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Subject: Re: [wsrp-interop] Java dynamic domain name workaround


Title:
I noticed that the networking layer wasn't immediately failing - it was just timing out after a very long time. So it might still make sense to flush before a failure.

Rich Thompson wrote:

I agree, but usually one can detect the failure to open within the networking layer. This reasonably contains where one would instruct the resolver to flush any caching for the failed ip address.

Rich Thompson




Andre Kramer <andre.kramer@eu.citrix.com>

06/24/2003 09:01 AM

       
        To:        Rich Thompson/Watson/IBM@IBMUS, wsrp-interop@lists.oasis-open.org
        cc:        
        Subject:        RE: [wsrp-interop] Java dynamic domain name workaround



IP addresses get recycled or don't provoke ICMP messages, so the error can be above the IP (packet) layer.
 
regards,
Andre
-----Original Message-----
From:
Rich Thompson [mailto:richt2@us.ibm.com]
Sent:
24 June 2003 13:32
To:
wsrp-interop@lists.oasis-open.org
Subject:
Re: [wsrp-interop] Java dynamic domain name workaround


Shouldn't this also be reported as a bug? With increasing use of dynamic addresses, the resolver should be told to flush the cached entry when the IP address is unable to be opened. While this would add a small overhead for when static addresses can't be contacted due to network problems, it eliminates permanently stranding a dynamic ip address.


Rich Thompson



David Ward <david.ward@oracle.com>

06/23/2003 06:11 PM

       
       To:        Richard Jacob <richard.jacob@de.ibm.com>

       cc:        wsrp-interop@lists.oasis-open.org

       Subject:        [wsrp-interop] Java dynamic domain name workaround




I just wanted to make sure I hadn't left this as a "loose end". Apologies if you have already gathered together this information...

Richard Jacob wrote:

Btw. could you report today about that problem and your circumvention, so
we can pass it to the primer editor's?

The problem was that our Java mid tier, which is in our 'DMZ' (Demilitarized Zone?) and doesn't use a proxy, was simply unable to contact the IBM service, even though our test environment which ran through a proxy worked fine.

This turned out to be due to the way Java caches IP addresses. The java.net.InetAddress class by default caches IP addresses forever once it has resolved them once. However, the IBM domain name wsrp.dyndns.org actually gets associated with a new IP address every 24 hours, so this was bound to cause problems for our servlet container JVM that stays up forever.

If we were running on JDK 1.4, it appears we would be able to control the "time to live" for cached IP addresses through a security policy. However, it seems that the 'private' sun.net.inetaddr.ttl System property mentioned in the JDK 1.4 docs also has the same effect on JDK 1.3.

My solution was to edit the config file containing the startup options for the servlet container JVM (in Oracle 9iAS this is in opmn/conf/opmn.xml) so that the sun.net.inetaddr.ttl property is set with a small timeout (I used 120 seconds).

E.g.

java -Dsun.net.inetaddr.ttl=120 <normal JVM startup options>

Regards

David
--


David Ward
Principal Software Engineer
Oracle Portal
Oracle European Development Centre
520 Oracle Parkway
Thames Valley Park
Reading
Berkshire RG6 1RA
UK
Email:
david.ward@oracle.com
Tel:
+44 118 924 5079
Fax:
+44 118 924 5005






--


David Ward
Principal Software Engineer
Oracle Portal
Oracle European Development Centre
520 Oracle Parkway
Thames Valley Park
Reading
Berkshire RG6 1RA
UK
Email: david.ward@oracle.com
Tel: +44 118 924 5079
Fax: +44 118 924 5005




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