MIME

The Internet content-typing standard at the heart of AS2 transport.

Definition

MIME (Multipurpose Internet Mail Extensions, RFC 2045 through 2049) defines how to declare the type of a piece of content (Content-Type, e.g. text/plain, application/pdf), its transfer encoding and the assembly of several parts (multipart). Designed for e-mail, it became the content-typing foundation of the whole Internet (HTTP included).

Role in EDI

In EDI, MIME is everywhere in transport:

• AS2 carries the EDI payload in a MIME envelope; RFC 1767 defines the application/edifact, application/edi-x12 and application/edi-consent types;
• S/MIME adds signing and encryption of those envelopes — the security mechanism of AS2;
• the MDN (AS2 receipt) is itself a MIME message (multipart/report).

Good to know

The media-type registry is maintained by IANA. In a hybrid invoice such as Factur-X, a MIME type (text/xml) also describes the XML file embedded in the PDF/A-3 container.