Step by Step solution about How to resolve the algorithm SOAP step by step in the Julia programming language

This provided source code implements a SOAP (Simple Object Access Protocol) client using the LibCURL library in Julia programming language. A SOAP client is used to send and receive SOAP messages over HTTP to interact with web services that follow the SOAP protocol. The code in question performs a SOAP call to the specified URL. Let's break down the code step by step:

1. Module Import:

   using LibCURL

   This line imports the LibCURL library, which provides a convenient interface for making HTTP requests and handling network operations.

2. Helper Functions:

   • read_data(ptr, size, nmemb, stream): This function is used as a callback for reading data from the input file and passing it to the SOAP request.
   • write_data(ptr, size, nmemb, stream): This function is used as a callback for receiving the SOAP response and writing it to the output file.

3. callSOAP Function:

   • This function takes three arguments:
     • url: The URL of the WSDL (Web Services Description Language) file that defines the SOAP service.
     • infilename: The path to the input file containing the SOAP request message.
     • outfilename: The path to the output file where the SOAP response will be written.
   • It opens the input and output files for reading and writing, respectively.
   • It creates an array (header) to store HTTP headers for the SOAP request. It adds the following headers:
     • Content-Type:text/xml: Specifies the type of the SOAP message as XML.
     • SOAPAction: rsc: Specifies the SOAP action to be performed.
     • Transfer-Encoding: chunked: Indicates that the request body will be sent in chunks.
     • Expect:: Sets the expectation header to an empty string to avoid potential issues with some servers.
   • It initializes a LibCURL easy handle (curl) and sets the following options:
     • CURLOPT_URL: Sets the URL of the SOAP service.
     • CURLOPT_POST: Specifies that this is a POST request.
     • CURLOPT_READFUNCTION: Sets the callback function for reading data from the input file.
     • CURLOPT_READDATA: Sets the user data to be passed to the callback function.
     • CURLOPT_WRITEFUNCTION: Sets the callback function for writing data to the output file.
     • CURLOPT_WRITEDATA: Sets the user data to be passed to the callback function.
     • CURLOPT_HTTPHEADER: Sets the array of HTTP headers.
     • CURLOPT_POSTFIELDSIZE_LARGE: Sets the size of the POST fields to -1, indicating that the size is unknown.
     • CURLOPT_VERBOSE: Enables verbose mode for debugging purposes.
   • It performs the SOAP request using curl_easy_perform(curl).
   • Finally, it cleans up the LibCURL resources by calling curl_easy_cleanup(curl).

4. main:

   • It calls the callSOAP function with the arguments provided as command-line arguments.
   • If any exception occurs during the SOAP call, it catches the exception and prints a usage message.

In summary, this code exemplifies a SOAP client in Julia that uses LibCURL to interact with a SOAP web service. It sends a SOAP request using the specified input file, receives the SOAP response, and writes it to the specified output file. The callSOAP function simplifies the process of making SOAP calls, making it easier to interact with SOAP web services.

using LibCURL

function callSOAP(url, infilename, outfilename)
    rfp = open(infilename, "r")
    wfp = open(outfilename, "w+")

    header = curl_slist_append(header, "Content-Type:text/xml")
    header = curl_slist_append(header, "SOAPAction: rsc");
    header = curl_slist_append(header, "Transfer-Encoding: chunked")
    header = curl_slist_append(header, "Expect:")

    curl = curl_easy_init();
    curl_easy_setopt(curl, CURLOPT_URL, URL)
    curl_easy_setopt(curl, CURLOPT_POST, 1L)
    curl_easy_setopt(curl, CURLOPT_READFUNCTION, read_data)
    curl_easy_setopt(curl, CURLOPT_READDATA, rfp)
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data)
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, wfp)
    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, header)
    curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE_LARGE, (curl_off_t)-1)
    curl_easy_setopt(curl, CURLOPT_VERBOSE,1L)
    curl_easy_perform(curl)

    curl_easy_cleanup(curl)
end

try
    callSOAP(ARGS[1], ARGS[2], ARGS[3])
catch y
    println("Usage : $(@__FILE__) <URL of WSDL> <Input file path> <Output File Path>")
end