Spec-Zone .ru
спецификации, руководства, описания, API
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Spec-Zone .ru
спецификации, руководства, описания, API
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Java™ Platform Standard Ed. 6 |
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See:
Description
| Interface Summary | |
|---|---|
| ARG_IN | Signifies an "input" argument to an invocation, meaning that the argument is being passed from the client to the server. |
| ARG_INOUT | Signifies an argument used for both input and output in an invocation, meaning that the argument is being passed from the client to the server and then back from the server to the client. |
| ARG_OUT | A constant that signifies an "output" argument to an invocation, meaning that the argument is being passed from the server to the client. |
| BAD_POLICY | A PolicyErrorCode which would be filled in the PolicyError exception. |
| BAD_POLICY_TYPE | A PolicyErrorCode which would be filled in the PolicyError exception. |
| BAD_POLICY_VALUE | Contains the value used to indicate a policy value that is
incorrect for a valid policy type in a call to the
create_policy method defined in the ORB class. |
| CTX_RESTRICT_SCOPE | A flag that can be used as the second parameter to the method
Context.get_values to restrict the search scope. |
| Current | Interfaces derived from the Current interface enable ORB and CORBA services to provide access to information (context) associated with the thread of execution in which they are running. |
| CurrentOperations | The interface for Current. |
| CustomMarshal | An abstract value type that is meant to be used by the ORB, not the user. |
| DataInputStream | Defines the methods used to read primitive data types from input streams for unmarshaling custom value types. |
| DataOutputStream | Defines the methods used to write primitive data types to output streams for marshalling custom value types. |
| DomainManager | Provides mechanisms for establishing and navigating relationships to superior and subordinate domains, as well as for creating and accessing policies. |
| DomainManagerOperations | Provides the DomainManager with the means to access policies. |
| DynAny | Deprecated. Use the new DynAny instead |
| DynArray | Deprecated. Use the new DynArray instead |
| DynEnum | Deprecated. Use the new DynEnum instead |
| DynFixed | Deprecated. Use the new DynFixed instead |
| DynSequence | Deprecated. Use the new DynSequence instead |
| DynStruct | Deprecated. Use the new DynStruct instead |
| DynUnion | Deprecated. Use the new DynUnion instead |
| DynValue | Deprecated. Use the new DynValue instead |
| IDLType | An abstract interface inherited by all Interface Repository (IR) objects that represent OMG IDL types. |
| IDLTypeOperations | This interface must be implemented by all IDLType objects. |
| IRObject | An IRObject IDL interface represents the most generic interface from which all other Interface Repository interfaces are derived, even the Repository itself. |
| IRObjectOperations | This is the Operations interface for the mapping from IRObject. |
| Object | The definition for a CORBA object reference. |
| OMGVMCID | The vendor minor code ID reserved for OMG. |
| Policy | Interfaces derived from the Policy interface allow an ORB or CORBA service access to certain choices that affect its operation. |
| PolicyOperations | Provides the operations for a Policy object. |
| PRIVATE_MEMBER | Constant to define a private member in the ValueMember class. |
| PUBLIC_MEMBER | Constant to define a public member in the ValueMember
class. |
| UNSUPPORTED_POLICY | One of the PolicyErrorCodes which would be filled if the requested Policy is understood to be valid by the ORB, but is not currently supported. |
| UNSUPPORTED_POLICY_VALUE | A PolicyErrorCode which would be filled if the value requested for the Policy is of a valid type and within the valid range for that type, but this valid value is not currently supported. |
| VM_ABSTRACT | Defines the code used to represent an Abstract interface in a typecode. |
| VM_CUSTOM | Defines the code used to represent a custom marshalled value type in a typecode. |
| VM_NONE | Defines the code used to represent the one of the values of a value type in a typecode. |
| VM_TRUNCATABLE | Defines the code used to represent a truncatable value type in a typecode. |
| Class Summary | |
|---|---|
| _IDLTypeStub | The Stub for IDLType. |
| _PolicyStub | The Stub for Policy. |
| Any | Serves as a container for any data that can be described in IDL or for any IDL primitive type. |
| AnyHolder | The Holder for Any. |
| AnySeqHelper | The Helper for AnySeq. |
| AnySeqHolder | The Holder for AnySeq. |
| BooleanHolder | The Holder for Boolean. |
| BooleanSeqHelper | The Helper for BooleanSeq. |
| BooleanSeqHolder | The Holder for BooleanSeq. |
| ByteHolder | The Holder for Byte. |
| CharHolder | The Holder for Char. |
| CharSeqHelper | The Helper for CharSeq. |
| CharSeqHolder | The Holder for CharSeq. |
| CompletionStatus | An object that indicates whether a method had completed running
when a SystemException was thrown. |
| CompletionStatusHelper | The Helper for CompletionStatus. |
| Context | An object used in Request operations
to specify the context object in which context strings
must be resolved before being sent along with the request invocation. |
| ContextList | An object containing a modifiable list of String objects
that represent property names. |
| CurrentHelper | The Helper for Current. |
| CurrentHolder | The Holder for Current. |
| DefinitionKind | The class that provides the constants used to identify the type of an Interface Repository object. |
| DefinitionKindHelper | The Helper for DefinitionKind. |
| DoubleHolder | The Holder for Double. |
| DoubleSeqHelper | The Helper for DoubleSeq. |
| DoubleSeqHolder | The Holder for DoubleSeq. |
| DynamicImplementation | Deprecated. org.omg.CORBA.DynamicImplementation |
| Environment | A container (holder) for an exception that is used in Request
operations to make exceptions available to the client. |
| ExceptionList | An object used in Request operations to
describe the exceptions that can be thrown by a method. |
| FieldNameHelper | The Helper for FieldName. |
| FixedHolder | The Holder for Fixed. |
| FloatHolder | The Holder for Float. |
| FloatSeqHelper | The Helper for FloatSeq. |
| FloatSeqHolder | The Holder for FloatSeq. |
| IdentifierHelper | The Helper for Identifier. |
| IDLTypeHelper | The Helper for IDLType. |
| IntHolder | The Holder for Int. |
| LocalObject | Used as a base class for implementation of a local IDL interface in the Java language mapping. |
| LongHolder | The Holder for Long. |
| LongLongSeqHelper | The Helper for LongLongSeq. |
| LongLongSeqHolder | The Holder for LongLongSeq. |
| LongSeqHelper | The Helper for LongSeqHelper. |
| LongSeqHolder | The Holder for LongSeq. |
| NamedValue | An object used in the DII and DSI to describe arguments and return values. |
| NameValuePair | Associates a name with a value that is an attribute of an IDL struct, and is used in the DynStruct APIs. |
| NameValuePairHelper | The Helper for NameValuePair. |
| NVList | A modifiable list containing NamedValue objects. |
| ObjectHelper | |
| ObjectHolder | The Holder for Object. |
| OctetSeqHelper | The Helper for OctetSeq. |
| OctetSeqHolder | The Holder for OctetSeq. |
| ORB | A class providing APIs for the CORBA Object Request Broker features. |
| ParameterMode | Enumeration of parameter modes for Parameter. |
| ParameterModeHelper | Enumeration of parameter modes for Parameter. |
| ParameterModeHolder | Enumeration of parameter modes for Parameter. |
| PolicyErrorCodeHelper | Encapsulates a reason a Policy may be invalid. |
| PolicyErrorHelper | Thrown to indicate problems with parameter values passed to the
ORB.create_policy operation. |
| PolicyErrorHolder | Thrown to indicate problems with parameter values passed to the
ORB.create_policy operation. |
| PolicyHelper | The Helper for Policy. |
| PolicyHolder | The Holder for Policy. |
| PolicyListHelper | The Helper for PolicyList. |
| PolicyListHolder | The Holder for PolicyList. |
| PolicyTypeHelper | The Helper for PolicyType. |
| Principal | Deprecated. Deprecated by CORBA 2.2. |
| PrincipalHolder | Deprecated. Deprecated by CORBA 2.2. |
| RepositoryIdHelper | The Helper for RepositoryId. |
| Request | An object containing the information necessary for invoking a method. |
| ServerRequest | An object that captures the explicit state of a request for the Dynamic Skeleton Interface (DSI). |
| ServiceDetail | An object that represents an ORB service: its service_detail_type
field contains the type of the ORB service, and its service_detail
field contains a description of the ORB service. |
| ServiceDetailHelper | |
| ServiceInformation | An IDL struct in the CORBA module that stores information about a CORBA service available in the ORB implementation and is obtained from the ORB.get_service_information method. |
| ServiceInformationHelper | |
| ServiceInformationHolder | The Holder for ServiceInformation. |
| SetOverrideType | The mapping of a CORBA enum tagging
SET_OVERRIDE and ADD_OVERRIDE, which
indicate whether policies should replace the
existing policies of an Object or be added to them. |
| SetOverrideTypeHelper | The Helper for SetOverrideType. |
| ShortHolder | The Holder for Short. |
| ShortSeqHelper | The Helper for ShortSeqHelper. |
| ShortSeqHolder | The Holder for ShortSeq. |
| StringHolder | The Holder for String. |
| StringSeqHelper | An array of Strings |
| StringSeqHolder | An array of Strings |
| StringValueHelper | The Helper for StringValue. |
| StructMember | Describes a member of an IDL struct in the
Interface Repository, including
the name of the struct member, the type of
the struct member, and
the typedef that represents the IDL type of the
struct member
described the struct member object. |
| StructMemberHelper | The Helper for StructMember. |
| TCKind | The Java mapping of the IDL enum TCKind, which
specifies the kind of a TypeCode object. |
| TypeCode | A container for information about a specific CORBA data type. |
| TypeCodeHolder | The Holder for TypeCode. |
| ULongLongSeqHelper | The Helper for ULongLongSeq. |
| ULongLongSeqHolder | The Holder for ULongLongSeq. |
| ULongSeqHelper | The Helper for ULongSeq. |
| ULongSeqHolder | The Holder for ULongSeq. |
| UnionMember | A description in the Interface Repository of a member of an IDL union. |
| UnionMemberHelper | The Helper for UnionMember. |
| UnknownUserExceptionHelper | The Helper for UnknownUserException. |
| UnknownUserExceptionHolder | The Holder for UnknownUserException. |
| UShortSeqHelper | The Helper for UShortSeq. |
| UShortSeqHolder | The Holder for UShortSeq. |
| ValueBaseHelper | |
| ValueBaseHolder | The Holder for ValueBase. |
| ValueMember | A description in the Interface Repository of
a member of a value object. |
| ValueMemberHelper | The Helper for ValueMember. |
| VersionSpecHelper | The Helper for VersionSpec. |
| VisibilityHelper | The Helper for Visibility. |
| WCharSeqHelper | The Helper for WCharSeq. |
| WCharSeqHolder | The Holder for WCharSeq. |
| WrongTransactionHelper | The Helper for WrongTransaction. |
| WrongTransactionHolder | The Holder for WrongTransaction. |
| WStringSeqHelper | An array of WStrings |
| WStringSeqHolder | An array of WStrings |
| WStringValueHelper | org/omg/CORBA/WStringValueHelper.java Generated by the IDL-to-Java compiler (portable), version "3.0" from orb.idl 31 May 1999 22:27:30 o'clock GMT+00:00 The class definition has been modified to conform to the following OMG specifications : ORB core as defined by CORBA 2.3.1 () IDL/Java Language Mapping as defined in |
| Exception Summary | |
|---|---|
| ACTIVITY_COMPLETED | The ACTIVITY_COMPLETED system exception may be raised on any
method for which Activity context is accessed. |
| ACTIVITY_REQUIRED | The ACTIVITY_REQUIRED system exception may be raised on any
method for which an Activity context is required. |
| BAD_CONTEXT | Exception thrown when an operation is invoked by a client but the passed context does not contain the context values required by the operation. |
| BAD_INV_ORDER | This exception indicates that the caller has invoked operations in the wrong order. |
| BAD_OPERATION | Exception thrown when an object reference denotes an existing object, but that the object does not support the operation that was invoked. |
| BAD_PARAM | Exception thrown when a parameter passed to a call is out of range or otherwise considered illegal. |
| BAD_QOS | The BAD_QOS exception is raised whenever an object cannot
support the quality of service required by an invocation parameter that
has a quality of service semantics associated with it. |
| BAD_TYPECODE | Exception thrown when the ORB has encountered a malformed type code (for example, a type code with an invalid TCKind value). |
| Bounds | A user exception thrown when a parameter is not within the legal bounds for the object that a method is trying to access. |
| CODESET_INCOMPATIBLE | This exception is raised whenever meaningful communication is not possible between client and server native code sets. |
| COMM_FAILURE | This exception is raised if communication is lost while an operation is in progress, after the request was sent by the client, but before the reply from the server has been returned to the client. |
| DATA_CONVERSION | This exception is raised if an ORB cannot convert the representation of data as marshaled into its native representation or vice-versa. |
| FREE_MEM | Exception thrown when the ORB failed in an attempt to free dynamic memory, for example because of heap corruption or memory segments being locked. |
| IMP_LIMIT | This exception indicates that an implementation limit was exceeded in the ORB run time. |
| INITIALIZE | Exception thrown when an ORB has encountered a failure during its initialization, such as failure to acquire networking resources or detecting a configuration error. |
| INTERNAL | This exception indicates an internal failure in an ORB, for example, if an ORB has detected corruption of its internal data structures. |
| INTF_REPOS | Exception raised when an ORB cannot reach the interface repository, or some other failure relating to the interface repository is detected. |
| INV_FLAG | Exception thrown when an invalid flag was passed to an operation (for example, when creating a DII request). |
| INV_IDENT | This exception indicates that an IDL identifier is syntactically invalid. |
| INV_OBJREF | This exception indicates that an object reference is internally malformed. |
| INV_POLICY | Standard exception thrown when an invocation cannot be made because of an incompatibility between Policy overrides that apply to the particular invocation. |
| INVALID_ACTIVITY | The INVALID_ACTIVITY system exception may be raised on the
Activity or Transaction services' resume methods if a transaction or
Activity is resumed in a context different to that from which it was
suspended. |
| INVALID_TRANSACTION | Exception thrown when the request carried an invalid transaction context. |
| MARSHAL | A request or reply from the network is structurally invalid. |
| NO_IMPLEMENT | This exception indicates that even though the operation that was invoked exists (it has an IDL definition), no implementation for that operation exists. |
| NO_MEMORY | Exception thrown when the ORB run time has run out of memory. |
| NO_PERMISSION | Exception thrown when an invocation failed because the caller has insufficient privileges. |
| NO_RESOURCES | Exception thrown when the ORB has encountered some general resource limitation. |
| NO_RESPONSE | This exception is raised if a client attempts to retrieve the result of a deferred synchronous call, but the response for the request is not yet available. |
| OBJ_ADAPTER | This exception typically indicates an administrative mismatch, for example, a server may have made an attempt to register itself with an implementation repository under a name that is already in use, or is unknown to the repository. |
| OBJECT_NOT_EXIST | Exception raised whenever an invocation on a deleted object was performed. |
| PERSIST_STORE | This exception indicates a persistent storage failure, for example, failure to establish a database connection or corruption of a database. |
| PolicyError | A user exception thrown when a policy error occurs. |
| REBIND | REBIND is raised when the current effective RebindPolicy,
has a value of NO_REBIND or NO_RECONNECT and an invocation on a bound
object reference results in a LocateReply message with status
OBJECT_FORWARD or a Reply message with status LOCATION_FORWARD. |
| SystemException | The root class for all CORBA standard exceptions. |
| TIMEOUT | TIMEOUT is raised when no delivery has been made and the
specified time-to-live period has been exceeded. |
| TRANSACTION_MODE | The CORBA TRANSACTION_MODE exception is thrown
by the client ORB if it detects a mismatch between the
InvocationPolicy in the IOR and the chosen invocation path
(i.e, direct or routed invocation). |
| TRANSACTION_REQUIRED | Exception indicates that the request carried a null transaction context, but an active transaction is required. |
| TRANSACTION_ROLLEDBACK | Exception thrown when the transaction associated with the request has already been rolled back or marked to roll back. |
| TRANSACTION_UNAVAILABLE | The CORBA TRANSACTION_UNAVAILABLE exception is thrown
by the ORB when it cannot process a transaction service context because
its connection to the Transaction Service has been abnormally terminated. |
| TRANSIENT | Exception thrown when the ORB attempted to reach an object and failed. |
| UNKNOWN | This exception is raised if an operation implementation throws a non-CORBA exception (such as an exception specific to the implementation's programming language), or if an operation raises a user exception that does not appear in the operation's raises expression. |
| UnknownUserException | A class that contains user exceptions returned by the server. |
| UserException | The root class for CORBA IDL-defined user exceptions. |
| WrongTransaction | The CORBA WrongTransaction user-defined exception. |
Provides the mapping of the OMG CORBA APIs to the JavaTM programming language, including the class ORB, which is implemented so that a programmer can use it as a fully-functional Object Request Broker (ORB).
For a precise list of supported sections of official CORBA specifications with which the Java[TM] Platform, Standard Edition 6 complies, see Official Specifications for CORBA support in Java[TM] SE 6.
The classes and interfaces described in this section can be put into four groups: ORB classes, Exceptions, Helper classes, and Holder classes.
An ORB handles (or brokers) method invocations between a client and the method's implementation on a server. Because the client and server may be anywhere on a network, and because the invocation and implementation may be written in different programming languages, an ORB does a great deal of work behind the scenes to accomplish this communication.
Most of what an ORB does is completely transparent to the user, and a major portion of the CORBA package consists of classes used by the ORB behind the scenes. The result is that most programmers will use only a small part of this package directly. In fact, most programmers will use only a few methods from the ORB class, some exceptions, and occasionally, a holder class.
Before an application can enter the CORBA environment, it must first:
The following operations are provided to initialize applications and obtain the appropriate object references:
When an application requires a CORBA environment it needs a mechanism to get an ORB object reference and possibly an OA object reference (such as the root POA). This serves two purposes. First, it initializes an application into the ORB and OA environments. Second, it returns the ORB object reference and the OA object reference to the application for use in future ORB and OA operations.
In order to obtain an ORB object reference, applications call the ORB.init operation. The parameters to the call can comprise an identifier for the ORB for which the object reference is required, and an arg_list, which is used to allow environment-specific data to be passed into the call.
These are the ORB methods that provide access to the ORB:
Using the init() method without parameters initiates a singleton ORB, which can only give typecode creation anys needed in code generated in Helper classes by idlj.
Applications require a portable means by which to obtain their initial object references. References are required for the root POA, POA Current, Interface Repository, and various Object Services instances. The functionality required by the application is similar to that provided by the Naming Service. However, the OMG does not want to mandate that the Naming Service be made available to all applications in order that they may be portably initialized. Consequently, the operations shown in this section provide a simplified, local version of the Naming Service that applications can use to obtain a small, defined set of object references which are essential to its operation. Because only a small well-defined set of objects are expected with this mechanism, the naming context can be flattened to be a single-level name space. This simplification results in only two operations being defined to achieve the functionality required.
Initial references are obtained via two operations provided in the ORB object interface, providing facilities to list and resolve initial object references. These are:
An example that uses some of these methods is Getting Started with Java IDL.
The documentation on Java IDL exceptions has more information and explains the difference between system exceptions and user-defined exceptions.
The following is a list of the system exceptions (which are unchecked exceptions inheriting through org.omg.CORBA.SystemException from java.lang.RuntimeException) that are defined in the package org.omg.CORBA:
BAD_CONTEXT
BAD_INV_ORDER
BAD_OPERATION
BAD_PARAM
BAD_TYPECODE
COMM_FAILURE
DATA_CONVERSION
FREE_MEM
IMP_LIMIT
INITIALIZE
INTERNAL
INTF_REPOS
INVALID_TRANSACTION
INV_FLAG
INV_IDENT
INV_OBJREF
INV_POLICY
MARSHAL
NO_IMPLEMENT
NO_MEMORY
NO_PERMISSION
NO_RESOURCES
NO_RESPONSE
OBJECT_NOT_EXIST
OBJ_ADAPTER
PERSIST_STORE
TRANSACTION_REQUIRED
TRANSACTION_ROLLEDBACK
TRANSIENT
UNKNOWN
The following is a list of user-defined exceptions defined in the package org.omg.CORBA.
Bounds
UnknownUserException
WrongTransaction
PolicyError
For example, the package org.omg.CORBA.TypeCodePackage contains two exceptions thrown by methods in the class TypeCode. These exceptions are:
Another package that is a subpackage of CORBA is the portable package. It provides a set of ORB APIs that makes it possible for code generated by one vendor's IDL compiler to run on another vendor's ORB.
Support for out and inout parameter passing modes requires the use of additional holder classes. Because the Java programming language does not support out or inout parameters, holder classes are needed as a means of passing a parameter that can be modified. To support portable stubs and skeletons, holder classes also implement the org.omg.CORBA.portable.Streamable interface.
Holder classes are named by appending "Holder" to the name of the type. The name of the type refers to its name in the Java programming language. For example, a holder class for the interface named Account in the Java programming language would be named AccountHolder.
Holder classes are available for all of the basic IDL datatypes in the org.omg.CORBA package. So, for example, there are already-defined classes for LongHolder, ShortHolder, FloatHolder, and so on. Classes are also generated for all named user-defined IDL types except those defined by typedefs. (Note that in this context user defined includes types that are defined in OMG specifications such as those for the Interface Repository, and other OMG services.)
Each holder class has:
The default constructor sets the value field to the default value for the type as defined by the Java language:
As an example, if the interface Account, defined in OMG IDL,
were mapped to the Java programming language, the following holder class
would be generated:
public final class AccountHolder implements
org.omg.CORBA.portable.Streamable
{
// field that holds an Account object
public Account value = null;
// default constructor
public AccountHolder ()
{
}
// creates a new AccountHolder from initialValue
public AccountHolder (Account initialValue)
{
value = initialValue;
}
// reads the contents of i and assigns the contents to value
public void _read (org.omg.CORBA.portable.InputStream i)
{
value = AccountHelper.read (i);
}
// writes value to o
public void _write (org.omg.CORBA.portable.OutputStream o)
{
AccountHelper.write (o, value);
}
// returns the typecode for Account
public org.omg.CORBA.TypeCode _type ()
{
return AccountHelper.type ();
}
}
For more information on Holder classes, see Chapter 1.4, Mapping for Basic Types in the . The Holder classes defined in the package org.omg.CORBA are:
AnyHolder AnySeqHolder BooleanHolder BooleanSeqHolder ByteHolder CharHolder CharSeqHolder CurrentHolder DoubleHolder DoubleSeqHolder FixedHolder FloatHolder FloatSeqHolder IntHolder LongHolder LongLongSeqHolder LongSeqHolder ObjectHolder OctetSeqHolder ParameterModeHolder PolicyErrorHolder PolicyListHolder PrincipalHolder ServiceInformationHolder ShortHolder ShortSeqHolder StringHolder StringSeqHolder TypeCodeHolder ULongLongSeqHolder ULongSeqHolder UnknownUserExceptionHolder UShortSeqHolder ValueBaseHolder WCharSeqHolder WrongTransactionHolder WStringSeqHolder
Helper files supply several static methods needed to manipulate the type. These include:
ValueHelper interface (if it is a user-defined
value type)
The helper class for a mapped IDL interface or abstract interface
also include narrow operation(s). The static narrow method allows
an org.omg.CORBA.Object to be narrowed to the object reference
of a more specific type. The IDL exception CORBA.BAD_PARAM
is thrown if the narrow fails because the object reference does not
support the requested type. A different system exception is raised
to indicate other kinds of errors. Trying to narrow a null will always
succeed with a return value of null. Generally, the only helper method an application programmer uses is
the narrow method. The other methods are normally used behind
the scenes and are transparent to the programmer.
Helper classes fall into two broad categories, helpers for value types and helpers for non value types. Because all of the helper classes in one category provide the same methods, one generic explanation of each category of helper classes is presented here.
When OMG IDL is mapped to the Java programming language,
a "helper" class is generated for each user-defined type.
This generated class will have the name of the user-defined type with
the suffix Helper appended. For example, if the
interface Account is defined in OMG IDL, the
idlj compiler will automatically generate a class named
AccountHelper. The AccountHelper class
will contain the static methods needed for manipulating instances of the type,
in this case, Account objects.
narrow Methodorg.omg.CORBA.Object object
or a java.lang.Object object. This object must be cast to its
more specific type before it can be operated on. For example, an
Account object will be returned as a generic object and must
be narrowed to an Account object so that Account
methods may be called on it.
The narrow method has two forms, one that takes an
org.omg.CORBA.Object object and one that takes a
java.lang.Object object. Whether the interface is abstract or
not determines which narrow method its helper class will provide.
The helper class for an interface
that is not abstract will have a narrow method that takes a CORBA
object, whereas the narrow method for an interface that is abstract
will
take an object in the Java programming language. The helper class for a
non-abstract interface that has at least one abstract base interface will provide
both versions of the narrow method.
The Hello World tutorial uses a narrow method that looks like this:
// create and initialize the ORB
ORB orb = ORB.init(args, null);
// get the root naming context
org.omg.CORBA.Object objRef =
orb.resolve_initial_references("NameService");
// Use NamingContextExt instead of NamingContext. This is
// part of latest Inter-Operable naming Service.
NamingContextExt ncRef = NamingContextExtHelper.narrow(objRef);
// resolve the Object Reference in Naming
String name = "Hello";
helloImpl = HelloHelper.narrow(ncRef.resolve_str(name));
narrow
method if the type defined in OMG IDL maps to an interface in the Java
programming language. Types that are not value types will have a basic
helper class generated for them.
For example, assuming that the interface Account is not a
value type IDL type and is also not an abstract interface and has no
abstract base interfaces, its AccountHelper class will look
like this:
abstract public class AccountHelper
{
private static String _id = "IDL:Account:1.0";
// inserts an Account object into an Any object
public static void insert (org.omg.CORBA.Any a, Account that)
{
org.omg.CORBA.portable.OutputStream out = a.create_output_stream ();
a.type (type ());
write (out, that);
a.read_value (out.create_input_stream (), type ());
}
// extracts an Account object from an Any object
public static Account extract (org.omg.CORBA.Any a)
{
return read (a.create_input_stream ());
}
private static org.omg.CORBA.TypeCode __typeCode = null;
// gets the typecode for this type
synchronized public static org.omg.CORBA.TypeCode type ()
{
if (__typeCode == null)
{
__typeCode = org.omg.CORBA.ORB.init ().create_interface_tc (AccountHelper.id (), "Account");
}
return __typeCode;
}
// gets the repository id for this type
public static String id ()
{
return _id;
}
// reads an Account object from an input stream
public static Account read (org.omg.CORBA.portable.InputStream istream)
{
return narrow (istream.read_Object (_AccountStub.class));
}
// writes an Account object to an outputstream
public static void write (org.omg.CORBA.portable.OutputStream ostream, Account value)
{
ostream.write_Object ((org.omg.CORBA.Object) value);
}
// converts (narrows) an Object to an Account object
public static Account narrow (org.omg.CORBA.Object obj)
{
if (obj == null)
return null;
else if (obj instanceof Account)
return (Account)obj;
else if (!obj._is_a (id ()))
throw new org.omg.CORBA.BAD_PARAM ();
else
{
org.omg.CORBA.portable.Delegate delegate = ((org.omg.CORBA.portable.ObjectImpl)obj)._get_delegate ();
_AccountStub stub = new _AccountStub ();
stub._set_delegate(delegate);
return stub;
}
}
}
Assuming that Address is a value type, the
AddressHelper class will look like this:
abstract public class AddressHelper
{
private static String _id = "IDL:Address:1.0";
// same as for non-value type
public static void insert (org.omg.CORBA.Any a, Address that)
{
org.omg.CORBA.portable.OutputStream out = a.create_output_stream ();
a.type (type ());
write (out, that);
a.read_value (out.create_input_stream (), type ());
}
// same as for non-value type
public static Address extract (org.omg.CORBA.Any a)
{
return read (a.create_input_stream ());
}
private static org.omg.CORBA.TypeCode __typeCode = null;
private static boolean __active = false;
// getting the typecode for the type
synchronized public static org.omg.CORBA.TypeCode type ()
{
if (__typeCode == null)
{
synchronized (org.omg.CORBA.TypeCode.class)
{
if (__typeCode == null)
{
if (__active)
{
return org.omg.CORBA.ORB.init().create_recursive_tc ( _id );
}
__active = true;
org.omg.CORBA.ValueMember[] _members0 = new org.omg.CORBA.ValueMember[0];
org.omg.CORBA.TypeCode _tcOf_members0 = null;
__typeCode = org.omg.CORBA.ORB.init ().create_value_tc (_id, "Address", org.omg.CORBA.VM_NONE.value, null, _members0);
__active = false;
}
}
}
return __typeCode;
}
// same as for non-value type
public static String id ()
{
return _id;
}
// reads a serializable instance of Address from the given input stream
public static Address read (org.omg.CORBA.portable.InputStream istream)
{
return (Address)((org.omg.CORBA_2_3.portable.InputStream) istream).read_value (id ());
}
// writes a serializable instance of Address to the given output stream
public static void write (org.omg.CORBA.portable.OutputStream ostream, Address value)
{
((org.omg.CORBA_2_3.portable.OutputStream) ostream).write_value (value, id ());
}
}
The Helper classes defined in the package org.omg.CORBA are:
AnySeqHelper
BooleanSeqHelper
CharSeqHelper
CompletionStatusHelper
CurrentHelper
DefinitionKindHelper
DoubleSeqHelper
FieldNameHelper
FloatSeqHelper
IdentifierHelper
IDLTypeHelper
LongLongSeqHelper
LongSeqHelper
NameValuePairHelper
ObjectHelper
OctetSeqHelper
ParameterModeHelper
PolicyErrorCodeHelper
PolicyErrorHelper
PolicyHelper
PolicyListHelper
PolicyTypeHelper
RepositoryIdHelper
ServiceDetailHelper
ServiceInformationHelper
SetOverrideTypeHelper
ShortSeqHelper
StringSeqHelper
StringValueHelper
StructMemberHelper
ULongLongSeqHelper
ULongSeqHelper
UnionMemberHelper
UnknownUserExceptionHelper
UShortSeqHelper
ValueBaseHelper
ValueMemberHelper
VersionSpecHelper
VisibilityHelper
WCharSeqHelper
WrongTransactionHelper
WStringSeqHelper
WStringValueHelper
This is why several interfaces in the org.omg.CORBA package consist of a single field, value, which is a short. This field is a constant used for such things as an error code or value modifier. For example, the value field of the interface BAD_POLICY is one of the possible reasons for the exception PolicyError to be thrown. To specify this error code, you would use BAD_POLICY.value.
The exception PolicyError uses the value field of the following interfaces as its possible error codes.
ValueMember object's
access method to denote the visibility of the ValueMember object.
An ORB does not require that there be an interface repository, and Java
IDL does not include one. Even though this release does not include an
implementation of an interface repository, the following IR classes and
interfaces have been included for the purpose of creating typecodes (see
create_value_tc, create_struct_tc, create_union_tc and create_exception_tc
methods in interface org.omg.CORBA.ORB):
&nbs
Some of the API included in org.omg subpackages is provided for conformance with the current OMG CORBA specification but is not implemented in Sun's release of the JDKTM. This enables other JDK licensees to provide implementations of this API in standard extensions and products.
Some of the API included in org.omg subpackages throw NO_IMPLEMENT exceptions for various reasons. Among these reasons are:
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