SEMI 1.14 Manual

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SEMI 1.14 Manual

This file documents SEMI, a MIME user interface for GNU Emacs.


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1 What is SEMI?

SEMI is a package for GNU Emacs to provide features related with MIME user interface.

SEMI provides two user interfaces: MIME-View and MIME-Edit.

MIME-View is a kernel of user interface to display or operate MIME messages, STD 11 messages or “localized RFC 822” messages.

MIME-Edit is a user interface to compose MIME messages.

Each MUA can use powerful MIME features to combine these features.


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2 MIME message viewing

MIME-View is a MIME viewer for wide use that runs on GNU Emacs.

MIME-View is the kernel of the user interface for browsing MIME messages. You can start some presentation-method which is a program for creating some representation, or some acting-method which is a program for processing the entity. Then you can deal with a variety of entities.


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2.1 Basic design

The representation form of the internet messages in electric letters or in net news is based on STD 11. The STD 11 message body is a plain text which consists of lines as its only structure, and the character code is fixed as us-ascii. Actually, there are “localized STD 11” messages that use some character code in their linguistic range instead of using us-ascii. Even in that case, the character code in the message is single. Therefore, Message User Agents have considered (byte row) = (us-ascii string), or (byte row) = (string in the character code in the linguistic range).

Although, the MIME message has the tree structure in entity unit. And one message can contain multiple character codes. The content of an entity can be not only a letter or an image that can be displayed simply, but also can be a voice or an animation that are played for some time interval, a data for some specific application, a source code of some program, or an external reference that consists of the usage of ftp or mail service, or some URL. Therefore the simple extension of STD 11 user interface, which only consider displaying the message, cannot treat all of the MIME functionalities. Then it is not sufficient to decode message along its MIME type, but it is also required to consider a playback processing through some dialogue with the user. The format of MIME messages is designed to easily be passed to automatic processing. But some contents in the MIME message should not be passed to automatic processing for security reasons. So it should be designed to ask user in such cases. After all, in order to deal with MIME message, it is required to distinguish the representation for information exchange which is written in STD 11 or MIME construction, and its result after some interpretation which is a display screen or a playback process. It is also needed to converse with user for playback processing.

Therefore, MIME-View uses two buffers for one document, one is the mime-raw-buffer that stores the representation for information exchange, and the other is the mime-preview-buffer that stores the representation for displaying.

MIME-View provides a mode in the mime-preview-buffer for reading MIME message, which is called as mime-view-mode. User can manipulate each entity there.


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2.2 Presentation of mime-preview-buffer

mime-view-mode displays information about each entity as

	[entity-button]
	(header)
	
	(body)
	(separator)

You can change their design or inhibit showing some of them, according to some condition.

See following example

From: morioka@jaist.ac.jp (MORIOKA Tomohiko)
Subject: Re: question?
Newsgroups: zxr.message.mime
Date: 22 Oct 93 11:02:44
Mime-Version: 1.0
Organization: Japan Advanced Institute of Science and Technology,
        Ishikawa, Japan

[1  (text/plain)]
  How to compose MIME message in MIME-Edit mode.

  C-c C-x ? shows its help.

C-c C-x C-t	insert a text message.
C-c C-x TAB	insert a (binary) file.
C-c C-x C-e	insert a reference to external body.
C-c C-x C-v	insert a voice message.
C-c C-x C-y	insert a mail or news message.
C-c C-x RET	insert a mail message.
C-c C-x C-s	insert a signature file at end.
C-c C-x t	insert a new MIME tag.
C-c C-m C-a	enclose as multipart/alternative.
C-c C-m C-p	enclose as multipart/parallel.
C-c C-m C-m	enclose as multipart/mixed.
C-c C-m C-d	enclose as multipart/digest.
C-c C-m C-s	enclose as PGP signed.
C-c C-m C-e	enclose as PGP encrypted.
C-c C-x C-k	insert PGP public key.
C-c C-x p	preview editing MIME message.
...

therefore, you should type C-c C-x C-i and specify the binary file
which you want to insert.

  You should select Base64 as MIME encoding for binary file.

[2  (image/gif)]

[3  (text/plain)]

  Like above, you can compose the message with image.

==================== Take A Cup Of Russian Tea  ======================
=========  ** Not With Jam Nor Marmalade But With Honey **  ==========
=========                 MORIOKA TOMOHIKO                  ==========
==============  Internet E-mail: <morioka@jaist.ac.jp>  ==============

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2.2.1 entity-button

entity-button is a tag on the top of the entity which shows brief information of the part.

Normally, it appears as

        [1.3 test (text/plain)]

The number on the head describes the place of the entity in the message (like the section number) and it is called as entity-number.

The string in the next describes its title. This information is taken from

  1. Title described in Content-Description field or Subject field
  2. File name specified by filename parameter in Content-Disposition field
  3. File name specified by name parameter in Content-Type field
  4. File name for uuencode’ing

If none of them are specified, displays a blank.

The 3rd item in the parenthesis describes media-type/subtype of the entity. If it is is not MIME entity, it displays nil.

This entity-button plays a role like icon that symbolically shows the content of the entity. For example, push v on

        [2  (image/gif)]

shows up the image contained there.

If the mouse operation is possible, you can display the image by pushing 2nd button (the middle button for 3 button mouse) too.


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2.2.2 entity-header

entity-header is the header of the entity. (Don’t blame me as “You say nothing more than as it is”, It is no more than that.)


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2.2.3 entity-body

entity-body is the content of the part.

Sophistication does not seem enough here also, but it is really such a thing.

Though, it actually be twisted a little.

The text entity is passed to code conversion according to its charset, and the image entity should be converted on XEmacs.

Details will be described later.


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2.3 Operation in mime-preview-buffer

mime-preview-buffer posesses following functionalities.

u

go back to upper part (in the first part of the message, go back to the Summary mode (*1))

p

go to previous part

M-TAB

go to previous part

n

go to next part

TAB

go to next part

SPC

scroll up

M-SPC

scroll down

DEL

scroll down

RET

go to next line

M-RET

go to previous line

v

play current part (*2)

e

extract file from current part (*2)

C-c C-p

print current part (*2)

mouse-button-2

start the mouse button in preview-buffer

on content-button, play current part (*2)

on URL-button, start WWW browser

[Notice]

(*1) Do not go back to Summary mode unless appropriately configured for mime-view in the MUA.

(*2) actual behavior depends on the associated method


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3 MIME message editing

MIME-Edit is a general MIME composer for GNU Emacs.


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3.1 Minor-mode to edit MIME message

mime-edit-mode is a minor mode to compose MIME message. In this mode, tag represents various kinds of data, so you can edit multi part message consists of various kinds of data, such as text, image, audio, etc.

There are 2 kinds of tags:

single-part tag represents single part, this form is following:

        --[[TYPE/SUBTYPE;PARAMETERS][ENCODING]
        OPTIONAL-FIELDS]

TYPE/SUBTYPE and PARAMETERS indicates type/subtype and parameters of Content-Type ((mime-en)Content-Type) field. TYPE/SUBTYPE is required, PARAMETERS is optional.

ENCODING indicates Content-Transfer-Encoding ((mime-en)Content-Transfer-Encoding) field. It is optional too.

OPTIONAL-FIELDS is to represent another fields except Content-Type field and Content-Transfer-Encoding field.

multi-part tags represent multi part. They consist of a pair of multi-part beginning tag and multi-part ending tag.

multi-part beginning tag’s form is following:

        --<<TYPE>>-{

multi-part ending tag’s form is following:

        --}-<<TYPE>>

A region from multi-part beginning tag to multi-part ending tag is called as enclosure.


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3.2 Operations for single-part

Operations to make single-part are following:

C-c C-x C-t

Insert single-part tag indicates text part.

C-c C-x C-i

Insert file as a MIME attachment. If C-u is followed by it, it asks media-type, subtype or encoding even if their default values are specified. (cf. file-type specification)

C-c C-x C-e

Insert external part.

C-c C-x C-v

Record audio input until C-g is pressed, and insert as a audio part. (It requires /dev/audio in default.)

C-c C-x C-y

Insert current (mail or news) message. (It is MUA depended.)

C-c C-x C-m

Insert mail message. (It is MUA depended.)

C-c C-x C-w, C-c C-x C-s

Insert signature.

C-c C-x C-k

Insert PGP (PGP) public key. (It requires Mailcrypt package.)

C-c C-x t

Insert any single-part tag.


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3.3 Operations for enclosure

Operations to make enclosure are following:

C-c C-m C-a

Enclose specified region as multipart/alternative.

C-c C-m C-p

Enclose specified region as multipart/parallel.

C-c C-m C-m

Enclose specified region as multipart/mixed.

C-c C-m C-d

Enclose specified region as multipart/digest.

C-c C-m C-s

Digital-sign to specified region. (cf. PGP)

C-c C-m C-e

Encrypt to specified region. (cf. PGP)

C-c C-m C-q

avoid to encode tags in specified region. In other words, tags is interpreted as such string. (In current version, it may be incomplete. Maybe PGP-signature does not work for this enclosure.)


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3.4 Other operations

There are another operations in mime-edit-mode.

C-c C-c

Send current editing message.

C-c C-x p

Preview current editing message. (cf. MIME-View)

C-c C-x C-z

Exit mime-edit-mode without sending.

C-c C-x /

Set current editing message to enable automatic splitting or not. Form of automatic split messages is message/partial.

C-c C-x 7

Set 7bit ((mime-en)7bit) to transfer level (transfer level).

C-c C-x 8

Set 8bit ((mime-en)8bit) to transfer level (transfer level).

C-c C-x v

Set current editing message to digital-sign or not. (cf. PGP)

C-c C-x h

Set current editing message to encrypt or not. (cf. PGP)

C-c C-x ?

Display help message.


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3.5 How to detect tag for inserted file

When C-c C-x C-i (mime-edit-insert-file) is pressed, tag parameters for inserted file, such as media-type or encoding, are detected by variable mime-file-types.

When C-u is followed by it or parameter is not found from the variable, it asks from user. (When C-u is followed by it, detected value is used as default value)

If you want to change default value for file names, please change variable mime-file-types.

Variable: mime-file-types

Specification of default value of tag for file name of inserted file.

It is a list of following list:

	(FILE_PAT TYPE SUBTYPE PARAMS ENCODING
	 DISPOSITION_TYPE DISPOSITION_PARAMS)

Each element of the list is following:

FILE_PAT

regular expression of file name

TYPE

primary-type of media-type

SUBTYPE

subtype of media-type

PARAMS

parameters of Content-Type field

ENCODING

Content-Transfer-Encoding

DISPOSITION_TYPE

disposition-type

DISPOSITION_PARAMS

parameters of Content-Disposition field

Example: Specify application/rtf as default media type for *.rtf

(eval-after-load
    "mime-edit"
  '(set-alist 'mime-file-types
	      "\\.rtf$"
	      '("application" "rtf" nil nil
		"attachment" (("filename" . file)))
	      ))

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3.6 transfer level

Each content inserted in a message is represented by 7bit ((mime-en)7bit), 8bit ((mime-en)8bit) or binary ((mime-en)binary).

If a message is translated by 7bit-through MTA ((mime-en)MTA), there is no need to encode 7bit data, but 8bit and binary data must be encoded to 7bit data.

Similarly, if a message is translated by 8bit-through MTA, there is no need to encode 7bit or 8bit data, but binary data must be encoded to 7bit or 8bit data.

[Memo]

EBCDIC MTA breaks 7bit data, so in this case, 7bit data must be encoded by base64. But I don’t know EBCDIC. (^_^;

Similarly, I wish ASCII-printable only MTA and code-conversion MTA disappeared. (^_^;

Maybe there are binary-through MTA, but I think it is not major.

transfer level represents how range data are available. mime-edit has a variable mime-transfer-level to represent transfer level.

Variable: mime-transfer-level

transfer level.

If transfer level of a data is over it, a data is encoded to 7bit.

Currently, 7 or 8 is available. Default value is 7.

In extension plan, EBCDIC will be 5, ASCII printable only will be 6, binary will be 9. But it will not be implemented.

[Memo]

transfer level is only for body, not for message header (entity-header). MIME extends RFC 822 ((mime-en)RFC 822) to use 8bit data in body, but it requires to use us-ascii ((mime-en)us-ascii) in header.


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3.7 Splitting

Variable: mime-edit-split-message

Split large message if it is non-nil.

Variable: mime-edit-message-default-max-lines

Default maximum lines of a message.

Variable: mime-edit-message-max-lines-alist

Alist of major-mode vs maximum lines of a message.

If it is not specified for a major-mode, mime-edit-message-default-max-lines is used.

Variable: mime-edit-split-blind-field-regexp

Regular expression to match field-name to be ignored when split sending.


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4 Miscellaneous


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4.1 PGP

mime-edit provides PGP encryption, signature and inserting public-key features based on PGP/MIME (RFC 2015) or PGP-kazu (draft-kazu-pgp-mime-00.txt).

This feature requires your pgp command.

Variable: pgg-default-scheme

Version of PGP or GnuPG command to be used for encryption or sign. The value should be a symbol. Allowed versions are gpg, pgp or pgp5.

Variable: pgg-scheme

Version of PGP or GnuPG command to be used for decryption or verification. The value should be a symbol. Allowed versions are gpg, pgp or pgp5.

Variable: pgg-insert-url-function

The function to fetch public key from the keyserver. Use Emacs/W3 by the default setting. To use emacs-w3m instead, set as follows:

(setq pgg-insert-url-function #'w3m-retrieve)

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4.2 Mouse button

Variable: mime-button-face

Face used for content-button or URL-button of MIME-Preview buffer.

Variable: mime-button-mouse-face

Face used for MIME-preview buffer mouse highlighting.

Variable: mime-browse-url-function

Function to browse URL.


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4.3 Utility for configuration

Function: mime-add-condition target-type condition &optional mode file

Add condition to database specified by target-type.

target-type must be preview or action.

If optional argument mode is strict or nil (omitted), condition is added strictly.

If optional argument mode is with-default, condition is added with default rule.

If optional argument file is specified, it is loaded when condition is activate.


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5 Concept Index

Jump to:   E   M   P   T  
Index Entry  Section

E
enclosure: mime-edit-mode
entity-body: entity-body
entity-button: entity-button
entity-header: entity-header
entity-number: entity-button

M
MIME-Edit: MIME-Edit
mime-edit-mode: mime-edit-mode
multi-part beginning tag: mime-edit-mode
multi-part ending tag: mime-edit-mode

P
PGP-kazu: PGP
PGP/MIME: PGP

T
tag: mime-edit-mode
transfer level: transfer level

Jump to:   E   M   P   T  

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6 Function Index

Jump to:   M  
Index Entry  Section

M
mime-add-condition: Acting-condition configuration

Jump to:   M  

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7 Variable Index

Jump to:   M   P  
Index Entry  Section

M
mime-browse-url-function: Buttons
mime-button-face: Buttons
mime-button-mouse-face: Buttons
mime-edit-message-default-max-lines: message/partial sending
mime-edit-message-max-lines-alist: message/partial sending
mime-edit-split-blind-field-regexp: message/partial sending
mime-edit-split-message: message/partial sending
mime-file-types: file-type specification
mime-transfer-level: transfer level

P
pgg-default-scheme: PGP
pgg-insert-url-function: PGP
pgg-scheme: PGP

Jump to:   M   P