What are Microservices?

Microservices, also known as microservice architecture, is an architectural style that structures an application as a set of loosely coupled services that are lightweight, deployable, and scalable independently. These services are based on business capabilities and can be deployed separately.

Let us compare the microservice style to the monolithic style: a monolithic style structures an application as a single unit. Change cycles are intertwined; a change to a small section of the program necessitates rebuilding and deploying the full monolith.

In addition, it's generally difficult to maintain a solid modular structure over time, making it extremely hard to keep changes that should only affect one module within that module. Therefore scaling a module of the application necessitates scaling the entire application rather than just the module that requires more resources.

However, the microservice architectural style structure programs as a collection of services. Each service offers a strong module boundary, allowing different services to be built in different programming languages and managed by different teams.

While there is no formal definition of the microservices architecture style, there is an attempt to identify what we believe to be common characteristics of structures that meet the designation;

Software in a microservices architecture is made up of small, self-contained services that communicate over well-defined channels such as APIs, events, messages, and so on. These small components are split out such that each one focuses on one task and executes it effectively, all while working together to provide a fully functional application.

The Walkman portable audio cassette players, which were popular in the 1980s, are an example. The batteries provide power, audiotapes serve as the medium, headphones supply output, and the primary tape player accepts input via keystrokes. When you combine them, you get music.

Likewise, microservices must be separated, with each service focusing on a single task. A microservices architecture also provides for easy replacement or update. If the headphones on a Walkman are worn out, we can replace them without having to replace the tape player.

Also, we can replace an account management service in our e-commerce application that is lagging and operating too slowly with a better performing, streamlined component without affecting or interrupting the operations of other microservices in the system.

Before microservices, system design used to be organized around technology capabilities like user interface, database, and server-side logic. In a microservices-based approach, each development team owns the lifecycle of its service from conception to delivery to the consumer.

A catalog team, for example, will be responsible for the development, deployment, production support, and customer feedback collection.

Furthermore, It allows teams to release features at their own pace and promotes responsibility and accountability that build an ownership culture, allowing teams to better connect with their organization's goals and be more productive.

Organizations with mature applications and successful software adoption that wish to keep and grow their user base will likely be more successful if they focus on the customer and end-user experience.

One way organizations do this is by treating software components as products that can be iteratively enhanced and are always evolving in order to simplify operations, and boost efficiency.

This is in contrast to the software as a project approach. That is, completed by a team of engineers and then handed over to an operations team to maintain. When software architecture is broken down into small microservices, each microservice can function as its own product.

The main advantage of treating software as a product is that it enhances the user’s experience. The code developed by the organization will be better architectured for future work and eventually produce an improvable product.

Additionally, treating software as a product makes the software simpler to use, maintain, and extend. Consumers value software that is reliable.

“Once launched into production, our software will continue to evolve as the way it is used changes. For most things we create, we have to accept that once the software gets into the hands of our customers we will have to react and adapt, rather than it being a never-changing artifact. Thus, our architects need to shift their thinking away from creating the perfect end product, and instead focus on helping create a framework in which the right systems can emerge, and continue to grow as we learn more.” Sam Newman (Building Microservices).

The numerous components of a monolith are all involved in the same process. However, Components in a microservices context are separated by rigid boundaries. At scale, the various components of a microservices environment are frequently distributed throughout a cluster of servers and are not always co-located on the same server.

As a result, there are two primary modes of service communication:

Request/Response: When a service makes an explicit request to store or obtain data from another service.

Publish/Subscribe: When a service implicitly invokes another service that is listening for an event.

Hence, HTTP request-response with resource APIs and lightweight messaging with a message broker tool are the two most frequent approaches used for communication between microservices.

In addition, the ability to decentralize the architecture is a key feature of smart endpoints and dumb pipes, especially when it comes to how endpoints are maintained, updated, and extended. Therefore, allowing concurrent work on distinct edges of the architecture without interfering with each other. Dumb pipes allow each microservice to encapsulate its own logic for structuring incoming requests and supplementing outgoing answers.

Decentralized governance is an approach that complements microservices. For example, traffic lights in cities can be timed individually or in small groups, or they can respond to sensors on the pavement.

However, in order to keep cars flowing in the city as a whole, there is no need for a "master" traffic control center. Local optimizations that are implemented separately work together to give a city-wide solution.

Using the decentralized governance approach, each team can utilize its expertise to select the most appropriate tools to handle their particular problem. Because the problems they are solving are not all the same, forcing everyone to utilize the same database or runtime language isn't a good idea.

Although, decentralized governance does not exist in a vacuum. Using standards throughout the organization, such as a consistent build and code review procedure, is beneficial since it allows each team to continue to function together.

The microservices architectural style requires that each service have its data store and data schema. As a result, each service team selects the database type and schema that best suits their application.

Also, the service teams are responsible for selecting the database type. It is an example of decentralized decision-making, with no central authority imposing standards other than some basic connectivity guidelines.

Furthermore, decentralized data management improves application architecture by allowing the application to use the optimal database for the job. Also, it:

Eliminates the hard effort of a shared database upgrade.
Allows for more autonomous decisions.
Allow teams to be self-contained and evolve according to their own set of guidelines.

Microservices require not only disposable infrastructure-as-code, but also the ability to build, test, and deploy automatically. It also requires constant integration and delivery to function properly, with each service having its own pipeline that can handle the team's many and varied technological choices.

Hence, an automated infrastructure ensures that environments can be set up fast and with reliability. Each of these environments can be dedicated to a particular task: development, integration, or performance testing, and production. As a result, encouraging experimentation and creativity.

As a result of using services as components, applications must be built in such a way that they can withstand service failure. Any service call could be aborted owing to service provider unavailability; the client must handle this as graciously as possible.

This is a drawback in comparison to a monolithic architecture since it adds to the difficulty of handling it. Hence, microservice teams have to think ahead on tackling how service failures affect the user experience.

Additionally, Products designed for failure will have more uptime and help protect the organization from outages that could damage customer confidence.

Most modern designs do not have all of the requirements upfront. As a result, a detailed design process at the start of a project might not be feasible. Various software iterations must be used to evolve the services by learning from real-world usage to help evolve the functionality of the services as they are utilized.

Therefore, a service team can create the minimum viable features required to set up the software and distribute it to users, then concentrate on the necessary components to refine the design in response to end-user feedback.

The Microservices Architecture style has a number of important benefits, such as

Improved scalability and agility: Individual teams can use microservices to implement, debug, test, and deploy code without having to deal with the requirements and deadlines of other teams.

Support for multiple technologies: Microservices enable development teams to select the best tools for the job at hand. For the implementation of a certain service, teams can choose any programming language, development approach, or database structure without compromising the functionality of other services.

Improved fault isolation: Because microservices allow numerous services to run at the same time when one fails, the entire system is not completely disrupted.

Improved Productivity: Microservices enable each independent service to be powered by a small, focused team that is responsible for the service's uptime and ensures that the proper resources are selected to sustain it.

Faster time to market: Because microservices allow for pluggability, application development and upgrades are quick. The development team can instantly design or modify a service before plugging it into the system, reducing the chance of operational conflicts and system outages.

Microservices may be popular and highly adopted, but the architecture is not without some flaws with potential pain points like,

Managing Microservices: Controlling the entire microservices life cycle, including how they are created, tested, versioned, deployed, and maintained, may be difficult and cumbersome, especially as the number of microservices increases.
Monitoring and diagnosing the microservices: Considering the speed and dynamic nature of microservices, organizations will need to monitor
CPU usage.
Scalability
Communication flow.
Service failure.
Testing.
Testing and Quality Assurance: Testing and quality assurance are much more complicated in a microservices architecture due to the various services that make up an application.
Cultural and Organizational Change: Microservices migration necessitates adjustments to a DevOps automation and Agile culture.

Microservice development tools are typically split into the following categories, each of which plays an important role in microservice development by enhancing the productivity of teams.

Architectural Frameworks: Spring Cloud, Goa, and Kong are key architectural frameworks that are used to construct applications.
Programming Language: The advantage of microservice development is that it may be produced utilizing a variety of programming languages and technologies. Which programming language should be used for development is entirely dependent on the requirements of the business function. Examples include Elixir, Spring Boot, etcetera.
Message Brokers: Microservices-based applications are a system in which independent services communicate synchronously and asynchronously with each other or inside themselves. Microservices make use of message brokers to communicate between themselves. Examples include RabbitMQ, Amazon Simple Queue Service (SQS), Apache Kafka, etcetera.
Containerization: Containerization entails creating an application with all of its dependencies and configuration files in order to run it in a different computing environment, such as on a developer machine or across servers (each of which may run a different operating system); it works on the principle of build, ship, and run any app anywhere across different environments. Examples include Docker, Hyper-V, LXC, etcetera.
Cloud Deployment: Infrastructure as a service (IaaS) is provided by cloud service providers such as Amazon and Microsoft Azure for microservice deployment.
Application Monitoring: It's important to monitor the application's working events in the production environment after it's been developed and deployed. Examples include Logstash, Graylog, etcetera.
API Testing & Management: When creating microservices solutions, it is crucial to ensure that all of the various services can communicate with one another through APIs. Examples include Postman, API Fortress, Tyk, etcetera.

Microservices architectural style is a significant concept for enterprise applications to explore. Amazon, Netflix, The Guardian, realestate.com.au, Forward, and comparethemarket.com are among the companies that have lately established and prefer this style.

Despite its implementation problems and complexity, it is still commonly accepted as one of the optimum choices for developing enterprise applications.