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    On 05/07/2012 10:08 PM, 陈军 wrote:
    <blockquote
      cite="mid:1336442882.45591.YahooMailNeo@web92401.mail.cnh.yahoo.com"
      type="cite">
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        <div><span>Every service that receives requests with a token
            needs to communicate with keystone to verify a user's
            identity.</span></div>
        <div>A rough diagram of how keystone works can be found in the
          sequence diagram:<span><a class="moz-txt-link-freetext" href="http://docs.openstack.org/trunk/openstack-identity/admin/content/what-is.html">http://docs.openstack.org/trunk/openstack-identity/admin/content/what-is.html</a></span></div>
        <div><span><br>
          </span></div>
        <div><span>While there is a mass of users or the scale of cloud
            becomes huge,</span><span> will </span><span> keystone be
            the bottlenect?<br>
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      <pre wrap="">_______________________________________________
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</pre>
    </blockquote>
    I think so, which is why I am working on this:<br>
    <a class="moz-txt-link-freetext" href="https://blueprints.launchpad.net/keystone/+spec/pki">https://blueprints.launchpad.net/keystone/+spec/pki</a><br>
    <br>
    <br>
    THe tl;dr  version:  provide the roles in the token as a
    cryptographically signed document.  The services like Glance and
    Nova will use a public key from Keystone to verify the tokens and
    roles instead of talking back to the Keystone server.<br>
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