In today's digital sphere, the question is no longer "to be in the cloud or not to be." Rather, more and more organizations treat the cloud as a resource component added to an increasingly complex infrastructure. To ensure compatibility, many applications are developed directly for the cloud. These cloud-native apps often use a microservices infrastructure, which enables you to separate functionalities into containers.
What are microservices?
Microservices are application services or functionalities separated into containers to enable modular operations. Microservices are often used in cloud-native application architectures. This is because the arrangement enables flexibility and scalability that traditional (monolithic) architectures don't.
Features of microservice architectures include:
- A self-contained stack, including database and data models
- Component communication via API, message brokers, or event streaming
- Organization using bounded contexts, separating services according to business capabilities
The primary benefits of microservices are that you can more easily update code and applications and can more flexibly deploy components. When updates are made, only the service being updated is affected. Flexible deployment enables services to be scaled independently or reused for multiple applications.
How are microservices different from traditional monolith applications?
Traditional monolithic applications exist in a single package or executable and rely on binaries and dependencies in the host environment. Microservices incorporate these dependencies, removing the reliance on the host and enabling applications to be broken into component parts, each in a separate container.
These differences affect many aspects of application operations, including those involved with deployment, maintenance, reliability, and releases.
Deployment: Monolithic applications are deployed once and rest on a single point of failure. Any updates have to be made to the application as a whole, which is then redeployed. Microservices are deployed and then redeployed as needed to maintain security, availability, or to add new functionality. Individual services require orchestration but eliminate single points of failure.
Maintenance: Infrastructure maintenance for monolithic apps requires the same skill sets as any other traditional infrastructure. Operations and development teams need to be familiar with running on virtual machines or bare metal architecture in a self-contained OS.
With microservices, teams need to take on a DevOps strategy and be familiar with specialized tools. These tools include containerization solutions, like Docker, orchestration tools, like Kubernetes, or serverless services, like AWS Step Functions. These tools, although gaining in popularity, are not default required knowledge for operations or IT teams.
Reliability: Monolithic applications are reliant on all functionality within the application remaining functional and available. If one part doesn’t work, the entire application stops functioning. With microservices, individual functionalities (services) operate independently and do not affect the over functionality (i.e., reliability) of the application.
Releasing: Microservices can be updated and rolled-out on the fly without interfering with other services. This enables teams to slowly switch over users (via blue-green deployments) or to test versions prior to official release (AB testing).
With monolithic apps, there is no way to release individual updates without patching the whole application. This makes it more difficult to transition users or to test releases.
Best practices for effective microservices architecture
Several best can help you ensure that you are deploying your applications effectively when implementing a microservices architecture.
Leverage API gateways
API gateways are servers that provide a single endpoint for your microservices. The API is tailored to your client and can be responsible for authentication, load balancing, monitoring, request management, and caching. You use API gateways to route requests, translate protocols, and aggregate traffic from multiple microservices.
The benefit of API gateways is that you can have clients interact with the gateway rather than individual services. This simplifies client code, prevents tight coupling between service and client, and reduces the number of request round-trips. These benefits can make services easier to monitor, secure, and manage.
Use domain-driven design
Domain-driven design is a principle that expresses business models using practical rules in an object-oriented way. When microservices are built using domain-driven design, each service is designed to match your business domains.
This methodology enables you to create bounded contexts for services while using a common or ubiquitous language (UL). This UL helps prevent misunderstandings between business units and DevOps teams when services are built, ensuring that services are effective and functional. The use of UL also helps ensure that documentation is accessible and that the reasons for application design are clearly explained.
Implement asynchronous communication
Microservices must be able to communicate efficiently to be effective. This communication often involves chains of requests to various services for each action that is performed. If these communications are performed synchronously, the latency compounds and user experience suffers. Additionally, synchronous communication can lead to failure cascading, undermining the benefits of distributed services.
In contrast, asynchronous communications help ensure that services are loosely coupled and reduce total latency. Typically, async communications in microservices are accomplished through message queues, REST API, or command query responsibility segregation (CQRS).
Consider deploying dedicated databases for microservices
Using distributed databases requires more maintenance and more elaborate orchestration. Teams have to manage transaction and locking for each database or table, sync data between microservices, and manage permissions across more components. In exchange, services remain loosely coupled and more scalable.
The alternative is using shared databases or tables. These are less complex to manage but create single points of failure or bottlenecks for many services at once. Shared databases also make it more difficult to segregate data and can make security more challenging. For forward-thinking applications, dedicated databases are preferable but require more effort upfront, which teams may not be able or willing to invest.
As opposed to traditional monolithic architectures, microservices enable modular operations. With a microservices architecture design, you can quickly deploy features and updates, without having to shift the entire build. Microservices also make it easier to automate orchestration, ensure reliability per feature, and roll-out on the fly.
To ensure the effectiveness of microservices, you should leverage API gateways as a single endpoint for microservices. You should also use domain-driven design so that each service matches your business domain. For efficient communication, consider implementing asynchronous communication through REST APIs. You can also deploy dedicated databases for your microservices and get more capabilities and control.