API Gateway Interview Questions for Freshers/API Gateway Interview Questions and Answers for Freshers & Experienced

What is elastic blockage storage in Lambda?

It is basically a virtual storage area network where tasks can be started. It can tolerate faults easily and users need not worry about the loss of data even in case the disk damages in the RAID. Provisioning and allocating the storage can also be done in Elastic Block Storage. If required, it can also be connected to the API

Posted Date:- 2021-11-27 08:54:12

What are the best practices for security in Lambda?

For security, there are some of the best options available in Lambda. One can use Identity Access and Management. This would be beneficial when it comes to controlling access to resources. Privilege is another option that basically opens up the permissions. Access can be restricted to hosts that are not trusted or unauthorized. There are rules in the security group that can be reviewed with time to keep up the pace simply.

Posted Date:- 2021-11-27 08:53:26

Do you think there is a relation between Instance and AMI?

Yes, they are associated with each other. Lambda offers a query API that is good in terms of query parameters. Requests such as HTTPs can simply be handled and managed.

Posted Date:- 2021-11-27 08:52:39

Name the type of Storage provided by Amazon?

For Instance, there are several storage options provided by Amazon and the best thing is every option is best in terms of durability as well as performance. In case you want to use them in combination, there is not a problem. Independent access is also available. The first storage is EBS which is actually block-level storage. It comes with an encryption feature and is a good option to consider when independent storage is required.

The next type is the EC2 Instance store which is directly connected to the host PC as a storage disk. For temporary needs, it is a good option to consider. The data on this storage remains valid only when the instance is valid. If the same is deleted, data will also be gone. Another storage type is “Adding Storage”. When the root storage device is created, an instance is launched. It generally contains information related to boot Instance.

The Amazon S3 is another option available for storage which is known to be an inexpensive option and can store any amount of data.

Posted Date:- 2021-11-27 08:51:30

What do you know about Auto-Scaling?

It is basically a feature in the Amazon Web Services that simply enables you to automatically configure and spin the novel instances. The good thing is there is no need for you to interfere at any stage. However, users can monitor everything through metrics and thresholds. To enable this task, you simply need to cross a threshold and you can see without any interference, the instances have scaled horizontally.

Posted Date:- 2021-11-27 08:50:45

What do you know about AMI?

It stands for Amazon Machine Image and many times it is used in processed that is based on Lambda or even in conjunction with the same. Basically, it’s a template that contains an application server, OS, or other applications. It is possible to create its copy in the cloud. It has several instances and running multiple instances is also possible. AMI can also run a virtual server in a cloud.

Posted Date:- 2021-11-27 08:49:00

There are some of the very complex querying capabilities that need to be handled without having a warehouse? Which database do you consider during such a case?

The Amazon RDS is a good option as others such as ElasticCache suffer from some issues.RDS makes it easy to set up and manage every task reliably. Also, it is compatible with all modern tools.

Posted Date:- 2021-11-27 08:46:50

What do you know about Zero downtime deployment?

Deployments are generally considered in the form of functions. AWS Lambda divides it into units in case they are complex. The fact here is app remains in offline mode during such a time period. However, the results are always good.

Posted Date:- 2021-11-27 08:43:28

What is the time limit for execution in Lambda when you perform DDOS?

The time limit is 5 minutes.

Posted Date:- 2021-11-27 08:40:32

How to achieve zero-downtime deployment(blue/green) when there is a database change?

The deployment scenario becomes complex when there are database changes during the upgrade. There can be two different scenarios: 1. database change is backward compatible (e.g. adding a new table column) 2. database change is not compatible with an older version of the application (e.g. renaming an existing table column)

1. Backward compatible change: This scenario is easy to implement and can be fully automated using Flyway. We can add the script to create a new column and the script will be executed at the time of deployment. Now during blue/green deployment, two versions of the application (say v1 and v2) will be connected to the same database. We need to make sure that the newly added columns allow null values (btw that’s part of the backward compatible change). If everything goes well, then we can switch off the older version v1, else application v2 can be taken off.

2. Non-compatible database change: This is a tricky scenario, and may require manual intervention in-case of rollback. Let's say we want to rename first_name column to fname in the database. Instead of directly renaming, we can create a new column fname and copy all existing values of first_name into fname column, keeping the first_name column as it is in the database. We can defer non-null checks on fname to post-deployment success. If the deployment goes successful, we need to migrate data written to first_name by v1 to the new column (fname) manually after bringing down the v1. If the deployment fails for v2, then we need to do the otherwise.

Posted Date:- 2021-11-27 08:39:36

What makes Lambda a time-saving approach?

There are certain reasons for this. The one is it’s possible to simply store everything in the local server memory. Also, data can be stored directly into the database without affecting the performance. In addition to this, testing is not much complicated. Integration testing can simply be made powerful through multiple vendors.

Posted Date:- 2021-11-27 08:38:34

Is there any disadvantage of using this approach too? What do you think?

Well, everything has its own pros and cons depending on the work we perform through it. When it comes to the serverless approach, the fact is applicable here too. In a few cases, there is a strict upper limit on vendor control in a serverless approach and this clearly means more downtime and thus losses. The loss of functionality and system limits are the other issues. Also, there is no dedicated hardware available for the serverless approach. Thus performance and security become challenges at several stages. Sometimes customer errors can also create problems. The new deployment, as well as monitoring tools, become the only option when it comes to switching to Google Cloud functions.

Posted Date:- 2021-11-27 08:38:00

Is it possible to debug and troubleshoot the micro or small services?

Yes, it’s possible. It can be performed even when the function is running and appropriate tasks are being performed.hat

Posted Date:- 2021-11-27 08:37:32

What are the advantages of using the Serverless approach?

The very first thing about this approach is simple operations which mean quick time to market and better sales. Users only need to pay when the code is running and thus a lot o cost can simply be saved which enhances profits. Also, managing the larger application components is not a big deal. In addition to this, there is no need to have the additional infrastructure. The biggest thing is users need not worry about the servers on which the code runs.

Posted Date:- 2021-11-27 08:36:53

Tell us about the frameworks which are available for serverless?

There are several frameworks and serverless is extremely powerful. Its great support to Lambda and open whisk, as well as azure functions, makes it simply the best in every aspect. When it comes to extending the cloud formation, the Serverless Application Model can easily be considered. Scripting the changes to API becomes extremely simple with this approach and the best thing is the task is very quick and reliable.

Posted Date:- 2021-11-27 08:36:24

What should be preferred communication style in microservices: synchronous or asynchronous?

1. You must use asynchronous communication while handling HTTP POST/PUT (anything that modifies the data) requests, using some reliable queue mechanism (RabbitMQ, AMQP, etc.)

2. It's fine to use synchronous communication for Aggregation pattern at API Gateway Level. But this aggregation should not include any business logic other than aggregation. Data values must not be transformed at Aggregator, otherwise, it defeats the purpose of Bounded Context. In Asynchronous communication, events should be published into a Queue. Events contain data about the domain, it should not tell what to do (action) on this data.

3. If microservice to microservice communication still requires synchronous communication for GET operation, then seriously reconsider the partitioning of your microservices for bounded context, and create some tasks in backlog/technical debt.

Posted Date:- 2021-11-27 08:34:51

Why Microservices are better than Monoliths?

Microservices architecture is meant for developing large distributed systems that scale with safely. There are many benefits of microservices architecture over monoliths, for example:

Monolith application is built as a single unit, it is usually composed of 3 components – a database (usually a RDBMS), a server-side executable (war file deployed in tomcat, websphere etc) and a client interface (JSP, etc.)
Whenever we want to add/update functionality, developers need to change at least one of these three components and deploy the new version to production. The entire system is tightly coupled, have limitations in choosing technology stack, have low cohesion.
When we need to scale a monolith, we deploy the same version of the monolith on multiple machines, by copying the big war/ear file again and again. Everything is contained into a single executable file.
Microservices Architecture, on the other hand, is composed of small autonomous services, divided over business capabilities that communicate with each other over network mostly in async fashion.

Posted Date:- 2021-11-27 08:30:05

Explain how can you scale a microservice based system?

Assuming that the majority of providers using microservices architecture,

* One can scale the system by increasing the number of instances of service by bringing up more containers.
* One can also apply to cache at microservice layer which can be easy to manage as an invalidation of the cache can be done very easily as the microservice will be the single source of truth.
* Caching can also be introduced at the API Gateway layer where one can define caching rules like when to invalidate the cache.
* One can also shut down some containers when the requirement is less. That is, scale down.

Posted Date:- 2021-11-27 08:28:38

What is client side and server side service discovery?

Instead of clients directly connecting to load balancer, in this architectural pattern the client connects to the service registry and tries to fetch data or services from it.

Once it gets all data, it does load balancing on its own and directly reaches out to the services it needs to talk to.

This can have a benefit where there are multiple proxy layers and delays are happening due to the multilayer communication.

In server-side discovery, the proxy layer or API Gateway later tries to connect to the service registry and makes a call to appropriate service afterward. Over here client connects to that proxy layer or API Gateway layer.

Posted Date:- 2021-11-27 08:26:40

Mention which markup language can be used in restful web api?

JSON and XML are the two markup language that can be used in restful web api.

Posted Date:- 2021-11-27 08:26:10

Mention what is the difference between RPC or document style web services? How you determine to which one to choose?

In document style web services, we can transport an XML message as part of SOAP request which is not possible in RPC style web service. Document style web service is most appropriate in some application where XML message behaves as document and content of that document can alter and intention of web service does not rely on the content of XML message.

Posted Date:- 2021-11-27 08:24:36

List out the tools or API for developing or testing web api?

Testing tools for web services for REST APIs includes

* Spring REST web service using MVC
* Jersey API
* Axis
* Restlet,

Posted Date:- 2021-11-27 08:23:54

How would you test microservice based architecture?

One should have unit and integration tests where all the functionality of a microservice can be tested. One should also have component based testing.

One should have contract tests to assert that the expectations by the client is not breaking. End-to-end test for the microservices, however, should only test the critical flows as these can be time-consuming. The tests can be from two sides, consumer-driven contract test and consumer-side contract test.

You can also leverage Command Query Responsibility Segregation to query multiple databases and get a combined view of persisted data.

Posted Date:- 2021-11-27 08:20:57

When should one consider microservice kind of architecture?

There are two cases.

* If you already have a monolith application and it grows to an extent where there are problems in scaling or we are not able to reutilize the components/modules/services across different projects/platforms and there is a need to do so. As well as at the same time implementing new features is painful and more error-prone and it is difficult to scale further.

* For new applications where implementation has not started yet started, we can think of a business case to be efficiently implemented, which can be easily maintainable, testable and scalable in the future and might be used across other projects/products/platforms at the same time.

Posted Date:- 2021-11-27 08:20:26

What are microservices and why would someone want to look at implementing it.

Microservices is an architectural style which structures and application as a collection of loosely coupled, independently maintainable, testable and deployable services which are organized around business capabilities.

If you have a business focus and you want to solve a use case or a problem efficiently without the boundaries of technology, want to scale an independent service infinitely, highly available stateless services which are easy to maintainable and managed as well as independently testable then we would go ahead and implement Microservices architecture.

Posted Date:- 2021-11-27 08:18:59

Mention what is JAX-WS and JAX-RS?

Both JAX-WS and JAX-RS are libraries (APIs) for doing communication in various ways in Java. JAX-WS is a library that can be used to do SOAP communication in JAVA, and JAX-RS lets you do the REST communication in JAVA.

Posted Date:- 2021-11-27 08:14:43

Mention what is the difference between RPC or document style web services? How you determine to which one to choose?

In document style web services, we can transport an XML message as part of SOAP request which is not possible in RPC style web service. Document style web service is most appropriate in some application where XML message behaves as document and content of that document can alter and intention of web service does not rely on the content of XML message.

Posted Date:- 2021-11-27 08:14:14

What kind of testing environment is needed for API?

Setting up the API testing environment can be difficult because you have to configure both the server and the database without the use of GUI.

Posted Date:- 2021-11-27 08:13:02

What tests can be performed on APIs?

Tests can and should be performed on APIs for several reasons, including testing the return values or inputting conditions.

Posted Date:- 2021-11-27 08:12:13

What factors help inform your decision on which style of Web services—SOAP or REST—to use?

REST is usually preferred because of its simplicity, performance, scalability and support across many data formats. However, SOAP is a viable choice when service requires an advanced level of security and reliability.

Posted Date:- 2021-11-27 08:11:47

Mention what are resources in a REST architecture?

Resources are identified by logical URLs; it is the key element of a RESTful design. Unlike, SOAP web services in REST, you view the product data as a resource and this resource should contain all the required information.

Posted Date:- 2021-11-27 08:11:21

Mention whether you can use GET request instead of PUT to create a resource?

No, you are not supposed to use PUT for GET. GET operations should only have view rights, while PUT resource is used for updating a data.

Posted Date:- 2021-11-27 08:10:41

What is the difference between API and Web services?

Web services must be exposed over the web and have three styles of communication: SOAP, REST and XML-RPC. They always need a network to operate. However, APIs have multiple methods of communication. A network is unnecessary for their operation, and they don’t have to be exposed over the Web.

Posted Date:- 2021-11-27 08:10:14

What kinds of bugs does API testing find most commonly?

I have often used API testing to find several different issues, such as missing or duplicate functionality, failure to handle errors effectively and seamlessly as well as any performance, stress, multi-threading, reliability or security issues. However, unimplemented and improper errors, unused flags and inconsistent error handling are some of the other errors that can be found through API testing.

Posted Date:- 2021-11-27 08:09:48

What are the primary challenges of API testing?

I find selecting and combining parameters and sequencing calls to be the most challenging parts of API testing.

Posted Date:- 2021-11-27 08:09:24

What is the procedure for performing API testing?

When performing API testing, you’ll first choose the suite where you’d like to add the API case that you wish to test, then you choose the test development mode. After that, you create test cases for the desired API methods, configure the control parameters and test conditions of the application as well as the method of validation. Then you can perform the API test. Once the test is complete, you check the test reports, filter and sequence all of the API test cases.

Posted Date:- 2021-11-27 08:09:02

What are the advantages of API Testing?

API testing gives access to the application without needing a user interface. This allows you to detect the minor issues before they become big problems during GUI testing.

Also, API testing is typically less time consuming than GUI testing because it uses less code. As a result, it offers a more effective and efficient test coverage.

Another benefit is that the data is transferred using XML or JSON. These modes of exchange are language-independent, allowing users to select any coding language when choosing automation testing services. Additionally, API testing is easily integrated with GUI testing.

Posted Date:- 2021-11-27 08:08:43

What are some styles for creating a Web API?

Common Web API architectural styles are XML/JSON as a formatting language, stateless communication, basic URI as the address for the services and HTTP for communication between the client and server. Personally, I prefer XML over JSON.

Posted Date:- 2021-11-27 08:08:25

What are the types of API ?

There are 2 types of API:
RESTful APIs--
Used for optimizing the serverless workloads and HTTP backends using HTTP APIs, it is required for API proxy functionality and API management features in a single solution, API Gateway also offers REST APIs.
These are built real time two way communication applications like chat apps and streaming dashboards.It also maintains persistent connection for handling messages for transfering between our backend service and our clients.

Posted Date:- 2021-11-27 08:05:43

How can we call an API Gateway API?

The app developer helps in working with API Gateway Service component for API execution which is named executeapi, that is used for invoking API which was created or deployed in an API Gateway.These underlying programming entities that are exposed by the created API and there are several ways for calling an API.

Posted Date:- 2021-11-27 08:05:20

How can we use API Gateway to create HTTP APIs?

HTTP APIs are designed for low latency, cost effective integrations with the services also including with AWS Lambda and HTTP endpoints.HTTP also supports OIDC and OAuth authorization and supports CORS and automatic deployments.Previous-generation REST APIs currently offer more features.
HTTP APIs helps in enabling us for creating RESTful APIs with lower latency and lower cost than RESTAPIs.It also helps in sending mrequests to the AWS Lambda functions to any routable HTTP endpoints.We can also create an HTTP APIs that integrates with a lambda functions on the function.

Posted Date:- 2021-11-27 08:05:04

What is AWS Lambda Function?

AWS Lambda is used for uploading codes or business logic to the AWS infrastructure and aslo manages it, it is provided by Amazon.This uploading code is known as Lamda Function, we can use the code as -
An event driven service which triggers on some change like a change in the data of an S3 bucket or a Dynamo DB table.
As the back-end of an AWS API gateway.

Posted Date:- 2021-11-27 08:04:45

What is a resource?

Resource is a object which is typed and is a part of our API domain.Each resource that have associated data model, relationships to other resources and also can respond to different methods and also can define resources as variables for intercepting requests for multiple child resources.

Posted Date:- 2021-11-27 08:04:28

What API types are supported by Amazon API Gateway?

Types of APIs supported by AWS API Gateway are:

* HTTP API - optimized for building APIs that are proxy for AWS Lambda.
* REST API - offers proxy functionality and API management features.
* WebSocket API - helps in enabling real-time message communication.

Posted Date:- 2021-11-27 08:04:15

What are the Features of API Gateway?

Features of API Gateway are as follows:
* Cost Effective helps in low cost and efficient as API provides a tiered pricing model for API reuests.
* Scalable autoscaling groups responding to API requests and scales automatically.
* Caching and Throttling used for caching the endpoint responses that improves the latency of requests to our API.
* Flexible implements for launching an EC2 instance or setting up the Gateway Software.
* Security integrate with a gateway that provides tools such as AWS credentials, i.e., access and secret keys to access an API.

Posted Date:- 2021-11-27 08:03:46

What is API Caching?

Caching API is used for storing and retrieving all the network requests and also in corresponding responses.It is created for enabling service workers for cache network requests do so it can help in providing fast responses, speed or availibility.Caching is the ability for storing copies of freaquently accessed data in several places along the request response path and also indicates wether a response can be cached or no.
We can enable API Caching in AWS API Gateway for caching our endpoint responses, we can reduce the number of calls made to our endpoint and in improving the latency of requests to our API.

Posted Date:- 2021-11-27 08:02:59

What are the processes involved in working with AWS lambda and API Gateway?

Process involved in working with AWS Lambda and API Gateway are as follows:

Create IAM role for permission
Create AWS lambda function
Create API Gateway
Link lambda function to API Gateway
Passing data to API Gateway

Posted Date:- 2021-11-27 08:02:37

Explain the Architecture of API Gateway?

An API Gateway is a server that is the single entry point into the system. It is similar to the Facade pattern from object‑oriented design. The API Gateway encapsulates the internal system architecture and provides an API that is tailored to each client. ... The API Gateway can also provide each client with a custom API.

Posted Date:- 2021-11-27 08:01:58

How Ansible Works?

Ansible works by connecting nodes and pushing out all small programs known as Ansible Modules, it executes modules and removes them when they are finished.Modules helps in residing any machine, and there are no servers, daemons and database required.
Ansible removes the modules once they are installed and connects to the host machine, also executes the instruction when it is successfully installed removes the code which is copied on the host machine which is executed.

Posted Date:- 2021-11-27 08:01:04

What is AWS API Gateway?

AWS API Gateway is used by the developers for creating, publishing, maintaining, monitoring and securing APIs at any scale.By using this API, we can create RESTfulAPIs and WebSocket APIs which helps in enabling real time two way communication applications.
API Gateway helps in providing WebSocket API Management functionality as follows:Monitoring and throttling of connections and messages. Using AWS X-Ray to trace messages as they travel through the APIs to backend services. Easy integration with HTTP/HTTPS endpoints.

Posted Date:- 2021-11-27 08:00:54

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