I’m calling a SOAP webservice using HttpRequestMessage in .NET 8.
The content of the request is a xml string containing data about a person.
But the data type expected by the webservice is an base64Binary.

If I use the Visual Studio Connected Services to generate the contract classes, the content is expected as a byte[], wich I can generate by simply converting the xmlstring to base64 and then to byte array and the request is sucessfull.

My problem is to pass the byte[] to HttpRequestMessage inside the string content:

Here is my code:

using System.Text;

namespace SigafHttpRequest;

internal class Program
{
    private static readonly HttpClient httpClient = new HttpClient();

    static async Task Main(string[] args)
    {
        string url = "https://sigafhomologa.mg.gov.br/webserver/soap_server.php";

        string xmlSoapLogin =
            @"<?xml version=""1.0"" encoding=""utf-8""?>
            <soapenv:Envelope xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"" xmlns:xsd=""http://www.w3.org/2001/XMLSchema"" xmlns:soapenv=""http://schemas.xmlsoap.org/soap/envelope/"" xmlns:sig=""sigaf"">
                <soapenv:Header/>
                <soapenv:Body>
                    <sig:login soapenv:encodingStyle=""http://schemas.xmlsoap.org/soap/encoding/"">
                        <user xsi:type=""xsd:string"">315500</user>
                        <password xsi:type=""xsd:string"">Wt2023</password>
                    </sig:login>
                </soapenv:Body>
            </soapenv:Envelope>";

        //extract the token from the response and pass into token_login field of the next request
        string tokenAccessResult = await PostSOAPRequestAsync(url, xmlSoapLogin);

        string xmlData =
              "<?xml version="1.0" encoding="utf-8"?>" +
              "<root>"
            + " <identificador>"
            + "     <stEsferaEnvio>M</stEsferaEnvio>"
            + "     <coMunicipioIbge>310000</coMunicipioIbge>"
            + "     <dsEmail>[email protected]</dsEmail>"
            + "     <noUsuario>usuarioteste</noUsuario>"
            + "     <tpXML>DP</tpXML>"
            + " </identificador>"
            + " <paciente>"
            + "     <noNome>MARCOS XXXXXX</noNome>"
            + "     <noMae>CHIRLENE XXXXXX</noMae>"
            + "     <dsLogradouro>ESPERANCA</dsLogradouro>"
            + "     <dsBairro>ESPERANCA</dsBairro>"
            + "     <nuCep>35000000</nuCep>"
            + "     <sgUfNaturalidade>MG</sgUfNaturalidade>"
            + "     <coMunicipioIbgeNaturalidade>310000</coMunicipioIbgeNaturalidade>"
            + "     <coMunicipioIbge>310000</coMunicipioIbge>"
            + "     <dtNascimento>1990-01-01</dtNascimento>"
            + "     <nuCpf>11111111111</nuCpf>"
            + "     <tbSexo>M</tbSexo>"
            + "     <tpAtendimento>B</tpAtendimento>"
            + " </paciente>"
            + "</root>";

        var textAsBytes = Encoding.UTF8.GetBytes(xmlData);
        var base64 = Convert.ToBase64String(textAsBytes);
        var bytes = Convert.FromBase64String(base64);
        var byteString = BitConverter.ToString(bytes);

        string xmlSoapPersonRequest =
            $@"<soapenv:Envelope xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"" xmlns:xsd=""http://www.w3.org/2001/XMLSchema"" xmlns:soapenv=""http://schemas.xmlsoap.org/soap/envelope/"" xmlns:sig=""sigaf"">
               <soapenv:Header/>
               <soapenv:Body>
                  <sig:recebeDados soapenv:encodingStyle=""http://schemas.xmlsoap.org/soap/encoding/"">
                     <token_login xsi:type=""xsd:string"">76727072747074727570777177737373727677777675.MzE1NTAw</token_login>
                     <source xsi:type=""xsd:base64Binary"">{byteString}</source>
                  </sig:recebeDados>
               </soapenv:Body>
            </soapenv:Envelope>";

        try
        {
            string result = await PostSOAPRequestAsync(url, xmlSoapPersonRequest);
            Console.WriteLine(result);
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }

        Console.ReadKey();
    }

    private static async Task<string> PostSOAPRequestAsync(string url, string text)
    {
        using (HttpContent content = new StringContent(text, Encoding.UTF8, "text/xml"))
        using (HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, url))
        {
            request.Content = content;
            using (HttpResponseMessage response = await httpClient.SendAsync(request, HttpCompletionOption.ResponseHeadersRead))
            {
                //response.EnsureSuccessStatusCode();
                return await response.Content.ReadAsStringAsync();
            }
        }
    }
}

The problem is at the line <source xsi:type=””xsd:base64Binary””>{byteString}.

How can I pass a byte array inside this string concatenation?
I’ve tried to pass the base64, but no success, the webserver return “Error on XML structure”: it doesnt interpret the message as it should (the xml content is correct, I’ve checked).