MIME and Media Types
The Multipurpose Internet Mail Extensions (MIME) standard is a means of specifying media types such as images, program data , audio files, and text. Described in Internet Engineering Task Force (IETF) Request for Comments (RFC) documents 2045 through 2049, it includes a comprehensive list of known types and has inspired a registry for many more.
MIME was developed originally to extend the paradigm of email from plain text to a rich array of media. Email transport systems, such as the Simple Mail Transfer Protocol (SMTP), can only deal with 7-bit ASCII text. You cannot simply append a binary file to the end of a message and have it bounce happily across the Internet. The data has to be encoded in an ASCII-compatible way. There are other requirements as well, such as a minimum line length and absence of certain control characters. MIME introduces methods to transform data into a safe form. It also describes how to package this data in a recognizable way for mail transfer agents and clients to work with.
One of the ways MIME describes a resource is by assigning it a
media type (or
content-type) which names the general category
that best describes the data. Each type includes a set of subtypes that
exactly identify the resource. The type and subtype are usually written
together, joined by a slash character (/). For example,
image/jpeg denotes a
graphical resource in the JPEG format. The major types include:
Textual information that can be read in a traditional ...
Get Learning XML, 2nd Edition now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.