REST vs SOAP API

Table of Contents:

• Introduction (SOAP and REST API)
• Comparison between SOAP and REST API
• How to write SOAP API and Rest API

1) Introduction

A) SOAP API:

A SOAP (Simple Object Access Protocol) API is a type of web service that uses the SOAP protocol to send and receive messages. SOAP is a standard protocol for communication between systems, and it is often used in conjunction with other web standards such as WSDL (Web Service Description Language) and UDDI (Universal Description, Discovery, and Integration).

To create a SOAP API in C#, you will need to use the System.Web.Services namespace, which provides classes and attributes for creating web services.

The first step in creating a SOAP API is to create a Web Service project in your development environment. This will provide you with a skeleton for your web service and allow you to start adding code.

Next, you will need to define the methods that you want to expose through your SOAP API. These methods should be defined in a class, and you should decorate them with the [WebMethod] attribute to indicate that they should be exposed as part of the API.

You will also need to add any necessary input parameters to your methods. These can be simple data types, such as integers or strings, or they can be complex types such as custom classes or data structures.

Once you have defined your methods and added any necessary input parameters, you can implement the logic for your methods. This will involve writing code to perform the necessary operations and return the appropriate results.

Finally, you will need to decorate your methods with the [SoapDocumentMethod] attribute, which will specify the SOAP action and encoding style for your method. This attribute is optional, but it is recommended as it allows you to specify additional information about your method and how it should be used.

Once you have completed these steps, you can build and publish your web service, which will make it available to clients who can then access your methods through the SOAP API.

B) REST API

REST (Representational State Transfer) is an architectural style for building web APIs (Application Programming Interfaces). It is based on a set of constraints and principles that define how a web API should be structured and accessed.

In a REST API, resources (such as data or functionality) are accessed through a set of endpoints. Each endpoint is a specific URL that represents a particular resource or group of resources. Endpoints are accessed using HTTP methods, such as GET, POST, PUT, and DELETE, which correspond to different actions that can be performed on the resource.

REST APIs are designed to be flexible and scalable, and they can be used to access a wide range of resources and data. They are often used to expose data and functionality from web-based systems and mobile applications, and they can be consumed by a variety of clients including web browsers, mobile apps, and other servers.

Here are some key characteristics of REST APIs:

Stateless: REST APIs are stateless, which means that they do not store any state information on the server. This allows them to be scalable and flexible, as the server does not need to maintain a connection or session with the client.

Cacheable: REST APIs are designed to be cacheable, which means that clients can store responses locally and reuse them without making additional requests to the server. This can improve performance and reduce load on the server.

Uniform interface: REST APIs use a uniform interface, which means that they have a consistent set of rules for accessing resources. This allows clients to interact with the API in a predictable and standard way, regardless of the underlying implementation.

Layered system: REST APIs are designed to be a layered system, which means that they can be used in conjunction with other systems and APIs. This allows different parts of a system to be decoupled and modified or replaced independently.

Here is an example of a simple REST API that allows a client to retrieve a list of users from a server:

GET /users HTTP/1.1

Host: api.example.com

In this example, the client is sending a GET request to the /users endpoint on the api.example.com server. The server will respond with a list of users in the desired format (e.g. JSON or XML).

2) Comparison Between SOAP API and REST API

SOAP (Simple Object Access Protocol) and REST (Representational State Transfer) are two different styles of web APIs (Application Programming Interfaces). Both are used to allow applications to communicate with each other over the web, but they differ in a number of key ways:

Structure: SOAP is a standards-based protocol that defines a set of rules for structuring messages and exchanging data between systems. It consists of a set of envelopes, headers, and bodies that are used to transmit information. REST, on the other hand, is an architectural style that defines a set of constraints and principles for building web APIs. It does not have a specific structure or set of rules, and developers are free to design their APIs in any way they see fit.

Format: SOAP messages are typically formatted as XML documents, while REST APIs can use a variety of formats including XML, JSON, and HTML.

Protocol: SOAP APIs are typically transmitted over HTTP, but they can also be transmitted over other protocols such as SMTP (Simple Mail Transfer Protocol). REST APIs are always transmitted over HTTP.

Coupling: SOAP APIs are tightly coupled, meaning that they are highly dependent on one another. This can make it difficult to modify or replace one part of a system without affecting the other parts. REST APIs, on the other hand, are loosely coupled, meaning that they are less dependent on one another and can be modified or replaced more easily.

Here are some examples of how SOAP and REST APIs might be used:

SOAP API example:

A banking system might have a SOAP API that allows external applications to access account information and perform transactions. The API might have methods such as GetAccountBalance, TransferFunds, and CloseAccount, which are exposed through a WSDL (Web Service Description Language) document. To use the API, an external application would need to send SOAP messages to the API, which would be processed by the bank's servers and returned with the appropriate results.

REST API example:

A social media platform might have a REST API that allows external applications to access user information and perform actions such as posting updates or reading feeds. The API might have endpoints such as /users/{id}, /posts, and /feed, which can be accessed using HTTP methods such as GET, POST, and DELETE. To use the API, an external application would send HTTP requests to the appropriate endpoints and receive responses in the desired format (e.g. JSON or XML).

3) How to write SOAP API and REST API using C#

A) SOAP API:

To write a SOAP API in C#, you will need to do the following:

Create a Web Service project in your development environment. This will provide you with a skeleton for your web service and allow you to start adding code.

Define the methods that you want to expose through your SOAP API. These methods should be defined in a class, and you should decorate them with the [WebMethod] attribute to indicate that they should be exposed as part of the API.

Add any necessary input parameters to your methods. These can be simple data types, or they can be complex types such as custom classes or data structures.

Implement the logic for your methods. This will involve writing code to perform the necessary operations and return the appropriate results.

Decorate your methods with the [SoapDocumentMethod] attribute, which will specify the SOAP action and encoding style for your method.

Build and publish your web service. This will make it available to clients who can then access your methods through the SOAP API.

Here is an example of a simple SOAP API written in C#:

using System.Web.Services;
[WebService(Namespace = "http://example.com/")]
public class MyWebService
{
    [WebMethod]
    [SoapDocumentMethod(Action = "http://example.com/GetData",
        RequestNamespace = "http://example.com/",
        ResponseNamespace = "http://example.com/",
        Use = SoapBindingUse.Literal,
        ParameterStyle = SoapParameterStyle.Wrapped)]
    public string GetData(int value)
    {
        return string.Format("You entered: {0}", value);
    }
}
 

This example defines a single method, GetData, which takes an integer as an input parameter and returns a string. The [SoapDocumentMethod] attribute specifies the SOAP action and encoding style for the method, and the [WebMethod] attribute indicates that it should be exposed as part of the API.

B) REST API:

To write a REST API in C#, you will need to:

Choose a web framework that supports the development of REST APIs, such as ASP.NET Core or NancyFX.

Define your API endpoints and the HTTP methods (GET, POST, PUT, DELETE) they will support.

Implement the API endpoints by writing C# functions or methods that handle the incoming HTTP requests and return the appropriate response.

Use the HTTP status codes to indicate the success or failure of the API request.

Test your API using a tool like Postman or curl.

Here is an example of a simple REST API implemented using ASP.NET Core:

using Microsoft.AspNetCore.Mvc;
[Route("api/[controller]")]
public class ValuesController : Controller
{
    // GET api/values
    [HttpGet]
    public IEnumerable<string> Get()
    {
        return new string[] { "value1", "value2" };
    }
    // GET api/values/5
    [HttpGet("{id}")]
    public string Get(int id)
    {
        return "value";
    }
    // POST api/values
    [HttpPost]
    public void Post([FromBody]string value)
    {
    }
    // PUT api/values/5
    [HttpPut("{id}")]
    public void Put(int id, [FromBody]string value)
    {
    }
    // DELETE api/values/5
    [HttpDelete("{id}")]
    public void Delete(int id)
    {
    }
}

      

This API has five endpoints that support the four basic HTTP methods: GET, POST, PUT, and DELETE. The [Route] attribute specifies the URI for the API, and the [HttpMethod] attributes specify which HTTP method the endpoint supports. The methods in the controller handle the incoming requests and return the appropriate response.

I hope this helps! Let me know if you have any questions.