<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; ">So far, neither OpenID nor CardSpace define the notion of a session, so no common logout is possible within the standard protocols.<DIV><BR class="khtml-block-placeholder"></DIV><DIV>What we do in our code at NetMesh is to add a convention where</DIV><DIV> RP-URL?lid=OPENID</DIV><DIV>is the same thing as "submitted OpenID URL in the first form", to which the RP-URL responds with a redirect to the OP, while</DIV><DIV> RP-URL?lid=</DIV><DIV>means "become anonymous again" aka "logout".</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>There are substantial usability issues with common logout in a decentralized, "internet-scale" approach, however, that nobody has really solved as far as I know.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV><BR><DIV><DIV>On Apr 6, 2007, at 9:15, McGovern, James F ((HTSC, IT)) wrote:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"><P><FONT size="2" face="Arial">Curious question that someone asked that I didn't know the answer to. OpenID/Cardspace allow for easy SSO into web sites. How does one perform the equivalent logout from an Identity Selector?</FONT></P> <FONT size="3"><BR> <BR> *************************************************************************<BR> This communication, including attachments, is<BR> for the exclusive use of addressee and may contain proprietary,<BR> confidential and/or privileged information. If you are not the intended<BR> recipient, any use, copying, disclosure, dissemination or distribution is<BR> strictly prohibited. If you are not the intended recipient, please notify<BR> the sender immediately by return e-mail, delete this communication and<BR> destroy all copies.<BR> *************************************************************************<BR> </FONT><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">_______________________________________________</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">specs mailing list</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><A href="mailto:specs@openid.net">specs@openid.net</A></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><A href="http://openid.net/mailman/listinfo/specs">http://openid.net/mailman/listinfo/specs</A></DIV> </BLOCKQUOTE></DIV><BR></DIV></BODY></HTML>