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Common Object Request Broker Architecture — All Issues

  • Acronym: CORBA
  • Issues Count: 6
  • Description: All Issues
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Issues Descriptions

ForwardRequest is impossible to detect in clients

  • Legacy Issue Number: 5266
  • Status: closed  
  • Source: Oracle ( Andrew Piper)
  • Summary:

    REQUIREMENT

    To be able to use interceptors, and in particular ForwardRequest, in a client to perform active, per-request, load-balancing.

    PROBLEM

    It is not possible to detect in an interceptor whether ForwardRequest has previously been thrown for the same client request. Thus it is possible for a client to go into an infinite loop throwing ForwardRequest.

    DISCUSSION

    The basic problem is that although for a single client request the request-scoped PICurrent is shared across across interceptor invocations - even when ForwardRequest is thrown - it is not possible to modify this information in an interceptor to indicate to a future invocation that the invocation has been seen. The two relevant parts of the spec here are:

    21.3.6.5

    For retries, depending on the policies in effect, a new request may or may not follow
    when a retry has been indicated. If a new request does follow, while this request is a
    new request, with respect to Interceptors, there is one point of correlation between the
    original request and the retry: because control has not returned to the client, the request
    scoped PortableInterceptor::Current for both the original request and the retrying
    request is the same (see Chapter 21, Portable Interceptors on page 21-32).

    21.4.2

    Before an invocation is made, PICurrent is obtained via a call to
    ORB::resolve_initial_references ("PICurrent")
    From within the interception points, the data on PICurrent that has moved from the
    thread scope to the request scope is available via the get_slot operation on the
    RequestInfo object. A PICurrent can still be obtained via
    resolve_initial_references, but that is the Interceptor's thread scope PICurrent.
    See section 21.4.4.4, Request Scope vs Thread Scope on page 21-36 for a detailed
    discussion of the scope of PICurrent.

    Thus modifications to the thread's PICurrent are lost on retries and modifications to the request's PICurrent are not possible.

    PROPOSED RESOLUTION

    I have made several different attempts at coming up with a portable way of solving this problem without changing the spec, but have failed. It seems to me that it really should be possible for the interceptor to know that a retry is in effect and I can think of a number of different solutions to this:

    1. add:
    void set_slot (in SlotId id, in any data) raises (InvalidSlot);
    to RequestInfo. This would allow interceptors to transfer information between invokes of the same client request and thus a retry could be detected.

    2. Add a new function to RequestInfo to indicate that a forward is in operation. The minimalist fix here would be to allow forward_reference() to be accessed in send_request() as well as in receive_other(). i.e. returning the object from the previous ForwardRequest if that has been thrown.

    I'm ambivalent about which of these is best but for the sake of simplicity I'm going to plump for (1) because this is already allowed in ServerRequestInfo.

    So:

    • Change the IDL in 21.3.12 to include
      void set_slot (in SlotId id, in any data) raises (InvalidSlot);
    • After 21.3.12.12 move in the text from 21.3.14.6
    • Change the IDL in 21.3.14 to remove set_slot()
  • Reported: CORBA 2.6.1 — Thu, 2 May 2002 04:00 GMT
  • Disposition: Deferred — CORBA 3.4
  • Disposition Summary:

    Deferred

    This proposal was generated automatically by request of the Task Force Chair Adam Mitz.

  • Updated: Mon, 30 Mar 2020 19:47 GMT

DATA_CONVERSION minor code 2 not listed in Table 4-3

  • Key: CORBA3-129
  • Legacy Issue Number: 5322
  • Status: closed  
  • Source: Floorboard Software ( Jonathan Biggar)
  • Summary:

    It is used by RealTime CORBA as documented in 24.17.2

  • Reported: CORBA 2.6.1 — Thu, 23 May 2002 04:00 GMT
  • Disposition: Resolved — CORBA 3.0
  • Disposition Summary:

    non issue...editorial, issue withdrawn

  • Updated: Fri, 6 Mar 2015 21:38 GMT

Minor codes in specified NO_IMPLEMENT exceptions incomplete/inconsistent

  • Key: CORBA3-64
  • Legacy Issue Number: 5329
  • Status: closed  
  • Source: Xanalys ( Martin Simmons)
  • Summary:

    The minor codes in the specified NO_IMPLEMENT exceptions are incomplete/inconsistent.

    In particular:

    1) In 3.7.6.1 "Semantics", minor code 3 is mentioned for DII support pseudo-operations, but 3.7.6.2 seems to specify minor code 4 for these (though it uses different wording).

    2) 3.7.6.2 "LocalObject" doesn't specify the minor code for "is_a" etc, though presumably it should be 3 as in 3.7.6.2.

    3) The explanation for minor code 3 is "Unable to use any profile in IOR." but that isn't particular clear for local objects, which probably don't have an IOR at all.

  • Reported: CORBA 2.6.1 — Tue, 28 May 2002 04:00 GMT
  • Disposition: Resolved — CORBA 3.0.2
  • Disposition Summary:

    see above

  • Updated: Fri, 6 Mar 2015 20:58 GMT

Avoiding Interceptors for colocated method requests

  • Key: CORBA3-62
  • Legacy Issue Number: 5296
  • Status: closed  
  • Source: International Business Machines ( Ann Collins)
  • Summary:

    Could we please discuss the possibility of introducing a performance
    optimization for Interceptors.

    There may be considerable overhead involved in invoking Portable
    Interceptors. While some interceptors need to be invoked when caller
    and target are colocated (the locally optimized path), many do not.
    I think it would be useful to introduce a mechanism to allow this
    unnecessary overhead to be avoided for interceptors that do not need
    to be invoked on the colocated path, for example by adding a
    'run_local' parameter to the add_xxx_request_interceptor methods of
    the ORBInitInfo interface.

    I realise that this issue was touched upon during discussion of interop
    issue 4291 but, at the time, the focus was on getting the interceptor
    mechanism to work correctly in the colocated case; the performance
    aspect of the issue seems to have been lost.

  • Reported: CORBA 2.6.1 — Mon, 13 May 2002 04:00 GMT
  • Disposition: Resolved — CORBA 3.0.2
  • Disposition Summary:

    Provide means for the optimization as shown below

  • Updated: Fri, 6 Mar 2015 20:58 GMT

pragma prefix syntax

  • Key: CORBA3-63
  • Legacy Issue Number: 5327
  • Status: closed  
  • Source: Triodia Technologies Pty Ltd ( Michi Henning)
  • Summary:

    suppose the following [pseudo-]idl:

    #pragma prefix "2abc.def"

    module xyz {
    interface q

    {...}

    ;
    };

    It would generate a Java class 'q' within package 'def.2abc.xyz'.
    The package name '2abc' is not that popular with the java compiler
    since it starts with a digit.

    From what I could see in CORBA 2.6.1, identifiers have to start
    with a character (or at least not a digit). So, I guess that the
    prefix pragma is erroneous here, right ?

    The OpenORB IDL parser 1.2.0 did though generate Java code without any
    complaints, which confuses me ...

  • Reported: CORBA 2.6.1 — Sat, 25 May 2002 04:00 GMT
  • Disposition: Resolved — CORBA 3.0.2
  • Disposition Summary:

    see above

  • Updated: Fri, 6 Mar 2015 20:58 GMT

Codeset negotiation and the CODESET_INCOMPATIBLE exception

  • Key: CORBA3-61
  • Legacy Issue Number: 5270
  • Status: closed  
  • Source: Floorboard Software ( Jonathan Biggar)
  • Summary:

    1. There's no minor code assigned to the use of CODESET_INCOMPATIBLE
    for a failed codeset negotiation in 13.10.2.6.

    2. There's no indication of what a server should do if the client
    delivers a codeset via a CodeSetContext that the server does not support
    as a transmission codeset). This isn't likely to happen, but we ought
    to close the hole. I propose that we have the server raise
    CODESET_INCOMPATIBLE (with a different minor code from 1) in this case
    too.

    3. Would it be a good idea for us to include recommendations on how to
    change a persistent server's native codeset while remaining backwards
    compatible with existing IORs floating around the world with obsolete
    CodeSetComponent data? Or is it too obvious? (Just make sure the new
    server advertises (or at least continues to support) the old native
    codeset as a transmission codeset.)

  • Reported: CORBA 2.6.1 — Tue, 7 May 2002 04:00 GMT
  • Disposition: Resolved — CORBA 3.0.2
  • Disposition Summary:

    see above

  • Updated: Fri, 6 Mar 2015 20:58 GMT