Handling SOAP faults

Tutorial 5 of 5

Introduction

This tutorial aims to help you understand how to handle SOAP (Simple Object Access Protocol) faults in your HTML applications. SOAP faults are standard error messages that provide debugging and error handling information in SOAP-based web services.

By the end of this tutorial, you will be able to:
- Understand what SOAP faults are and how they are structured
- Handle SOAP faults in your HTML applications
- Use SOAP faults for debugging and error handling

Prerequisites:
- Basic understanding of HTML and XML
- Familiarity with SOAP-based web services

Step-by-Step Guide

SOAP faults are error messages that are returned to the sender when an error occurs at the receiver's end. They are XML structures that are defined in the SOAP standard and contain information like fault code, fault string, and detailed error messages.

Here is an example of a SOAP Fault:

<SOAP-ENV:Fault>
  <faultcode>SOAP-ENV:Client</faultcode>
  <faultstring>Invalid message</faultstring>
  <faultactor>http://www.example.com/soap/actor</faultactor>
  <detail>
    <e:myfaultdetails xmlns:e="http://www.example.com/">
      <message>Couldn't parse SOAP message.</message>
      <errorcode>1001</errorcode>
    </e:myfaultdetails>
  </detail>
</SOAP-ENV:Fault>

The faultcode element is a code that identifies the fault. The faultstring provides a human-readable description of the fault. The faultactor indicates who caused the fault, and the detail element holds application-specific error information.

Code Examples

Let's start with a simple HTML page that makes a SOAP request and handles possible SOAP faults.

<!DOCTYPE html>
<html>
<head>
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
</head>
<body>

<h2>SOAP Fault Handling Example</h2>

<button>Send SOAP Request</button>

<p id="response"></p>

<script>
$(document).ready(function(){
  $("button").click(function(){
    $.ajax({
      url: "http://www.example.com/soap-endpoint",
      type: "POST",
      dataType: "xml",
      data: "<soapenv:Envelope xmlns:soapenv='http://schemas.xmlsoap.org/soap/envelope/'><soapenv:Body></soapenv:Body></soapenv:Envelope>",
      success: function(data, status, xhr) {
        // If response contains a SOAP Fault
        if ($(data).find("SOAP-ENV:Fault").length > 0) {
          var faultString = $(data).find("faultstring").text();
          $("#response").html("<b>SOAP Fault:</b> " + faultString);
        } else {
          $("#response").html("<b>Success!</b>");
        }
      },
      error: function(xhr, status, error) {
        $("#response").html("<b>Error:</b> " + error);
      }
    });
  });
});
</script>

</body>
</html>

In this example, we use jQuery's AJAX function to send a SOAP request. If the response contains a SOAP Fault, we display the faultstring in a paragraph. If the request is successful and there is no SOAP Fault, we display a success message.

Summary

In this tutorial, we have covered:
- The structure of SOAP faults and their role in SOAP-based web services
- How to handle SOAP faults in an HTML application using JavaScript and jQuery

To further your understanding, consider exploring SOAP fault subcodes and how to generate custom SOAP faults in your web service.

Practice Exercises

Modify the above code to display the faultcode, faultstring, and faultactor when a SOAP Fault is returned.
Create a SOAP web service that returns a custom SOAP Fault when an error occurs.
Write a client application that sends a request to your web service and handles the custom SOAP Fault.

Remember that practice is key to mastering a new concept. Happy coding!