org.omg.DynamicAny.package.html Maven / Gradle / Ivy
Provides classes and interfaces that enable traversal of the data value
associated with an any at
runtime, and extraction of the primitive constituents of the data value.
An any can be passed to a program that doesn't have any static information
for the type of the any (code generated for the type by an IDL compiler has not
been compiled with the object implementation). As a result, the object receiving the
any does not have a portable method of using it.
DynAnys enable traversal of the data value associated with an
any at runtime, and extraction of the primitive constituents of the data value.
This is especially helpful for writing powerful generic servers (bridges, event channels
supporting filtering). Similarly, this facility enables the construction of an
any at runtime, without having static knowledge of its type. This is especially
helpful for writing generic clients (bridges, browsers, debuggers, user interface tools).
Any values can be dynamically interpreted (traversed) and constructed through
DynAny objects. A DynAny object is associated with a data
value which corresponds to a copy of the value inserted into an Any. A
DynAny object may be viewed as an ordered collection of component
DynAnys. For DynAnys representing a basic type, such as long,
or a type without components, such as an empty exception, the ordered collection of
components is empty.
Each DynAny object maintains the notion of a current position into its collection
of component DynAnys. The current position is identified by an index value that runs
from 0 to n-1, where n is the number of components. The special index value -1
indicates a current position that points nowhere.
For values that cannot have a current position (such as an empty exception),
the index value is fixed at -1.
If a DynAny is initialized with a value that has components, the index is
initialized to 0.
After creation of an uninitialized DynAny (that is, a DynAny that
has no value but a TypeCode
that permits components), the current position depends on the type of value represented by
the DynAny. (The current position is set to 0 or -1, depending on whether the
new DynAny
gets default values for its components.)
The iteration operations rewind, seek, and next
can be used to change the current position
and the current_component operation returns the component at the current
position.
The component_count operation returns the number of components of a
DynAny.
Collectively, these operations enable iteration over the components of a
DynAny, for example,
to (recursively) examine its contents.
A constructed DynAny object is a DynAny object associated with
a constructed type.
There is a different interface, inheriting from the DynAny interface,
associated with
each kind of constructed type in IDL (fixed, enum, struct, sequence, union, array,
exception, and value type). A constructed DynAny object exports operations
that enable the creation of new DynAny objects,
each of them associated with a component of the constructed data value.
As an example, a DynStruct is associated with a struct value. This
means that the DynStruct
may be seen as owning an ordered collection of components, one for each structure member.
The DynStruct object exports operations that enable the creation of new
DynAny objects,
each of them associated with a member of the struct.
If a DynAny object has been obtained from another (constructed)
DynAny object,
such as a DynAny representing a structure member that was created from a
DynStruct,
the member DynAny is logically contained in the DynStruct.
Calling an insert or get operation leaves the current position
unchanged.
Destroying a top-level DynAny object (one that was not obtained as a component
of another DynAny)
also destroys any component DynAny objects obtained from it.
Destroying a non-top level DynAny object does nothing.
Invoking operations on a destroyed top-level DynAny or any of its descendants
raises OBJECT_NOT_EXIST.
If the programmer wants to destroy a DynAny object but still wants to
manipulate some component
of the data value associated with it, then he or she should first create a
DynAny for the component
and, after that, make a copy of the created DynAny object.
The behavior of DynAny objects has been defined in order to enable efficient
implementations
in terms of allocated memory space and speed of access. DynAny objects are
intended to be used
for traversing values extracted from anys or constructing values of
anys at runtime.
Their use for other purposes is not recommended.
Handling DynAny objects
Insert and get operations are necessary to handle basic
DynAny objects
but are also helpful to handle constructed DynAny objects.
Inserting a basic data type value into a constructed DynAny object
implies initializing the current component of the constructed data value
associated with the DynAny object. For example, invoking
insert_boolean on a
DynStruct implies inserting a boolean data value at the current
position
of the associated struct data value.
A type is consistent for inserting or extracting a value if its TypeCode is
equivalent to
the TypeCode contained in the DynAny or, if the
DynAny has components, is equivalent to the TypeCode
of the DynAny at the current position.
Basic operations include:
- insert_boolean, get_boolean
- insert_char, get_char
- insert_short, get_short
- insert_ushort, get_ushort
- insert_long, get_long
- insert_ulong, get_ulong
- insert_double, get_double
- insert_string, get_string
- insert_reference, get_reference
- insert_typecode, get_typecode
- insert_longlong, get_longlong
- insert_ulonglong, get_ulonglong
- insert_longdouble, get_longdouble
- insert_wchar, get_wchar
- insert_wstring, get_wstring
- insert_any, get_any
- insert_dyn_any, get_dyn_any
- insert_val, get_val
- insert_octet, get_octet
- insert_float, get_float
- get_value
- get_as_string
- get_as_ulong
- get_members
- get_members_as_dyn_any
- get_discriminator
- get_length
- get_elements
- get_elements_as_dyn_any
- get_boxed_value
- get_boxed_value_as_dyn_any
DynAny and DynAnyFactory objects are intended to be local to
the process in which they are
created and used. This means that references to DynAny and
DynAnyFactory objects cannot be exported
to other processes, or externalized with ORB.object_to_string().
If any attempt is made to do so, the offending operation will raise a MARSHAL system
exception.
Since their interfaces are specified in IDL, DynAny objects export operations
defined in the standard
org.omg.CORBA.Object interface. However, any attempt to invoke operations
exported through the Object
interface may raise the standard NO_IMPLEMENT exception.
An attempt to use a DynAny object with the DII may raise the NO_IMPLEMENT
exception.
Package Specification
For a precise list of supported sections of official specifications with which
the Java[tm] Platform, Standard Edition 6 ORB complies, see Official Specifications for CORBA
support in Java[tm] SE 6.
@since 1.4
@serial exclude