This doesn't need to be done, LOCATION_FORWARD_PERM has been deprecated before
we implemented it ;-)

Issue 1486: LOCATE_FORWARD_PERM and hash() (interop)
Click here for this issue's archive.
Nature: Uncategorized Issue
Severity:
Summary: Summary: With GIOP 1.2, we added LOCATE_FORWARD_PERM to the protocol,
which permanently replaces an IOR with a different one. I believe we shouldn"t
have done this because it creates an internal inconsistency. The Object::hash()
operation requires that the hash value for a reference must be immutable during
its life time. (Unfortunately, "life time" isn"t well-defined.)

Discussion:
At the final meeting of the Interop2000 rtf, it was agreed that unless fixes to
the identified problems could be found, use of locate forward perm should be
depricated.

Resolution:
Since these fixes have not arrived, the resolution proposed is to depricated use
of LOCATE_FORWARD_PERM
Proposed Revised Text:
Add the following statement to 13.4.3.2 at the end of the bullet list containing
the explanation for LOCATE_FORWARD_PERM:
"
Note: Usage of LOCATE_FORWARD_PERM is now depricated, due to problems it causes
with the semantics of the Object::hash() operation.   LOCATE_FORWARD_PERM
features will be removed from future GIOP versions.
"
Add the following statement to 13.4.6.1 at the end of the bullet list containing
the explanation for OBJECT_FORWARD_PERM:
"
Note: Usage of OBJECT_FORWARD_PERM is now depricated, due to problems it causes
with the semantics of the Object::hash() operation.   OBJECT_FORWARD_PERM
features will be removed from future GIOP versions.
"

In 15.6, immediately after the paragraph beginning "For GIOP version 1.2, the
usage of LOCATION_FORWARD_PERM (OBJECT_FORWARD_PERM) behaves like ...", add the
following
"
Note: Usage of LOCATE_FORWARD_PERM and OBJECT_FORWARD_PERM is now depricated,
due to problems it causes with the semantics of the Object::hash() operation.  
LOCATE_FORWARD_PERM and OBJECT_FORWARD_PERM will be removed from future GIOP
versions.

Actions taken:
June 3, 1998: received issue

Hi Johnny,

I'm not sure this is as straight forward as all that. See "23.2.5 - Accessing
Server Object Groups". It states:

"As object
replicas fail and are replaced by new replicas, a stage may be reached at which
all of
the original replicas, cited in the original interoperable object group
reference for the
object, are inaccessible. Continued use of the original reference will cause system
failure. The LOCATION_FORWARD_PERM exception allows such a reference to
be replaced by an updated reference that contains profiles for the new replacement
replicas. Thus, the LOCATION_FORWARD_PERM exception is not deprecated
when it is used to return an interoperable object group reference. The use of the
LOCATION_FORWARD_PERM exception to return a reference that is not an
interoperable object group reference continues to be deprecated."

To be fully fault tolerant TAO should be able to take the appropriate and
distinct action when it receives one.

You are right, did miss the FT part, reopen

Created attachment 510 [details]
tar-gz containing patch and tests

The tar-gz, attached 03/28/06, contains the feature patch for
LOCATION_FORWARD_PERM, and unit tests, to test the feature.

To use this feature, the applications must be linked against libraries 
"pi_server" and  "ftorb", for example see test application
TAO/orbsvcs/tests/FaultTolerance/GroupRef_Manipulation. 

The LOCATION_FORWARD_PERM will be sent by server instead of normal
LOCATION_FORWARD, if two conditions are given:
* the incoming request message has a FT-service-context attached.
* the forward-location object which shall be returned to client contains
FT-TaggedComponents in first profile (index 0), for details see
FT_Service_Callbacks::is_permanent_forward_condition().


The receiving  side will receive the LOCATION_FORWARD_PERM target and handles it
similar to normal LOCATION_FORWARD, the only difference is that
TAO_Stub::add_forward_object() will be called with flag indicating it should be
handled as permanent forward. Due to the fact that the "base_profiles" within
each TAO_Stub must be constant for hashing purpose and not protected against
concurrent access the "base_profiles" are not replaced by new permanent target.

Instead following design has been choosen, using the thread-safe
"forward_profiles" stack.

In case the client receives a LOCATION_FORWARD_PERM in object's TAO_Stub the
complete forward_profiles_ stack will be reset and the permanent target will be
pushed onto. A new TAO_Stub member-attribute will mark the new "permanent"
target; more non-permanent forward locations can be handled and are pushed onto
the stack. Non-permanent forward targets can be popped from stack if not
reachable anymore, until the "permanent" targets (MProfile)  at bottom are
reached. This feature of TAO_Stub is tested with TAO/tests/Permanent_Forward.

As before, hashvalues of objects references are computed based on
TAO_Stub::base_profiles_. No difference with IOGRs, here the hashvalue is
computed based on group-id encoded in base_profiles. Therefore for IOGR, it does
not make a difference calculating hash-values based on base_profiles or the new
permanent target profiles after  LOCATION_FORWARD_PERM. 

Marshaling object references, the new permanent-targets on bottom of
"forward_profiles" stack take precedence, otherwise the "base_profiles" are
marshaled into stream.

This has the following consequence, if object-references are initialized from
corbalocs, and permanently forwarded later to IOGR object reference, identity is
not retained  after transformation to stringified  representation and back. This
is due to the fact that corbalocs do not feature FT-Groups. If identity is
required, FT-objects must be initilized from stringified or binary IOGR.

NICE-TO_Have for future releases: introduce service-configuration to
enable/disable the LOCATION_FORWARD_PERM feature.

patch has been committed:

Commit authorized, you are a member of the release team
Checking in TAO/orbsvcs/orbsvcs/FaultTolerance/FT_Service_Callbacks.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/orbsvcs/orbsvcs/FaultTolerance/FT_Service_Callbacks.cpp,v
 <--  FT_Service_Callbacks.cpp
new revision: 1.36; previous revision: 1.35
done
Checking in TAO/orbsvcs/orbsvcs/FaultTolerance/FT_Service_Callbacks.h;
/project/cvs-repository/ACE_wrappers-repository/TAO/orbsvcs/orbsvcs/FaultTolerance/FT_Service_Callbacks.h,v
 <--  FT_Service_Callbacks.h
new revision: 1.26; previous revision: 1.25
done
Checking in
TAO/orbsvcs/tests/FaultTolerance/GroupRef_Manipulation/Server_Request_Interceptor.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/orbsvcs/tests/FaultTolerance/GroupRef_Manipulation/Server_Request_Interceptor.cpp,v
 <--  Server_Request_Interceptor.cpp
new revision: 1.17; previous revision: 1.16
done
Checking in
TAO/orbsvcs/tests/FaultTolerance/GroupRef_Manipulation/Server_Request_Interceptor.h;
/project/cvs-repository/ACE_wrappers-repository/TAO/orbsvcs/tests/FaultTolerance/GroupRef_Manipulation/Server_Request_Interceptor.h,v
 <--  Server_Request_Interceptor.h
new revision: 1.3; previous revision: 1.2
done
Checking in TAO/orbsvcs/tests/FaultTolerance/GroupRef_Manipulation/client.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/orbsvcs/tests/FaultTolerance/GroupRef_Manipulation/client.cpp,v
 <--  client.cpp
new revision: 1.5; previous revision: 1.4
done
Checking in TAO/orbsvcs/tests/FaultTolerance/GroupRef_Manipulation/test.idl;
/project/cvs-repository/ACE_wrappers-repository/TAO/orbsvcs/tests/FaultTolerance/GroupRef_Manipulation/test.idl,v
 <--  test.idl
new revision: 1.4; previous revision: 1.3
done
Checking in TAO/tao/GIOP_Message_Base.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/GIOP_Message_Base.cpp,v
 <--  GIOP_Message_Base.cpp
new revision: 1.119; previous revision: 1.118
/home/frehberger/dead.letter... Saved message in /home/frehberger/dead.letter
/home/frehberger/dead.letter... Saved message in /home/frehberger/dead.letter
done
Checking in TAO/tao/GIOP_Message_Generator_Parser.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/GIOP_Message_Generator_Parser.cpp,v
 <--  GIOP_Message_Generator_Parser.cpp
new revision: 1.16; previous revision: 1.15
done
Checking in TAO/tao/Invocation_Adapter.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/Invocation_Adapter.cpp,v
 <--  Invocation_Adapter.cpp
new revision: 1.25; previous revision: 1.24
done
Checking in TAO/tao/Invocation_Adapter.h;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/Invocation_Adapter.h,v 
<--  Invocation_Adapter.h
new revision: 1.20; previous revision: 1.19
done
Checking in TAO/tao/ORB_Core.h;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/ORB_Core.h,v  <-- 
ORB_Core.h
new revision: 1.301; previous revision: 1.300
done
Checking in TAO/tao/ORB_Core.i;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/ORB_Core.i,v  <-- 
ORB_Core.i
new revision: 1.161; previous revision: 1.160
done
Checking in TAO/tao/Object.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/Object.cpp,v  <-- 
Object.cpp
new revision: 1.175; previous revision: 1.174
/home/frehberger/dead.letter... Saved message in /home/frehberger/dead.letter
done
Checking in TAO/tao/Service_Callbacks.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/Service_Callbacks.cpp,v
 <--  Service_Callbacks.cpp
new revision: 1.17; previous revision: 1.16
done
Checking in TAO/tao/Service_Callbacks.h;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/Service_Callbacks.h,v 
<--  Service_Callbacks.h
new revision: 1.19; previous revision: 1.18
done
Checking in TAO/tao/Stub.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/Stub.cpp,v  <--  Stub.cpp
new revision: 1.172; previous revision: 1.171
/home/frehberger/dead.letter... Saved message in /home/frehberger/dead.letter
done
Checking in TAO/tao/Stub.h;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/Stub.h,v  <--  Stub.h
new revision: 1.113; previous revision: 1.112
done
Checking in TAO/tao/Stub.i;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/Stub.i,v  <--  Stub.i
new revision: 1.54; previous revision: 1.53
done
Checking in TAO/tao/Synch_Invocation.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/Synch_Invocation.cpp,v 
<--  Synch_Invocation.cpp
new revision: 1.34; previous revision: 1.33
done
Checking in TAO/tao/TAO_Server_Request.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/TAO_Server_Request.cpp,v
 <--  TAO_Server_Request.cpp
new revision: 1.50; previous revision: 1.49
done
Checking in TAO/tao/DynamicInterface/DII_Invocation_Adapter.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/DynamicInterface/DII_Invocation_Adapter.cpp,v
 <--  DII_Invocation_Adapter.cpp
new revision: 1.13; previous revision: 1.12
/home/frehberger/dead.letter... Saved message in /home/frehberger/dead.letter
done
Checking in TAO/tao/DynamicInterface/Request.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/DynamicInterface/Request.cpp,v
 <--  Request.cpp
new revision: 1.42; previous revision: 1.41
done
Checking in TAO/tao/Messaging/Asynch_Invocation_Adapter.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/Messaging/Asynch_Invocation_Adapter.cpp,v
 <--  Asynch_Invocation_Adapter.cpp
new revision: 1.20; previous revision: 1.19
done
Checking in TAO/tao/Messaging/Asynch_Reply_Dispatcher.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/Messaging/Asynch_Reply_Dispatcher.cpp,v
 <--  Asynch_Reply_Dispatcher.cpp
new revision: 1.23; previous revision: 1.22
done
Checking in bin/tao_orb_tests.lst;
/project/cvs-repository/ACE_wrappers-repository/bin/tao_orb_tests.lst,v  <-- 
tao_orb_tests.lst
new revision: 1.98; previous revision: 1.97
done
/home/frehberger/dead.letter... Saved message in /home/frehberger/dead.letter
Checking in ChangeLog;
/project/cvs-repository/ACE_wrappers-repository/ChangeLog,v  <--  ChangeLog
/home/frehberger/dead.letter... Saved message in /home/frehberger/dead.letter
new revision: 4.10077; previous revision: 4.10076
/home/frehberger/dead.letter... Saved message in /home/frehberger/dead.letter
done
RCS file:
/project/cvs-repository/ACE_wrappers-repository/TAO/tests/Permanent_Forward/Permanent_Forward.mpc,v
done
Checking in TAO/tests/Permanent_Forward/Permanent_Forward.mpc;
/project/cvs-repository/ACE_wrappers-repository/TAO/tests/Permanent_Forward/Permanent_Forward.mpc,v
 <--  Permanent_Forward.mpc
initial revision: 1.1
done
RCS file:
/project/cvs-repository/ACE_wrappers-repository/TAO/tests/Permanent_Forward/run_test.pl,v
done
Checking in TAO/tests/Permanent_Forward/run_test.pl;
/project/cvs-repository/ACE_wrappers-repository/TAO/tests/Permanent_Forward/run_test.pl,v
 <--  run_test.pl
initial revision: 1.1
done
RCS file:
/project/cvs-repository/ACE_wrappers-repository/TAO/tests/Permanent_Forward/StubTest.cpp,v
done
Checking in TAO/tests/Permanent_Forward/StubTest.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/tests/Permanent_Forward/StubTest.cpp,v
 <--  StubTest.cpp
initial revision: 1.1
done
RCS file:
/project/cvs-repository/ACE_wrappers-repository/TAO/tests/Permanent_Forward/README,v
done
Checking in TAO/tests/Permanent_Forward/README;
/project/cvs-repository/ACE_wrappers-repository/TAO/tests/Permanent_Forward/README,v
 <--  README
initial revision: 1.1
done

I don't see a changelog entry

Wed Mar 29 17:15:00 UTC 2006  Frank Rehberger  <frehberger@prismtech.com>

          Guard reply_status() operation with if-else-endif macro for
          MINIMUM builds.

Checking in ChangeLog;
/project/cvs-repository/ACE_wrappers-repository/TAO/ChangeLog,v  <--  ChangeLog
new revision: 1.7746; previous revision: 1.7745
done
Checking in ./tao/DynamicInterface/DII_Invocation_Adapter.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/DynamicInterface/DII_Invocation_Adapter.cpp,v
 <--  DII_Invocation_Adapter.cpp
new revision: 1.14; previous revision: 1.13
done
Checking in ./tao/Messaging/Asynch_Invocation_Adapter.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/Messaging/Asynch_Invocation_Adapter.cpp,v
 <--  Asynch_Invocation_Adapter.cpp
new revision: 1.21; previous revision: 1.20
done
Checking in ./tao/Invocation_Adapter.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/Invocation_Adapter.cpp,v
 <--  Invocation_Adapter.cpp
new revision: 1.26; previous revision: 1.25
done

Sorry, the ChangeLog entry slipped thru, has been comitted a bit later:

ChangeLogTag: Tue Mar 28 23:59:00 UTC 2006 Frank Rehberger
<frehberger@prismtech.com>

/project/cvs-repository/ACE_wrappers-repository/TAO/ChangeLog,v <-- ChangeLog
new revision: 1.7742; previous revision: 1.7741 

ChangeLogTag: Thu Mar 30 03:30:00 UTC 2006  Frank Rehberger 
<frehberger@prismtech.com>
        * TAO/tao/Stub.i: add missing call to
          orb_core->reinitialize_object (this), to optimize for colocal
          case.

        * TAO/tests/Permanent_Forward/StubTest.cpp: Removed code at end of
          test, which caused error messages even if the test run thru all
          test-cases successfully.

Checking in ChangeLog;
/project/cvs-repository/ACE_wrappers-repository/TAO/ChangeLog,v  <--  ChangeLog
new revision: 1.7749; previous revision: 1.7748
done
Checking in tao/Stub.i;
/project/cvs-repository/ACE_wrappers-repository/TAO/tao/Stub.i,v  <--  Stub.i
new revision: 1.55; previous revision: 1.54
done
Checking in tests/Permanent_Forward/StubTest.cpp;
/project/cvs-repository/ACE_wrappers-repository/TAO/tests/Permanent_Forward/StubTest.cpp,v
 <--  StubTest.cpp
new revision: 1.2; previous revision: 1.1
done

Colocal LOCATION_FORWARD(_PERM) case currently not supported, due to bug
reported in 2301

Setting to fixed.