<s>
Yadis	B-General_Concept
is	O
a	O
communications	O
protocol	O
for	O
discovery	O
of	O
services	O
such	O
as	O
OpenID	O
,	O
OAuth	O
,	O
and	O
XDI	O
connected	O
to	O
a	O
Yadis	B-General_Concept
ID	O
.	O
</s>
<s>
While	O
intended	O
to	O
discover	O
digital	B-Application
identity	I-Application
services	O
,	O
Yadis	B-General_Concept
is	O
not	O
restricted	O
to	O
those	O
.	O
</s>
<s>
A	O
Yadis	B-General_Concept
ID	O
can	O
either	O
be	O
a	O
traditional	O
URL	O
or	O
a	O
newer	O
XRI	O
i-name	O
,	O
where	O
the	O
i-name	O
must	O
resolve	O
to	O
a	O
URL	O
.	O
</s>
<s>
The	O
so-called	O
Yadis	B-General_Concept
URL	O
either	O
equals	O
the	O
Yadis	B-General_Concept
ID	O
(	O
if	O
this	O
is	O
a	O
URL	O
)	O
or	O
the	O
resolved	O
URL	O
of	O
the	O
XRI	O
i-name	O
.	O
</s>
<s>
Furthermore	O
,	O
Yadis	B-General_Concept
specifies	O
how	O
to	O
use	O
the	O
Yadis	B-General_Concept
URL	O
to	O
retrieve	O
a	O
service	O
descriptor	O
called	O
Yadis	B-General_Concept
Resource	O
Descriptor	O
.	O
</s>
<s>
This	O
descriptor	O
follows	O
the	O
XRDS	O
format	O
and	O
connects	O
several	O
services	O
,	O
like	O
authentication	O
or	O
authorization	O
to	O
the	O
Yadis	B-General_Concept
URL	O
.	O
</s>
<s>
Yadis	B-General_Concept
follows	O
the	O
REST-ful	O
,	O
"	O
small	O
pieces	O
loosely	O
joined	O
"	O
paradigm	O
that	O
has	O
proven	O
to	O
be	O
successful	O
in	O
the	O
development	O
of	O
the	O
web	O
.	O
</s>
<s>
Yadis	B-General_Concept
then	O
associates	O
an	O
XRDS	O
document	O
(	O
an	O
XML-based	O
capability	O
file	O
)	O
with	O
each	O
URL	O
that	O
expresses	O
the	O
associated	O
capabilities	O
or	O
services	O
.	O
</s>
<s>
The	O
owner	O
of	O
a	O
Yadis	B-General_Concept
identifier	O
can	O
choose	O
which	O
services	O
he	O
wishes	O
to	O
use	O
in	O
his	O
XRDS	O
document	O
.	O
</s>
<s>
After	O
retrieving	O
this	O
document	O
,	O
a	O
relying	O
party	O
such	O
as	O
a	O
website	O
accepting	O
Yadis	B-General_Concept
identifiers	O
can	O
select	O
an	O
appropriate	O
services	O
of	O
the	O
XRDS	O
document	O
,	O
e.g.	O
</s>
<s>
This	O
can	O
allow	O
existing	O
web	O
sites	O
,	O
like	O
blogs	O
,	O
to	O
easily	O
implement	O
basic	O
Yadis	B-General_Concept
functionality	O
(	O
for	O
instance	O
,	O
redirecting	O
users	O
who	O
arrive	O
at	O
a	O
blog	O
to	O
relevant	O
information	O
about	O
the	O
person	O
the	O
blog	O
belongs	O
to	O
)	O
while	O
also	O
making	O
it	O
possible	O
to	O
build	O
more	O
advanced	O
applications	O
(	O
for	O
example	O
,	O
allowing	O
complex	O
queries	O
of	O
a	O
site-owner	O
'	O
s	O
information	O
to	O
be	O
submitted	O
directly	O
to	O
the	O
Yadis	B-General_Concept
site	O
)	O
.	O
</s>
<s>
The	O
URL	O
is	O
a	O
Yadis	B-General_Concept
identity	O
URL	O
.	O
</s>
<s>
This	O
URL	O
supports	O
version	O
1.0	O
and	O
version	O
2.0	O
of	O
the	O
LID	B-General_Concept
protocol	O
,	O
with	O
a	O
delegate	O
.	O
</s>
<s>
because	O
a	O
relying	O
party	O
does	O
not	O
support	O
OpenID	O
,	O
or	O
because	O
the	O
LiveJournal	O
server	O
is	O
unavailable	O
)	O
,	O
the	O
owner	O
would	O
like	O
to	O
use	O
the	O
LID	B-General_Concept
URL	O
http://mylid.net/liddemouser	O
(	O
priority	O
20	O
)	O
,	O
followed	O
by	O
the	O
MyOpenID	O
service	O
(	O
priority	O
50	O
)	O
.	O
</s>
<s>
Yadis	B-General_Concept
was	O
initiated	O
by	O
developers	O
of	O
the	O
Light-weight	B-General_Concept
Identity	I-General_Concept
(	O
LID	B-General_Concept
)	O
and	O
OpenID	O
protocols	O
.	O
</s>
<s>
However	O
,	O
Yadis	B-General_Concept
is	O
an	O
open	O
initiative	O
,	O
so	O
other	O
developers	O
will	O
start	O
using	O
XRDS	O
lightweight	O
capabilities	O
description	O
,	O
making	O
possible	O
a	O
"	O
mix	O
and	O
match	O
"	O
approach	O
to	O
building	O
Yadis-enabled	O
applications	O
,	O
enabling	O
application	O
developers	O
to	O
choose	O
their	O
own	O
balance	O
between	O
ease	O
of	O
implementation	O
on	O
one	O
hand	O
,	O
and	O
range	O
of	O
features	O
on	O
the	O
other	O
.	O
</s>
