Weird "No Instance Available" and its fix
Weird "No Instance Available" and its fix
- Subject: Weird "No Instance Available" and its fix
- From: Mike Schrag <email@hidden>
- Date: Thu, 20 Apr 2006 10:12:08 -0400
Occasionally I run into something really odd, and I thought I'd pass
along the solution in case someone else runs into it ...
One of our clients is running a prototype WO app and launching it
from Eclipse. Yesterday they changed the IP of that machine and all
of a sudden, the app just gives everyone's favorite friend "No
instance available". No error messages anywhere. Console looks
fine. After dorking around for quite a while, Brendan Duddridge
recommended I try changing my adaptor URL from 127.0.0.1 to localhost
to see if it made any difference. Upon changing it, instead of no
instance available, Safari tells me it can't find
host228.theirdomain.com, which was SUPPOSED to be the DNS name of the
box running the WO app (i.e. it doesn't know itself by its own
name). It turns out that there was ONLY a reverse DNS entry and not
a forward DNS entry. Somewhere deep in the bowels of WO, this caused
a series of explosions that resulted in silent failure -- my favorite
kind of time-wasting failure. By temporarily adding an /etc/hosts
entry, it immediately started working again.
So the moral of the story is to make sure the name that WO/Apache/etc
are using are resolvable, or you are going to have really strange
problems. At least with Wonder installed (this might display on
regular WO apps also? been a while), it will print out at startup
the InetAddress it's binding to. The toString of InetAddress is
("x.y.z.w/host.domain.com"). Whatever name is displayed on the right
side of the toString needs to be the name that is resolved. If you
just run locally, it's probably a rendezvous .local name, which
should be fine. But if it's a full-blown DNS name, make sure that
the entry for that name is configured properly.
Hope this saves someone at least a little time someday ...
ms
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