Serialize a FileStream for transport - wcf

Question

See also this question: Can I pass a System.Net.MailMessage to a WCF service?
I'd like to add attachments to the mail being sent. Attachments are either files on the local disc, or dynamically created Streams. A WCF contract can contain a Stream, but only when all arguments are of type Stream. So, what is the best way to pass one or more Attachments to a WCF service?

Answer 1

Alright I've solved this myself. The trick here is to convert the attachment to a Base64 encodes string, much the same way email systems do this. I've created a class to handle this. Posted here for others:
[DataContract]
public class EncodedAttachment
{
[DataMember(IsRequired=true)]
public string Base64Attachment;
[DataMember(IsRequired = true)]
public string Name;
/// <summary>
/// One of the System.Net.Mime.MediaTypeNames
/// </summary>
[DataMember(IsRequired = true)]
public string MediaType;
}
public EncodedAttachment CreateAttachment(string fileName)
{
EncodedAttachment att = new EncodedAttachment();
if (!File.Exists(fileName))
throw new FileNotFoundException("Cannot create attachment because the file was not found", fileName);
FileInfo fi = new FileInfo(fileName);
att.Name = fi.Name;
att.MediaType = System.Net.Mime.MediaTypeNames.Text.Plain;
using (FileStream reader = new FileStream(fileName, FileMode.Open))
{
byte[] buffer = new byte[reader.Length];
reader.Read(buffer, 0, (int)reader.Length);
att.Base64Attachment = Convert.ToBase64String(buffer);
}
return att;
}
And on the client side:
public void SendEmail(SmallMessage msg)
{
using (MailMessage message = new MailMessage())
{
message.Body = msg.Body;
message.Subject = msg.Subject;
message.To.Add(new MailAddress(msg.To));
message.From = new MailAddress(msg.From);
foreach (EncodedAttachment att in msg.Attachments)
{
message.Attachments.Add(CreateAttachment(att));
}
SmtpClient client = new SmtpClient();
client.Send(message);
}
}
Attachment CreateAttachment(EncodedAttachment encodedAtt)
{
MemoryStream reader = new MemoryStream(Convert.FromBase64String(encodedAtt.Base64Attachment));
Attachment att = new Attachment(reader, encodedAtt.Name, encodedAtt.MediaType);
return att;
}