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<TITLE>RADIUS/Radiator concurrency enforcement race condition?</TITLE>
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<P DIR=LTR><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">Hi folks,</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">I</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">’</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">m a little rusty here, so help me understand. But I seem to have discovered a problem, and I</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">’</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">m not sure whether it</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">’</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">s fundamental to the RADIUS protocol or just Radiator</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">’</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">s implementation.</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> </SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">Here</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">’</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">s an illustration:</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">1) </FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT COLOR="#0C02CA" FACE="Verdana">“</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">mikem</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">”</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana"> is allowed only one session at a time</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">, and is currently offline</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">.</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">2) </FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT COLOR="#0C02CA" FACE="Verdana">“</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">mikem</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">”</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana"> is clever, and he sets up 20</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT COLOR="#0C02CA" FACE="Verdana">access</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana"> clients to all log in at the same time.</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">3) </FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT COLOR="#0C02CA" FACE="Verdana">Radiator receives 20 Access-Requests</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana"> for</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT COLOR="#0C02CA" FACE="Verdana">“</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">mikem</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">”</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">, and processes them rapidly.</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT COLOR="#0C02CA" FACE="Verdana">Because he was offline,</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT COLOR="#0C02CA" FACE="Verdana">the SessionDatabase shows no hits for</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT COLOR="#0C02CA" FACE="Verdana">“</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">mikem</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">”</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">, and all Access-Reque</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">sts are approved.</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> </SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">4) </FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT COLOR="#0C02CA" FACE="Verdana">One by one, mikem</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">’</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">s access clients receive these Access-Accepts and opens up a session. As each session goes online, an Accounting-Request is sent to Radiator</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">, and Radiator adds it to the session database. </FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">5) </FONT></SPAN><SPAN LANG="en-us"> <FONT COLOR="#0C02CA" FACE="Verdana">At the end, the session database shows all 20 sessions online</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">,</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT COLOR="#0C02CA" FACE="Verdana">and mikem has successfully evaded simultaneous-use limits.</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">In other words, the problem is caused by the fact that</FONT></SPAN><SPAN LANG="en-us"><I></I></SPAN><SPAN LANG="en-us"><I> <FONT COLOR="#0C02CA" FACE="Verdana">the step that checks for concurrency is separate</FONT></I></SPAN><SPAN LANG="en-us"><I></I></SPAN><SPAN LANG="en-us"><I><FONT COLOR="#0C02CA" FACE="Verdana">d</FONT></I></SPAN><SPAN LANG="en-us"><I></I></SPAN><SPAN LANG="en-us"><I><FONT COLOR="#0C02CA" FACE="Verdana"> from the step that logs the session</FONT></I></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">.</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT COLOR="#0C02CA" FACE="Verdana">A DB Admin will describe this as a lack of</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT COLOR="#0C02CA" FACE="Verdana">“</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">transaction processing</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">”</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">.</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> </SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">Now, normally, this might be a rare situation. But we are working on a solution that will use Radiator to enforce concurrency</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT COLOR="#0C02CA" FACE="Verdana">with a</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT COLOR="#0C02CA" FACE="Verdana">“</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">NAS</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">”</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana"> that will be hit with an automatic (software) dialer which will rapid-fire the requests as illustrated.</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> </SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">Any thoughts or fee</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">dback is most welcome!</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT COLOR="#0C02CA" FACE="Verdana">Dave</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN></P>
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