The landing page that the generated URL points to should correspond to + the format described in XEP-0379 §3.3, and it needs to + convey the following information:
+If the landing page is hosted by Romeo's server, the server MAY display + additional information based on the supplied TOKEN value, like the name + of the inviter or validity information.
If Juliet does not have an XMPP client installed, she will not be able + to open the xmpp: link from the invitation page. + For this case, the landing page needs to indicate that a client must be + installed first, and that the link will not work as intended without. + The automatic installation of an appropriate IM client when a user + clicks on an xmpp: is outside of the scope of this + document.
+With an XMPP client installed, Juliet can open the + xmpp: link and have the client process it + appropriately, as follows:
+If Juliet's client is already configured with an account, the default + action for the presented + xmpp:inviter@example.com?roster;... URI is to add the + inviter to Juliet's roster. This should be performed as described in + §3.4 of XEP-0379, by sending a presence subscription + request containing the 'preauth' token.
+If Juliet already has Romeo in her roster, her client should open the + appropriate chat interface instead.
+If Juliet's client does not have an XMPP account configured, she + needs to login or register an account first. Therefore, the client + should provide an interface with the following options:
+If the xmpp: URI provided by Romeo contains the + ibr=y parameter, it indicates that the server + supports the Pre-Authenticated In-Band + Registration defined in this document. If Juliet chooses this + approach, the server will ensure that after the registration, Romeo is + added to her roster with a full presence subscription.
If + Juliet chooses to login or register with a different server, her + client must complete the respective process and issue a subscription + request as described in §3.4 of XEP-0379.
+If Romeo is the administrator of an XMPP server, he might want to + ensure that Juliet obtains an account on this server, with a username + defined either by Romeo or by Juliet, and in a way that does not require + the out-of-band communication of user passwords.
+TODO: description of overall process steps, design motivation.
xmpp:example.com?register;preauth=TOKEN
+ TODO: note about sensitivity of TOKEN
In order to allow invited users to register on a server, in-band - registration as defined in &xep0077; needs to be extended. - The invited user MUST send the following extended stanza in order to - register an account with a token.
+In order to allow invited users to register on a server, the + registration processs as defined in &xep0077; needs to be extended. The + invited user's client MUST add a <preauth> element in the 'TODO' + namespace to the 'jabber:iq:register' query in order to inform the + server that it wants to perform Pre-Authenticated IBR:
If the server supports and is ready to perform Pre-Authenticated IBR, + it MUST add a <token> element to the response (TODO: 'token' or + 'preauth'?):