Microservices, aka Microservice Architecture, is an architectural style that structures an application as a collection of small autonomous services, modeled around a business domain.
Refer to the above diagram. Here, each hexagonal shape represents an individual service component. Similar to the working of bees, each agile team builds an individual service component with the available frameworks and the chosen technology stack. Just as in a beehive, each service component forms a strong microservice architecture to provide better scalability. Also, issues with each service component can be handled individually by the agile team with no or minimal impact on the entire application.
A microservice architecture has the following components:
Developing a number of smaller microservices sounds easy, but the challenges often faced while developing them are as follows.
Monolithic Architecture is similar to a big container wherein all the software components of an application are assembled together and tightly packaged.
A Service-Oriented Architecture is a collection of services which communicate with each other. The communication can involve either simple data passing or it could involve two or more services coordinating some activity.
Microservice Architecture is an architectural style that structures an application as a collection of small autonomous services, modeled around a business domain.
| Pros of Microservice Architecture | Cons of Microservice Architecture |
| Freedom to use different technologies | Increases troubleshooting challenges |
| Each microservices focuses on single capability | Increases delay due to remote calls |
| Supports individual deployable units | Increased efforts for configuration and other operations |
| Allow frequent software releases | Difficult to maintain transaction safety |
| Ensures security of each service | Tough to track data across various boundaries |
| Mulitple services are parallelly developed and deployed | Difficult to code between services |
As we know that each Microservice owning its own database is an independently deployable program unit, this, in turn, lets us create a State Machine out of it. So, we can specify different states and events for a particular microservice.
For Example, we can define an Order microservice. An Order can have different states. The transitions of Order states can be independent events in the Order microservice.
While working with microservices, testing becomes quite complex as there are multiple microservices working together. So, tests are divided into different levels.
REST Though you can implement microservices in multiple ways, REST over HTTP is a way to implement Microservices. REST is also used in other applications such as web apps, API design, and MVC applications to serve business data.
Microservices Microservices is an architecture wherein all the components of the system are put into individual components, which can be built, deployed, and scaled individually. There are certain principles and best practices of Microservices that help in building a resilient application.
In a nutshell, you can say that REST is a medium to build Microservices.
Bounded Context is a central pattern in Domain-Driven Design. It is the focus of DDD’s strategic design section which is all about dealing with large models and teams. DDD deals with large models by dividing them into different Bounded Contexts and being explicit about their inter-relationships.
Distributed Transaction is any situation where a single event results in the mutation of two or more separate sources of data which cannot be committed atomically. In the world of microservices, it becomes even more complex as each service is a unit of work and most of the time multiple services have to work together to make a business successful.
The Two types of credentials are:
PACTis an open source tool to allow testing interactions between service providers and consumers in isolation against the contract made so that the reliability of Microservices integration increases.
Usage in Microservices:
End-to-end testing validates each and every process in the workflow is functioning properly. This ensures that the system works together as a whole and satisfies all requirements.
In layman terms, you can say that end to end testing is a kind of tests where everything is tested after a particular period.
Containers are a good way to manage microservice based application to develop and deploy them individually. You can encapsulate your microservice in a container image along with its dependencies, which then can be used to roll on-demand instances of microservice without any additional efforts required.
DRYstands forDon’t Repeat Yourself. It basically promotes the concept of reusing the code. This results in developing and sharing the libraries which in turn result in tight coupling.
A microservice architecture is based on a concept wherein all its services should be able to interact with each other to build a business functionality. So, to achieve this, each microservice must have an interface. This makes the web API a very important enabler of microservices. Being based on the open networking principles of the Web, RESTful APIs provide the most logical model for building interfaces between the various components of a microservice architecture.
Semantic monitoring, also known as synthetic monitoring combines automated tests with monitoring the application in order to detect business failing factors.
For example, for an empty stack, you can create a stub that just returns true for empty() method. So, this does not care whether there is an element in the stack or not.
For example, for a Customer object, you can mock it by setting name and age. You can set age as 12 and then test for isAdult() method that will return true for age greater than 18. So, your Mock Customer object works for the specified condition.
Reactive Extensions also are known as Rx. It is a design approach in which we collect results by calling multiple services and then compile a combined response. These calls can be synchronous or asynchronous, blocking or non-blocking. Rx is a very popular tool in distributed systems which works opposite to legacy flows.
Hope these Microservices Interview Questions would help you in your Microservices Architect Interviews.
If you wish to learn Microservices and build your own applications, then check out our Microservices Architecture Training which comes with instructor-led live training and real-life project experience. This training will help you understand Microservices in depth and help you achieve mastery over the subject.
An architect in microservices architecture plays the following roles:
WebMvcTest annotation is used for unit testing Spring MVC Applications in cases where the test objective is to just focus on Spring MVC Components. In the snapshot shown above, we want to launch only the ToTestController. All other controllers and mappings will not be launched when this unit test is executed.
Spring Boot actuator provides restful web services to access the current state of running an application in the production environment. With the help of actuator, you can check various metrics and monitor your application.
According to the official website of Spring Cloud, Spring Cloud provides tools for developers to quickly build some of the common patterns in distributed systems (e.g. configuration management, service discovery, circuit breakers, intelligent routing, leadership election, distributed sessions, cluster state).
Representational State Transfer (REST)/RESTful web services are an architectural style to help computer systems communicate over the internet. This makes microservices easier to understand and implement.
Microservices can be implemented with or without RESTful APIs, but it’s always easier to build loosely coupled microservices using RESTful APIs.
If you have to define the Ubiquitous Language (UL), then it is a common language used by developers and users of a specific domain through which the domain can be explained easily.
The ubiquitous language has to be crystal clear so that it brings all the team members on the same page and also translates in such a way that a machine can understand.