Microservices Interview Questions & Answers

Answer:

1. Microservices or Microservices Architecture refers to an SDLC approach that can build large applications as a collection of small functional modules. Such functional modules are independently scalable, deployable, & communicate with each other over the standard protocols. These modules can be implemented through different programming languages & have their databases in different software environments. Here, each module is minimal & complete.
2. Microservices, also known as Microservice Architecture, is an architectural style that structures large applications as a collection of small autonomous services modeled across a business domain.
3. Microservices is a variant of the SOA (Service-Oriented Architecture), an architectural style that structures apps as loosely coupled services. In the Microservices Architecture, services must be fine-grained & protocols must be lightweight. The benefit of decomposing an app into smaller services is that it boosts modularity & makes an application easier to develop, understand, & test. It also parallelizes development by allowing small autonomous teams to deploy, scale, & build their respective services independently. It enables an architecture of the individual service to emerge by continuous refactoring. Architectures based on Microservices enable continuous deployment & delivery.

Answer:

1. Monolithic architecture is a big container that compacts all the software components of applications in a single package.
2. Monolithic architecture is a type of big container wherein all application software components are clubbed inside a single package.

Answer:

1. Below are some significant perks of using Microservices:
   • Microservices can easily mix with other database, frameworks, & libraries; thus, enables technology diversity.
   • It has fault isolation that means the whole system does not get down in case of a service failure.
   • Microservices provides greater support for smaller & parallel teams.
   • It provides independent deployment & development, which reduces the time.

2. Advantages	Description
   Independent Development	Microservices can be easily built on their individual functionalities.
   Independent Deployment	They can also be deployed individually in any application based on their services.
   Fault Isolation	Even if an application’s service does not work, the system continues to function.
   Mixed Technology Stack	Through Microservices, different technologies & languages can be used to develop different services of the same application.
   Granular Scaling	Individual components are scalable as required, so there is no need to scale all the components together.

3. There are various advantages of Microservices as follows:
   • The code’s tiny base in Microservices is easy to maintain;
   • As Microservices have individual components, it is also easy to scale;
   • It supports independent implementation;
   • Microservices drastically reduces installation time;
   • It offers great support for parallel teams;
   • Microservices facilitate technological diversity.

Answer:

1. Spring cloud refers to an Integration software that can integrate with external systems. It enables Microservices to build applications that can perform restricted data processing.
2. Spring cloud in Microservices is a system that provides integration with external systems. It supports faster application development. Being associated with finite data processing, it plays a crucial role in the Microservice Architecture. Spring Cloud provides a set of extensive features as mentioned below:
   • Discovery of the service registration.
   • Versioned & distributed configuration.
   • Service to service calls.
   • Routing
   • Load balancing & circuit breakers.
   • Cluster state & leadership election.
   • Distributed messaging & global locks.

Answer:

1. Reports & dashboards monitors & upkeeps Microservices. It has several app monitoring tools that help to assist Microservices.
2. Reports & dashboards are commonly used to monitor a system. For Microservices, Reports & Dashboards help to:
   • Identify which Microservice supports which resource;
   • Find out services that are impacted when changes are made or occur in components;
   • Provide easy access for documentation purposes;
   • Review versions of deployed components;
   • Obtain compliance from components;
3. Reports & dashboards are mainly used to upkeep & monitor Microservices. It has various tools that can serve this purpose. Reports & dashboards can be used to:
   • Find which Microservices expose what resources
   • Find impacted services whenever any changes in a component occur or made
   • It provides an easy point that can be accessed when documentation is required
   • To acquire maturity & compliance from the components.

Answer:

1. Microservices Architecture	Monolithic Architecture
   Service Startup is very fast	Service startup is slow & takes time
   Microservices Architecture is a loosely coupled architecture.	Monolithic Architecture is tightly coupled.
   Changes in a single data model do not affect other Microservices.	Any changes in a data model affect the entire database.
   Microservices focus on products, not projects	Monolithic emphasizes the entire project.

2. Below are the differences between Microservices Architecture & Monolithic Architecture:

   Microservices Architecture	Monolith Architecture
   In Microservices Architecture, we build apps as a collection of narrowly focused services built for a business domain.	All application software components are clubbed in a single autonomous unit.
   It is easy to scale up & down on a demand basis.	It is not easy to scale up & down on demand.
   Each Microservice has its database.	Monolithic Architecture has a shared database.
   Failure of service doesn’t affect other services.	A failure may cause the entire system to go down.
   It supports faster deployment as each service is deployed individually.	You need to deploy the whole system in one go, so it is time-consuming.
   You can utilize different technologies & languages to build different services as per the business needs.	It is impossible to implement different technologies or languages as everything is tightly coupled.
   Communication between services is complex. If your application consists of thousands of Microservices, the application becomes complex when the services talk to each other.	Secure data transferring & processing is easier at the system level.
   You need to test every service individually.	Testing is very easy.

Answer:

1. • Microservices rely on each other. Thus, they need to communicate with each other.
   • As it is distributed system, it becomes a heavily involved model.
   • If you’re using a Microservice Architecture, you need to be ready for the operations overhead.
   • You require skilled professionals support to manage heterogeneous distributed Microservices.
2. The challenges in Microservices can be both functional & technical. Let’s look at the main challenges in Microservices:
   • It requires heavy investment
   • It has a heavy Infrastructure Setup
   • Needs excessive planning to manage operations overhead
   Here are the challenges from a technical standpoint:
   • Communication between different Microservices in an application.
   • Automate Components
   • App maintenance
   • Configuration Management
   • Heavy Operations Overhead
   • Deployment, Debugging & Testing Challenges
3. Building a no. of smaller Microservices may sound easy, but there are several challenges that you may face while developing:
   • Automate the Components: It is difficult to automate components as there are several smaller components. So, for each component, you need to follow the stages of the build, deploy & monitor.
   • Perceptibility: Maintaining a large no. of components together becomes difficult to maintain, deploy, identify, & monitor problems. It needs a great perceptibility around the components.
   • Configuration Management: Sometimes, it becomes tough to maintain configurations for all the components around various environments.
   • Debugging: It is difficult to find each & every service for the error. It is important to maintain dashboards & centralized logging to debug problems.

Answer:

1. Many large-scale websites like Netflix, Amazon, & Twitter have advanced from a Monolithic Architecture to a Microservices Architecture.
2. • Netflix- It is regarded as a pioneer of the Microservices movement. Back in 2009, Netflix made a decision to break from Monolith to Microservices. Due to having a Monolithic Architecture, they experienced growing pains & regular server outages. However, after adopting a Microservice Architecture, it led to phenomenal business growth.
   • Amazon-In 2001, Amazon retail website was the largest architectural monolith. Back then, it struggled to manage its increasing online presence. Today, Amazon has become the most prominent advocate of Microservices, with AWS providing the infrastructure needed for companies to manage & launch containers & Microservices on the fly.
   • Uber- The world’s popular taxi-hailing app commences its journey with a Monolithic Architecture built to serve a single city (San Francisco). Ubers’ tightly coupled & unified codebase delivered many core business processes, such as connecting drivers with the riders, payments & billings. However, as the business grew, they found it difficult to scale efficiently across the globe. Microservices was identified as a solution & Uber is still using micro to date.
   • eBay-The CTO of eBay says that eBay uses more than 1,000 services with frontend services sending API calls & backend services executing tasks like administration & shipping. Each development team has its set of services at eBay. If a team wishes to create a new service, they can access a specially built internal cloud portal to test, develop and deploy services through Microservices.
   • SoundCloud- Before adopting Microservices Architecture, SoundCloud was built on the legacy of the Monolithic Rails system. However, when dealing with the challenge of scaling an extensive social network with the media distribution capability, SoundCloud made a decision to build their Microservices in Ruby, Scala, & Clojure.

Answer:

1. • Easy Infrastructure automation
   • Essential messaging frameworks
   • Decentralized Governance
   • Design for failure
2. Below are the main characteristics of a Microservices Architectures:
   • Microservices utilizes essential messaging frameworks
   • Decentralized governance
   • Easy infrastructure automation
   • Design for failures
   • Infrastructure automation

Answer:

1. In Microservice architecture, tests are divided into three broad categories:
   • At the bottom-level test, one can perform a general test like unit & performance tests. Such tests are entirely automated.
   • At the middle-level test, one can perform exploratory tests such as usability tests & stress tests.
   • At the top-level test, one can conduct acceptance tests which are usually fewer in numbers. It helps stakeholders to know about the different software features.
2. While working with the Microservices, testing becomes complex as multiple Microservices are working together. Therefore, tests are divided into three different levels:
   • At the bottom level, there are technology-facing tests such as performance tests & unit tests, which are completely automated.
   • At the middle level, we have exploratory tests like usability & stress tests.
   • At the top level, there are acceptance tests that help stakeholders in verifying & understanding software features.
3. Below are the three broad categories of tests in Microservices.
   • System Test or Top-level Test: The tests in this category span the complete Microservices system & are implemented through GUI.
   • Service Test or Middle-level Test: In this category, developers perform tests against one but only one complete Microservice.
   • Unit Test or Bottom-level Test: In this category, developers test a small piece of functionality in the Microservice.

Answer:

1. Client certificates refer to a digital certificate that client systems use to make authenticated requests to a remote server.
2. The client certificate is a digital certificate used by client systems to make authenticated requests to the remote server. It plays a crucial role in several mutual authentication designs by providing strong assurance of the requester’s identity.
3.  It is a type of digital certificate used by client systems for making an authenticated request to a remote server. It plays a vital role in authenticating designs that are mutual & provides strong assurance of a requester’s identity. However, you need to have a fully configured backend service for authenticating your client certificate.

Answer:

1. PACT refers to an open-source tool that enables testing interactions between consumers & service providers, but a contract separates it. It increases the reliability of Microservices applications. PACT is used to implement a Consumer-Driven Contract in the Microservices.
2. PACT is an open-source tool that helps in testing interactions between the consumer & a service provider. However, it isn’t included in the contract that increases the reliability of the applications. The consumer service developer first writes a test that defines the mode of interaction with a service provider. The test includes the provider’s state, request body & expected response. Based on it, PACT then creates a stub against which a test is executed. The output is then stored in a JSON file.
3. PACT means an open-source tool that allows testing interactions between consumers & service providers in isolation against the contract that boosts the reliability of Microservices integration.
   Microservices is used:
   • Used to implement the consumer-driven contract in the Microservices.
   • Test consumer-driven contracts between the consumers & providers of a Microservice.

Answer:

1. OAuth is an acronym of Open Authorization Protocol. It enables you to access client applications on HTTP for third-party providers Facebook, GitHub, etc. It helps you share resources stored on a site with another site without needing their credentials.
2. OAuth or Open-standard Authorization framework or protocol describes how unrelated services or servers can safely enable authenticated access to their assets without sharing an initial related, single-login credential. It is secure, third-party, user-agent, & delegated authorization.
3.  Open Authorization Protocol or OAuth helps to access client apps using third-party protocols such as GitHub, Facebook, etc, through HTTP. You can also share resources between different websites without needing any credentials. OAuth enables the account information of an end-user to be used by a third party like Facebook while keeping it secure.

Answer:

1. End-to-end testing means validating the functionality of each process in the workflow. It ensures the system works together as a whole & satiates all requirements.
2. End-to-end is a testing technique that helps test an application’s entire flow through a business transaction. As various components are there in the Microservices Architecture, the end-to-end tests can cover gaps during integration or unit testing. In addition, it provides end-to-end confidence & ensures the network parameters are configured appropriately, thus help Microservices evolve.
3. End-to-end testing of Microservices application ensures & validates that each process in the system is appropriately running. As a Microservices application is built using multiple modules dynamically orchestrated, end-to-end testing can cover all the gaps between the services.
   Below are the steps to follow for end-to-end Microservices testing:
   • Define what you expect from end-to-end testing.
   • Now, define the scope to be tested in the system.
   • Perform authentication in the test environment.
   • Select a testing framework that addresses most issues.
   • Test asynchronous flows.
   • Lastly, automate the testing.

Answer:

1. Containers are the most effective & easiest method to manage Microservices-based applications. It helps you to deploy & develop individually. The containerized Microservices are more robust than the traditional monolithic applications. With containers, one can replicate Microservices across a cluster of smaller Virtual Machines.
2. Containers are a good way to manage Microservices-based applications to deploy & develop them individually. You can encapsulate your Microservice in the container image with its dependencies, which then is used to roll on-demand Microservices instances without requiring any additional efforts.

Answer:

1. Semantic monitoring combines automated tests with application monitoring. It enables you to identify the reasons for your business losses and understand why it is not getting more profits.
2. Semantic or Synthetic Monitoring refers to running a subset of the application’s automated tests against the live production system. The results are monitored, & alerts are generated if there are any failures. Semantic monitoring approaches Microservice monitoring from a business transaction perspective. So, rather than monitoring each component, semantic monitoring ensures how well the transaction performs for the users & the business. It also detects the faulty service layer & corresponding Microservice instance at the same flow. This approach reduces the meantime to repair & allows for faster triaging.
3. Semantic monitoring or synthetic monitoring combines the automated tests with the monitoring application to detect business failing factors.
4. Semantic monitoring combines an entire application’s monitoring with automated tests. Its primary advantage is that it finds the factors profitable to your business. Once it detects an issue, it provides faster isolation by reducing the time required to repair. Semantic monitoring also triages the transaction layer & service layer to determine the transactions affected by poor performance or availability.

Answer:

1. CDC stands for Consumer-Driven Contract. It is a pattern for building Microservices & evolving services so the external systems can use them. Each consumer in CDC captures their provider into a separate contract. All the contracts are then shared with the provider to help them get an insight into the obligations they must fulfill for each client.
2. CDC is a pattern for developing Microservices to make them accessible for external systems. When working on the Microservices, a particular provider builds it & one or more consumers utilizes it. Often, the provider mentions the interfaces in the XML document. However, in CDC, each service’s consumer conveys the interface expected from the provider.

Answer:

1. Reactive Extensions or Rx is a design pattern that collects results by calling multiple services & compiling a combined response. It is one of the popular tools in distributed systems that works opposite to the legacy flows.
2. Reactive Extensions (Rx) refers to a design approach through which results are gathered by calling multiple services to compile a combined response. Such calls can be synchronous or asynchronous
3. Reactive Extensions, also are known as Rx, is a design approach wherein we collect results by calling multiple services & compiling a combined response. These calls can either be synchronous or asynchronous. Rx is a popular tool in the distributed systems & works opposite to legacy flows.

Answer:

1. Continuous monitoring refers to a method for searching compliance & risk issues associated with a company’s operations & finances. It contains working systems, human, & processes which support actual & efficient operations.
2. Continuous Monitoring (CM) does an in-depth monitoring coverage, from in-browser frontend performance metrics, through an application performance, & down for hosting virtualized infrastructure metrics.

Answer:

1. Mostly, developers use HTTP/REST with Binary protocol or JSON enable communication between Microservices. However, you can use any communication protocol based on your project needs.
2. Microservices communicates with each other through:
   • Websockets for streaming;
   • HTTP for traditional request-response;
   • Server or Broker Programs running advanced routing algorithms.
   You can use Kafka, Nats, RabbitMQ, each built for a specific message semantic for messages. Another way is to use (BaaS) Backend-as-a-Service like Space Cloud, which automates the entire backend.