Introduction to Microservices
This tutorial helps you understand and get acquainted with everything you need to know about Microservices. As you go further, you will gain complete knowledge regarding the architecture, features, applications, certifications, and the job structure of microservices in the market.
With a steady increase in the market size for the Microservices since 2016 in the US, many large players are migrating to it. This popularity is mainly because; the enterprises are looking forward to becoming more agile and adopt DevOps with continuous testing capabilities.
It is important for a tech-savvy engineer to understand the concept of Microservices and its bigger picture in the market. So, let's get started.
What are Microservices?
Microservices is a method of software development which packages an application as a set of loosely-coupled services with light-weight protocols for communication. Basically, it is a set of services that work independently to contribute to a user-defined task. Here, each business task is handled by a service that works independently with a dedicated server.
It borrows its architectural style from the Service-Oriented Architecture.
Note: Service-Oriented Architecture is a design of software development where services are provided by the application components to other components through network protocols.
Microservices are also popularly known as Microservice Architecture. Every service in the application is an independent, self-contained service and they implement single business capability.
The old monolithic architecture of applications was one of the reasons for the development of microservice architecture.
Before understanding the reasons to adopt Microservices, let us understand the structure of Monolithic architecture and the flaws that compelled us to design a new architecture.
The whole architecture is built as a single, autonomous, business unit, where all the components inside the system are interconnected and are interdependent.
Below are the reasons for migrating over monolithic architecture.
Defects (Effects) of Monolithic Architecture
- It is not flexible, as only one programming language can be used to develop all the services of varied demands.
- Any change to one component affects the whole system. Hence, if any small change is made to a component, the effects have to be introspective for all the fellow components and a new software version of the entire application has to be released.
- As one single server handles all the services (components), the maintenance of the server becomes expensive and complex.
- Owing to the monolithic nature of the architecture, the addition of new services and scaling becomes difficult.
- It is not meant for complex applications as they have tightly coupled dependencies
- It takes a lot of time to build the monolithic application, as the whole architecture has to be done in a single programming language, with each component built, one after the other.
[Related Page: Guide to Cloud Native Microservices]
Microservice Architecture as an alternative
To address the overhead issues encountered in the Monolithic architecture, Microservices was developed.
Microservices are made of small, autonomous business units or services, which are independently deployable in a system. They communicate with each other through independent network protocols and constitute the distributed architecture.
The smaller services making up for the functionality of the entire application improve the modularity of the system. This modular structure reduces the resistance for development, unlike the former one. Any changes to a component can be independently addressed to the component, without affecting the whole system. This reduces the cost of maintenance, as the independent revised software updates can be released, without having to release an entirely new version of the application. This agile flow helps the enterprises to develop better infrastructure for DevOps and otherwise, with a much simpler and lighter internal arrangement.
Let us understand the difference between the monolithic and microservice architecture through an example.
In an e-commerce application, there are a lot of services involved with every user interaction with the site. Until recent times, the architecture followed in the big shark e-commerce applications like Amazon was the monolithic architecture.
The image shown below represents the monolithic application.
The crucial services of an e-commerce site, like search, review, payments were all handled by a single server in a monolithic architecture. If there had to be any bug fix made on any of the services, a new version of the application had to be deployed. Besides this, if there had to be any scaling made to handle the load, multiple instances of the server had to be run.
This was observed to be very heavy for maintenance and development.
To overcome these drawbacks, Amazon migrated to the microservice architecture, where independent services managed the application.
The image below represents the microservice architecture of an e-commerce website.
Here, the services like search, reviews, and payments work as autonomous business units which are maintained by separate servers and database.
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Any changes demanded by any of these services can be independently fixed and deployed, without forcing for a new version of the application.
[Related Page: Microservices Security And How Do You Secure Them?]
Architecture of Microservices
After understanding the need of Microservices, let us understand the architecture that constitutes Microservices
In Microservice architecture, each service is self-contained and implements a small business capability.
Services constitute the main component of the microservice architecture.
Some of the characteristics of services are:
- Services in the microservice architecture are autonomous, small, and loosely-coupled.
- Each service can be independently developed by a separate development team, with a unique choice of the programming language that suits the service best, without having to depend on the technical specifications of other services.
- All services are separated based on their domains and functionalities, where each of them is allocated with a separate microservice.
- Each of these microservices has its own load balancer and execution environment, where they execute and manage their own data.
- Each microservice communicates with the other through the stateless server, which is either the Message bus or the REST API.
Besides the services, there are other typical components of the microservice architecture that are discussed below.
- Management: Management component is responsible for placing the services on nodes, balancing services across nodes, identifying failures, etc.
- Service Discovery: It maintains a list of services and the nodes corresponding to each service. It is responsible for enabling the service lookup and locating the service endpoint.
- API Gateway: API Gateway receives the service request from the client, looks up for the appropriate service, and redirects the request to the service. In some situations, the API Gateway aggregates the responses from several services and returns the aggregated response.
Features of API Gateway
- It decouples the services and the clients. This way, the services can be revised or refactored, without having to update all the clients.
- Services can use messaging protocols like AMQP, which are not web-friendly.
- It can also handle some cross-cutting functions like authentication, logging, SSL termination, and load balancing.
When to go for Microservices Architecture?
The following are the cases where microservice architecture can be adopted for the best benefits.
- Applications that need continuous scaling
- Applications that demand high release velocity or simply the applications that demand agile releases.
- An organization having small development teams.
- Applications with many subdomains or with rich domains.
There are many distinct features of microservices that make it stand unique from the monolithic architecture. They are:
- Decoupling: All the services constituting the architecture are decoupled from one another, hence making it easier to build, alter, and scale the services.
- Components: Each service is regarded as a component, which is easy to scale and upgrade.
- Business Capabilities: Each service is self-contained and owns an independent business capability.
- Autonomy: Since services are autonomous, the developer teams can work independently on each service, contributing to the speed of development.
- Continuous Delivery: It allows for frequent software releases, through continuous software testing and development.
- Agility: The architecture allows for immediate integration and deletion of new features, contributing to agile development and release.
Benefits of Microservices
Below are some of the benefits of using Microservices:
- Independent deployments: You can update and test a service independently and release it, without redeploying the whole application. Roll-back and roll forward of the updates can be easily attained if anything goes wrong during the deployment. In total, bug fixes and feature releases are less risky and more sustainable.
- Independent Development: The development of each service can be carried out independently by each development team. Teams are not obligated to work on the same technology for all the services, as it happens in monolithic. Different technology can be chosen for different services, based on necessity and demands. This also contributes to faster innovation and easier application.
- Focused teams: Since each team can be focused on one service, the code base will be less complex, more robust, and very crisp. The smaller scope radius, adds these advantages.
- Fault Isolation: If there is any defect with any component, the whole system need not be brought down. It can be independently addressed and fixed.
- Granular Scaling: The services can be scaled separately, independent of the system scaling.
Web service Vs. Microservices
Microservices has taken over the back-end architecture of many companies like Netflix, Amazon, Uber, etc. Though the services and the benefits offered by microservices are great, it is not always the best choice for all the situations. Sometimes, it's best to employ the good old web services in development. Just like microservices, web service uses separate domains, but with a wider functionality. In this section, let us understand the differences between the web service and microservice and know which one to adopt, and when to adopt.
Web service is a specific case of a service-oriented architecture (SOA). It exposes the functionality of one application to another, without a user interface. It basically exposes an API over HTTP, as a service.
The web service performs a specific function in an application, where it is deployed and enables the applications developed in different programming languages to communicate with each other through common formats like XML, Jason, etc.
Web services are not specific to any particular OS or development technology. They work in a similar way both in a Java-based application as well as in an iOS application. They are not bound to any environment.
Differences between web service and microservice
|It helps in better service reusability||It is more focused on decoupling and self-contained environment.|
|The existing monolithic architecture can be modified to include web services.||The monolithic architecture has to completely change to create new services.|
|It uses the Enterprise Service Bus (ESB) for communication.||It uses less elaborate and simple messaging systems.|
|It allows for multiple message protocols||It uses HTTP, REST, or Thrift APIs, which are lightweight protocols.|
|It deploys all the services into a common platform||Generally, the cloud platform is used for deployment. Application servers are less used.|
|Integration with containers (Dockers), is less common||The container integration works very well with the microservices.|
|The services share common data storage.||Each microservice has dedicated data storage.|
|It works on common standards of governance.||It employs relaxed and decentralized governance, with more focus on team collaboration and freedom of choice.|
How to choose between web services and microservices?
The web services and microservices have come a long way from the monolithic architecture. Both are developed with better advantages over the monolithic architecture. Hence, it is difficult to say, which is better over the other. However, each one can become the best choice for a particular scenario.
Microservices are best suited for mobile applications, which require more control over the features and have distinct service demands. The web services are easily adaptable in cases where the application is migrating from monolithic architecture and has certain functionalities, which cannot be assembled into an independent service unit.
Challenges in Microservices
Like any other software development model, microservices also has some challenges that are due to its way of modeling. Some of them are mentioned below:
- Compared to monolithic architecture, there are a lot of services, which are developed using different languages and possess their own database. This makes it difficult to monitor the entire system.
- The distributed model of the microservices makes the structure, inherently complex.
- Due to a number of services, there exist a lot of service mechanisms, with a large amount of memory for unstructured data.
- Effective management and teamwork are required to maintain a distributed system without recurring cascading issues.
- Reproducing a particular bug will be difficult if it was fixed in one version and re-appears in another.
- Managing the application becomes tedious when new services are added continuously.
- A wide set of developers is needed to maintain a heterogeneous, distributed system.
- It becomes expensive to maintain separate servers for different business tasks.
Best practices to adopt for Microservices
In order to avoid the common losses that incur during migration and adaptation to microservices, here are a few best practices that need to be adopted.
- Maintain separate data storage for each microservice.
- Maintain the same level of code maturity across the architecture.
- To have a separate build for each microservice.
- Always treat the server to be stateless.
Owing to the diversity of programming languages and technologies that can be adopted during the development of services in microservices, there is no specific technology requisite that can be mentioned.
Though the Microservices architectural style is gaining optimistic popularity day by day, there are some trade-offs for this method, like any other. Developers now have to handle an ecosystem of smaller services of the varied code base, than a single monolithic architecture. Consequently, if you do not possess certain competencies required for this, then the microservice is not the architectural domain for you. Some of these competencies are described below:
To handle the microservices thoroughly, you should be competent enough to fire up a new server rapidly. This is something more natural with cloud computing, but this can be done without full cloud service. To cope up with such rapid provisioning, you may have to deal with a lot of automation. Though not much automation is needed to start with, you will need it to do some serious microservices.
Since the environment is bubbled with a lot of services that are loosely coupled in production, you should be ready with an efficient management team that can detect the fails fast and works on its fixes. Though the common problems might refer to the technology fails, you have to be well aware of management lapses as well (which includes the drop in the orders), etc. Continuous monitoring of such a system is demanded in a microservice architecture.
Rapid Application Deployment
Since the number of services to deploy is more and varied, you need to be quick in deploying them both to the test environments as well as to the production environments. Generally, the Development Pipeline is used to deploy, which does the task within a few hours. Some manual intervention will be considered in the initial stages however, things should be automated for better efficiency in the future.
These capabilities are not focused on an individual but point to a collaborative environment of both the developers and the operations. With this kind of set up, a good number of services can be deployed at the early stages. With experience in continuous monitoring and failure management, the system can be scaled to include a number of services more.
How to get certified as a Microservices Developer?
There are many firms in the market that are offering courses to gain microservices developer certification
Mindmajix is one such institution that is aiming at providing the best online course for the Microservices. It includes all the essential tools to be certified as a Microservices Developer.
Once you are accredited from Mindmajix as a Microservices developer, you will be well equipped with the theoretical expertise along with the practical mindset to scale to become a successful Microservices professional.
Jobs and Salary
The general job roles available for the work related to "microservice" are:
- Software Architect
- Senior Microservices Developer
- Technical Lead
- Engineering Lead
- Software Engineer
- Java microservices Developer
- Senior DevOps Engineer
Below represents the average salary of some of the common microservice job posts in the US according to the latest statistics.
- Java Microservices Developer - $120,900 per year
- Software Architect - $141,779 per year
- Senior Microservices Developer - $152,500 per year
- Technical Lead - $124,255 per year
- Engineering Lead - $117,165 per year
- Post Doctoral fellow - $49,077 per year
- Software Engineer - $108,108 per year
Future of Microservices
The microservices is already playing big in the market. The scope of the microservices in future is, as a serverless and functions as a service. It is worked on to bring more decentralization and progress towards more intelligence-driven microservices. Real-time data science and analytics with in-memory computers are the areas looked upon in the future. Overall, the development in microservice is focused on bringing more business value and seems to be the architecture of the future systems.
Principles of MicroServices
The Main Principles of Microservices are as follows:
1. Isolated Failure
The failure of a single module cannot affect the complete application. As the service can fail at any time, the failure must be identified rapidly.
2. Single Responsibility Principle
This principle tells us that a module of a program should have only one responsibility.
3. Deploy Independently
Microservices can be deployed independently without troubling other services.
4. Modeled around Business Domain
Microservices never limit themselves from endorsing required databases or technology stack.
5. Infrastructure automation
Infrastructure automation is a procedure of environment scripting. Through environment scripting, we can use the same configuration to a single node or multiple nodes.
Advantages of Microservices
- They are independent module and self-contained
- Scaling expenses are less than monolithic architecture.
- Low dependency and simple to test.
Challenges of Microservices Architecture
The architecture of MicroServices is more complicated than the architecture of Legacy systems. During the implementation of Microservices, many organizations face the following challenges:
The conventional method of monitoring is not arrayed well properly with the microservices as we have different services which include the same functionality formerly endorsed by a single application.
2. Fault Tolerance
It is an individual service which does not take down the whole system. If any failure occurs, the application will work to some extent. In the absence of fault tolerance, a single fault can lead to entire system failure.
3. DevOps Culture
Microservices suits completely into DevOps. It gives cost-effective data, faster-delivery access. The use of containerization is expanded by changing from service-oriented-architecture to Microservice architecture.
4. Bounded Text
The concept of Bounded text is generated from Domain-Driven Design circles. The bounded context defines particular accountability.
How to create a Microservice
- Step 1: Through Spring Initialiser, a Maven Project should be created.
- Step 2: Select the spring boot version, and the snapshot version should not be selected.
- Step 3: Group name should be given.
- Step 4: Give Artifact id. Limits-service should be provided.
- Step 5: Some dependencies like Config Client, Spring Web, Spring Boot Actuator should be added.
- Step 6: Select Generate Project, a zip file will be downloaded, and that file will be extracted into Hard Disk.
- Step 7: When the project is downloaded, we should go to the directory where the project is downloaded.
- Step 8: Now, you can run a java application.