namespace delegation

# HG changeset patch # User Goffi # Date 1415884215 -3600 # Node ID b04be960ebdf6a819db6afbea3bac362d2c0cffa # Parent b27e7f9ad4792f4ecd0ac22002990f48c824d09b xep: namespace delegation first draft: this xep provides a way for XMPP server to delegate treatments for a namespace to an other entity diff -r b27e7f9ad479 -r b04be960ebdf xmpp/xep-proto-namespace-delegation.xml --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/xmpp/xep-proto-namespace-delegation.xml Thu Nov 13 14:10:15 2014 +0100 @@ -0,0 +1,574 @@ + + +%ents; +]> + + +

+ namespace delegation + This specification provides a way for XMPP server to delegate treatments for a namespace to an other entity + + This XMPP Extension Protocol is copyright (c) 1999 - 2014 by the XMPP Standards Foundation (XSF). + Permission is hereby granted, free of charge, to any person obtaining a copy of this specification (the "Specification"), to make use of the Specification without restriction, including without limitation the rights to implement the Specification in a software program, deploy the Specification in a network service, and copy, modify, merge, publish, translate, distribute, sublicense, or sell copies of the Specification, and to permit persons to whom the Specification is furnished to do so, subject to the condition that the foregoing copyright notice and this permission notice shall be included in all copies or substantial portions of the Specification. Unless separate permission is granted, modified works that are redistributed shall not contain misleading information regarding the authors, title, number, or publisher of the Specification, and shall not claim endorsement of the modified works by the authors, any organization or project to which the authors belong, or the XMPP Standards Foundation. + ## NOTE WELL: This Specification is provided on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. In no event shall the XMPP Standards Foundation or the authors of this Specification be liable for any claim, damages, or other liability, whether in an action of contract, tort, or otherwise, arising from, out of, or in connection with the Specification or the implementation, deployment, or other use of the Specification. ## + In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall the XMPP Standards Foundation or any author of this Specification be liable for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising out of the use or inability to use the Specification (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if the XMPP Standards Foundation or such author has been advised of the possibility of such damages. + This XMPP Extension Protocol has been contributed in full conformance with the XSF's Intellectual Property Rights Policy (a copy of which may be found at <http://xmpp.org/extensions/ipr-policy.shtml> or obtained by writing to XSF, P.O. Box 1641, Denver, CO 80201 USA). + + xxxx + ProtoXEP + Standards Track + Standards + Council + + XMPP Core + XEP-0004 + XEP-0297 + + + + NOT_YET_ASSIGNED + + Jérôme + Poisson + goffi@goffi.org + goffi@jabber.fr + + + 0.0.1 + 2014-11-13 + jp +

First draft.

+ +

Some XMPP features must be offered by the server itself, or can't be available, that's the case of &xep0163; which is used in several places (e.g. bookmarks storage). But it can be desirable to use an external entity to manage some of these features, because it implements things that the server don't, or because it use a special implementation useful in a particular case. Some people may also want to decentralize a feature on an entity under their control. This XEP try to solve these cases.
Additionaly, a method to do generic treatments (independant of server) on stanza is also provided.

This XEP is complementary to priviliged entity XEP (and works in a similar way), although they can be used together or separely

Here are some use cases of namespace delegation:

use an external component for a PEP service because the server doesn't implement it or lack some features
decentralize a server feature to an entity under client control
do a component which react on new user registration, independent of server implementation
server agnostic roster filtering

+ + +

Namespace delegation can be used in two modes:

admin mode, where delegation is specified by the server administrator.
client mode, where it can be requested by any user.

In admin mode, the managing entity manage stanza of the delegated namespace for all users registered on the server. The namespace delegation MUST be totally transparent for the managed entities.

In client mode, a managing entity MUST have an explicit autorization for any namespace he wants to use. Client SHOULD be able to check and revoke granted permissions, and if it's not possible, permissions MUST be revoked after a disconnection.

+ + +

Delegated namespace — the namespace being managed by an external entity.
Managing entity — the entity which actualy manage the delegated namespace.
Managed entity — an entity which wants to have a namespace of its server delegated to a managing entity.

+ + + + + +

Once the managing entity is authentified and stream is started, the entity can request to manage a namespace. It do it by sending an &IQ; stanza with 'urn:xmpp:delegation:0' namespace. The &QUERY; element MUST have a type of value "request" and MAY have a 'delegation' attribute with the value "admin".

Namespace delegations are asked with a <delegate/> element, which MUST contain a 'namespace' attribute set to the requested namespace

Only <iq/> stanza namespaces can be delegated.

+ + + + + + + ]]> + + +

If the server accept the delegation (e.g.: namespace mapping specified in configuration), it MUST return an &IQ; result stanza, with allowed delegations in <delegate> elements:

+ + + + + + +]]> +

Note: the granted delegations MAY be different from the requested ones, according to server's configuration.

The server MUST then forward all requests done to itself on this namespace to the managing entity, except the request done by the managing entity itself (see below).
+ The server MUST NOT forward any request done to an other entity than itself or a bare jid with its domain.

+ + +

If the server reject the delegation, it MUST return a &forbidden; error:

+ + + + + + ]]> + + + + +

When a server receives a stanza for a delegated namespace which is either directed to him (no 'to' attribute, or 'to' attribute with its own jid), or directed to the bare jid of the sender (e.g. if 'from' attribute is "juliet@capulet.lit/balcony" and 'to' attribute is "juliet@capulet.lit"), it MUST forward it to the managing entity by replacing the 'to' attribute with the jid of the managing entity:

+ + + + + + + curse my nurse! + + + + + +]]> +

The server get this stanza, see that this namespace is delegated to pubsub.capulet.lit, so it forward it:

+ + + + + + + + curse my nurse! + + + + + +]]> + +

The managing entity reply normally to the stanza:

+ + + +]]> + +

Then the server MUST change the from field of managing entity to its own field, and send the answer back to Julied with the original &IQ; id

+ + + + +]]> + +

The workflow is fully transparent for Juliet

+ +

If a stanza is sent by the managing entity on a managed namespace, the server MUST NOT forward it. This way, the managing entity can use privileged entity to do special treatments

In the following examples, juliet@capulet.lit has its "jabber:iq:roster" namespace delegated to filter.capulet.lit. filter.capulet.lit is a server agnostic component which filter allowed entity (which can be added to a roster), and sort them in enforced groups

+ + + + + + + +]]> + + + + + + + +]]> + +

filter.capulet.lit accept to add Romeo, but all jids with a montaigu.lit must be in a "Rivals" group, so it first return a success result (romeo is accepted)

+ +]]> + +]]> + +

At this stade, the entity is accepted, but not added to the roster. filter.capulet.lit is also a privileged entity which can manage "jabber:iq:roster", so it use this ability to add romeo with the enforced group:

+ + + + Rivals + + + +]]> +

The namespace is delegated, but as the stanza is from the managing entity, the server manage it normally. The entity is also privileged, so it can change the stanza of Juliet, the server accept:

+ + +]]> + +

The server will then send the roster pushes (with the enforced group) normally.

+ + + + + + + + + + +

In client mode, the managing entity is not certified by the server administrator, so the delegation MUST be explicitly allowed by the managed entity. This is initiated by the managing entity (it can be after an interaction with a managed entity, like a subscription). It's done in the same way as for admin mode with the following exceptions:

the delegation type is client instead of admin
the delegation is done per entity, so the managed entity MUST be specified in a 'to' attribute

If an entity want to manage PEP service for juliet, it can ask the delegation like this: +

+ + + + + + ]]> +

Once received the delegation request, the server ask to the client if it grant access to the requested namespace using &xep0004;. The server use a challenge which it MUST have generated itself. +

+ + + pubsub.montaigu.lit wants to manage a feature normally managed by the server. + Do you you allow him to manage the following features ? + + Be careful ! According management to entity is a serious thing, + think twice that you can trust the entity before doing this. + + + Delegation request + pubsub.montaigu.lit wants to manage the following features: + Do you allow it? + 5439123 + + urn:xmpp:delegation:0 + + + 0 + + + + + + ]]> +

The server SHOULD include a warning message, SHOULD translate the namespace to human friendly names (and MAY keep the original namespace in addition) and MUST set the default value to '0' (permission refused). The server SHOULD use namespace as field var, so a client can use it to have a customized display.

The client can then answer to the form:

+ + + + + + 5439123 + 1 + + + ]]> +

Here juliet accept that pubsub.montaigu.lit manage the PubSub (and then PEP) service.

Finaly, the server notify the entity of the delegation granted. For this it use a &QUERY; element with the 'allowed' type, and put the client jid in a 'from' attribute:

+ + + + + + ]]> +

The managing entity can now manage the namespace the same way as in admin mode.

+ + + + + +

Server SHOULD provide a way to clients to check already delegated namespaces, and revoke them by using &xep0050; on the well-defined command node of 'urn:xmpp:delegation:0#configure'.

If present, the configurations commands MUST allow at least to check delegations granted to a managing entity, and to revoke them. A server MAY offer an option to keep delegations from one session to an other (see business rules).

+ + + + +

If a server or an entity supports the namespace delegation protocol, it MUST report that fact by including a service discovery feature of "urn:xmpp:delegation:0" in response to a &xep0030; information request:

+ + + + ]]> + + + ... + + ... + + + ]]> + + + +

When a server delegate a namespace to a managing entity, the later can have particular features which must be advertised by the former with disco protocol.

This is done by using a disco node, which is done in the following way: if pubsub.capulet.int manage pubsub namespace, it MUST report that fact in discovery feature, and have a 'urn:xmpp:delegation:0::http://jabber.org/protocol/pubsub' node which report features managed.

The node name is obtained by concatenating this XEP namespace (urn:xmpp:delegation:0), a '::' separator, and the delegated namespace (here http://jabber.org/protocol/pubsub).
The server MUST advertise the result in its own discovery answer, and MUST ignore features of its internal component (here internal PubSub service).

In the following example, the capulet.int server delegate it's internal PEP component to pubsub.capulet.int. capulet.int only support REQUIRED PubSub features and auto-create, while pubsub.capulet.int support also REQUIRED PubSub features and publish-options, but not auto-create.
juliet@capulet.int ask its server what it is capable of, she is specially interested in PubSub capabilities.

+ + + + ]]> + +

Server delegate its PubSub namespace to pubsub.capulet.lit, so it ask its available features for this namespace like this

+ + + + ]]> + +

Note that in real situation, server has probably this information already in cache (see Implementation Notes).
+ pubsub.capulet.lit return its available features

+ + + + + + + + + ]]> + +

Server include the results in its own discovery info results:

+ + + + ... + + + + + ... + + + ]]> + +

Note that 'http://jabber.org/protocol/pubsub#auto-create' is not available.

+ + +

As an entity may ask for discovery informations on bare jid, which the server would answer, the managing entity must be able to send this kind of information.

To do so, the mechanism is the same as for server features, but the separator is ':bare:' instead of '::':

+ + + + + ]]> + +

Server delegate its PubSub namespace to pubsub.capulet.lit, so it ask its available features for this namespace like this

+ + + + ]]> + +

As for general case, server has probably this information already in cache.
+ pubsub.capulet.lit return its available features

+ + + + + + + + + + + + + + + ... + + + ]]> + +

then the server return the answer to Juliet, as in general case, with requested bare jid in 'from' field.

+ + + + + + + + + + + + + + + + ... + + + ]]> + + + + + + + +

In client mode, server MAY keep delegations granted to an entity by a client from one session to an other, but if it do so, it MUST provide configuration like explained in the suitable section. If server offer this feature, it SHOULD add a field directly in configuration commands.
If a client can't check or revoke delegations (i.e. it doesn't support &xep0050;) when granting them, the server MUST NOT keep granted delegations from one session to an other, and delegations will be asked on each new session.
If delegations are changed during a session, server MUST notify managing entity of the new delegations, like in client delegation request use case
The namespace of this XEP (urn:xmpp:delegation:0) MUST NOT be delegated. If an entity request it, the server MUST return a &forbidden; error

+ + +

As admin mode is far more easy to implement than client mode, and client mode may impact performances, a server MAY choose to only implement the former.
Because of the performance impact, a server SHOULD ask for disco features to nest to managing entity when delegation is accepted, and keep them in cache.

+ + +

Managing entity can manage sensitive data, admin delegation should be granted carefuly, only if you absolutely trust the entity.
A server MAY choose to filter allowed namespaces. In this case, it MUST always set the allowed type of filtered namespaces to 0
In case of filtering, a whitelist system is more secure and SHOULD be prefered to a blacklist (idealy, configuration would allow no filtering, whitelist filtering and blacklist filtering)

+ + +

This document requires no interaction with &IANA;.

+ + + +

The ®ISTRAR; includes 'urn:xmpp:delegation:0' in its registry of protocol namespaces (see &NAMESPACES;).

urn:xmpp:delegation:0

+ + + &NSVER; + + + +

+ + +

This XEP is linked with XEP-XXXX privileged entity and works in a similar way.

The client mode delegation mechanism is inspired from &xep0321; permission request.

+ +