As people's reliance on electronic devices continues to grow, more demanding applications are emerging that require significant amounts of computing power and must be adjusted to operate in dynamic network environments. Applications that stream videos, as well as other services like Netflix and Uber, are typical examples. In order to fully utilize the computing resources, it is necessary to improve the design of the various services due to the rise in user requests for them as well as the demanding applications.
Microservices architecture has assisted in bringing a new era of software development. In this article, you'll learn what microservices are and what they bring to the table. Let's get started!
Monolith and Its Challenges
A monolithic architecture was the norm for application development before microservices emerged. Monolithic architecture indicates that the entire application is a single unit. For instance, all the code for an online store application's components, such as user authentication, a shopping cart, a product catalog, sales campaigns, notifications, and so forth, would be contained in a single code base as a single monolithic application.
The application must be written in a single language using a single technology stack with a single runtime because everything is developed, deployed, and scaled as a single unit. Additionally, if different teams are working on different application components, they must coordinate to prevent interfering with one another's efforts. You cannot simply update and deploy just the changes to the payment functionality separately; rather, you must build the entire application and deploy it as a package if developers make changes to the code for the payment functionality.
This was, therefore, a common method of developing applications, but as the size and complexity of the applications increased, many challenges emerged.
- The larger code and the more intricately intertwined components of the application made it more challenging for teams to coordinate.
- To scale just that portion of the application in the event of an unexpected spike in usage, such as during peak holiday periods, the entire application must be scaled. Higher infrastructure costs and less flexibility in scalability for your application follow from this.
- Another issue is, for example, if a payment functionally used a third-party module with one version while notifications featured needed the same module but required another instead, in a monolith application, you would have to pick one or the other because it's a single application and you can only have one dependency of the same module.
- Monolithic applications have yet another significant drawback: their release cycles are longer because, to deploy changes to any feature or component of the application, you must first test and build the entire application.
Microservices architecture provided the solution to each of these problems.
What Are Microservices?
Microservices are more compact, loosely coupled services that are independent of one another. The word "services" describes a variety of an application's features. In a microservices architecture, an application's functions are therefore divided into numerous smaller components that each serve a specific purpose.
These fine-grained components or services typically have separate technology stacks, data management strategies, and databases, and they can communicate with other application services using streaming, message brokers, and Rest APIs. Since the services in the microservices architecture are distributed and loosely coupled, even if something goes wrong in one of them, it won't affect the rest of the system. Unlike traditional approaches, loose coupling reduces the complexity and dependencies of an application.
To meet growing business needs, development teams can speed up the process of creating new app components. It should be noted that the terms "microservices" and "microservice" are completely different from one another and have different meanings depending on the industry. A microservice operates independently and represents an application's core functionality. The term "microservices," on the other hand, refers to the entire architecture for developing an application. It transcends fundamental operations and loose coupling. Additionally, microservices define your communication and development processes to make it possible to integrate new features, offer scalability, and be ready for errors and problems.
Next, let's examine a few microservices examples to gain a more clear understanding. The most successful businesses, including Amazon, Netflix, PayPal, Meta, Twitter, etc., have transitioned from a traditional monolithic architecture to microservices. With its seamless scaling, business agility, and higher profits, this architecture has undoubtedly contributed to their greater success.
Let's use Amazon as an example so that you can better comprehend the idea. We all know that Amazon was not as popular in the early 2000s as it is now. The retail site was a monolithic application back then, which made it difficult for developers to scale or upgrade Amazon's systems because the monolithic application had multiple components and tiers that were intricately linked. As a result, as the application grew, it reduced flexibility and increased complexity. This burdened development teams and slowed down their overall process, making it harder to meet the application's scaling requirements and live up to customer expectations.
They adopted the microservices architecture as a result. They started by carefully analyzing all of their source code, and then they extracted code units that served a single function. They then enclosed those code units in a web-based service interface for user-friendliness. For instance, they created a separate payment service that functions as a single component for their "buy" option. In addition, to increase scalability, Amazon gave developers ownership of certain services so that they could monitor them closely and address problems as soon as they arose.
Types of Microservices
Microservices can be broadly divided into stateless and stateful microservices. Each type of microservice has a specific application. Distributed systems are made up of stateless microservices. They are called "stateless" because they don't track or store any session state between requests. Additionally, the service's overall processing logic is unaffected even if a service instance is deleted. This is why stateless microservices are seamlessly incorporated into distributed systems.
Stateful microservices, on the other hand, preserve or store session states or data in the code. These kinds of microservices always keep track of service requests when they talk to one another. Between the two, stateless microservices are more frequently used.
Components of Microservices
Next, let's learn about the different components of microservices
Clients: These can be software programs, websites, or other services. Various types of clients are included in the microservices architecture to handle tasks like searching, configuring, building, etc.
API gateway: this is where clients enter the system so they can send requests to the appropriate services. Since the clients do not directly call the services, an api gateway is used. There are numerous advantages to using API gateways, including maintaining the services' updates, offering load balancing, security, and more.
Identity providers: Client requests are sent to identity providers, who authenticate them and pass them along to internal services through an API gateway.
Data handling: Microservices use private databases to store information and implement business functionality.
Messaging: To handle client requests, microservices communicate with one another via messages. These messages can be either synchronous, in which case the server waits for a prompt response, or asynchronous, in which case the client acts immediately.
Static content: After exchanging information with one another, microservices upload additional static content to a cloud storage service to enable content delivery networks to deliver it directly to clients (or CDN)
Service delivery: This microservice's guide to locating inter-microservice communication channels. It oversees a service list that contains nodes.
Benefits of Microservices
The main benefit of a microservices architecture is that it provides a solution to a system's growing complexity. The developer is compelled to split the application into distinct services with distinct boundaries by using microservices. By doing this, we can create modules that are much clearer, much more loosely coupled, and that can be developed more quickly.
Another key benefit of this architecture is that any microservice can be created with it using any technology and language. The API that it must support is the only constant. So, depending on the unique features that each microservice has, developers can select any number of languages or technologies. Additionally, it makes it possible for new microservices to use tools that weren't available when the older ones were developed. Finally, due to their small size, microservices may even be developed entirely from scratch using more recent technology.
In contrast to the monolithic application, where deployment was a laborious and complex process, now each microservice is deployed independently. Each follows its own pace of development and can go live in production as soon as testing is finished. In other words, one part of the application stops creating obstacles to the other, and everything waits for a third party, which was a classic scenario in the past.
A particularly important problem of a mature monolithic application is scaling. With microservices, we can scale whatever microservice is required and to the extent that it is also needed. It is common when the orchestrator (e.g. Kubernetes) sees a microservice reaching its limits to spin up more instances. Also, different microservices can run on different hardware depending on the needs and specificities of each one.
Disadvantages of Microservices
A system developed with microservices is a distributed system. For this reason, the developer must write code for the communication between the microservices and also do error handling if some microservices are not available. This adds an overhead to the amount of programming developers have to do. Along with the distributed system comes the distributed architecture at the base. Instead of a global base in which we can check all transactions, each microservice has its own base.
Also, usually for the execution of an operation, transactions must be made in several databases. This should be treated as a single transaction with extra code and complexity on the developer's part. As mentioned, microservices make testing easier but, at the same time, a bit more complex in terms of their orchestration. For features that require changes to more than one microservice, it is important to program how these changes will be implemented to satisfy the dependencies. Of course, this is not a frequent problem if microservices are properly structured.
Along with the application's increased flexibility and power, there was an increase in complexity in its deployment. A traditional monolithic application only has one server. We merely have identical servers if scaling is also present. However, with microservices, we have a wide variety of applications running in various VMs/dockers. Although this system as a whole is much more flexible, it is also much harder to organize.
Microservices is an architectural style that structures an application as a collection of loosely coupled services which implement specific business capabilities. This approach offers several benefits over a more traditional, monolithic architecture. One of the main advantages is that microservices can be developed, tested, and deployed independently, allowing for more efficient and agile software development. This can make it easier for a team to add new features or make changes to an application, as they can work on a single service without impacting the entire system. Additionally, microservices can be deployed on different hardware or in different environments, providing greater flexibility and scalability. Overall, the microservices approach can help organizations build more resilient and scalable applications that are better suited to today's dynamic business environment.
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