AWS Lambda (Node.js) calling SOAP service

REST service:

Uses HTTP for exchanging information between systems in several ways such as JSON, XML, Text etc.

SOAP service:

A Protocol for exchanging information between systems over internet only using XML.

Requirement:

Calling SOAP services from Lambda.
We'll use this npm package: https://www.npmjs.com/package/soap
With this npm package - its a 3 step process:

1. Create a soap client
2. Call SOAP method by passing JSON input.
3. Convert XML output to JSON

Create SOAP client:

const soap = require('soap');
let client = await soap.createClientAsync(url);

url - is the wsdl url. For example: http://sampledomainname/services/sampleserice?wsdl (just for representation - this wsdl url does not works).

wsdl doc has all the details. But if you are like me who can best understand JSON data then use client.describe() to get soap service details in JSON format.

console.log(client.describe());
Output log below:

{
  "SomeService": {
    "SomeServicePort": {
      "someServiceMethod": {
        "input": {
          "serviceRequest": {
            "field1": "xsd:string"
          }
        }
      }
    }
  }
}

Convert JSON to XML (pass input to SOAP): soap npm package takes care of this conversion. Pass JSON, & converts to XML.

Call SOAP method by passing JSON input:

client.SomeService.SomeServicePort_http.someServiceMethod(args, function(err, result) {
    if(err) console.error("Error - ", err); 
    console.log(result); // is a javascript object
}, { postProcess: function(_xml) { 
    console.log('XML - ', _xml); //this prints the input XML
    return _xml.replace('test', 'newtest'); // any mapping or string conversion, add here.
}});

Consider this args JSON as input to soap method

Let args = {
"one":"1"
}

The args JSON would be converted by soap npm package as below XML:

<?xml version=\"1.0\" encoding=\"utf-8\"?>
 <soap:Envelope xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\"    xmlns:xsi=\"http://www.w3.org/2001/XMLSchema- instance\">
    <soap:Body>
        <ns1:someServiceMethod>
            <ns1:one>1</ns1:one>
        </ns1:someServiceMethod>
    </soap:Body>
 </soap:Envelope>

Before we discuss about response XML to JSON (result of soap call). Let's see how to use async/await way of calling soap method.

let resultArr = await client.someServiceMethodAsync(args);

Just add suffix Async to the soap method you wish to call, would return a promise. Note the above call results an array with 4 elements in both success and failure scenarios.

Array element 0: result is a javascript object.
Array element 1: rawResponse is the raw xml response string.
Array element 2: soapHeader is the response soap header as a javascript object (contains WS Security info-so let us not log this!).
Array element 3: rawRequest is the raw xml request string.

So the Array element O is already converted the XML response to JSON. Let's put altogether below:

const soap= require('soap');
let client = await soap.createClientAsync("http://sampledomainname/services/sampleserice?wsdl");
let resultArr= await client.someServiceMethodAsync(args); console.log("Response JSON-, resultArr[0]);

Secured Soap Call:

All enterprise soap services would require authentication and in below section let's discuss about WSSecurity.

let wsSecurity = new soap. WSSecurity('username', 'password", options); client.setSecurity(wsSecurity):

Putting altogether:

const soap = require('soap');
let client = await soap.createClientAsync('http://sampledomainname/services/sampleserice?wsdl'); 
let options = {
  hasNonce: true,
  actor: 'actor'
}
let wsSecurity = new soap.WSSecurity('username', 'password', options); 
client.setSecurity(wsSecurity); 
let resultArr = await client.someServiceMethodAsync(args); 
console.log('Response JSON-', resultArr[0]);

Image by SplitShire from Pixabay