org.dvb.io.ixc

Class IxcRegistry

java.lang.Object

org.dvb.io.ixc.IxcRegistry

public class IxcRegistry
extends Object

This is the bootstrap mechanism for obtaining references to remote objects residing in other Xlets executing on the same MHP terminal, using a URL-like syntax. The identification of a remote object is given using a syntax indicating the organisation ID and application ID:
/organisation_id/application_id/name
organisation_id = the organisation ID of the Xlet, as signalled in the application_identifier record, defined in the MHP specification.
application_id = the application ID of the Xlet, as signalled in the application_identifier record, defined in the MHP specification.
name = the name under which the remote object was exported.

The organisation ID and the application ID shall each be encoded as a hexadecimal string, as would be accepted by java.lang.Integer.parseInt(String s, 16).

When RMI is used to communicate over a network, stubs generated by a tool like rmic are often required. This is not necessary for inter-xlet communication initiated with IxcRegistry. If such stubs are present, they shall be ignored.

Similarly, network RMI objects often extend the class server.RemoteObject, in order to get appropriate implementations for Object.hashCode(), Object.equals(), and Object.toString(). Overriding Object's implementation of these methods in this way is not necessary for inter-xlet communication initiated with IxcRegistry, although it is not harmful. Note that the class server.RemoteObject is not required in all MHP profiles.

Field Summary

Fields

Modifier and Type	Field and Description
static int	GLOBAL Definition of the scope for bind or rebind - exported object is visible to any Xlet running within the same MHP terminal subject to requirements of the security model.
static int	PAGE Definition of the scope for bind or rebind - exported object is only visible to Xlets within the same DVB-HTML application.
static int	SERVICE Definition of the scope for bind or rebind - exported object is only visible to Xlets running within the same service context

Method Summary

Methods

Modifier and Type	Method and Description
static void	bind(XletContext xc, String name, Remote obj) Exports an object under a given name in the namespace of an Xlet.
static void	bind(XletContext xc, String name, Remote obj, int scope) Exports an object under a given name in the namespace of an Xlet.
static String[]	list(XletContext xc) Returns an array of string path objects available in the registry.
static Remote	lookup(XletContext xc, String path) Returns a remote object previously exported by an Xlet that has not been destroyed.
static void	rebind(XletContext xc, String name, Remote obj) Rebind the name to a new object in the context of an Xlet; replaces any existing binding.
static void	rebind(XletContext xc, String name, Remote obj, int scope) Rebind the name to a new object in the context of an Xlet; replaces any existing binding.
static void	unbind(XletContext xc, String name) Unbind the name.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

SERVICE

public static final int SERVICE

Definition of the scope for bind or rebind - exported object is only visible to Xlets running within the same service context

Since:

MHP 1.1.2

See Also:

Constant Field Values

PAGE

public static final int PAGE

Definition of the scope for bind or rebind - exported object is only visible to Xlets within the same DVB-HTML application. Note that an embedded Xlet with a different app ID than its enclosing HTML page is still considered to be the same application as that which contains the enclosing page.

Since:

MHP 1.1.2

See Also:

Constant Field Values

GLOBAL

public static final int GLOBAL

Definition of the scope for bind or rebind - exported object is visible to any Xlet running within the same MHP terminal subject to requirements of the security model.

Since:

MHP 1.1.2

See Also:

Constant Field Values

Method Detail

lookup

public static Remote lookup(XletContext xc,
            String path)
                     throws NotBoundException,
                            RemoteException

Returns a remote object previously exported by an Xlet that has not been destroyed. The identification of a remote object is given using a syntax indicating the organisation ID and application ID:
/organisation_id/application_id/name
organisation_id = the organisation ID of the Xlet, as signalled in the application_identifier record.
application_id = the application ID of the Xlet, as signalled in the application_identifier record.
name = the name under which the remote object was exported.

The organisation ID and the application ID shall each be encoded as a hexadecimal string, as would be accepted by java.lang.Integer.parseInt(String s, 16). If the caller is not authorized to import a given object due to the security policy, then this API will behave as though the object had not been exported, that is, a NotBoundException shall be thrown.

Parameters:

xc - The context of the current Xlet (that is, the Xlet importing the object).

path - A file pathname-like string identifying the Xlet and the name of the object to be imported.

Returns:

A remote object

Throws:

NotBoundException - If the path is not currently bound.

RemoteException - If a remote stub class cannot be generated for the object being imported.

IllegalArgumentException - If the path is not formatted in the syntax given above.

NullPointerException - if path is null

bind

public static void bind(XletContext xc,
        String name,
        Remote obj)
                 throws AlreadyBoundException

Exports an object under a given name in the namespace of an Xlet. The name can be any valid non-null String. No hierarchical namespace exists, e.g. the names "foo" and "bar/../foo" are distinct. If the exporting xlet has been destroyed, this method may fail silently.

The object shall be made visible to other applications running in the same service context. A call to bind(xc, name, obj) is thus equivalent to a call to bind(xc, name, obj, SERVICE).

Parameters:

xc - The context of the Xlet exporting the object.

name - The name identifying the object.

obj - The object being exported

Throws:

AlreadyBoundException - if this Xlet has previously exported an object under the given name.

NullPointerException - if xc, name or obj is null

bind

public static void bind(XletContext xc,
        String name,
        Remote obj,
        int scope)
                 throws AlreadyBoundException

Exports an object under a given name in the namespace of an Xlet. The name can be any valid non-null String. No hierarchical namespace exists, e.g. the names "foo" and "bar/../foo" are distinct. If the exporting xlet has been destroyed, this method may fail silently.

Parameters:

xc - The context of the Xlet exporting the object.

name - The name identifying the object.

obj - The object being exported

scope - The scope to which the object is to be exported

Throws:

AlreadyBoundException - if this Xlet has previously exported an object under the given name.

NullPointerException - if xc, name or obj is null

Since:

MHP 1.1

unbind

public static void unbind(XletContext xc,
          String name)
                   throws NotBoundException

Unbind the name.

Parameters:

xc - The context of the Xlet that exported the object to be unbound.

name - The name identifying the object.

Throws:

NotBoundException - if this is not currently any object exported by this Xlet under the given name.

NullPointerException - if xc or name is null

rebind

public static void rebind(XletContext xc,
          String name,
          Remote obj)

Rebind the name to a new object in the context of an Xlet; replaces any existing binding. The name can be any valid non-null String. No hierarchical namespace exists, e.g. the names "foo" and "bar/../foo" are distinct. If the exporting xlet has been destroyed, this method may fail silently.

The object shall be made visible to other applications running in the same service context. A call to rebind(xc, name, obj) is thus equivalent to a call to rebind(xc, name, obj, SERVICE).

Parameters:

xc - The context of the Xlet that exported the object.

name - The name identifying the object.

obj - The object being exported

Throws:

NullPointerException - if xc, name or obj is null

rebind

public static void rebind(XletContext xc,
          String name,
          Remote obj,
          int scope)

Rebind the name to a new object in the context of an Xlet; replaces any existing binding. The name can be any valid non-null String. No hierarchical namespace exists, e.g. the names "foo" and "bar/../foo" are distinct. If the exporting xlet has been destroyed, this method may fail silently.

Narrowing the scope of the binding (e.g. from GLOBAL to SERVICE) shall have the same effect as a call to unbind for any applications which had references to that object and which were in scope but which are now out of scope.

Parameters:

xc - The context of the Xlet that exported the object.

name - The name identifying the object.

obj - The object being exported

scope - The scope to which the object is to be exported

Throws:

NullPointerException - if xc, name or obj is null

Since:

MHP 1.1

list

public static String[] list(XletContext xc)

Returns an array of string path objects available in the registry. The array contains a snapshot of the names present in the registry that the current Xlet would be allowed to import using IxcRegistry.lookup.

Parameters:

xc - The context of the current Xlet.

Returns:

A non-null array of strings containing a snapshot of the path names of all objects available to the caller in this registry.

See Also:

lookup(javax.tv.xlet.XletContext,String)