Also, she loves to binge watch and catch on the trending TV series.