Python in a Nutshell

Chapter 21. MIME and Network Encodings

What travels on a network are streams of bytes or text. However, what you want to send over the network often has more structure. The Multipurpose Internet Mail Extensions (MIME) and other encoding standards bridge the gap by specifying how to represent structured data as bytes or text. Python supports such encodings through many library modules, such as base64, quopri, uu, and the modules of the email package. This chapter covers these modules.

Encoding Binary Data as Text

Several kinds of media (e.g., email messages) contain only text. When you want to transmit binary data via such media, you need to encode the data as text strings. The Python standard library supplies modules that support the standard encodings known as Base 64, Quoted Printable, and UU.

The base64 Module

The base64 module supports the encoding specified in RFC 1521 as Base 64. The Base 64 encoding is a compact way to represent arbitrary binary data as text, without any attempt to produce human-readable results. Module base64 supplies four functions.

The quopri Module

The quopri module supports the encoding specified in RFC 1521 as Quoted Printable (QP). QP can represent any binary data as text, but it’s mainly intended for data that is textual, with a relatively modest amount of characters with the high bit set (i.e., characters outside of the ASCII range). For such data, QP produces results that are both compact and rather human-readable. Module quopri supplies ...