Microservices Or Microservices Architecture Is An Approach To Application Development In Which A Large Application Is Broken Into Modular Components Or Services, So That Each Module Is Responsible For Performing A Task, A Simple User Interface, And It Communicates With Other Services Through Application Programming Interfaces (API).

Martin Fowler, a well-known software developer, was the first person to propose the philosophy of breaking large applications into small services and modules and moving from service-oriented architecture (SOA) to microservices architecture.

What is a microservice?

Microservice is a solution to divide an application into small, lightweight, independent, and manageable parts or services. To be more precise, microservice is a distributed software development architecture.

If you look carefully at Figure 1, you can see that these services are designed to manage only one specific task. For example, one benefit is responsible for managing users, while another is designed to search the site. Considering that microservices are separate and independent from each other, it is possible to write them in different programming languages. Also, to store the related data, it is possible to use separate database management systems. To be more precise, for some services, it is possible to store data traditionally in a database such as MySQL. In other situations where we have an unpredictable data structure, it is possible to use NoSQL databases.

Now we come to the critical question of how different services of an application based on microservice architecture communicate with each other. If you look carefully at Figure 1, you can see that HTTP protocol dialogs and a series of functional interfaces based on the RESTful design pattern are responsible for this.

figure 1

What is Service Oriented Architecture?

An essential question that software developers ask is, what is the difference between service-oriented architecture (SOA) and microservices? Service-oriented architecture has been the focus of software teams for the past decade, but it lacks much flexibility. While microservice is more flexible than service-oriented architecture, you can easily remove a service or module from a project and transfer it to another project without making notable changes. Also, the service-oriented architecture itself is implemented in another architecture called monolithic.

To be more precise, in service-oriented architecture, we have components or modules that provide services to other members. These components can be unique to a particular application. In the microservice architecture, these components are independent services that can be deployed individually. Another thing we should mention about the differences between these two architectures is the size of the modules.

 Microservices services or modules are more minor than service-oriented modules, making them easier to manage.

In general, we should say that service-oriented architecture is a software architecture in which each service uses protocols to communicate with each other. Service-oriented architecture has been recognized as a standard development method for nearly two decades. However, the above architecture faced challenges in interacting with cloud computing. For example, it cannot support scalability and has a late response to changes, which limits the application development process.

Most developers believe that microservices provide a more precise mechanism than service-oriented architecture. Proponents of the above model believe that the microservice architecture is a natural evolution of the service-oriented architecture that emerged to adapt to cloud computing and respond to the increasing demands of software development cycles.

Differences between microservice, service-oriented and monolithic architecture

In monolithic or integrated architecture, different modules of an application are closely related to each other. This mutual and close relationship is called Tightly Coupled. In the above architecture, if we intend to apply a change in one of the sections, we will face a problem. This issue causes “Continuous Deployment” to suffer. Service-oriented architecture has a more flexible approach than monolithic architecture so that we can divide the application into separate parts from each other. However, each piece is under the umbrella of the leading platform. Microservice architecture is unlike the two different architectures; each module is independent of the other. This separation of modules from each other is called Loosely Coupled.

In a unified architecture, all code resides in a single main executable, which makes troubleshooting, testing, and updating difficult because a problem in one code base can negatively impact a portion of the software. Code integration not only increases testing time but every small change or update to an integrated application requires creating and deploying an entirely new version. Developing an integrated program requires significant planning, preparation, time, and cost.

Compared to integrated software architecture, the microservice architecture makes software development and deployment faster and increases business agility. 

Microservices can make it easier to test and deploy changes. In addition, the isolation of services improves the debugging process. If a problem occurs in the software, it is possible to try and investigate the faulty service without testing the entire application as in traditional integrated architectures.

Another problem with integrated applications is their limited scalability. When an integrated program reaches a capacity limitation, such as a low data transfer or processing rate or some other bottleneck, the only practical option is to write and distribute a new version of the program aimed at overcoming the problem. The microservice architecture allows developers to solve the problem of low traffic transfer rates by managing load-balancing mechanisms.

In general, we must say a program based on a microservices architecture that uses container instances allows the extensibility process to be carried out in the scope of each service separately from other services.

The above approach makes the scaling of microservices more efficient regarding resource consumption or optimal use of resources than scaling applications based on integrated architecture.

The microservices development paradigm separates services from each other. However, a big problem with microservices is managing many services. This issue makes centralized monitoring and management of all services difficult.

For example, careful monitoring and management to check service availability and high performance are time-consuming. Figure 2 shows the difference between microservice and integrated architectures.

figure 2

How does microservice architecture work?

In a microservices architecture, an application is divided into individual services that can communicate with each other. Each service runs a unique process and has its database. Typically, a service can have its alerts, incoming and outgoing data, user interfaces, and user identification or authentication mechanism.

An important point to mention in this context is that the microservices paradigm provides development teams with a decentralized approach to building software. So that individual services can be produced, rebuilt, deployed twice, and managed independently. For example, suppose an application isn’t generating reports correctly. In that case, IT staff can trace the problem to a specific service and then test, patch, and restart it as needed, independently of other benefits.

Advantages of microservice architecture

Today, modularity is a substantial competitive advantage in software development. So that the expensive equipment of the information technology world, such as servers, is also inclined towards being modular.

Microservices entered the software world to allow developers to develop their applications based on components or services that are independent of each other and can be easily changed, removed, and updated; Without the overall structure of the program facing problems. Microservices designs and deployments have grown thanks to cloud and containerization significantly.

 All in all, microservices have provided software developers with significant benefits, including the following:

•  They reduce development time.
•  They accelerate the scalability process.
•  They simplify the reusability of modules in different projects.
•  They facilitate the debugging process.
•  They are a suitable option for relatively small software teams.
•  It is possible to use them with containers without any problems.
•  Microservices can be developed and deployed using a variety of languages ​​and tools.
•  They shorten the deployment process and make load balancing efficient, so they use the least amount of system resources.

Contrary to monolithic architecture, services are never divided based on MVC architecture but on what they do in an application based on microservices architecture. To be more precise, a file upload service includes a user interface, database-related models, a controller, reporting system, etc.

In this case, the developer will develop a service called File Uploader and will have the ability to use the service in other projects that have the same application. In a microservices architecture, developers do not have to use only one programming language or technology to complete a task.

Microservices are extensible. The independent nature of different microservice modules allows us to develop an application using a specific language, a specific database, and a particular server and, if necessary, upgrade only the resources of the same platform.

Microservices architecture challenges

While microservices provide us with brilliant advantages, they also have disadvantages. Among the drawbacks of this paradigm, the following should be mentioned:

•  It takes a lot of effort to communicate between services.

•  Their testing process is complicated. 

•  Their management process takes more time. 

•  If the security category is not paid attention to at the design time, they may create vulnerabilities. 

•  Services that are supposed to perform multiple tasks cause a delay in the performance of the application. 

•  Due to the division of software into different parts, they overload the details. 

•  Since each service performs a specific task, we will have a wide range of services in large applications. Therefore, communicating between these services and monitoring them is a complex process. 

•  Because services call other services to fulfill their needs, it is difficult to monitor them and debug the process. 

•  Each service has its reporting mechanism, so there is no central monitoring system to review the reports. In such a situation, the development team should think about developing a central report management system. 

•  Because services communicate with each other through application programming interfaces, the number of requests is more than in monolithic architecture. 

• It is difficult to deploy applications based on microservices architecture manually. In such a situation, advanced automation tools are needed for deployment. 

•  Versioning of microservices must be done separately, so we need a solution to determine which version of service A should communicate with which version of service Z should be deployed. 

•  These programs are more difficult to document than common examples because, due to the independent nature of each module, the services must be fully established.

•  Since several different programming languages and technologies are likely used in developing applications, the cost of maintaining these systems is often high because other developers must be employed. 

•  Today, most applications must simultaneously delete or update several records from the database to meet users’ needs. This is done simply because the monolithic architecture is designed based on only one database. Still, in microservices, such deletions or updates are problematic because it is possible that a record in the database of one of the services in a particular server together with another record in the service the other on another server coordinate with each other. 

What are the characteristics of microservices architecture and design?

Microservices architecture consists of separate components and services that require communication channels to communicate and exchange data.

In general, programs based on microservices architecture have a series of standard features, the most important of which are the following:

• Are unique: in such a way that a service is designed and installed to perform a specific task.
• Decentralized: Ideally, services have few dependencies, although they require various dependencies to perform specific processes, especially connecting to the Internet.
• They are resilient: The most prominent feature of microservice architecture is its fault tolerance threshold. More precisely, if a service crashes, the application can still run.
• Uses APIs: A microservices architecture relies heavily on APIs and gateways to facilitate communication.
• Ability to separate data: Each service has access to its database or storage space.

When should we use microservices?

•  If the application or software project you plan to work on includes the following conditions, it’s time to move on to microservices architecture.
•   If your project’s source code is so large, it is challenging to develop it locally, such as uploading the entire project to the integrated development environment; uploading the project may take more than a few minutes.
•  Only some parts of the application need to be developed, and the entire project does not need to be upgraded.
•  In a situation where the developers are not with each other.

Microservices and containers

A container is a single, executable software package containing all the dependencies an application requires. Containers allow different containers to be deployed in a production environment by providing a single isolated mechanism. In a microservices architecture, each service is deployed separately from other services in the background.

One thing to note is that virtual machines can be used as an alternative to containers for building microservices. In this case, each service can use a virtual machine to host a feature. However, virtual machines may not be ideal for microservices, as each requires a separate operating system and incurs significant overhead. Containers are much more resource efficient as they only need the underlying code and associated dependencies to run the service.

Microservices security

Microservice architecture can solve some of the security issues that integrated applications face. Well-designed microservices simplify the process of monitoring applications from a security perspective because different parts of an application are isolated. In such a situation, a security breach in one piece of software affects only that part and does not affect the performance of other services. Microservices do not consume critical server resources at once when used with containers and can withstand distributed denial-of-service attacks.

However, the above architecture creates challenges in the field of cyber security, the most important of which are the following:

•  Parts of the network may be infected with vulnerabilities.
•  The process of updating applications becomes complicated, which increases the risk of security breaches in an application.
•  Since services use different ports and APIs, more areas may be exposed to attack.

To overcome such problems, developers should use preventive strategies. Using a security scanner, restricting access to services and controlling access, securing the internal network and environments that host containers, and closely monitoring software or external users who intend to communicate with services are effective policies to deal with cyber threats.