-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathxep-0334.xml
160 lines (156 loc) · 7.42 KB
/
xep-0334.xml
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE xep SYSTEM 'xep.dtd' [
<!ENTITY % ents SYSTEM 'xep.ent'>
%ents;
]>
<?xml-stylesheet type='text/xsl' href='xep.xsl'?>
<xep>
<header>
<title>Message Processing Hints</title>
<abstract>This document defines a way to include hints to entities routing or receiving a message.</abstract>
&LEGALNOTICE;
<number>0334</number>
<status>Deferred</status>
<lastcall>2017-03-01</lastcall>
<lastcall>2017-02-22</lastcall>
<type>Standards Track</type>
<sig>Standards</sig>
<approver>Council</approver>
<dependencies>
<spec>XMPP Core</spec>
</dependencies>
<supersedes/>
<supersededby/>
<shortname>hints</shortname>
&mwild;
<revision>
<version>0.3.0</version>
<date>2018-01-25</date>
<initials>XEP Editor (jwi)</initials>
<remark>Defer due to lack of activity.</remark>
</revision>
<revision>
<version>0.2</version>
<date>2015-09-01</date>
<initials>dg</initials>
<remark>
<p>Fixed the wrong use of no-storage instead of no-store</p>
<p>Added a message hint <store/></p>
</remark>
</revision>
<revision>
<version>0.1</version>
<date>2013-07-11</date>
<initials>psa</initials>
<remark><p>Initial published version approved by the XMPP Council.</p></remark>
</revision>
<revision>
<version>0.0.1</version>
<date>2013-06-18</date>
<initials>mw</initials>
<remark><p>First draft.</p></remark>
</revision>
</header>
<section1 topic='Introduction' anchor='intro'>
<p>Message types ('normal', 'chat', 'headline', etc.) provide an existing framework for determining how an entity should deliver or handle a message. For example &xmppim; defines that messages of type 'headline' should not be stored offline by the server, and that messages of type 'groupchat' must not be directed to other resources.</p>
<p>However this framework of rules is quite inflexible, and new extensions are being developed that push at the boundaries of what is capable of. This specification defines a more flexible approach that allows the sender to add finer-grained 'hints' to messages, which can be used as a generic mechanism for XMPP entities to handle messages.</p>
<p>A similar but much more extensive framework is defined in &xep0079; for applications that need it.</p>
</section1>
<section1 topic='Requirements' anchor='reqs'>
<p>This specification aims to solve the following common problems, and allow a sender to hint to
the recipient:</p>
<ul>
<li>Whether to store a message (e.g. for archival or as an 'offline message').</li>
<li>Whether to copy a message to other resources.</li>
<li>Whether to store a message that would not have been stored under normal conditions</li>
</ul>
</section1>
<section1 topic='Use Cases' anchor='usecases'>
<section2 topic="Session-based stanzas" anchor='usecases-session'>
<p>Suppose that Romeo and Juliet are avoiding the surveillance of Prince Escalus and communicating using a session-based
encryption protocol between their laptops. In order to prevent Juliet's tablet computer that uses &xep0280; from receiving
copies of the encrypted messages (and not being able to decrypt them), Romeo inserts the <no-copy/> hint into the
messages he sends. Since it is also useless for these messages to be archived, he additionally adds the <no-store/>
hint:</p>
<example caption='Sending a message with no-copy and no-store hints'><![CDATA[
<message
from='[email protected]/laptop'
to='[email protected]/laptop'>
<body>V unir avtug'f pybnx gb uvqr zr sebz gurve fvtug</body>
<no-copy xmlns="urn:xmpp:hints"/>
<no-store xmlns="urn:xmpp:hints"/>
</message>
]]></example>
</section2>
<section2 topic="Notifications" anchor='usecases-notification'>
<p>Some automated notifications may be transient, and there would be no purpose in delaying their delivery. Such
messages may be marked with the <no-store/> hint.</p>
</section2>
<section2 topic="Sensitive messages" anchor='usercases-sensitive'>
<p>A sender may want to indicate their preference to have no permanent record of a message (also known as "off the
record" messages), but may be happy for it to be stored temporarily as a normal part of delivery (e.g. if the
recipient is offline at the time of sending). Such a message can be marked with the <no-permanent-store/> hint.
</p>
</section2>
<section2 topic="Storage-worthy messages" anchor='store-worthy'>
<p>Offline storage and &xep0313; can define their own rules on what messages to store and usually only store messages that contain a body element. However a sender may want to indicate that a message is worth storing even though it might not match those rules (e.g. an encrypted message that carries the payload outside the body element). Such a message can be marked with a <store/> hint.</p>
</section2>
</section1>
<section1 topic="Hints" anchor="hints">
<section2 topic="No permanent store" anchor="no-permanent-store">
<p>The <no-permanent-store/> hint informs entities that they shouldn't store the message in
any permanent or semi-permanent public or private archive (such as described in &xep0136; and &xep0313;)
or in logs (such as chatroom logs).
</p>
</section2>
<section2 topic="No store" anchor="no-store">
<p>A message containing a <no-store/> hint should not be stored by a server either permanently (as above)
or temporarily, e.g. for later delivery to an offline client, or to users not currently present in a chatroom.
</p>
</section2>
<section2 topic="No copies" anchor="no-copy">
<p>Messages with the <no-copy/> hint should not be copied to addresses other than the one to which it is
addressed, for example through &xep0280;.</p>
<p>This hint MUST only be included on messages addressed to full JIDs and explicitly does not override the behaviour
defined in &xmppim; for handling messages to bare JIDs, which may involve copying to multiple resources, or multiple
occupants in a &xep0045; room.
</p>
</section2>
<section2 topic="Store">
<p>A message containing the <store/> hint that is not of type 'error' SHOULD be stored by the entity.</p>
</section2>
</section1>
<section1 topic='Business Rules' anchor='rules'>
<p>It is important to note that message hints are, as the name implies, just hints. Implementations
MUST NOT rely on other entities interpretation of the hints for any particular purpose.</p>
</section1>
<section1 topic='Security Considerations' anchor='security'>
<p>This specification introduces no known security considerations.</p>
</section1>
<section1 topic='IANA Considerations' anchor='iana'>
<p>This document requires no interaction with &IANA;.</p>
</section1>
<section1 topic='XMPP Registrar Considerations' anchor='registrar'>
<p>This document requires no interaction with ®ISTRAR;.</p>
</section1>
<section1 topic='XML Schema'>
<code><![CDATA[
<?xml version='1.0' encoding='UTF-8'?>
<xs:schema
xmlns:xs='http://www.w3.org/2001/XMLSchema'
targetNamespace='urn:xmpp:hints'
xmlns='urn:xmpp:hints'
elementFormDefault='qualified'>
<xs:element name='no-permanent-store' type='empty'/>
<xs:element name='no-store' type='empty'/>
<xs:element name='no-copy' type='empty'/>
<xs:element name='store' type='empty'/>
<xs:simpleType name='empty'>
<xs:restriction base='xs:string'>
<xs:enumeration value=''/>
</xs:restriction>
</xs:simpleType>
</xs:schema>
]]></code>
</section1>
</xep>