Microservices describes an architectural style in software development using small, independent services with defined APIs to ensure scalability and rapid release. Loosely coupled, individually deployable, and team-owned, microservices are built around business capabilities for speed and stability.
In nature, bigger isn’t always better. And while a great white shark may be the scourge of the oceans, there are many instances where a school of fish is more capable of surviving and thriving as a group than any single organism. In fact, success by collaboration is a common theme throughout the animal kingdom; ant colonies, beehives, wolf packs, etc. all benefit from working within loosely coupled systems to distribute control and achieve common goals. And should one member of the colony, hive, or pack perish, the rest of the group can continue to function and make up for the loss.
Microservices take this approach and apply it to software development and system architecture. The idea is that it is often faster, easier, safer, and more efficient to build a number of component functions or services separately, than it is to install the same functionality into a self-contained and fully interconnected system. Here, we take a closer look at microservices, along with their attributes, benefits, and challenges.
Perhaps the best approach to understanding what microservices are is to first identify what microservices are not. There are a number of distinctions between microservices and other organizational approaches. Here, we compare microservices to traditional monolith architecture, as well as the more-recent service-oriented architecture (SOA).
As the name suggests, monoliths are large, unified applications where each component is largely interconnected and dependent on neighboring components. Monoliths are the traditional approach to development, with all functions managed and served in one place, and everything built on a single code base. Any changes that developers may wish to implement in monolith structures will naturally change the entire stack. Activities such as testing apply to the entire stack as well and so changes are grouped together in large release that can take a relatively long time from start to finish. Microservices are distinct from monoliths, in that they are composed of a number of smaller, self-contained, loosely-joined components. Changes may be implemented on the individual components without affecting other services within the application.
The distinction between microservices and SOA is more subtle. However, while both rely on reusable components that may be modularly applied to different applications, SOA is not nearly as granular. Where microservices are containerized to the point where every service performs only a single function, each SOA component may be a complete subsystem responsible for a range of business functionality. Additionally, SOA optimizes component sharing and dependencies, while microservices simply try to minimize these aspects as much as possible.
Typically, microservices feature the following characteristics:
Because microservices are designed as a collection of individual, independent services, they can be easily tested as standalone components. Issues within the components can be quickly isolated, rather than having to test entire systems and applications, and then invest large amounts of time in trying to isolate specific failures.
To operate in tandem, microservices must maintain communication with one another. That said, this is a loose connection, where changes implemented within one service do not directly affect other services.
Rather than sharing data stores across services, each constituent component maintains its own data store. This helps prevent accidental coupling of different services, and ensures that changes do not unintentionally impact other independent services.
Individual services are changed and deployed into the production environment without having to employ any other services. All deployments within the system are managed in this manner making it very quick to enhance a microservice.
Microservices make use of cross-functional teams, which are organized around a single business purpose. These teams often consist of developers, database engineers, testers, infrastructure engineers, and others, with the goal being to develop specific products based on multiple independent services.
In microservices, each independent service is capable of receiving, processing, and responding to requests. This is greatly simplified over many of the more-traditional systems, where complex routing and business-rule application layers can end up slowing the process.
For a microservice system to completely fail, essentially all of its independent services must fail at the same time. By relying on loosely-connected services, a system may continue to operate near optimal capacity even in the event of a failure in one of its services. Because the services are decentralized, the loss of one should have little to no impact on neighboring services.
Because microservices are modular in nature, it is relatively easy to add new services when needed. This makes it possible for organizations to adapt current systems to new uses, and to scale systems up or down to meet changing demand.
When developing a new service, organizations have the freedom to choose from various technology stacks. At the same time, new technology stacks may likewise be employed when making changes to existing services.
Microservices architectures offer a versatile approach to software development and deployment, catering to a broad range of use cases. This modularity and flexibility enable organizations to adopt microservices for many applications, enhancing scalability, reliability, and agility in the process. Below, are various scenarios where microservices can be particularly effective:
Microservices can significantly augment data processing capabilities—particularly in extending support for cloud-based services. Each service can focus on a specific aspect of data processing while simplifying the integration of new data sources and processing technologies.
A microservices setup ensures high availability and accessibility, essential for delivering media content directly to web and mobile platforms. It also allows for easier scaling and updating of media processing and storage components without impacting the entire system.
Traditional, monolithic websites often face scalability and agility challenges as they grow. Microservices architecture makes it easy to move these complex websites to more dynamic, cloud-based, and containerized platforms. This shift not only facilitates easier management and deployment but also enhances the website's ability to scale on-demand, improve resilience, and accelerate feature development.
Microservices architecture excels in segregating the components of a system, such as payment processing and invoicing, into independent units of service. This separation ensures that critical functions, like accepting payments, remain operational even if other parts of the system, such as invoicing, encounter issues. Such resilience is vital for maintaining business continuity and ensuring customer satisfaction.
The modular, containerized approach used in microservices development makes it a natural partner to both DevOps and continuous integration/continuous delivery (CI/CD). Because each service is approached as its own unit, multiple teams can work separately to develop functionality concurrently, applying DevOps principles and moving projects quickly through CI/CD pipelines.
Although it is possible for microservices to communicate directly with each other, many businesses prefer to integrate API gateways to function as intermediary layers to help route requests, provide additional authentication, and improve security. API communication may be particularly effective when microservices are first establishing state.
Microservices represent a shift from traditional development architecture, and provide a number of advantages over more-conventional organizational approaches. These benefits include the following:
Microservices empower small, independent teams to act within clearly-defined contexts. This allows them to accomplish more in less time, and to respond with increased agility to unanticipated changes.
Microservices break down complex applications and systems into smaller, simpler components. Developers can more easily see distinctions between services and make necessary updates and improvements.
Rather than being locked into a single language or technology stack, developers have the freedom to select the best solutions, tools, or resources for each individual function—without having to worry about communication between services being affected.
Because microservice-based applications are highly modular, they can be developed and deployed with relative ease. Teams can coordinate together to work concurrently on individual, small components, and each component can be deployed independently.
In traditional application architecture, meeting changing demand often means scaling the entire application. Microservices allow developers to redirect resources towards scaling only the applicable services and components, improving scaling speeds while reducing associated costs.
In the event that one microservice fails, neighboring microservices remain unaffected. This means that microservice-based applications do not tend to crash; if one or more components fails, the application itself will continue to operate at reduced functionality until the affected service can be repaired.
Because each service is self-contained and designed to independently perform a specific function, developers can reuse and recycle services for use across a number of different applications. Components can function as ‘building blocks,’ significantly reducing the need to create new code from scratch for every new project.
Improved agility, increased reusability, and simplified deployment all promote shorter development cycles and faster time to market. This has the potential to improve business returns and deliver a more-satisfying user experience.
The advantages represented by microservices also carry with them certain difficulties. Here, we take a closer look at some of the challenges organizations may encounter when implementing a microservices approach:
Making the switch to microservices means identifying and cataloging any and all dependencies between services. Due to dependencies, completing a single build may directly lead to having to implement a number of other builds, which can be frustrating and time consuming.
A key factor in microservices is that each component has its own, isolated database. But with each new database comes increased complexity in management. The more services, and the more databases, being employed, the less convenient it is to manage the data itself.
When updating applications to new versions using microservices, there is a chance that backward compatibility may be affected. The solutions—building in conditional logic or standing up multiple live versions for different clients—may be overly complex in terms of maintenance and management.
Microservices are designed to simplify deployment. But the complexity of working with a large number of independent components can be overwhelming. Automation may help resolve this issue.
Logging can become difficult when every service uses its own database. Establishing centralized logging solutions may be necessary. Similarly, monitoring and managing each service may be unfeasible without a centralized view and single source of truth.
With potentially hundreds of microservices incorporated into a single application, traditional debugging is not an option.
While microservice architecture gives teams a fair amount of independence, issues that span more than one service within an application may demand detailed cross-team communication and coordination to set right.
Because microservices applications are distributed systems, it is not unheard of for teams to unknowingly duplicate tasks. This can result in wasted effort and inefficient applications.
In addition to the challenges addressed above, there are certain pitfalls that organizations should be aware of when considering adopting a microservices architecture:
Although a very popular approach to development architecture, microservices are generally best suited to repairing and revising existing applications that have gotten overly complex and difficult to maintain. They are not nearly as effective when used as a starting point. If the traditional approach hasn’t reached unmanageable levels, then it’s not actually a monolith in need of restructuring.
As with anything else, a service can always be divided into smaller parts. And while microservices should be granular, consisting of limited functions designed to support a greater whole, it is possible to take things too far. Instead, many companies find that starting with larger services, and then only breaking them down into microservices when they become slow to deploy or too complex to manage, helps ensure that the solution doesn’t offset the potential gains.
A large, distributed system can easily get out of hand. To ensure microservices effectiveness, organizations should incorporate advanced deployment and monitoring automation, along with managed cloud services. This can help ease much of the burden of transitioning to microservices.
There is a lot that goes into determining how effective an organization’s approach to microservices may be. To maximize the benefits while minimizing the possible impact of pitfalls, consider the following best practices:
Services should communicate through APIs that hide implementation details, focusing instead on domain-relevant interfaces. This approach prevents tight coupling and makes services more consumable and easier to integrate.
Shift responsibilities like authentication and SSL termination to an API gateway, freeing individual services from these common, non-business-specific tasks. This simplification supports a cleaner service architecture.
Avoid practices that lead to service interdependencies, such as shared databases or inflexible communication protocols. Strive for loose coupling to facilitate independent service evolution and deployment.
Design services to mirror the organization's business domains. This alignment simplifies understanding and evolving the system as the business' needs change, ensuring that services remain relevant and focused on delivering value.
Data storage should be service-specific, with each service having exclusive control over its data store. Opt for the most appropriate storage mechanism based on the service's requirements and the nature of its data, enhancing data management and access efficiency.
Empower individual teams with the responsibility for their services, from design to deployment. Avoid the pitfalls of shared codebases and data schemas, which can lead to tight coupling and may complicate independent service evolution.
The API gateway should route requests without understanding or processing business logic, preventing it from becoming a bottleneck or a point of tight coupling among services.
Adopt patterns such as circuit breakers and bulkheads to isolate and manage failures, preventing issues in one service from impacting others. This approach ensures system reliability and availability.
Regularly review and adapt service boundaries and practices based on evolving business needs and technological advancements. Continuous improvement is key to maintaining an effective microservices architecture.
ServiceNow can help with the management aspects of services built leveraging microservices as well as by connecting to the methodologies and tools used in the build phases such as CI/CD and other DevOps solutions.
Given the potential for large numbers of microservices and their transitory nature, ServiceNow provides options for automatically populating the CMDB and Service Graph to help track relationships and maintain the definition of services. This is part of our IT Operations Management offering which also provides broader cloud management capabilities.
As with any code developed with DevOps practices, speed is a common goal when maintaining microservices – I.e. providing the fastest possible path between a developer and a production system. But larger or regulated organizations must maintain strong change controls, so IT Service Management Professional includes our DevOps Change Velocity feature that connects to the CI/CD pipeline, gathers information during the development process, and utilizes it alongside previously defined policies to automate the change management process.
Finally, ServiceNow is a rich source of capabilities that can be utilized by internal and external applications in a microservice-like way in addition to supporting the integration with external microservices as part of ServiceNow workflows.