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From Henry Story <henry.st...@bblfish.net>
Subject Re: Logged in as multiple users, how should application deal with this new feature?
Date Thu, 19 May 2011 14:15:53 GMT

On 19 May 2011, at 14:36, Reto Bachmann-Gmuer wrote:

> Hello
> 
> I've noticed that with the change to principals one can be logged in
> as multiple users.

To be precise the changes made use of the flexibility of Java's Subject class. 

http://download.oracle.com/javase/6/docs/api/javax/security/auth/Subject.html

The subject class is designed to allow one to have multiple Principals.
From the documentation

[[
A Subject represents a grouping of related information for a single entity, such as a person.
Such information includes the Subject's identities as well as its security-related attributes
(passwords and cryptographic keys, for example).

Subjects may potentially have multiple identities. Each identity is represented as a Principal
within the Subject. Principals simply bind names to aSubject. For example, a Subject that
happens to be a person, Alice, might have two Principals: one which binds "Alice Bar", the
name on her driver license, to the Subject, and another which binds, "999-99-9999", the number
on her student identification card, to the Subject. Both Principals refer to the same Subject
even though each has a different name.
]]

So this is not that different from Foaf. We can have multiple identifiers: social security
number, webid, username... These are all inverse functional properties.

> How are applications supposed to deal with this? In
> my wall-applcation and blogging engine I assumes a request originating
> from exactly one user (which can be user anonymous). I know wanted to
> updated my apps and was wondering how to do this.

What we need is to improve the ways to identify the user so that he can log in
various ways (including openid in the future or facebook connect).

I think we should do the following. Currently the user is identified in the 
graph <http://tpf.localhost/system.graph>

@prefix perm: <http://clerezza.org/2008/10/permission#> .
@prefix zz: <http://clerezza.org/2009/08/platform#> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .

</user/admin/profile#me>
    perm:hasPermission [
        perm:javaPermissionEntry "(java.security.AllPermission \"\" \"\")"
    ] ;
    perm:passwordSha1 "d033e22ae348aeb5660fc2140aec35850c4da997" ;
    zz:lastLogin "2011-05-17T18:03:48.558Z"^^<http://www.w3.org/2001/XMLSchema#dateTime>
;
    zz:userName "admin" ;
    a foaf:Agent ;
    foaf:mbox <mailto:noreply@clerezza.org> .


so here the user has already two identities 
 - the WebID </user/admin/profile#me>
 - the zz:userName "admin"
 
It would be easy to extend this to allow openid by adding the relation

</user/admin/profile#me> foaf:openid <http://bblfish.net/> .

The principal can therefore be either:
 - the webid
 - the openid
 - the account name ("admin", "joe",...)
 - facebook account, ...
it does not matter.

What we should do is to create subclasses of Principal (which anyway is just an interface)
to allow one to distinguish these different types of principals.

Each principal can then be used to get the resource (bnode or uri) that is the 
foaf:Agent, and the zz:userName should be shown if it exists, or some 
zz:preferredUserName, which could be set automatically. 


> The same difficulty occurs with the displayed username in the menu,
> and where the menu-item "control-panel" shall point to.

It should point to the home page, as now. 

If there are two non fused identities, the user should be asked if he wants to fuse them,
and which he prefers to have as his new home. I suppose one could also give him the opportunity
to log in as one or the other, by changing a menu.

There is also  CLEREZZA-515 "ugly account name when logging into ZZ with a foreign WebID"
though this would be just as valid for OpenIDs.

I can work on the core auth code change if someone can help me with the UI piece from there.

Henry

> 
> Reto

Social Web Architect
http://bblfish.net/


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