draft-ietf-extra-imap-fetch-preview-01.txt		draft-ietf-extra-imap-fetch-preview-02.txt
	EXTRA M. Slusarz		EXTRA M. Slusarz
	Internet-Draft Open-Xchange Inc.		Internet-Draft Open-Xchange Inc.
	Intended status: Standards Track January 22, 2019		Intended status: Standards Track February 13, 2019
	Expires: July 26, 2019		Expires: August 17, 2019
	IMAP4 Extension: Message Preview Generation		IMAP4 Extension: Message Preview Generation
	draft-ietf-extra-imap-fetch-preview-01		draft-ietf-extra-imap-fetch-preview-02
	Abstract		Abstract
	This document specifies an IMAP protocol extension which allows a		This document specifies an IMAP protocol extension which allows a
	client to request that a server provide an abbreviated representation		client to request that a server provide an abbreviated representation
	of a message that can be used by a client to provide a useful		of a message that can be used by a client to provide a useful
	contextual preview of the message contents.		contextual preview of the message contents.
	Status of This Memo		Status of This Memo
	skipping to change at page 1, line 33 ¶		skipping to change at page 1, line 33 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on July 26, 2019.		This Internet-Draft will expire on August 17, 2019.
	Copyright Notice		Copyright Notice
	Copyright (c) 2019 IETF Trust and the persons identified as the		Copyright (c) 2019 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 2, line 17 ¶		skipping to change at page 2, line 17 ¶
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	2. Conventions Used In This Document . . . . . . . . . . . . . . 3		2. Conventions Used In This Document . . . . . . . . . . . . . . 3
	3. FETCH Data Item . . . . . . . . . . . . . . . . . . . . . . . 4		3. FETCH Data Item . . . . . . . . . . . . . . . . . . . . . . . 4
	3.1. Command . . . . . . . . . . . . . . . . . . . . . . . . . 4		3.1. Command . . . . . . . . . . . . . . . . . . . . . . . . . 4
	3.2. Response . . . . . . . . . . . . . . . . . . . . . . . . 4		3.2. Response . . . . . . . . . . . . . . . . . . . . . . . . 4
	4. PREVIEW Algorithms . . . . . . . . . . . . . . . . . . . . . 5		4. PREVIEW Algorithms . . . . . . . . . . . . . . . . . . . . . 5
	4.1. FUZZY . . . . . . . . . . . . . . . . . . . . . . . . . . 5		4.1. FUZZY . . . . . . . . . . . . . . . . . . . . . . . . . . 5
	5. PREVIEW Priority Modifiers . . . . . . . . . . . . . . . . . 6		5. PREVIEW Priority Modifiers . . . . . . . . . . . . . . . . . 6
	5.1. LAZY . . . . . . . . . . . . . . . . . . . . . . . . . . 6		5.1. LAZY . . . . . . . . . . . . . . . . . . . . . . . . . . 6
	6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 6		6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 6
	7. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 9		7. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 8
	8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10		8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
	9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10		9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
	10. Security Considerations . . . . . . . . . . . . . . . . . . . 11		10. Security Considerations . . . . . . . . . . . . . . . . . . . 10
	11. References . . . . . . . . . . . . . . . . . . . . . . . . . 11		11. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
	11.1. Normative References . . . . . . . . . . . . . . . . . . 11		11.1. Normative References . . . . . . . . . . . . . . . . . . 10
	11.2. Informative References . . . . . . . . . . . . . . . . . 12		11.2. Informative References . . . . . . . . . . . . . . . . . 11
	Appendix A. Change History (To be removed by RFC Editor before		Appendix A. Change History (To be removed by RFC Editor before
	publication) . . . . . . . . . . . . . . . . . . . . 12		publication) . . . . . . . . . . . . . . . . . . . . 11
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 13		Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 12
	1. Introduction		1. Introduction
	Many modern mail clients display small extracts of the body text as		Many modern mail clients display small extracts of the body text as
	an aid to allow a user to quickly decide whether they are interested		an aid to allow a user to quickly decide whether they are interested
	in viewing the full message contents. Mail clients implementing the		in viewing the full message contents. Mail clients implementing the
	Internet Message Access Protocol [RFC3501] would benefit from a		Internet Message Access Protocol [RFC3501] would benefit from a
	standardized, consistent way to generate these brief previews of		standardized, consistent way to generate these brief previews of
	messages.		messages.
	skipping to change at page 7, line 11 ¶		skipping to change at page 7, line 11 ¶
	PREVIEW extension.		PREVIEW extension.
	6. Examples		6. Examples
	Example 1: Requesting FETCH without explicit algorithm selection.		Example 1: Requesting FETCH without explicit algorithm selection.
	C: A1 CAPABILITY		C: A1 CAPABILITY
	S: * CAPABILITY IMAP4rev1 PREVIEW=FUZZY		S: * CAPABILITY IMAP4rev1 PREVIEW=FUZZY
	S: A1 OK Capability command completed.		S: A1 OK Capability command completed.
	[...a mailbox is SELECTed...]		[...a mailbox is SELECTed...]
	C: A2 FETCH 1 (RFC822.SIZE PREVIEW)		C: A2 FETCH 1 (RFC822.SIZE PREVIEW)
	S: * 1 FETCH (RFC822.SIZE 20000 PREVIEW (FUZZY {58}		S: * 1 FETCH (RFC822.SIZE 5647 PREVIEW (FUZZY {200}
	S: This is the first line of text from the first text part.		S: Lorem ipsum dolor sit amet, consectetur adipiscing elit.
			S: Curabitur aliquam turpis et ante dictum, et pulvinar dui congue.
			S: Maecenas hendrerit, lorem non imperdiet pellentesque, nulla
			S: ligula nullam
	S: ))		S: ))
	S: A2 OK FETCH complete.		S: A2 OK FETCH complete.
	Example 2: Requesting FETCH with explicit algorithm selection.		Example 2: Requesting FETCH with explicit algorithm selection.
	C: B1 CAPABILITY		C: B1 FETCH 1 (RFC822.SIZE PREVIEW (FUZZY))
	S: * CAPABILITY IMAP4rev1 PREVIEW=FUZZY		S: * 1 FETCH (RFC822.SIZE 91377 PREVIEW (FUZZY {53}
	S: B1 OK Capability command completed.		S: Preview text generated from message body text data.
	[...a mailbox is SELECTed...]
	C: B2 FETCH 1 (RFC822.SIZE PREVIEW (FUZZY))
	S: * 1 FETCH (RFC822.SIZE 20000 PREVIEW (FUZZY {58}
	S: This is the first line of text from the first text part.
	S: ))		S: ))
	S: B2 OK FETCH complete.		S: B1 OK FETCH complete.
	Example 3: Requesting FETCH with invalid explicit algorithm		Example 3: Requesting FETCH with invalid explicit algorithm
	selection.		selection.
	C: C1 CAPABILITY		C: C1 CAPABILITY
	S: * CAPABILITY IMAP4rev1 PREVIEW=FUZZY		S: * CAPABILITY IMAP4rev1 PREVIEW=FUZZY
	S: C1 OK Capability command completed.		S: C1 OK Capability command completed.
	[...a mailbox is SELECTed...]		[...a mailbox is SELECTed...]
	C: C2 FETCH 1 (RFC822.SIZE PREVIEW (UNKNOWN-PREVIEW-ALGO))		C: C2 FETCH 1 (RFC822.SIZE PREVIEW (UNKNOWN-PREVIEW-ALGO))
	S: C2 BAD FETCH contains invalid preview algorithm name.		S: C2 BAD FETCH contains invalid preview algorithm name.
	Example 4: Use explicit algorithm priority selection, with LAZY		Example 4: Use explicit algorithm priority selection, with LAZY
	modifier, to obtain previews during initial mailbox listing if		modifier, to obtain previews during initial mailbox listing if
	readily available; otherwise, load previews in background.		readily available; otherwise, load previews in background.
	C: D1 CAPABILITY		C: D1 FETCH 1:3 (ENVELOPE PREVIEW (LAZY=FUZZY))
	S: * CAPABILITY IMAP4rev1 PREVIEW=FUZZY
	S: D1 OK Capability command completed.
	[...a mailbox is SELECTed...]
	C: D2 FETCH 1:3 (ENVELOPE PREVIEW (LAZY=FUZZY))
	S: * 1 FETCH (ENVELOPE ("Wed, 25 Oct 2017 15:03:11 +0000" [...])		S: * 1 FETCH (ENVELOPE ("Wed, 25 Oct 2017 15:03:11 +0000" [...])
	PREVIEW (FUZZY {58}		PREVIEW (FUZZY "Preview text for message 1."))
	S: This is the first line of text from the first text part.
	S: ))
	S: * 2 FETCH (PREVIEW (FUZZY "") ENVELOPE		S: * 2 FETCH (PREVIEW (FUZZY "") ENVELOPE
	("Thu, 26 Oct 2017 12:17:23 +0000" [...]))		("Thu, 26 Oct 2017 12:17:23 +0000" [...]))
	S: * 3 FETCH (ENVELOPE ("Fri, 27 Oct 2017 22:19:21 +0000" [...])		S: * 3 FETCH (ENVELOPE ("Fri, 27 Oct 2017 22:19:21 +0000" [...])
	PREVIEW (FUZZY NIL))		PREVIEW (FUZZY NIL))
	S: D2 OK FETCH completed.		S: D1 OK FETCH completed.
	[...Client knows that message 2 has a preview that is empty;		[...Client knows that message 2 has a preview that is empty;
	therefore, client only needs to request message 3 preview again		therefore, client only needs to request message 3 preview again
	(e.g. in background)...]		(e.g. in background)...]
	C: D3 FETCH 3 (PREVIEW (FUZZY))		C: D2 FETCH 3 (PREVIEW (FUZZY))
	S: * 3 FETCH (PREVIEW (FUZZY {27}		S: * 3 FETCH (PREVIEW (FUZZY {30}
	S: First sentence of mail 3.		S: Message data from message 3.
	S: ))		S: ))
	S: D3 OK Fetch completed.		S: D2 OK Fetch completed.
	Example 5: Retrieve preview information for search results within a		Example 5: Retrieve preview information for search results within a
	single mailbox. Use SEARCHRES [RFC5182] extension to save a round-		single mailbox. Use SEARCHRES [RFC5182] extension to save a round-
	trip.		trip.
	C: E1 CAPABILITY		C: E1 CAPABILITY
	S: * CAPABILITY IMAP4rev1 PREVIEW=FUZZY SEARCHRES		S: * CAPABILITY IMAP4rev1 PREVIEW=FUZZY SEARCHRES
	S: E1 OK Capability command completed.		S: E1 OK Capability command completed.
	[...a mailbox is SELECTed...]		[...a mailbox is SELECTed...]
	C: E2 SEARCH RETURN (SAVE) FROM "FOO"		C: E2 SEARCH RETURN (SAVE) FROM "FOO"
	C: E3 FETCH $ (UID PREVIEW (LAZY=FUZZY))		C: E3 FETCH $ (UID PREVIEW (LAZY=FUZZY))
	S: E2 OK SEARCH completed.		S: E2 OK SEARCH completed.
	S: * 5 FETCH (UID 13 PREVIEW (FUZZY {10}		S: * 5 FETCH (UID 13 PREVIEW (FUZZY "Preview!"))
	S: Preview!
	S: ))
	S: * 9 FETCH (UID 23 PREVIEW (FUZZY NIL))		S: * 9 FETCH (UID 23 PREVIEW (FUZZY NIL))
	S: E3 OK FETCH completed.		S: E3 OK FETCH completed.
	[...Retrieve message 9 preview in background...]		[...Retrieve message 9 preview in background...]
	C: E4 UID FETCH 23 (PREVIEW (FUZZY))		C: E4 UID FETCH 23 (PREVIEW (FUZZY))
	S: * 9 FETCH (PREVIEW (FUZZY {18}		S: * 9 FETCH (PREVIEW (FUZZY "Another preview!"))
	S: Another preview!
	S: ))
	S: E4 OK FETCH completed.		S: E4 OK FETCH completed.
	7. Formal Syntax		7. Formal Syntax
	The following syntax specification uses the augmented Backus-Naur		The following syntax specification uses the augmented Backus-Naur
	Form (BNF) as described in ABNF [RFC5234]. It includes definitions		Form (BNF) as described in ABNF [RFC5234]. It includes definitions
	from IMAP [RFC3501].		from IMAP [RFC3501].
	capability =/ "PREVIEW=FUZZY"		capability =/ "PREVIEW=" (preview-alg / preview-mod-ext)
	fetch-att =/ "PREVIEW" [SP "(" preview-alg-fetch *(SP		fetch-att =/ "PREVIEW" [SP "(" preview-alg-fetch *(SP
	preview-alg-fetch) ")"]		preview-alg-fetch) ")"]
	msg-att-dynamic =/ "PREVIEW" SP "(" preview-alg SP nstring ")"		msg-att-dynamic =/ "PREVIEW" SP "(" preview-alg SP nstring ")"
	preview-alg = "FUZZY" / preview-alg-ext		preview-alg = "FUZZY" / preview-alg-ext
	preview-alg-ext = preview-atom ; New algorithm names MUST		preview-alg-ext = preview-atom ; New algorithm names SHOULD be
			; registered with IANA and MUST
	; conform with the		; conform with the
	; recommendations described in		; recommendations described in
	; RFC 6648, Section 3		; RFC 6648, Section 3
	preview-alg-fetch = preview-alg / preview-mod "=" preview-alg		preview-alg-fetch = preview-alg / preview-mod "=" preview-alg
	preview-atom = 1*<any ATOM-CHAR except "=">		preview-atom = 1*<any ATOM-CHAR except "=">
	preview-mod = "LAZY" / preview-mod-ext		preview-mod = "LAZY" / preview-mod-ext
	preview-mod-ext = preview-atom ; New priority modifier names		preview-mod-ext = preview-atom ; New priority modifier names
	; MUST conform with the		; SHOULD be registered with IANA
			; and MUST conform with the
	; recommendations described in		; recommendations described in
	; RFC 6648, Section 3		; RFC 6648, Section 3
	8. Acknowledgements		8. Acknowledgements
	The author would like to thank the following people for their		The author would like to thank the following people for their
	comments and contributions to this document: Stephan Bosch, Bron		comments and contributions to this document: Stephan Bosch, Bron
	Gondwana, Teemu Huovila, Steffen Lehmann, Alexey Melnikov, Chris		Gondwana, Teemu Huovila, Steffen Lehmann, Alexey Melnikov, Chris
	Newman, Jeff Sipek, Timo Sirainen, Steffen Templin, and Aki Tuomi.		Newman, Jeff Sipek, Timo Sirainen, Steffen Templin, and Aki Tuomi.
	skipping to change at page 13, line 29 ¶		skipping to change at page 12, line 29 ¶
	6648		6648
	o Added DoS attack info to security considerations		o Added DoS attack info to security considerations
	o Distinguish between NIL response and zero-length string		o Distinguish between NIL response and zero-length string
	o Don't use deprecated "X-" convention in example		o Don't use deprecated "X-" convention in example
	o Spelling and nits		o Spelling and nits
			Changes from draft-ietf-extra-imap-fetch-preview-01:
			o Fix capability ABNF
			o Removed CAPABILITY string for examples where it did not add
			valuable context
			o Altered preview data in examples to cover a variety of potential
			server return scenarios
			o Added "SHOULD be registered" language to algorithm names and
			priority modifiers
	Author's Address		Author's Address
	Michael M. Slusarz		Michael M. Slusarz
	Open-Xchange Inc.		Open-Xchange Inc.
	530 Lytton Avenue		530 Lytton Avenue
	Palo Alto, California 94301		Palo Alto, California 94301
	US		US
	Email: michael.slusarz@open-xchange.com		Email: michael.slusarz@open-xchange.com
End of changes. 19 change blocks.
	45 lines changed or deleted		49 lines changed or added
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