When BIRT iHub receives a DownloadFile request, it creates an HTTP header for the response. This header specifies the multipart-related content type and the chunked transfer-encoding method. The client application must be able to process the information in the header.

Following the HTTP header, BIRT iHub sends a DownloadFile response that includes a Content element. ContentId and ContentType in this element map to Content-ID and Content-Type in the MIME header of the attachment that follows the response.

The requested file content streams to the client as an attachment. BIRT iHub creates MIME boundaries randomly to ensure that the message is unique.