WebService remove <xml> tag from my XmlDocument

I use a WebService to transform and XmlDocument into a PDF.

The XmlDocument I send to the Web service looks like this.

<?xml version="1.0" encoding="utf-16" ?> 
<fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">
...
</fo:root>

I had a problem so I went in debug mod to find out that when the XmlDocument object is transferred from my asp website itself to the Web Service which works on .NET 1.1 sees his xml tag. Is there a reason why this tag is removed? Could it be caused by the SOAP response?

Is there a way around other than manually add the tag back in the document?

Edit

To answer John's question, yes I mean the processing instruction. It just goes off and I was wondering why because the library I use to convert doesn't work without it. If I manually add it, it 开发者_Go百科works fine but I just wanted to know why it disappear.

Edit 2

Even if it isn't a tag, the library that requires the XmlDocument just doesn't work without it that's why I need it. Other than that, the rest of the document is processed correctly. The generated Reference.cs from the Web Reference looked like this for the called method :

/// <remarks/>
    [System.Web.Services.Protocols.SoapDocumentMethodAttribute("http://tempuri.org/GeneratePdfFromXml", RequestNamespace="http://tempuri.org", ResponseNamespace="http://tempuri.org", Use=System.Web.Services.Description.SoapBindingUse.Literal, ParameterStyle=System.Web.Services.Protocols.SoapParameterStyle.Wrapped)]
    [return: System.Xml.Serialization.XmlElementAttribute(DataType="base64Binary")]
    public byte[] GeneratePdfFromXml(XmlNode FormattedObjectXml) {
        object[] results = this.Invoke("GeneratePdfFromXml", new object[] {
                    FormattedObjectXml});
        return ((byte[])(results[0]));
    }

It is the same issue as another problem I had, in which the XmlDocument are referenced as XmlNode since the SOAP response is a XmlDocument itself.

I just changed this to a string ; MyXmlDocument.OuterXml; That way, everything is kept and no problem.

It is most likely an encoding issue. The XML Declaration is claiming the document is in UTF-16, which is two bytes per character. The other library probably is assuming, in its absence, some other encoding.

You will never get an XML Declaration or processing instruction passed to via an XmlNode, XmlElement or XmlDocument parameter to an ASMX service. The reason is obvious if you think about it. The SOAP Request would be something like:

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" >
    <SOAP-ENV:Body>
        <parameter>
            <?xml version="1.0" encoding="utf-16" ?> 
            <fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">
            </fo:root>
        </parameter>
    </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

But an XML declaration can only appear at the very beginning of the document, so this is invalid.

The solution, as you found, is to send this XML as a string. Make your parameter type string, and either use XmlNode.OuterXml.