Introduction to ASP.NET Core Web API

Introduction to ASP.NET Core Web API

In this article, I am going to give a brief introduction to the ASP.NET Core Web API Framework. At the end of this article, you will understand the following pointers.

  1. What is Web API?
  2. What is ASP.NET Core Web API?
  3. Why We Need ASP.NET Core Web API?
  4. ASP.NET Core Web API Features
  5. What is Rest?
  6. What are the REST Principles?
  7. Differences Between REST and SOAP Services.
  8. Difference Between ASP.NET Web API and ASP.NET Core Web API.
What is Web API?

API stands for Application Programming Interface. Web API is a concept (not a technology) that works on the HTTP Protocol and is used to extend the functionality of an application.

A Web API, or Web Application Programming Interface, is a set of rules and protocols that allows different software applications to communicate with each other over the internet or a network. It enables the exchange of data and functionality between various systems, using HTTP (Hypertext Transfer Protocol) as the communication protocol. 

What is ASP.NET Core Web API?

The term API stands for Application Programming Interface. ASP.NET Core Web API is a framework provided by Microsoft that makes it easy to build Web APIs, i.e., HTTP-based services. The ASP.NET Core Web API is ideal for building Restful services on top of the .NET Platform, commonly known as the .NET Core Platform. These Web API services can then be consumed by a variety of clients, such as

  1. Browsers
  2. Mobile applications
  3. Desktop applications
  4. IOTs, etc.

ASP.NET Core Web API is commonly used for building RESTful APIs that expose data and services over HTTP. It’s suitable for various scenarios, including building back-end services for web, mobile, and desktop applications, providing data to single-page applications (SPAs), and creating microservices that can be deployed independently.

Why We Need ASP.NET Core Web API?

Nowadays, a web application is not sufficient or enough to reach all its customers. People are becoming very smart; they are using different types of devices, such as mobile, iPhones, tablets, etc., in their daily lives. These devices have a lot of apps that make their life easy. In simple words, we can say that we are moving toward the app world from the web.

So, if we want to expose our data (business data) to the browsers and to all these modern device apps in a fast, secure, and simple way, then we should have an API that should be compatible with browsers and all these modern devices.

The ASP.NET Core Web API is a great framework for building HTTP services that can be consumed by a broad range of clients, including browsers, mobiles, iPhones, and tablets.

ASP.NET Core Web API Features:

Below are some of the key features of ASP.NET Core Web API that we are going to discuss in this course:

  • Cross-Platform Support: NET Core Web APIs can run on Windows, Linux, and macOS, making your Web APIs platform-independent.
  • Performance: NET Core has been designed to have a smaller memory footprint and improved performance compared to its predecessors. It’s optimized for modern cloud-based applications.
  • Routing: Supports attribute routing, which allows the development of -SEO-friendly URLs.
  • Model Binding and Validation: Automatically maps data from HTTP requests to action method parameters. Model validation is also automatically performed, and any validation errors can be handled and returned to the client.
  • Dependency Injection: Built-in support for dependency injection (DI). This allows for more modular and testable code.
  • Middleware Support: NET Core’s middleware pipeline enables you to add components that inspect and process HTTP requests/responses, allowing for custom processing like authentication, logging, encryption decryption, etc.
  • Content Negotiation and Serialization: Automatically serializes your data to and from JSON, XML, or any other format, depending on client preferences and server capabilities.
  • Versioning: Supports API versioning, which is important for handling new clients with new APIs without breaking existing clients.
  • OpenAPI/Swagger Support: Provides built-in support for generating OpenAPI (formerly Swagger) descriptions of your API, which can then be used to generate beautiful interactive documentation, client SDK generation, and more.
  • Security: Supports authentication and authorization mechanisms, including OAuth 2.0, Basic Authentication, HMAC, JWT (JSON Web Tokens), and more, to secure your web APIs.
  • Testability: Designed to support unit testing. You can write tests for your API like any other ASP.NET Core application.
  • Extensibility: Highly extensible and customizable to suit various needs, from custom filters to new serialization formats.
  • Integrated Configuration System: The Web API can read application configuration data from various sources, like JSON files, environment variables, and more.
  • Environment-based Configuration: Supports development, staging, and production environments, allowing different configurations for each environment.
What is Rest?

REST stands for Representational State Transfer. This is an architectural pattern used for exchanging data over a distributed environment. At rest, there is something called a Client and a Server, and the data will be exchanged between the client and server over a distributed environment.

A Distributed Environment means the client can be on any platform like Java, .NET, PHP, etc.; the server can also be on any platform like Java, .NET, PHP, etc. The REST architectural pattern treats each service as a resource, and a client can access those resources by using HTTP Protocol methods such as GET, POST, PUT, PATCH, and DELETE.

What are the REST Principles?

The REST architectural pattern specifies a set of constraints that a system should adhere to. Here are the REST constraints or principles.

Client-Server Constraint:

This constraint specifies that a client sends a request to the server, and the server sends a response back to the client. This separation of concerns supports the independent development of client- and server-side logic. That means client applications and server applications should be developed separately without any dependency on each other. A client should only know resource URIs, and that’s all. 

Stateless Constraint:

The stateless constraint specifies that the client and server communication must be stateless between requests. That means the server should not be storing anything related to the client on the server. The request from the client should contain all the necessary information so that the server can identify the client and process that request. This ensures that each request can be treated independently by the server.

Cacheable Constraint:

In real-time applications, some data provided by the server is not changed that frequently, like the list of Countries, the list of States, the list of Cities, and some master data. RESTful APIs can take advantage of HTTP caching mechanisms. Responses can include cache directives to enable client-side caching, reducing the load on the server and improving performance.

Uniform Interface Constraint:

The Uniform Interface Constraint defines an interface between the client and the server. Resources are represented using standard data formats such as JSON or XML. To understand the uniform interface constraint, first, we need to understand what a resource is and the HTTP verbs such as GET, PUT, POST, PATCH, and DELETE.

In the context of a RESTFUL Service, resources typically represent data entities. The Product, Employee, Customer, Country, State, City, etc. are all resources. The HTTP verb (GET, PUT, POST, PATCH, and DELETE) that is sent with each request tells the API what to do with the resource. Each resource is identified by a specific URI (Uniform Resource Identifier).

Content Negotiation:

One of the constraints of the REST service is that the client should be able to decide in which format they want the response – whether they want the response in XML or JSON, etc. This is called Content Negotiation.

Layered System:

RESTful architectures can be composed of multiple layers, where each layer provides specific functionality. For example, REST allows us to use a layered system architecture where we deploy the APIs in server A, store data on server B, and authenticate requests in server C. A client cannot simply tell whether it is connected directly to the server or to an intermediary along the way. This allows for scalability, separation of concerns, and ease of maintenance.

By following these principles, RESTful Web APIs provide a standard and scalable approach to designing and developing web services. They promote loose coupling between clients and servers, enabling easy integration with various platforms and technologies. RESTful APIs are widely used in web and mobile application development, enabling clients to interact with server resources in a flexible and efficient manner.

What are the Differences Between REST and SOAP Services?

Let us discuss the difference between the REST and SOAP service:

  • SOAP stands for Simple Object Access Protocol, whereas REST stands for Representational State Transfer.
  • SOAP is an XML-based protocol, whereas REST is not a protocol. Rather, it is an architectural pattern, i.e., resource-based architecture.                        
  • SOAP has stateless and state-full implementation specifications, whereas REST is completely stateless.
  • SOAP enforces the message format XML, whereas REST does not enforce the message format XML or JSON.
  • The SOAP message consists of an envelope with SOAP headers and a body to store the information we want to send. In contrast, REST uses the HTTP build-in headers (with various media types) to store the information and uses HTTP Methods such as GET, POST, PUT, PATCH, and DELETE to perform CRUD operations.
  • SOAP is operation-based, where services are exposed as operations, while REST is resource-based, where services are exposed as resources identified by URLs.
  • REST is more flexible and offers better performance due to its stateless nature and support for a broader range of data formats. SOAP, with its rigid structure and XML format, is slower. SOAP performance is slow compared to REST.
  • REST is generally considered easier to work with and is more commonly used in modern web service applications, especially for public APIs.
Difference Between ASP.NET Web API and ASP.NET Core Web API

ASP.NET Web API and ASP.NET Core Web API represent two different approaches to building Web APIs (Restful Services) within the ASP.NET framework, with several key distinctions:

Platform Support:
  • ASP.NET Web API is designed specifically for the Windows platform and the .NET Framework.
  • ASP.NET Core Web API, on the other hand, is cross-platform and can be run on Windows, macOS, or Linux, making it more versatile in terms of development and deployment environments.
Framework and Runtime:
  • ASP.NET Web API is built on the .NET Framework.
  • ASP.NET Core Web API uses the .NET Core runtime, which is a more modular and lightweight framework.
Performance:
  • ASP.NET Core Web API is known for higher performance than ASP.NET Web API. This is partly due to ASP.NET Core’s optimized code path, reduced memory footprint, and other performance improvements.
Development Tools:
  • ASP.NET Core Web API can be developed using various tools like Visual Studio, Visual Studio for Mac, or Visual Studio Code and supports C# or F#.
  • ASP.NET Web API development is predominantly done in Visual Studio using C#, VB, or F#.
API Design:
  • In ASP.NET Core, MVC 6 combines the features of MVC and Web API, allowing controllers to return both views (HTML) and data objects (e.g., JSON). This unification simplifies the development process.
  • The ASP.NET Web API focused more on creating REST APIs and did not integrate the MVC features as seamlessly.
Hosting:
  • ASP.NET Core Web API can be hosted on IIS, Kestrel, Docker, Linux, macOS, and Windows, offering more flexibility.
  • ASP.NET Web AP is generally hosted on Internet Information Services (IIS) but can also be self-hosted.
Dependency Injection:
  • ASP.NET Core Web API provides built-in comprehensive support for dependency injection.
  • ASP.NET Web API provides limited support for dependency injection natively. Often requires third-party libraries like Autofac or Ninject for more complex scenarios.
Middleware:
  • ASP.NET Core Web provides robust middleware support, allowing for a highly customizable request/response pipeline.
  • ASP.NET Web API provides limited middleware support. Uses HTTP handlers and modules for request processing.
Use Cases:
  • ASP.NET Core Web API is Ideal for modern web applications that require high performance, scalability, and cross-platform capabilities.
  • ASP.NET Web API is Ideal for applications that are firmly within the Windows/.NET Framework ecosystem.
Choosing Between ASP.NET Web API and ASP.NET Core Web API:
  • If you’re working on a new project and want the latest features, performance optimizations, and cross-platform capabilities, ASP.NET Core Web API is recommended.
  • Suppose you have an existing application based on the .NET Framework or specific dependencies on Windows-only features. In that case, ASP.NET Web API might be the appropriate choice, though migration to .NET Core should be considered for long-term sustainability.

In the next article, I will discuss HTTP (Hyper Text Transport Protocol), i.e., HTTP Verbs or Methods, HTTP Status Codes, HTTP Requests, and Responses. Here, in this article, I try to give a brief introduction to the ASP.NET Core Web API Framework. I hope you enjoy this Introduction to ASP.NET Core Web API article.

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