How to Implement a SOAP API in Laravel (Step-by-Step Guide)

APIs are the backbone of modern applications. While RESTful APIs dominate today, many enterprise systems still expose services through the SOAP protocol. As a Laravel developer, you may come across projects where you need to integrate with SOAP web services.

For a complete working project, check out this GitHub repository: MantraIdeas/soapImplementation

In this guide, we’ll cover:

• What is a SOAP API?
  
• SOAP API vs REST API
  
• Understanding WSDL and XML-based APIs
  
• Installing and configuring a SOAP client in Laravel
  
• Example: Calling a SOAP API in Laravel
  
• Testing and handling SOAP requests & responses

What is a SOAP API?

SOAP (Simple Object Access Protocol) is a protocol for exchanging structured data between applications over a network. Unlike REST, which typically uses JSON, SOAP APIs rely on XML-based APIs with strict formatting rules.

A SOAP API is usually defined by a WSDL (Web Services Description Language) file, which describes available operations, input/output data types, and the service endpoint.

• Available operations (e.g., Add, Subtract)
  
• Input/output data types (e.g., int, string)
  
• Service endpoint (e.g., http://www.dneonline.com/calculator.asmx)

In short: A WSDL is the contract between client and server.

SOAP API vs REST API

• SOAP API → XML-based, strongly typed, enterprise-focused, uses WSDL for contracts.
  
• REST API → Lightweight, JSON-based, stateless, more flexible for web and mobile apps.
  
• GraphQL → Query-based, client-driven, allows fetching only required fields.

In Laravel API development, you may encounter SOAP APIs when integrating with legacy systems, banks, payment gateways, or enterprise APIs.

Step 1: Enable or Install SOAP Client in Laravel

Laravel uses PHP’s built-in SOAP extension. First, make sure it’s enabled.
On Linux / Mac

Edit your php.ini:

extension=soap

Then restart your server:

sudo service php8.2-fpm restart

On Windows (XAMPP / WAMP)

Uncomment the line in php.ini:

;extension=soap

Remove the ; and restart Apache

Verify Installation

Run:

php -m | grep soap

If you see soap in the list, you’re good to go.

Step 2: Create a Service Class for SOAP Integration

Instead of directly calling SOAP in controllers, we’ll create a service class.

<?php

namespace App\Services;

use SoapClient;
use SoapFault;

class CalculatorSoapService
{
    private SoapClient $client;

    public function __construct()
    {
        try {
            $this->client = new SoapClient('http://www.dneonline.com/calculator.asmx?WSDL');
        } catch (SoapFault $e) {
            throw new \Exception("SOAP Client Error: " . $e->getMessage());
        }
    }

    public function add(int $a, int $b): int
    {
        $response = $this->client->__soapCall("Add", [["intA" => $a, "intB" => $b]]);
        return $response->AddResult;
    }

    public function subtract(int $a, int $b): int
 {
        $response = $this->client->__soapCall("Subtract", [["intA" => $a, "intB" => $b]]);
        return $response->SubtractResult;
    }
}

Step 3: Use the SOAP Service in a Controller

<?php

namespace App\Http\Controllers;

use App\Services\CalculatorSoapService;

class SoapApiController extends Controller
{
    public function calculate()
    {
        $service = new CalculatorSoapService();

        $sum = $service->add(10, 5);
        $diff = $service->subtract(10, 5);

        return response()->json([
            "sum" => $sum,
            "difference" => $diff,
        ]);
    }
}

Step 4: Define Routes

In routes/web.php:

use App\Http\Controllers\SoapApiController;

Route::get('/soap-calc', [SoapApiController::class, 'calculate']);

Visit:

http://your-app.test/soap-calc

You should see:

{
  "sum": 15,
  "difference": 5
}

Step 5: SOAP Request & Response (Behind the Scenes)

When you call the Add method, Laravel generates a SOAP request XML like this:

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Body>
    <Add xmlns="http://tempuri.org/">
      <intA>10</intA>
      <intB>5</intB>
    </Add>
  </soap:Body>
</soap:Envelope>

And the SOAP API sends back a response:

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Body>
    <AddResponse xmlns="http://tempuri.org/">
      <AddResult>15</AddResult>
    </AddResponse>
  </soap:Body>
</soap:Envelope>

Your Laravel SoapClient automatically converts this into a PHP object.

Step 6: SOAP API Testing

For SOAP API testing, you can use tools like:

• Postman (supports SOAP with raw XML requests).
  
• SoapUI (dedicated SOAP testing tool).
  
• PHP Artisan Tinker to manually test SoapClient calls.

Example in Tinker:

php artisan tinker
>>> $service = new App\Services\CalculatorSoapService();
>>> $service->add(20, 30);
=> 50

Bonus: Laravel SOAP API Example with REST Integration

Sometimes, you’ll need to wrap a SOAP API in a Laravel REST API so that modern apps can consume it.

Example REST endpoint:

Route::get('/api/add/{a}/{b}', function ($a, $b) {
    $service = new \App\Services\CalculatorSoapService();
    return response()->json([
        'result' => $service->add($a, $b)
    ]);
});

Now your SOAP API is exposed as a RESTful API in Laravel

Final Thoughts

• SOAP API is still widely used in enterprise APIs, banks, and government systems.
  
• Laravel makes SOAP integration easy with PHP’s built-in SoapClient.
  
• Always abstract SOAP calls into a service class for cleaner code.
  
• You can expose SOAP APIs as REST APIs for modern applications.