RFC 1521, the Multipurpose Internet Mail Extensions memo, defines a structure which is the base for all messages read and written by modern mail and news programs. It is also partly the base for the HTTP protocol. Just like RFC 0822, MIME declares that a message should consist of two entities, the headers and the body. In addition, the following properties are given to these two entities:
A MIME-Version header must be present to signal MIME compatibility
A Content-Type header should be present to describe the nature of the data in the message body. Seven major types are defined, and an extensive number of subtypes are available. The header can also contain attributes specific to the type and subtype.
A Content-Transfer-Encoding may be present to notify that the data of the body is encoded in some particular encoding.
Raw data to be interpreted according to the Content-Type header
Can be encoded using one of several Content-Transfer-Encodings to allow transport over non 8bit clean channels
The MIME module can extract and analyze these two entities from a stream of bytes. It can also recreate such a stream from these entities. To encapsulate the headers and body entities, the class MIME.Message is used. An object of this class holds all the headers as a mapping from string to string, and it is possible to obtain the body data in either raw or encoded form as a string. Common attributes such as message type and text char set are also extracted into separate variables for easy access.
The Message class does not make any interpretation of the body data, unless the content type is multipart. A multipart message contains several individual messages separated by boundary strings. The Message->create method of the Message class will divide a multipart body on these boundaries, and then create individual Message objects for each part. These objects will be collected in the array Message->body_parts within the original Message object. If any of the new Message objects have a body of type multipart, the process is of course repeated recursively.
- Inherit ___MIME