Function return System.IO.MemoryStream?

Question

Hi!

I trying to display image in picture box. The application have two part. First part is windows application, and second part is web service (asmx).

This is the code for windows application:

Public Sub PrikazSlike()
             Dim p As localhost.Service1 = New localhost.Service1()
        PictureBox1.Image = Image.FromStream(p.PictureShow()) 
End Sub

And this is the code for web service:

Imports System.Web.Services
Imports System.Web.Services.Protocols
Imports System.ComponentModel
Imports System.IO

' To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.
' <System.Web.Script.Services.ScriptService()> _
<System.Web.Services.WebService(Namespace:="http://tempuri.org/")&gt; _
<System.Web.Services.WebServiceBinding(ConformsTo:=WsiProfiles.BasicProfile1_1)> _
<ToolboxItem(False)> _
Public Class Service1
    Inherits System.Web.Services.WebService

    <WebMethod()> _
    Public Function PictureShow() As System.IO.MemoryStream
        Dim client As New System.Net.WebClient()
        Dim stream1 As New System.IO.MemoryStream()
        Dim data As Byte() = client.DownloadData("http://www.psp-themes.net/.../assassins%20creed%203.jpg")
        client.Dispose()
        stream1.Write(data, 0, data.Length)
        Return stream1
    End Function
End Class

The problem is that function in web service does not return System.IO.MemoryStream data type so I getting error message can not convert: Error 1 Value of type 'WindowsApplication1.localhost.MemoryStream' cannot be converted to 'System.IO.Stream'.

How I can resolve this?

Many thanks!

Answer 1

Try to return byte array instead of Stream.

Answer 2

The MemoryStream resides on the server and can't be serialized to the client.

You should return a bytearray from your webservice then transform this to a image.

Answer 3

The error message says that your method returns the type WindowsApplication1.localhost.MemoryStream and not a System.IO.MemoryStream.

I suspect that your web service is set up to return a MemoryStream object. Try to change it to return a byte[] array instead. On your receiving side retrieve the byte array and create a System.IO.MemoryStream from that array.

Answer 4

This is the update code for web service:

   <WebMethod()> _
    Public Function PrikazSlike() As Byte
        Dim client As New System.Net.WebClient()
        'Dim data As Byte

        Dim data As Byte() = client.DownloadData("http://www.psp-themes.net/.../assassins%20creed%203.jpg")
        Dim stream1 As New System.IO.MemoryStream(data)
        client.Dispose()
        stream1.Write(data, 0, data.Length)
        Return Convert.ToByte(stream1)
    End Function
End Class

This is the windows application code:

Public Sub Show.Picture()
         Dim p As localhost.Service1 = New localhost.Service1()
         PictureBox1.Image = Image.FromStream(p.PictureShow()) 
         End Sub

Now I getting error:

Error 1 Value of type 'Byte' cannot be converted to 'System.IO.Stream'.