org.omg.CORBA
Class ORB

java.lang.Object   
  org.omg.CORBA.ORB

Direct Known Subclasses:

ORB

public abstract class ORB
extends Object   

A class providing APIs for the CORBA Object Request Broker features. The ORB class also provides "pluggable ORB implementation" APIs that allow another vendor's ORB implementation to be used.

An ORB makes it possible for CORBA objects to communicate with each other by connecting objects making requests (clients) with objects servicing requests (servers).

The ORB class, which encapsulates generic CORBA functionality, does the following: (Note that items 5 and 6, which include most of the methods in the class ORB, are typically used with the Dynamic Invocation Interface (DII) and the Dynamic Skeleton Interface (DSI). These interfaces may be used by a developer directly, but most commonly they are used by the ORB internally and are not seen by the general programmer.)

1. initializes the ORB implementation by supplying values for predefined properties and environmental parameters
2. obtains initial object references to services such as the NameService using the method resolve_initial_references
3. converts object references to strings and back
4. connects the ORB to a servant (an instance of a CORBA object implementation) and disconnects the ORB from a servant
5. creates objects such as
   • TypeCode
   • Any
   • NamedValue
   • Context
   • Environment
   • lists (such as NVList) containing these objects
6. sends multiple messages in the DII

The ORB class can be used to obtain references to objects implemented anywhere on the network.

An application or applet gains access to the CORBA environment by initializing itself into an ORB using one of three init methods. Two of the three methods use the properties (associations of a name with a value) shown in the table below.

Standard Java CORBA Properties:

Property Name	Property Value
org.omg.CORBA.ORBClass	class name of an ORB implementation
org.omg.CORBA.ORBSingletonClass	class name of the ORB returned by init()

These properties allow a different vendor's ORB implementation to be "plugged in."

When an ORB instance is being created, the class name of the ORB implementation is located using the following standard search order:

1. check in Applet parameter or application string array, if any
2. check in properties parameter, if any
3. check in the System properties
4. check in the orb.properties file located in the user.home directory (if any)
5. check in the orb.properties file located in the java.home/lib directory (if any)
6. fall back on a hardcoded default behavior (use the Java IDL implementation)

Note that Java IDL provides a default implementation for the fully-functional ORB and for the Singleton ORB. When the method init is given no parameters, the default Singleton ORB is returned. When the method init is given parameters but no ORB class is specified, the Java IDL ORB implementation is returned.

The following code fragment creates an ORB object initialized with the default ORB Singleton. This ORB has a restricted implementation to prevent malicious applets from doing anything beyond creating typecodes. It is called a singleton because there is only one instance for an entire virtual machine.

    ORB orb = ORB.init();
 

The following code fragment creates an ORB object for an application. The parameter args represents the arguments supplied to the application's main method. Since the property specifies the ORB class to be "SomeORBImplementation", the new ORB will be initialized with that ORB implementation. If p had been null, and the arguments had not specified an ORB class, the new ORB would have been initialized with the default Java IDL implementation.

    Properties p = new Properties();
    p.put("org.omg.CORBA.ORBClass", "SomeORBImplementation");
    ORB orb = ORB.init(args, p);
 

The following code fragment creates an ORB object for the applet supplied as the first parameter. If the given applet does not specify an ORB class, the new ORB will be initialized with the default Java IDL implementation.

    ORB orb = ORB.init(myApplet, null);
 

An application or applet can be initialized in one or more ORBs. ORB initialization is a bootstrap call into the CORBA world.

Since:

JDK1.2

Constructor Summary

ORB ()

Method Summary

void	connect (Object obj) Connects the given servant object (a Java object that is an instance of the server implementation class) to the ORB.
TypeCode	create_abstract_interface_tc (String id, String name) Create a TypeCode object for an IDL abstract interface.
abstract TypeCode	create_alias_tc (String id, String name, TypeCode original_type) Creates a TypeCode object representing an IDL alias (typedef).
abstract Any	create_any () Creates an IDL Any object initialized to contain a Typecode object whose kind field is set to TCKind.tc_null.
abstract TypeCode	create_array_tc (int length, TypeCode element_type) Creates a TypeCode object representing an IDL array.
DynAny	create_basic_dyn_any (TypeCode type) Deprecated. Use the new DynAnyFactory API instead
abstract ContextList	create_context_list () Creates an empty ContextList object.
DynAny	create_dyn_any (Any value) Deprecated. Use the new DynAnyFactory API instead
DynArray	create_dyn_array (TypeCode type) Deprecated. Use the new DynAnyFactory API instead
DynEnum	create_dyn_enum (TypeCode type) Deprecated. Use the new DynAnyFactory API instead
DynSequence	create_dyn_sequence (TypeCode type) Deprecated. Use the new DynAnyFactory API instead
DynStruct	create_dyn_struct (TypeCode type) Deprecated. Use the new DynAnyFactory API instead
DynUnion	create_dyn_union (TypeCode type) Deprecated. Use the new DynAnyFactory API instead
abstract TypeCode	create_enum_tc (String id, String name, String [] members) Creates a TypeCode object representing an IDL enum.
abstract Environment	create_environment () Creates an Environment object.
abstract ExceptionList	create_exception_list () Creates an empty ExceptionList object.
abstract TypeCode	create_exception_tc (String id, String name, StructMember [] members) Creates a TypeCode object representing an IDL exception.
TypeCode	create_fixed_tc (short digits, short scale) Create a TypeCode object for an IDL fixed type.
abstract TypeCode	create_interface_tc (String id, String name) Creates a TypeCode object representing an IDL interface.
abstract NVList	create_list (int count) Allocates an NVList with (probably) enough space for the specified number of NamedValue objects.
abstract NamedValue	create_named_value (String s, Any any, int flags) Creates a NamedValue object using the given name, value, and argument mode flags.
TypeCode	create_native_tc (String id, String name) Create a TypeCode object for an IDL native type.
NVList	create_operation_list (Object oper) Creates an NVList initialized with argument descriptions for the operation described in the given OperationDef object.
abstract OutputStream	create_output_stream () Creates a new org.omg.CORBA.portable.OutputStream into which IDL method parameters can be marshalled during method invocation.
Policy	create_policy (int type, Any val) Can be invoked to create new instances of policy objects of a specific type with specified initial state.
abstract TypeCode	create_recursive_sequence_tc (int bound, int offset) Deprecated. Use a combination of create_recursive_tc and create_sequence_tc instead
TypeCode	create_recursive_tc (String id) Create a recursive TypeCode object which serves as a placeholder for a concrete TypeCode during the process of creating TypeCodes which contain recursion.
abstract TypeCode	create_sequence_tc (int bound, TypeCode element_type) Creates a TypeCode object representing an IDL sequence.
abstract TypeCode	create_string_tc (int bound) Creates a TypeCode object representing a bounded IDL string.
abstract TypeCode	create_struct_tc (String id, String name, StructMember [] members) Creates a TypeCode object representing an IDL struct.
abstract TypeCode	create_union_tc (String id, String name, TypeCode discriminator_type, UnionMember [] members) Creates a TypeCode object representing an IDL union.
TypeCode	create_value_box_tc (String id, String name, TypeCode boxed_type) Creates a TypeCode object for an IDL value box.
TypeCode	create_value_tc (String id, String name, short type_modifier, TypeCode concrete_base, ValueMember [] members) Create a TypeCode object for an IDL value type.
abstract TypeCode	create_wstring_tc (int bound) Creates a TypeCode object representing a bounded IDL wstring (wide string).
void	destroy () Destroys the ORB so that its resources can be reclaimed.
void	disconnect (Object obj) Disconnects the given servant object from the ORB.
Current	get_current () Deprecated. use resolve_initial_references.
abstract Context	get_default_context () Gets the default Context object.
abstract Request	get_next_response () Gets the next Request instance for which a response has been received.
abstract TypeCode	get_primitive_tc (TCKind tcKind) Retrieves the TypeCode object that represents the given primitive IDL type.
boolean	get_service_information (short service_type, ServiceInformationHolder service_info) Used to obtain information about CORBA facilities and services that are supported by this ORB.
static ORB	init () Returns the ORB singleton object.
static ORB	init (Applet app, Properties props) Creates a new ORB instance for an applet.
static ORB	init (String [] args, Properties props) Creates a new ORB instance for a standalone application.
abstract String []	list_initial_services () Returns a list of the initially available CORBA object references, such as "NameService" and "InterfaceRepository".
abstract String	object_to_string (Object obj) Converts the given CORBA object reference to a string.
void	perform_work () Performs an implementation-dependent unit of work if called by the main thread.
abstract boolean	poll_next_response () Finds out if any of the deferred (asynchronous) invocations have a response yet.
abstract Object	resolve_initial_references (String object_name) Resolves a specific object reference from the set of available initial service names.
void	run () This operation blocks the current thread until the ORB has completed the shutdown process, initiated when some thread calls shutdown.
abstract void	send_multiple_requests_deferred (Request [] req) Sends multiple dynamic (DII) requests asynchronously.
abstract void	send_multiple_requests_oneway (Request [] req) Sends multiple dynamic (DII) requests asynchronously without expecting any responses.
protected abstract void	set_parameters (Applet app, Properties props) Allows the ORB implementation to be initialized with the given applet and parameters.
protected abstract void	set_parameters