#summary XEP-0355 (Namespace Delegation) implementation
#labels Stage-Alpha

= Introduction =

Namespace Delegation is an extension which allows server to delegate some features handling to an entity/component.
Typical use case is an external PEP service, but it can be used more generally when your prefered server lack one internal feature and you found an external component which can do it.

= Details =

You can have all the details by reading the [http://xmpp.org/extensions/xep-0355.html XEP-0355]. Only the admin mode is implemented so far.

If you use it with a component, you need to patch core/mod_component.lua to fire a new signal. To do it, copy the following patch in a, for example, /tmp/component.patch file:
{{{
diff --git a/plugins/mod_component.lua b/plugins/mod_component.lua
--- a/plugins/mod_component.lua
+++ b/plugins/mod_component.lua
@@ -85,6 +85,7 @@
                session.type = "component";
                module:log("info", "External component successfully authenticated");
                session.send(st.stanza("handshake"));
+               module:fire_event("component-authenticated", { session = session });
 
                return true;
        end
}}}

Then, at the root of prosody, enter:

{{{patch -p1 < /tmp/component.patch}}}

= Usage =

To use the module, like usual add *"delegation"* to your modules_enabled. Note that if you use it with a local component, you also need to activate the module in your component section:

{{{
modules_enabled = {
		[...]
	
		"delegation";
}

[...]

Component "youcomponent.yourdomain.tld"
	component_secret = "yourpassword"
	modules_enabled = {"delegation"}
}}}

then specify delegated namespaces *in your host section* like that:

{{{
VirtualHost "yourdomain.tld"

	delegations = {
		["urn:xmpp:mam:0"] = {
			filtering = {"node"};
			jid = "pubsub.yourdomain.tld";
		},
		["http://jabber.org/protocol/pubsub"] = {
			jid = "pubsub.yourdomain.tld";
		},
	}
}}}

Here all MAM requests with a "node" attribute (i.e. all MAM pubsub request) will be delegated to pubsub.yourdomain.tld. Similarly, all pubsub request to the host (i.e. the PEP requests) will be delegated to pubsub.yourdomain.tld.

*/!\ Be extra careful when you give a delegation to an entity/component, it's a powerful access, only do it if you absoly trust the component/entity, and you know where the software is coming from*

= Configuration =
The configuration is done with a table which map delegated namespace to namespace data.
Namespace data MUST have a *jid* (in the form *jid = "delegated@domain.tld"*) and MAY have an additional *filtering* array. If filtering is present, request with attributes in the array will be delegated, other will be treated normally (i.e. by Prosody).

If your are not a developper, the delegated namespace(s)/attribute(s) are most probably specified with the external component/entity you want to use.

= Compatibility =
||dev||Need a patched core/mod_component.lua (see above)||
||0.9||Need a patched core/mod_component.lua (see above)||

= Note =
This module is often used with mod_privilege (c.f. XEP for more details)