Fannie  Zemlak

Fannie Zemlak

1595920200

Build Reactive REST APIs With Spring WebFlux

In this article, we will see how to build reactive REST APIs with Spring WebFlux. Before jumping into the reactive APIs, let us see how the systems evolved, what problems we see with the traditional REST implementations, and the demands from modern APIs.

If you look at the expectations from legacy systems to modern systems described below,

Evolution of application API needs

The expectations from the modern systems are: the applications should be distributed, Cloud Native, embracing for high availability, and scalability. So the efficient usage of system resources is essential. Before jumping into Why reactive programming to build REST APIs? Let us see how the traditional REST APIs request processing works.

Traditional REST API model

Below are the issues what we have with the traditional REST APIs,

  • Blocking and Synchronous → The request is blocking and synchronous. The request thread will be waiting for any blocking I/O and the thread is not freed to return the response to the caller until the I/O wait is over.
  • **Thread per request → **The web container uses a thread-per-request model. This limits the number of concurrent requests to handle. Beyond certain requests, the container queues the requests that eventually impact the performance of the APIs.
  • **Limitations to handle high concurrent users → **As the web container uses a thread-per-request model, we cannot handle high concurrent requests.
  • **No better utilization of system resources → **The threads will be blocking for I/O and sitting idle. But, the web container cannot accept more requests. During this scenario, we are not able to utilize the system resources efficiently.
  • **No backpressure support → **We cannot apply backpressure from the client or the server. If there is a sudden surge of requests the server or client outages may happen. After that, the application will not be accessible to the users. If we have backpressure support, the application should sustain during the heavy load rather than the unavailability.

Let us see how we can solve the above issues using reactive programming. Below are the advantages we will get with reactive APIs.

  • **Asynchronous and Non-Blocking → **Reactive programming gives the flexibility to write asynchronous and Non-Blocking applications.
  • **Event/Message Driven→ **The system will generate events or messages for any activity. For example, the data coming from the database is treated as a stream of events.
  • **Support for backpressure → **Gracefully we can handle the pressure from one system to on to the other system by applying back pressure to avoid denial of service.
  • **Predictable application response time → **As the threads are asynchronous and non-blocking, the application response time is predictable under the load.
  • **Better utilization of system resources → **As the threads are asynchronous and non-blocking, the threads will not be hogged for the I/O. With fewer threads, we could able to support more user requests.
  • Scale based on the load
  • **Move away from thread per request → **With the reactive APIs, we are moving away from thread per request model as the threads are asynchronous and non-blocking. Once the request is made, it creates an event with the server and the request thread will be released to handle other requests.

Now, let us see how Reactive Programming works. In the below example, once the application makes a call to get the data from a data source, the thread will be returned immediately, and the data from the data source will come as a data/event stream. Here, the application is a subscriber, and the data source is a publisher. Upon the completion of the data stream, the onComplete event will be triggered.

Data stream workflow

Below is another scenario where the publisher will trigger an onError event if any exception happens.

Data stream workflow

In some cases, there might not be any items to deliver from the publisher. For example, deleting an item from the database. In that case, the publisher will trigger the onComplete/onError event immediately without calling onNext event, as there is no data to return.

Data stream workflow

Now, let us see **what is backpressure **and how we can apply backpressure to the reactive streams.For example, we have a client application that is requesting data from another service. The service is able to publish the events at the rate of 1000TPS but the client application is able to process the events at the rate of 200TPS.

In this case, the client application should buffer the rest of the data to process. Over the subsequent calls, the client application may buffer more data and eventually run out of memory. This causes the cascading effect on the other applications which depends on the client application. To avoid this the client application can ask the service to buffer the events at their end and push the events at the rate of the client application. This is called backpressure. The below diagram depicts the same.

#java #tutorial #spring boot #reactive streams #project reactor #spring web flux

What is GEEK

Buddha Community

Build Reactive REST APIs With Spring WebFlux
Wilford  Pagac

Wilford Pagac

1594289280

What is REST API? An Overview | Liquid Web

What is REST?

The REST acronym is defined as a “REpresentational State Transfer” and is designed to take advantage of existing HTTP protocols when used for Web APIs. It is very flexible in that it is not tied to resources or methods and has the ability to handle different calls and data formats. Because REST API is not constrained to an XML format like SOAP, it can return multiple other formats depending on what is needed. If a service adheres to this style, it is considered a “RESTful” application. REST allows components to access and manage functions within another application.

REST was initially defined in a dissertation by Roy Fielding’s twenty years ago. He proposed these standards as an alternative to SOAP (The Simple Object Access Protocol is a simple standard for accessing objects and exchanging structured messages within a distributed computing environment). REST (or RESTful) defines the general rules used to regulate the interactions between web apps utilizing the HTTP protocol for CRUD (create, retrieve, update, delete) operations.

What is an API?

An API (or Application Programming Interface) provides a method of interaction between two systems.

What is a RESTful API?

A RESTful API (or application program interface) uses HTTP requests to GET, PUT, POST, and DELETE data following the REST standards. This allows two pieces of software to communicate with each other. In essence, REST API is a set of remote calls using standard methods to return data in a specific format.

The systems that interact in this manner can be very different. Each app may use a unique programming language, operating system, database, etc. So, how do we create a system that can easily communicate and understand other apps?? This is where the Rest API is used as an interaction system.

When using a RESTful API, we should determine in advance what resources we want to expose to the outside world. Typically, the RESTful API service is implemented, keeping the following ideas in mind:

  • Format: There should be no restrictions on the data exchange format
  • Implementation: REST is based entirely on HTTP
  • Service Definition: Because REST is very flexible, API can be modified to ensure the application understands the request/response format.
  • The RESTful API focuses on resources and how efficiently you perform operations with it using HTTP.

The features of the REST API design style state:

  • Each entity must have a unique identifier.
  • Standard methods should be used to read and modify data.
  • It should provide support for different types of resources.
  • The interactions should be stateless.

For REST to fit this model, we must adhere to the following rules:

  • Client-Server Architecture: The interface is separate from the server-side data repository. This affords flexibility and the development of components independently of each other.
  • Detachment: The client connections are not stored on the server between requests.
  • Cacheability: It must be explicitly stated whether the client can store responses.
  • Multi-level: The API should work whether it interacts directly with a server or through an additional layer, like a load balancer.

#tutorials #api #application #application programming interface #crud #http #json #programming #protocols #representational state transfer #rest #rest api #rest api graphql #rest api json #rest api xml #restful #soap #xml #yaml

An API-First Approach For Designing Restful APIs | Hacker Noon

I’ve been working with Restful APIs for some time now and one thing that I love to do is to talk about APIs.

So, today I will show you how to build an API using the API-First approach and Design First with OpenAPI Specification.

First thing first, if you don’t know what’s an API-First approach means, it would be nice you stop reading this and check the blog post that I wrote to the Farfetchs blog where I explain everything that you need to know to start an API using API-First.

Preparing the ground

Before you get your hands dirty, let’s prepare the ground and understand the use case that will be developed.

Tools

If you desire to reproduce the examples that will be shown here, you will need some of those items below.

  • NodeJS
  • OpenAPI Specification
  • Text Editor (I’ll use VSCode)
  • Command Line

Use Case

To keep easy to understand, let’s use the Todo List App, it is a very common concept beyond the software development community.

#api #rest-api #openai #api-first-development #api-design #apis #restful-apis #restful-api

Chaz  Homenick

Chaz Homenick

1602725748

Why You Should Consider Low-Code Approach to Building a REST API

APIs have been around for decades – they allow different systems to talk to each other in a seamless, fast fashion – yet it’s been during the past decade that this technology has become a significant force.

So then why all the interest in APIs? We all know the usual stories – Uber, Airbnb, Apple Pay… the list goes on, and the reasons are plentiful. Today the question is, how? Perhaps you are looking to differentiate your business or want a first-mover advantage.  How can you execute quickly and at low cost/risk to try new market offerings?

An API provides several benefits to an organisation, but without a dedicated team of trained developers, it might seem like an implausible option. Developers are expensive, and it can take months to develop an API from the ground up. If you don’t fancy outsourcing or have the capability in house to build internal APIs, a low-code platform might just be the answer.

Before You Begin: Plan long-term, start small.

For a small one-page application, this might only be a day or two of talking with stakeholders and designing business logic. The purpose of this first step is to ensure that the API will cover all use cases and provides stakeholders with what they need. Refactoring an entire coding design due to missing business logic is not only frustrating for the development team but adds high cost and time to the API project.

During the planning and design stage, remember that running an API requires more infrastructure than just resources to execute endpoint logic. You need a database to store the data, an email system to send messages, storage for files, and security to handle authorisation and authentication. These services can be farmed out to cloud providers to expedite the API build process (e.g. AWS provides all these infrastructure components, but Microsoft Azure is an optional cloud provider with SendGrid as the email application.)

**Planning considerations: **An API “speaks” in JSON or XML, so the output provided to client applications should be decided. Should you choose to later create endpoints for public developer consumption, you could offer both for ease-of-use and fostering more adoption. Ensuring the API follows OpenAPI standards will encourage more adoption and attract more developers.

#api #rest-api #api-development #restful-api #low-code-platform #low-code #build-a-rest-api #low-code-approach

Adonis  Kerluke

Adonis Kerluke

1596509565

RESTful API Design Driven Approach

In this tutorial I will show you the fundamentals of designing a RESTful API specification by applying REST principles and best practices, then you’ll be ready to try my online tutorial: How to design a REST API with API Designer?

If you already know what is meant by API in the context of RESTful web services, you can skip to the next section. If not, read on.

Level-Set on API

The abbreviation API stands for Application Programming Interface this in itself, does not help us understand what it is, however in the context of web services, it can refer to one of two things:

  1. The RESTful API specification is written using a modeling language such as Open API specification or RAML (RESTful API Modeling Language) that defines a contract for how software components can interact with a service.
  2. The implementation of a web service or microservice whose contract is designed by REST principles that describe how other services must interact with it.

In this post, I will use the first understanding of this term. Even though both are correct, the most technically relevant for this post is the first: an API is a contract for how software applications talk to each other.

Level-Set on REST

The acronym REST stands for REpresentational State Transfer. It is an architectural style used to represent the transmission of data from one application component to another. In the context of web services, we are talking about the representation of resources (i.e. data) transferred over HTTP by calling a URI that represents the data and via an HTTP method that represents the action to perform against the given data.

What Is RESTful API design?

RESTful API design is the activity of describing the behavior of a web service in terms of its data structures and the actions you allow other application components to perform on its data by the principles of REST. Those principles are covered later in this blog.

Why Design a RESTful API?

Imagine that you are an Architect (the kind the design building) and you set out to build an office block without a blueprint. You turn up on the first day with a truck full of bricks and some cement. What are the chances that you’ll be successful and build a structure that conforms to code and more importantly, doesn’t fall? It’s about zero. Without a blueprint the chance of failure is high.

The same approach applies to web service development. You need a blueprint, or more appropriately, an API specification. This is necessary to evaluate the API design and solicit feedback before even starting to build the implementation.

In addition to providing a specification for the web service’s development, an API contract serves to document its expected behavior, data types, and security requirements.

You should now be satisfied that API design is necessary for a RESTful web service, and should start to wonder how is the best approach to actually designing an API specification.

API Design Tooling

The tooling chosen by an API designer has substantial influence over the designer’s productivity. Highly productive tools such as the Anypoint API Designer from MuleSoft is perfect for designing APIs with OAS (swagger) or RAML.

#integration #api #rest #rest api #restful #api design #raml #rest api design