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XEP-0356 v0.2 -- see remarks
This commit is contained in:
Matthew A. Miller
parent
bd57162ad2
commit
a6726f9477
111
xep-0356.xml
111
xep-0356.xml
@ -26,6 +26,26 @@
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<email>goffi@goffi.org</email>
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<jid>goffi@jabber.fr</jid>
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</author>
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<revision>
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<version>0.2</version>
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<date>2015-03-23</date>
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<initials>jp</initials>
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<remark>
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<p>Several updates according to feedbacks + review:</p>
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<ul>
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<li>added links to PEP and namespace delegation XEPs</li>
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<li>removed MUST for default values in configuration</li>
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<li><forwarded/> element is now a child of a <privilege/> element</li>
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<li><perm/> "namespace" attribute has been renamed to "access"</li>
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<li>"headline" type restriction for "message" privilege has been removed</li>
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<li>"message" permission violation now result in a "forbidden" message error</li>
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<li>for "presence" permission, only &PRESENCE; stanza with no type or with a "unavailable" type are sent to privileged entity</li>
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<li>added specifitation for "presence" if a managed entity is unavailable and if a privileged entity is available after first &PRESENCE; stanzas have been received</li>
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<li>added Business Rules section</li>
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<li>Updated namespace to reflect incompatible changes</li>
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</ul>
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</remark>
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</revision>
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<revision>
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<version>0.1</version>
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<date>2015-01-27</date>
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@ -84,11 +104,12 @@
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<ul>
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<li>a step forward in decentralization: it is possible for an entity to do tasks which were before reserved to server itself. For example, a privileged pubsub component can offer access model based on publisher's roster</li>
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<li>better integration of components: a gateway can add items to an entity roster itself</li>
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<li>possibility to overpass a server limitation (typically: incomplete PEP implementation)</li>
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<li>possibility to overpass a server limitation (typically: incomplete &xep0163; implementation)</li>
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<li>quick development cycle: developers can implement the components they need without waiting for a new server release</li>
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<li>server agnostic</li>
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</ul>
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<p>Privileged entity has been created with the main goal to create an external, server agnostic, PEP service. It is restricted to only a couple of features, see <link url='#acks'>Acknowledgements section</link> for more details</p>
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<p>Privileged entity has been created with the main goal to create an external, server agnostic, PEP service. It is restricted to only a couple of features, see <link url='#acks'>Acknowledgements section</link> for more details.</p>
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<p>This XEP is complementary to &xep0355; (and works in a similar way), although they can be used together or separately. To build something like an external PEP service, it is necessary to use both XEPs.</p>
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</section1>
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<section1 topic='Requirements' anchor='reqs'>
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@ -113,19 +134,19 @@
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<section2 topic='Server Allows Roster Access' anchor='server_roster'>
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<p>Roster access is granted in the server configuration. Roster access can have 4 types:</p>
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<ul>
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<li><strong>none</strong> — the entity is not allowed to access managed entity roster at all. This MUST be the default value.</li>
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<li><strong>none</strong> — the entity is not allowed to access managed entity roster at all. This is usually the default value.</li>
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<li><strong>get</strong> — the entity is allowed to send &IQ; stanzas of type <em>'get'</em> for the namespace 'jabber:iq:roster'.</li>
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<li><strong>set</strong> — the entity is allowed to send &IQ; stanzas of type <em>'set'</em> for namespace 'jabber:iq:roster'.</li>
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<li><strong>both</strong> — the entity is allowed to send &IQ; stanzas of type <em>'get'</em> and <em>'set'</em> for namespace 'jabber:iq:roster'.</li>
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</ul>
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</section2>
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<section2 topic='Server Advertise Entity Of Allowed Permission' anchor='advertise_roster'>
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<p>Once an entity is authenticated and stream is started, the server send it a &MESSAGE; stanza with a <privilege> elements which MUST have the namespace 'urn:xmpp:privilege:0'. This element contains <perm> elements which MUST contain a 'namespace' attribute of the value "jabber:iq:roster" and a 'type' attribute which must correspond to the type configured as specified in <link url='#server_roster'>"Server Allows Roster Access" section</link></p>
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<example caption='Server Advertise Roster Privilege'><![CDATA[
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<section2 topic='Server Advertises Entity Of Allowed Permission' anchor='advertise_roster'>
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<p>Once a privileged entity is authenticated and stream is started, the server send it a &MESSAGE; stanza with a <privilege/> elements which MUST have the namespace 'urn:xmpp:privilege:1'. This element contains <perm/> elements which MUST contain a 'access' attribute of the value "roster" and a 'type' attribute which must correspond to the type configured as specified in <link url='#server_roster'>"Server Allows Roster Access" section</link></p>
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<example caption='Server Advertises Roster Privilege'><![CDATA[
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<message from='capulet.net' to='pubub.capulet.lit' id='12345'>
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<privilege xmlns='urn:xmpp:privilege:0'>
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<perm namespace='jabber:iq:roster' type='both'/>
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<privilege xmlns='urn:xmpp:privilege:1'>
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<perm access='roster' type='both'/>
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</privilege>
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</message>
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]]></example>
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@ -164,24 +185,23 @@
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<section2 topic='Authorizing Messages' anchor='auth_mess'>
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<p>In some cases, it can be desirable to send notifications (e.g. PEP service), so the privileged entity must be able to send &MESSAGE; stanzas. This is allowed in server configuration in the same way as for roster permission. The permission type can have the following values:</p>
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<ul>
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<li><strong>none</strong> — the entity is not allowed to send &MESSAGE; stanza in the name of the server. This MUST be the default value.</li>
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<li><strong>none</strong> — the entity is not allowed to send &MESSAGE; stanza in the name of the server. This is usually the default value.</li>
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<li><strong>outgoing</strong> — the entity is allowed to send &MESSAGE; stanzas in the name of the server, according to following restrictions.</li>
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</ul>
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<p>A privileged entity can then send message on the behalf either of the server or of a bare JID of the server, using &xep0297;, with the following restrictions:</p>
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<p>A privileged entity can then send message on the behalf either of the server or of a bare JID of an entity managed by the server (i.e. a bare jid with the same domain as the server), using &xep0297;. The <forwarded/> element MUST be a child of a <privilege/> element with a namespace of <em>'urn:xmpp:privilege:1'</em>, with the following restriction:</p>
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<ol>
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<li>forwarded &MESSAGE; 'type' attribute has the value of "headline"</li>
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<li>forwarded &MESSAGE; 'from' attribute MUST be a bare JID from the server, no resource is allowed</li>
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</ol>
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<p>If any of this rules is violated, the server MUST return a <not-authorized/> stream error and close the connection, as explained in &rfc6120; section 4.9.3.12.</p>
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<p>If this rule is violated, the server MUST return a &MESSAGE; error with condition <forbidden/>, as in &rfc6120; section 8.3.3.4.</p>
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</section2>
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<section2 topic='Advertising Permission' anchor='advertise_mess'>
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<p>Server advertise "message" permission in the same way as for "roster" permission, except that 'namespace' attribute has the value of "message", and the 'type' attribute as a value of 'outgoing':</p>
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<example caption='Server Advertise Roster And Message Privileges'><![CDATA[
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<p>Server advertises "message" permission in the same way as for "roster" permission, except that 'access' attribute has the value of "message", and the 'type' attribute as a value of 'outgoing':</p>
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<example caption='Server Advertises Roster And Message Privileges'><![CDATA[
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<message from='capulet.net' to='pubub.capulet.lit' id='54321'>
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<privilege xmlns='urn:xmpp:privilege:0'>
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<perm namespace='jabber:iq:roster' type='both'/>
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<perm namespace='message' type='outgoing'/>
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<privilege xmlns='urn:xmpp:privilege:1'>
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<perm access='roster' type='both'/>
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<perm access='message' type='outgoing'/>
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</privilege>
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</message>
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]]></example>
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@ -191,11 +211,11 @@
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<p>Now that <em>pubsub.capulet.lit</em> is allowed, it can send messages using <forwarded/> elements.</p>
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<example caption='privileged entity send a notificaction message'><![CDATA[
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<message from='pubsub.capulet.lit' to='capulet.lit' id='notif1'>
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<privilege xmlns='urn:xmpp:privilege:1'>
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<forwarded xmlns='urn:xmpp:forward:0'>
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<message from='juliet@capulet.lit'
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id='foo'
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to='romeo@montague.lit/orchard'
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type='headline'
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xmlns='jabber:client'>
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<event xmlns='http://jabber.org/protocol/pubsub#event'>
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<items node='http://jabber.org/protocol/tune'>
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@ -213,14 +233,14 @@
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<delay xmlns='urn:xmpp:delay' stamp='2014-11-25T14:34:32Z'/>
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</message>
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</forwarded>
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</privilege>
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</message>
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]]></example>
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<p>The server sees that forwarded message type is '<em>headline</em>', that <em>juliet@capulet.lit</em> is a bare JID of the server, and that outgoing message permission was granted in admin mode (so all bare JIDs from server are allowed); it can now send the notification:</p>
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<p>The server sees that forwarded message 'from' attribute (<em>juliet@capulet.lit</em>) is a bare JID of the server, and that outgoing message permission was granted; it can now send the notification:</p>
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<example caption='server sends the notification as if it was originating from him'><![CDATA[
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<message from='juliet@capulet.lit'
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id='bar'
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to='romeo@montague.lit/orchard'
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type='headline'>
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to='romeo@montague.lit/orchard'>
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<event xmlns='http://jabber.org/protocol/pubsub#event'>
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<items node='http://jabber.org/protocol/tune'>
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<item>
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<p>It can be often desirable for a privileged entity to have presence information of the managed entities (e.g. to know when to send them notificiations). As privileges must be transparent for the managed entity, this presence has to be sent by the server without modifying managed entity roster.</p>
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<p>This is allowed in server configuration in the same way as for <em>roster</em> and <em>message</em> permissions. The "presence" type can have the following values:</p>
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<ul>
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<li><strong>none</strong> — the entity is not allowed to access &PRESENCE; informations at all. This MUST be the default value.</li>
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<li><strong>none</strong> — the entity is not allowed to access &PRESENCE; informations at all. This is usually the default value.</li>
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<li><strong>managed_entity</strong> — the entity is allowed to receive managed entity presence (see below).</li>
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<li><strong>roster</strong> — the entity is allowed to receive presence informations of managed entity contacts, see <link url='#roster_presence'>Roster Presence section</link>.</li>
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</ul>
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<p>If the privilege is granted, the server MUST use a directed presence, as specified in &rfc6121; section 4.6 on the behalf of managed entity each time its presence information change.</p>
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<p>If the privilege is granted, the server MUST use a directed presence from the full jid of the managed entity, to the privileged entity, as specified in &rfc6121; section 4.6, on the behalf of managed entity each time its presence information change.</p>
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<p>Only presences with no 'type' attribute or with a 'type' attribute with the value "unavailable" are transmitted to the privileged entity, the server MUST NOT transmit &PRESENCE; stanza of any other type.</p>
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</section2>
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<section2 topic='Advertising Permission' anchor='advertise_managed_presence'>
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<p>Server advertise "presence" permission in the same way as for "roster" or "message" permissions, except that 'namespace' attribute has the value of "presence", and the 'type' attribute has a value of "managed_entity"</p>
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<p>Server advertises "presence" permission in the same way as for "roster" or "message" permissions, except that 'access' attribute has the value of "presence", and the 'type' attribute has a value of "managed_entity"</p>
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</section2>
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<section2 topic="Server Send presence informations" anchor='server_send_presence'>
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@ -281,23 +302,25 @@
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<section2 topic='Roster Presence' anchor='roster_presence'>
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<p>In addition to "<link url='#managed_ent_presence'>managed entity presence</link>", a privileged entity may need to know when a contact in managed entity roster is online (for example, it's necessary for a PEP service because of the presence default access model).</p>
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<p>As for other permissions, the access in granted in server's configuration, but there is a additional restriction: the privileged entity MUST have read permission on roster namespace (i.e. 'type' attribute in allowed <perm> of namespace <em>jabber:iq:roster</em> MUST have a value of either <strong>get</strong> or <strong>both</strong>).</p>
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<p>If the delegation is granted, the server MUST send to the privileged entity every presence information that the privileged entity is receiving. Having "roster" type for "presence" permission imply that you have also implicitly "managed_entity" type.</p><p>The server MUST reject the permission if the privileged entity doesn't have read permission on roster namespace.</p>
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<p>As for other permissions, the access is granted in server's configuration, but there is an additional restriction: the privileged entity MUST have read permission on roster namespace (i.e. 'type' attribute in allowed <perm> of access <em>roster</em> MUST have a value of either <strong>get</strong> or <strong>both</strong>).</p>
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<p>If the privilege is granted, the server MUST send to the privileged entity every presence information with no 'type' attribute or with a 'type' with a value of 'unavailable' that the privileged entity is receiving or would receive if it were available. It do it in the same way as for <link url='#managed_ent_presence'>managing entity</link> by using directed &PRESENCE; from the full jid of the entity from which presence information has changed, to the privileged entity. If the managed entity is unavailable but the privileged entity is available, the server MUST send &PRESENCE; stanza to the later anyway.</p>
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<p>Having "roster" type for "presence" permission imply that you have also implicitly "managed_entity" type.</p><p>The server MUST reject the permission if the privileged entity doesn't have read permission on roster namespace.</p>
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<p>Note: this permission should be given carefully, as it gives access to presence of potentially a lot of entities to the privileged entity (see <link url='#security'>security considerations</link>).</p>
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</section2>
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<section2 topic='Advertising Permission' anchor='advertise_roster_presence'>
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<p>Server advertise roster "presence" permission in the same way as for other permissions, except that the 'namespace' attribute has the value of "presence", and the 'type' attribute has a value of "roster"</p>
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<example caption='Server Advertise Roster, Message, Managed Entity Presence and Roster Presence Privileges'><![CDATA[
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<p>Server advertises roster "presence" permission in the same way as for other permissions, except that the 'access' attribute has the value of "presence", and the 'type' attribute has a value of "roster"</p>
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<example caption='Server Advertises Roster, Message, Managed Entity Presence and Roster Presence Privileges'><![CDATA[
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<message from='capulet.net' to='pubub.capulet.lit' id='54321'>
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<privilege xmlns='urn:xmpp:privilege:0'>
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<perm namespace='jabber:iq:roster' type='both'/>
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<perm namespace='message'/>
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<perm namespace='presence' type='roster'/>
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<privilege xmlns='urn:xmpp:privilege:1'>
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<perm access='roster' type='both'/>
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<perm access='message'/>
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<perm access='presence' type='roster'/>
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</privilege>
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</message>
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]]></example>
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<p>Note the presence of <em>jabber:iq:roster</em> permission request.</p>
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<p>Note the presence of <em>roster</em> permission request.</p>
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</section2>
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<section2 topic="Privileged Entity Receive Roster Presences" anchor='priv_rec_roster_presence'>
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@ -313,10 +336,18 @@
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</section2>
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</section1>
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<section1 topic='Business Rules' anchor='rules'>
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<ol>
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<li>For "presence" access, if a privileged entity is connected after first &PRESENCE; stanzas have been received, the server MUST send it all the &PRESENCE; stanzas with no 'type' attribute it would have had if it was connected first (in other words: all the presences informations for connected entities it has access to).</li>
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<li>For "presence" access, if a privileged entity is supposed to received several time the same &PRESENCE; stanza, the server SHOULD send it only once. For example: if <em>pubsub.capulet.lit</em> has a "presence" access with a "roster" type for <em>capulet.lit</em>, and <em>juliet@capulet.lit</em> and <em>nurse@capulet.it</em> both have <em>romeo@montague.lit</em> in their roster. When romeo is available, <em>pubsub.capulet.lit</em> shoud have its &PRESENCE; stanza only once (instead of 2 times).</li>
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</ol>
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</section1>
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<section1 topic='Security Considerations' anchor='security'>
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<ol>
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<li>Privileged entitiy has access to sensitive data, and can act as the server itself, permissions should be granted carefuly, only if you absolutely trust the entity.</li>
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<li><link url='#roster_presence'>Roster presence</link> is particulary sensitive, because presence informations of whole rosters are shared.</li>
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<li>Generaly, the server MUST NOT allow the privileged entity to do anything that the managed entity could not do.</li>
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</ol>
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</section1>
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@ -326,9 +357,9 @@
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<section1 topic='XMPP Registrar Considerations' anchor='registrar'>
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<section2 topic='Protocol Namespaces' anchor='ns'>
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<p>The ®ISTRAR; includes 'urn:xmpp:privilege:0' in its registry of protocol namespaces (see &NAMESPACES;).</p>
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<p>The ®ISTRAR; includes 'urn:xmpp:privilege:1' in its registry of protocol namespaces (see &NAMESPACES;).</p>
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<ul>
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<li>urn:xmpp:privilege:0</li>
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<li>urn:xmpp:privilege:1</li>
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</ul>
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</section2>
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<section2 topic='Protocol Versioning' anchor='registrar-versioning'>
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<xs:schema
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xmlns:xs='http://www.w3.org/2001/XMLSchema'
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targetNamespace='urn:xmpp:privilege:0'
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xmlns='urn:xmpp:privilege:0'
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targetNamespace='urn:xmpp:privilege:1'
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xmlns='urn:xmpp:privilege:1'
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elementFormDefault='qualified'>
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<xs:element name='privilege'>
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@ -351,9 +382,9 @@
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<xs:element name='perm'
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maxOccurs='unbounded'>
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<xs:complexType>
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<xs:attribute name='namespace' use='required' type='xs:string'/>
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<xs:attribute name='access' use='required' type='xs:string'/>
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<xs:simpleType base='xs:NMTOKEN'>
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<xs:enumeration value='jabber:iq:roster'/>
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<xs:enumeration value='roster'/>
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<xs:enumeration value='message'/>
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<xs:enumeration value='presence'/>
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</xs:simpleType>
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</section1>
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<section1 topic='Acknowledgements' anchor='acks'>
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<p>Thanks to Sergey Dobrov, Dave Cridland, Steven Lloyd Watkin, Lance Stout and Johannes Hund for their feedbacks. Thanks to Adrien Cossa for his typos/style corrections.</p>
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<p>Thanks to Sergey Dobrov, Dave Cridland, Steven Lloyd Watkin, Lance Stout, Johannes Hund, Kurt Zeilenga and Kevin Smith for their feedbacks. Thanks to Adrien Cossa for his typos/style corrections.</p>
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<p>Privileged entity was initialy written to be a generic identity based access control (IBAC) which allows an entity to access sensitive data. After <link url='http://mail.jabber.org/pipermail/standards/2014-December/029378.html'>a discussion on standard mailing list</link>, it has been decided to restrict the current XEP to immediate needs to build an external PEP service, and to implement separately an Attribute Based Access Control (ABAC) which is more modern, generic and flexible. This XEP is still interesting for being easy to implement and doing the job.</p>
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</section1>
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