Aristotle’s quote, “the whole is greater than the sum of its parts,” has long been used as a framework in business philosophy. The idea is that things are better off as one unit instead of in pieces. But microservices takes that theory and flips it on its head: The sum of the parts is, in fact, greater than the whole. It’s the reason so many companies are replacing their monolithic applications and architecture with a successful microservices approach, proving that there is more than one way to build software and technology stacks.
What is Microservices Architecture?
Microservice architecture, or just microservices, is an application or software systems development process that emphasizes creating single-purpose modules with specific operations and interfaces. A microservices approach uses several independently small services that are segmented and deployable while operating a unique method communicated through a smaller device to aid a business strategy, such as making a payment online, analyzing medical results, or routing network traffic.
Each microservice usually involves no more than 100 lines of code since it carries out a single task within a broader event-focused process. Ultimately, the microservices definition is meant to create measurable and scalable software that can be distributed on a routine basis. By combining microservices together, a fully efficient system or application emerges.
How Microservice Architecture Works
A microservice architecture breaks down an application into small parts to create independent APIs for each component, which are then hosted on their own virtual machines (VMs). Each service discovery within the microservice also needs its own database since a shared database is what defines a monolithic architectural style. Having independent databases is what allows these services to be loosely coupled. This kind of architecture is easier to manage and costs less to maintain than one big API.
Terms You Need to Know:
When it comes to microservices, there are two important terms to know: containers and Dockers.
Containers: Microservices go hand in hand with containers, which are the tools and processes used to develop and organize microservices. It’s a software package comprising of settings, code, system tools, runtime, and libraries. Containers separate software systems from one another as they run in the same environment, allowing simultaneous workflows on different microservices. For example, Linux containers (LXC) are used to run several isolated Linux systems on a controlled host using a Linux kernel.
Dockers: Simply put, Dockers are containerization tools that help manage containers, streamlining the process of creating scalable and easier to manage applications. Docker microservices allow for faster start times, quicker deployment, better computing resource usage, easier container management/scalability, and more support for multiple operating systems.
Understanding Monolithic Architectural Design
A monolithic architecture is a self-contained method, independent of other computer systems. Its design is a single-tiered software system where all components (database and user interface) are combined into one program from a single unit. But there are many associated drawbacks that make a monolithic approach more of a challenge than a benefit.
Monolithic architecture is inflexible when it comes to building applications using various technologies. This makes the approach unreliable because if one part fails, the entire system breaks down. And once a monolithic architecture is built, which often takes a long time, applications are unscalable. When an app needs an update, the whole system must be rebuilt. Thus, a monolithic approach doesn’t mesh with complex applications.
And these shortcomings of a monolithic architecture are the main reason why the monolithic vs. microservices debate has favored the microservices method.
Typical Microservices-Based Application Setup
A microservices architecture setup is defined by application components that are independent of the system’s other apps. But these standalone apps communicate with one another via RESTful web services, remote method invocation (RMI), and/or push messaging.
When designing microservices, the appropriate independent components should first be identified. These components are like mini applications, which are separately developed. They each go through their own specific development and deployment growth.
Within a system are various key components that are then independently deployed via their own mini applications. When data is needed from various components, a single request is made. An API gateway/front controller will then process data from individual components and feed them back.
A typical microservice architecture should also have inter-component communication, where components can talk via REST APIs, RMI, or messaging.
Microservices vs SOA
A microservices architecture and Service Oriented Architecture (SOA) have some similarities but also several important differences. With both methods, each service has a specific responsibility while developers handle complex architecture and distributed systems. Therefore, services are designed in numerous technology stacks.
But unlike SOA, microservices are deployed and operated separately from other services. With SOA, an Enterprise Service Bus (ESB), for example, becomes a single failure point, impacting an application as a whole. So, since all services are communicated through an ESB, when one service slows, the entire ESB becomes bogged down. But a microservice can compartmentalize so that when one microservice is disrupted, other microservices continue to operate properly.
However, unit testing as well as operational and deployment complexity can be equally problematic for microservices and SOA due to the different service types. And when it comes to data storage, SOA must share a database while a microservice database can work independently.
But the biggest difference between microservices and SOA is the overall size. The microservices footprint is much smaller than SOA, which can be a monolith or a combination of several microservices.
5 Characteristics of Microservices
- Multiple Components
The very essence of microservices is to have multiple components. Each service is deployed, altered, and redeployed on its own without compromising the application’s integrity. This allows the ability to change one specific service at a time rather than redoing an entire application.
- Simple Routing
Microservices receive requests, process them, and give the appropriate response. This routing method is simplified compared to an ESB. There are smarter endpoints that logically process data and information.
Many applications begin as a monolithic architecture but evolve into a microservice architecture through APIs. Microservices are designed to be evolutionary and are meant for systems that can’t predict what type of device might access a specific app.
- Failure resistant
Microservices are designed to handle a failed component without bringing down the whole system. Therefore, connected services and components function while the failed portion is fixed or replaced.
Microservices prefer decentralized governance since architects want to develop tools that can be used by others to solve similar problems. Microservices also favor decentralized data management whereas a monolithic system utilizes a single database for various apps.
Many large-scale apps and websites such as Amazon, eBay, Twitter, Netflix, and PayPal have progressed from a monolithic structure to a microservices architecture.
Amazon might be the ultimate microservices example. A user visiting Amazon’s website might see an easy-to-use interface, but behind the scenes there are processes for numerous services like accepting orders, determining a list of recommended items to purchase, a wish list, authenticating credit cards, and so much more.
Since Amazon has evolved into the holy grail of microservices, they get seemingly endless calls from numerous apps, including ones that manage the Amazon website itself to ones maintaining its web service API. That process would have been virtually impossible with its previous two-tiered structure.
Amazon organizes its microservices in a very unique way using something that CEO Jeff Bezos created called the “two pizza rule.” But what exactly is the “two pizza rule”? Teams shouldn’t be bigger than what two pizzas can feed. This rule was originally meant to explain how smaller groups at work can lead to more effective communication and eliminate process problems.
Essentially, it comes down to less is more, avoiding too many cooks in the kitchen. When you have a system that is broken down into smaller parts, it’s easier to manage and eliminates the possibility of one problem taking down the whole structure.
So, Amazon executes its enterprise microservices by:
- Breaking staff into two-pizza teams and allowing each team to own a microservice
- Designing teams to exist as part of the larger picture (Amazon.com, Amazon Prime, etc.) but to control every aspect of their microservice (DevOps, quality assurance, product planning, etc.)
- Building its own customized toolsets to deploy Amazon’s large-scale microservice operation
- Designing Apollo, a customized deployment tool that allows integrated status updates to guarantee newer software works as it should and one-click rollbacks/deployment
- Creating Pipelines, a continuous delivery tool to support company development workflows that automates alerting and action-taking
- Monitoring of host metrics, service metrics, log analytics, and build metrics
Since microservices are smaller independent services that work off one another, the method offers a variability that has grown in popularity among the IT crowd. The flexibility and scalability are preferred when operating a wide range of devices and platforms.
The primary concept behind a microservice architecture is that systems and applications are easier to build and manage when broken down into bite-size portions that can be deployed, redeployed, and worked on independently while still working together.
Here are several benefits to microservices:
- If one microservice fails, the others will still work
- Varying code services can be written in different languages
- Simplified integration with automated deployment
- The architecture allows continuous delivery
- Easily modified for developers, allowing new users to be quickly onboarded
- Code is customized for business capabilities
- Efficiently scales, integrates, and reused, even for third-party services
- Elements spans to multiple servers or database centers
- Integrates with containers and Docker
- Supplements cloud systems
- Security problems are isolated in order to preserve other unaffected portions
But that’s not to say a microservice architecture doesn’t have its pain points. But if some of the following challenges can be solved, microservices become more than valuable.
Team communication and formal documentation overhead
Since a microservice architecture has so many moving parts, communication is key among users for seamless system and application functionality to exist. Continually updated interface documents and schemas are a must for anyone running any component of the application or system.
Increased resource user and network communication
The upfront cost to operate an application isn’t cheap due to each separate component requiring a runtime container with CPU and memory. And since running these independent components communicate within a network, these systems need fast and reliable connections.
Non-uniform application and DevOps complexity
Choosing varying technology stacks for different components in the system leads to the issue of a non-uniformed application architecture, which drives up maintenance costs. A seasoned DevOps team is needed to deal with the complex microservice-based apps.
Network security and testing
To avoid security breaches, an internal communication service must be protected. Due to all the moving parts, the system is going to be more vulnerable to hacks. Additionally, the overall testing of a microservice applications is more difficult than a monolith architecture.
Production monitoring and upfront costs
The price to monitor microservices systems and applications is costly and the tools might not always be readily available. And the overall cost of a running various applications will drive up costs compared with a monolith system.
Marshalling and unmarshalling
The complexity of this requires much more processing when one part requests data from other components. In short, the dispatching component marshals data from its internal representation, while the receiving component unmarshals data for its own representation.
Design Principles for Microservices-Based Enterprise Application
According to Rajendran Balakrishnan and Chandrakanth Puvvada at Ness Digital Engineering, there are five key design principles for microservices that make an enterprise application a scalable and easy-to-maintain solution.
Principle 1: Domain-Driven Design
Domain-driven design focuses on the core domain and associated logic to reduce the chance of an application failing. It creates effective collaboration among DevOps and development teams to help understand what’s needed to scale and grow.
Principle 2: Hide Implementation Details
It’s important to hide the implementation details of each service within the architecture to ensure the scalability of one service apart from other services. The REST protocol helps services talk to one another with lightweight communication, and separating external and internal implementations allows these details to happen.
Principle 3: Decentralization
Since monolithic systems share a single database, it becomes difficult to alter down the road. Microservices allows each service to manage its own database in microservices, within the same database technology or different database systems altogether.
Principle 4: Failure Isolation
A faulty microservice, such as an unclosed database connection or a memory leak, will only impact that specific service, allowing other services to take on separate requests. This makes a microservice much more resilient than a monolithic architecture.
Principle 5: Continuous Delivery through DevOps Culture
Within a microservices structure, deployment units increase and require automation, which is enabled through automating the build and deploy processes with Jenkins and/or CHEK tools from DevOps. Microservices reduces Jenkins workloads to one single job for each release artifact.
Microservices has moved past being just a technological buzzword and has emerged as the preferred method to build enterprise applications. Amazon, Twitter, and Netflix have paved the way for companies to evolve from monolithic structures to microservice architectures, which will ultimately become the top choice of technology for developers.
With the rise of Internet of Things (IoT) development, microservices will become a part of every industry. The benefits of microservices outweigh the risk of monolithic architectures, creating a foundation of future innovation for any company.