Attachments

Attachments are arbitrary payloads that can be included with a message. They are stored and retrieved from a queue, just like a message, and can be manipulated via the MessageContext object.

For example, the File Reader device supports reading multiple associated files and including them as attachments along with the primary file.

Attachments are displayed in the queue device.

Attachments are exposed via the IMessageContext interface.

Here is some sample code showing attachment usage:

public override async Task ProcessMessageAsync(IMessageContext context, CancellationToken token)
{
  var hl7 = context.GetAsHL7Message();
  
  // working with the attachments collection
  context.Attachments.Clear();  // remove any existing attachments
  context.Attachments.Add("Att1", "This is a textual attachment");  // add string data
  context.Attachments.Add("Att2", System.IO.File.ReadAllBytes(@"C:\test\initial install\install.log"), true);  // add binary data
  context.Attachments.AddFile("Att3", @"C:\test\initial install\install_000_Integrator.UpdaterA.log", true);   // add files directly
  
  // access attachments by key
  var att1 = context.Attachments["Att1"].GetString();
  var att2 = context.Attachments["Att2"].GetBytes();
  context.Attachments.Add("Summary", $"{att1}, byte length = {att2.Length}");      
}

This code shows as follows in the queue UI:

Attachments are saved to the database when the primary message is stored in a queue. If you want to update an existing attachments collection in the source queue, you should call IMessageContext.Attachments.Save()