Receive (and send) XML via POST with ASP.NET

Question

I have to set up an XML \"web service\" that receives a POST where the \'Content-type header will specify “text/xml”.\'

What is the simplest way to get the XML into

Answer 1

Given Steven's warning, the answer may be to parse Request.InputStream manually with Tom Holland's test first, followed by XDocument.Load in the Page_Load event.

A Google search initiated before I asked the question, but only checked after, found this, also suggesting I'm on the right track.

Also I was going to ask the question implied by my point that the response had to be XML too, as to what is the best way for that, but I've found an answer here.

In summary, the final code is:

 Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

    If Request.ContentType <> "text/xml" Then _
        Throw New HttpException(500, "Unexpected Content-Type")

    Dim id = CheckBasicAuthentication

    Dim textReader = New IO.StreamReader(Request.InputStream)

    CheckXmlValidity(textReader)

    ' Reset the stream & reader
    Request.InputStream.Seek(0, IO.SeekOrigin.Begin)
    textReader.DiscardBufferedData()

    Dim xmlIn = XDocument.Load(textReader)

    ' process XML in xmlIn

    Dim xmlOut = 
                 
                     

                         <%= id.ToString() %>
                         To be inserted
                     
                     
                 

    ' Further generation of XML for output

    xmlOut..
..Value = Date.UtcNow.ToString(xmlDateFormat)
    xmlText.Text = xmlOut.ToString
End Sub

Private Function CheckBasicAuthentication() As Integer
    Dim httpAuthorisation = Request.Headers("Authorization")
    If Left(httpAuthorisation, 6).ToUpperInvariant <> "BASIC " Then _
        Throw New HttpException(401, "Basic Authentication Required")
    Dim authorization = Convert.FromBase64String(Mid(httpAuthorisation, 7))
    Dim credentials = Text.Encoding.UTF8.GetString(authorization).Split(":"c)
    Dim username = credentials(0)
    Dim password = credentials(1)

    Return ConfirmValidUser(username, password)
End Function

Private Shared Sub CheckXmlValidity(ByVal textReader As System.IO.StreamReader)
    Try
        ' Check for "interesting" xml documents.
        Dim settings = New System.Xml.XmlReaderSettings()
        settings.XmlResolver = Nothing
        settings.MaxCharactersInDocument = 655360
        ' Successfully parse the file, otherwise an XmlException is to be thrown. '
        Dim reader = System.Xml.XmlReader.Create(textReader, settings)
        Try
            While reader.Read()
                'Just checking.
            End While
        Finally
            reader.Close()
        End Try
    Catch ex As Exception
        Throw New HttpException(500, "Invalid Xml data", ex)
    End Try
End Sub

and the ASP.NET webpage.aspx is:

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="webpage.aspx.vb" Inherits="WebPage" ContentType="text/xml" %>

 

NB Throwing HTTPException is not a valid final solution for unwanted scenarios.