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REST vs SOAP: why we recommend REST APIs for A2P messaging

An increasing number of businesses use messaging APIs to simplify communications with stakeholders and customers. Business short message service (SMS) tools enable organisations to implement one-time password (OTP) verification, alerts, reminders, and other types of customer support as well as marketing campaigns. They also enable organisations to centrally manage invoicing, human resources, and other internal activities.

Though many applications continue to rely on the SOAP API standard for SMS functionality, the newer REST API standard is actually the better choice. REST offers greater flexibility and speed, while SOAP is more rigid and can be more difficult to learn. This article will explain why we recommend you should choose the REST API standard for your business SMS.

So why should you use REST APIs to send SMS?

There are various ways to transfer data across the web, with SOAP and REST being two of the most-used methods. Following are some of the reasons why we recommend using a REST API to send your business text messages.

REST is easier to use than SOAP

SOAP is a standardised, function-driven protocol for exchanging information that relies strictly on XML. REST, or representational state transfer, is a more lightweight, data-driven architectural style that can use multiple formats.

REST, which uses GET, POST, PUT, and DELETE commands to perform CRUD operations over the HTTP network, is easier to use than SOAP, which can save crucial time for developers.

Many developers are familiar with REST and HTTP protocols, so they’ll be better able to understand and use your API. By using the REST format, you can build SDKs for developers, allowing them to extend and customise the functionality of your product.

For example, at ClickSend, you can access the public API to easily integrate communication capabilities into your application.

REST Flexibility

When an application is accessed by many users simultaneously, multiple requests are sent to the integrated platform to send SMS. This can cause an overload on the server and result in bandwidth and latency issues.

To overcome these issues, you need to implement more advanced techniques like throttling and debouncing. With REST, these programming techniques can be implemented easily and are sometimes available as the default in some programming languages.

As above, SOAP only supports XML, but REST can be implemented using XML or JSON. The footprint of REST is small, so you’re sending and receiving less data with each transaction. And it’s easy to parse and write in, when using JSON or YAML to implement it.

The JSON structure is highly flexible and allows you to easily add nested data structures. For example, say your existing JSON API structure is as follows:

name: "John",
age: 24

You can update it by adding a new property and a nested JSON structure as its value:
name: “John”,
age: 24,
contact: {
home: 9567411122,
work: 9867588331

If there are any breaking changes in your REST API response, you can easily version them by either of the two most common methods:

  • Updating the URL prefix (/api/v1/users or /api/v2/users)
  • Adding a version header to the request (X-API-Version: 1)

Graphic showing the REST API Model showing client and requests and responses between API and server

Easily scale your applications with REST

REST is stateless; each request to the server is handled independently since no user session is stored, unlike authentication methods that store sessions on the server. This allows REST to scale infinitely, making it a good choice for large batch operations.

Two independent platforms can communicate with each other through REST without needing to know the other’s implementation details. This allows you to build and connect different services, including micro-services in different technologies.

For example, imagine you are working on a project with a Python backend and the frontend involves JavaScript. You can easily transfer data between them by creating a REST API. Send the JSON data from the frontend (JavaScript) to the backend (Python) as follows:

// define request data
const data = {
name: “John”,
age: 24,
// make HTTP call

Likewise, if you want to send a response from the backend to the frontend, you can do as follows:

import json
# define response data
data = {
“name”: “John”,
“age”: 24,
# send response

This way you can easily shift between different languages and frameworks without worrying about the other components in the system. You can also design your client and server independently. For example, if you have a backend that serves a REST API written in Node.js, you can switch your code to Python without affecting the format of the API.

REST offers strong support

One of the most important things to consider before investing your time in any technology is the quality of the community and support offered by that technology. No matter how good you are at programming, there’s always a chance of running into issues and needing help. This is where REST shines.

REST is straightforward to learn, and intermediate to experienced programmers generally know how to work with it. Almost all the programming languages include support for JSON, and there are built-in libraries for parsing and creating JSON-based data structures.

If you search Stack Overflow, you’ll find tens of thousands of questions related to REST APIs. This means that you can find plenty of information in case you get stuck somewhere when working with REST.

Sending SMS Using REST API

The following is an example of how to use the REST standard to send business SMS using the ClickSend Node.js API:

const api = require('./api.js');

const smsApi = new api.SMSApi("USERNAME", "API_KEY");
const smsMessage = new api.SmsMessage();

smsMessage.source = "sdk"; = "+0451111111";
smsMessage.body = "test message";

const smsCollection = new api.SmsMessageCollection();

smsCollection.messages = [smsMessage];

smsApi.smsSendPost(smsCollection).then(function(response) {
}).catch(function(err) {

If the request to send SMS succeeds, you’ll get the following response in JSON format:

"http_code": 200,
"response_code": "SUCCESS",
"response_msg": "Here is your data.",
"data": {
"total_price": 0.14,
"total_count": 1,
"queued_count": 1,
"messages": [
"direction": "out",
"date": 1436871253,
"to": "+0451111111",
"body": "test message",
"from": "sendmobile",
"schedule": 1436874701,
"message_id": "BF7AD270-0DE2-418B-B606-71D527D9C1AE",
"message_parts": 1,
"message_price": 0.07,
"custom_string": "this is a test",
"user_id": 1,
"subaccount_id": 1,
"country": "AU",
"carrier": "Telstra",
"status": "SUCCESS"
"_currency": {
"currency_name_short": "USD",
"currency_prefix_d": "$",
"currency_prefix_c": "¢",
"currency_name_long": "US Dollars"

You can use the data in the response to perform further operations, such as storing the response in a database.

Wrapping up

REST APIs offer a lot of benefits to your organisation, and they’re a better choice for your SMS marketing strategy than using SOAP-based implementations. You can use REST to create responsive and flexible SMS campaigns that help you grow your business with a minimum of time and effort.
Creating a REST API solution from scratch, however, can slow down your workflow. So take advantage of business messaging APIs, to easily send and receive SMS, emails, voice messages and more.

About the author

Ravgeet Dhillon Author Bio Pic

Ravgeet Dhillon 🇮🇳
Twitter: @ravgeetdhillon

Ravgeet Dhillon is a full-time software engineer and technical content writer who codes and writes about React, Vue, Flutter, Laravel, Node, Strapi, and Python. Based in India, he helps startups, businesses, and open source organisations with software consultancy.

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