CORBA 3.4 RTF Avatar
  1. OMG Issue

CORBA34 — processing TaggedComponents within an IOR

  • Key: CORBA34-173
  • Legacy Issue Number: 5439
  • Status: closed  
  • Source: International Business Machines ( Ann Collins)
  • Summary:

    The overhead of processing TaggedComponents within an IOR becomes
    significant when done many times, as in the case of J2EE
    implementations where multiple interceptors are used.

    The definition of IORs in the IOP module is intended to support
    transmission and interoperability, rather than efficient access to the
    local, ORB specific, internal structure.

    I would like to propose that an abstract model of an IOR is introduced
    which recognises that many of the constituent parts of IOR profiles are
    identical for different objects, along the following lines:-

    • an IOR has a type ID string, and contains TaggedProfile instances
    • a TaggedProfile has an ID and data
    • an IIOPProfile is a TaggedProfile; it is composed of an
      IIOPProfileTemplate and an object ID.
    • an IIOPProfileTemplate has IIOP addressing information, and contains
      TaggedComponents.
    • a TaggedComponent has an ID and data
    • a TaggedComponentFactory creates a TaggedComponent
    • a TaggedProfileFactory creates a TaggedProfile

    with corresponding IDL definitions that allow the language bindings
    to optimise conversion between transmission and internal IOR formats
    to provide a performant and natural interface for IOR access.

    Rationale:
    In Java, for example, it should be possible to manipulate IOR
    TaggedProfiles and IIOPProfileTemplate TaggedComponents using the
    facilities of the Java collections framework, or at least some
    equivalent facility that is a natural Java idiom.

    Templates can be used to create IIOPProfiles because the basic object
    adapter model for object creation is to establish many of the properties
    of an IOR when the object adapter is created.

    • This has been present for the POA essentially from the beginning, since
      policies can only be passed to create_POA, and cannot be changed on an
      existing POA.
    • The Portable Interceptors work has also made this clear, since the IOR
      interceptor establish_components method, which is the only time that
      user code can add tagged components to an IOR, is only guaranteed to
      be called once for each distinct set of server policies i.e need only
      be run when an object adapter is created.
    • It is also likely that more than one object within an adapter will
      map to a TCP endpoint.

    TaggedProfile and TaggedComponent are intended as frameworks that may be
    extended to support application defined tagged profiles and components.
    To support this it is necessary to be able to register TaggedProfile and
    TaggedComponentFactory instances with an ORB, in which case any IOR
    unmarshalled by that ORB instance will use the registered factory
    to unmarshal the tagged profile or component.

    Since there has already been quite a bit of discussion about this in the
    Java RTF, here is a proposal for review:-

    Proposal:

    • add the following sections after the IOR Interceptor Overview:-

    21.5.2 An Abstract Model for IORs

    To support efficient access to IORs, avoiding repeated marshaling and
    demarshaling of IOR components, it is helpful to have an abstract model
    of the, ORB specific, local representation of an IOR.

    Recognising that many of the constituent parts of IOR profiles are
    identical for different objects allows the following model to be
    defined:-

    • an IOR has a type ID string, and contains TaggedProfile instances
    • a TaggedProfile has an ID and data
    • an IIOPProfile is a TaggedProfile; it is composed of an
      IIOPProfileTemplate and an object ID.
    • an IIOPProfileTemplate has IIOP addressing information, and contains
      TaggedComponents.
    • a TaggedComponent has an ID and data
    • a TaggedComponentFactory creates a TaggedComponent
    • a TaggedProfileFactory creates a TaggedProfile

    21.5.3 Local IOR Interfaces

    The following interfaces provide access to the data within a local IOR
    using this model.

    TaggedProfile and TaggedComponent are generic interfaces. Users of the ORB
    may create implementations of them. Corresponding factories may be
    registered with the IORFactory.

    The IORFactory is obtained through a call to
    ORB::resolve_initial_references ("IORFactory") and may also be used to
    obtain an IOR for an Object.

    An ORB must return all tagged profiles in an IOR through the IOR
    getProfiles operations. The ProfileIterator interface allows a client
    to iterate through the TaggedProfiles using the next operation.
    Those profiles whose ids have a registered TaggedProfileFactory will
    be made available in the form returned by the registered factory's
    TaggedProfileFactory create operation, which must return a subtype of
    TaggedProfile.

    An ORB will provide a TaggedProfileFactory implementation for the
    IIOPProfile.

    Profiles with ids for which no TaggedProfileFactory has been registered
    will be made available as instances of a generic ORB implementation of
    TaggedProfile.

    Similarly, an ORB must return all tagged components in an IIOP profile
    through the IIOPProfile().getTemplate().getComponents() operations.
    The ComponentIterator interface allows a client to iterate through the
    TaggedComponents using the next operation.
    Those components whose ids have a registered TaggedComponentFactory
    will be made available in the form returned by the registered factory's
    TaggedComponentFactory create operation, which must return a subtype of
    TaggedComponent.
    Components with ids for which no TaggedComponentFactory has been
    registered will be made available as instances of a generic ORB
    implementation of TaggedComponent.

    module PortableInterceptor {

    local interface TaggedComponent

    { readonly attribute IOP::ComponentId component_id; readonly attribute CORBA::OctetSeq component_data; IOP::TaggedComponent convert(); }

    ;

    local interface ComponentIterator

    { TaggedComponent next(); boolean has_next(); }

    ;

    local interface TaggedProfile

    { readonly attribute IOP::ProfileId profile_id; readonly attribute CORBA::OctetSeq profile_data; IOP::TaggedProfile convert(); }

    ;

    local interface ProfileIterator

    { TaggedProfile next(); boolean has_next(); }

    ;

    local interface IOR

    { readonly attribute string type_id; ProfileIterator get_profiles (); ProfileIterator get_profiles_by_id (in IOP::ProfileId profile_id); }

    ;

    local interface IIOPProfileTemplate

    { readonly attribute IIOP::Version iiop_version; readonly attribute string host; readonly attribute unsigned short port; ComponentIterator get_components(); ComponentIterator get_components_by_id (in IOP::ComponentId id); }

    ;

    local interface IIOPProfile:TaggedProfile

    { readonly attribute CORBA::OctetSeq object_key; readonly attribute IIOPProfileTemplate profile_template; }

    ;

    local interface TaggedComponentFactory

    { readonly attribute IOP::ComponentId factory_id; TaggedComponent create_tagged_component (in CORBA::OctetSeq component_data); }

    ;

    local interface TaggedProfileFactory

    { readonly attribute IOP::ProfileId factory_id; TaggedProfile create_tagged_profile (in CORBA::OctetSeq profile_data); }

    ;

    local interface IORFactory

    { IOR create_ior (in Object obj); void register_tagged_profile_factory (in TaggedProfileFactory tpf); void register_tagged_component_factory (in TaggedComponentFactory tcf); }

    ;

    };

    21.5.3.1 IOR Factory Interface

    create_ior
    Return an IOR relating to the given Object.

    If create_ior is invoked when the object reference is not bound,
    standard system exception BAD_INV_ORDER with minor code n will be
    raised.

    register_tagged_profile_factory
    Register a TaggedProfileFactory to create TaggedProfiles with the id
    returned by the given factory's getId method. If a TaggedProfileFactory
    already exists for the given id, standard system exception
    BAD_INV_ORDER is raised with a standard minor code of n+1.
    Instances of this interface may be defined by users to support custom
    tagged profiles.

    register_tagged_component_factory
    Register a TaggedComponentFactory to read TaggedComponents with the id
    returned by the given factory's getId method. If a
    TaggedComponentFactory already exists for the given id, standard system
    exception BAD_INV_ORDER is raised with a standard minor code of n+2.
    Instances of this interface may be defined by users to support custom
    tagged components.

    21.5.3.2 IOR Interface

    This interface gives access to a local representation of an
    IOP::IOR.

    type_id
    The type id string from the IOR.

    get_profiles
    Returns an iterator over the TaggedProfiles within the IOR.

    get_profiles_by_id
    Returns an iterator over the TaggedProfiles with the given
    Profileid.

    21.5.3.3 TaggedProfile Interface

    This interface gives access to a local representation of an
    IOP::TaggedProfile.

    profile_id
    This attribute is the identifier for this TaggedProfile.

    profile_data
    This attribute is the data from the TaggedProfile. It is
    normally a CDR encapsulation.

    convert
    Create an IOP representation of this TaggedProfile

    21.5.3.4 TaggedComponent Interface

    This interface gives access to a local representation of an
    IOP::TaggedComponent.

    component_id
    This attribute is the identifier for this TaggedComponent.

    component_data
    This attribute is the data from the TaggedComponent. It is
    normally a CDR encapsulation.

    convert
    Create an IOP representation of this TaggedComponent.

    21.5.3.5 TaggedProfileFactory Interface

    factory_id
    This attribute is the identifier of profiles created by this
    TaggedProfileFactory.

    create
    Create a TaggedProfile from the given profile_data.

    21.5.3.6 TaggedComponentFactory Interface

    factory_id
    This attribute is the identifier of components created by this
    TaggedComponentFactory.

    create
    Create a TaggedComponent from the given component_data.

    21.5.3.7 ProfileIterator Interface

    next
    Returns the next TaggedProfile in the iteration. If next is called
    after the last TaggedProfile has been returned, BAD_INV_ORDER will
    be raised with a standard minor code of n+3.

    If an IOR is modified in between calls to next, the behavior of
    further calls to next is implementation dependent.

    has_next
    Returns true if the iteration has more elements. In other words,
    returns true if next would return an element rather than throwing
    an exception.

    21.5.3.8 ComponentIterator Interface

    next
    Returns the next TaggedComponent in the iteration. If next is called
    after the last TaggedComponent has been returned, BAD_INV_ORDER will
    be raised with a standard minor code of n+3.

    If a profile is modified in between calls to next, the behavior of
    further calls to next is implementation dependent.

    has_next
    Returns true if the iteration has more elements. In other words,
    returns true if next would return an element rather than throwing
    an exception.

    21.5.3.9 IIOPProfile Interface

    object_key
    This attribute is the Object key contained in this IIOPProfile.

    profile_template
    This attribute is the IIOPProfileTemplate associated with this
    IIOPProfile.

    21.5.3.10 IIOPProfileTemplate Interface

    iiop_version
    This attribute is the GIOP version of this profile. If the major
    value is 1 and the minor value is 0, this profile cannot contain
    any TaggedComponents.

    host
    This attribute is the host name string of this IIOPProfileTemplate.

    port
    This attribute is the port number of this IIOPProfileTemplate.

    get_components
    Return an iterator over the TaggedComponents within the
    IIOPProfileTemplate.

    get_components_by_id
    Returns an iterator over the TaggedComponents with the given
    ComponentId.

    In current Section 21.5.3:

    • add the following after the ORBInfo Interface

    local interface IORInfo_3_n:IORInfo

    { ProfileIterator get_profiles (); ProfileIterator get_profiles_by_id (in IOP::ProfileId profile_id); }

    ;

    • add the following sections:

    21.5.3.4 get_profiles
    Returns an iterator over the TaggedProfiles within the IOR.

    21.5.3.5 get_profiles_by_id
    Returns an iterator over the TaggedProfiles within the IOR with the
    given Profileid.

    Parameter Description
    profile_id The IOP::ProfileId of the profiles in the iteration
    to be returned.

    • add the IORFactory to the list of reserved ObjectIds for
      resolve_initial_references in section 4.5.2
  • Reported: CORBA 3.0 — Tue, 25 Jun 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