Microservices

What Are Microservices?
The term microservices stands for a combination of cloud services that serve a particular business domain or process. Example of domains for an e-commerce application is payment, order management, user authentication, etc.
Each microservice employs different services, databases, third-party applications, and languages.
What Is Microservice Architecture?
Microservice architecture is a particular style of programming that designs applications to be a collection of several microservices instead of one monolithic application with a tightly packed business logic. In a microservice architecture, the business logic is separated into individual units of code that can run independently of the other microservices.
Each microservice has its own set of data and executes only to answer the user's specific request. This way, the developer can run multiple functionalities so that they can scale without having to maintain one large resource-intensive application. Microservices allow for a high level of modularity and efficiency in execution. They can be deployed to a serverless environment or to a container.
Microservices characteristics:

•  Easy to maintain and test,      
•  Loosely coupled,
•  Can be developed and deployed independently,
•  Designed to serve a specific purpose or business logic.

What Are the Advantages of Microservice Architecture?
According to O’Reilly’s survey about “Microservice Adoption in 2020”, microservice architecture is a topic of interest for organizations of all sizes. Most respondents (61%) have been using microservices for a year or more.
A microservice architecture offers the following advantages:
•  Can be built independently and be owned and managed by smaller dev teams, facilitating the frequency of code releases and development of new features.
•  Allows for scalable use of cloud services, as with microservices, you need not scale an entire application but just the microservice that is used the most.
•  Improves fault isolation: in case of errors or crashes, other microservices will remain unaffected.
•  Allows for flexibility in choosing the tech stack for developing each microservice. As each microservice will have its own database and business logic, you can choose to develop them in any programming language or tech stack you choose independent of other microservices.
On the business side, O’Reilly’s survey respondents also mention the fastest response to changing technology and business requirements and lower development costs.

What Are the Challenges of Microservice Architecture?
As with any architecture, microservices have some challenges related to the changes in development practices associated with their properties. But they can be managed with the proper methodology and best practice adoption.
A few challenges to consider:
•  Monitoring is essential: Because microservices work with individual components, it can be more challenging to perform root-cause analysis on errors. Efficient monitoring will help reduce time during code reviews and help developers find issues faster.
•   Adoption of a DevOps culture: DevOps and microservices go hand-in-hand. Developers use automated services to deploy their code to microservice components, and manual promotions are no longer needed. They can even automate testing. Developers and operations teams need time to adopt the new culture and deployment changes.
•   Testing: Testing can be automated, but it must be thorough. Because microservices are decoupled from infrastructure and work independently, testing can be more challenging for developers unfamiliar with the new architecture.
•   Code design must be fault-tolerant: Decoupled services will work independently, but they also function as a single application. Failure in one component must not affect other sections of the application.

Cloud migration

What Are the Different Ways of Modernizing Legacy Systems?
When it comes to legacy modernization and cloud modernization in general, we can use one of the six R model to map the migration strategy for a particular application:
·       Retain, which is to revisit something later because it doesn't justify the cost of migrating right now.
·       Retire to get rid of something that's no longer business-critical.
·       Refactor an application, meaning that you rewrite the code and decouple it to use cloud-native services further.
·       Repurchase, to use something off the shelf, in place of something custom.
· And then the two more traditional cloud migration strategies of Replatform and Rehost, to lift and shift but not really change the structure of an application, to continue using largely the same core technologies that have quite a simple migration strategy.
What is a Minimum Viable Migration?
The concept of Minimum Viable Migration™ has been created by Ben Ellerby to explain how an orgnization can progressively migrate its legacy systems to the cloud.
In product development, a Minimum Viable Product™ consists in releasing versions of the product earlier to customers to provide feedback and mitigate risks. The same concept inspires Minimum Viable Migration™: it's a subsystem that can be migrated and used by customers before the overall system is fully migrated. If we break down migration from a system as-is to a system to-be into a series of Minimum Viable Migrations we can release rapidly and mitigate risk.
See the article related to this concept here.

Serverless

A Visual Representation of Serverless
What is Serverless?
Serverless technology provides businesses with the computing power and infrastructure to host applications without the added overhead of managing servers and their configurations.
The serverless environment is built with services from Cloud Services Providers (CSPs) that handle the standard functionalities. Thus, developers can write only code without worry about the configurations and maintenance of the back-end architecture. They can focus on translating the business logic into microservices, executed thanks to serverless functions(FaaS) that handle the different building blocks of the application.
All CSPs base the execution and billing on a per-request model.

What Is a Cloud Service Provider?
With serverless, the building blocks needed to run applications and workloads are managed by third-party providers in the cloud. The main providers in the industry today are Amazon (AWS Lambda), Google (Cloud Functions), Microsoft (Azure Functions), Oracle (Functions), IBM (Cloud Functions),and Alibaba (Function Compute).

What Means the Term 'Serverless'?
The term “serverless” does not mean applications aren't hosted on servers. But with serverless, workloads are managed in the cloud, and all infrastructure is housed and managed by the CSP. Developers no longer need to manage provisioning, patching, maintaining, and securing applications, and can solely focus on writing code.

Other

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