Registry (Java SE 11 & JDK 11 )
Keywords: java.rmi.registry.Registry interface

Module java.rmi
Package java.rmi.registry

## Interface Registry

- All Superinterfaces:
    `Remote`

      public interface Registry
      extends Remote

  `Registry` is a remote interface to a simple remote object registry that provides methods for storing and retrieving remote object references bound with arbitrary string names. The `bind`, `unbind`, and `rebind` methods are used to alter the name bindings in the registry, and the `lookup` and `list` methods are used to query the current name bindings.

  In its typical usage, a `Registry` enables RMI client bootstrapping: it provides a simple means for a client to obtain an initial reference to a remote object. Therefore, a registry's remote object implementation is typically exported with a well-known address, such as with a well-known `ObjID` and TCP port number (default is `1099`).

  The `LocateRegistry` class provides a programmatic API for constructing a bootstrap reference to a `Registry` at a remote address (see the static `getRegistry` methods) and for creating and exporting a `Registry` in the current VM on a particular local address (see the static `createRegistry` methods).

  A `Registry` implementation may choose to restrict access to some or all of its methods (for example, methods that mutate the registry's bindings may be restricted to calls originating from the local host). If a `Registry` method chooses to deny access for a given invocation, its implementation may throw `AccessException`, which (because it extends `RemoteException`) will be wrapped in a `ServerException` when caught by a remote client.

  The names used for bindings in a `Registry` are pure strings, not parsed. A service which stores its remote reference in a `Registry` may wish to use a package name as a prefix in the name binding to reduce the likelihood of name collisions in the registry.

  Since:
    1.1
  See Also:
    `LocateRegistry`

- - ### Field Summary

    Fields
    Modifier and Type | Field | Description
    --- | --- | ---
    `static int` | `REGISTRY_PORT` | Well known port for registry.

  - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `void` | `bind​(String name, Remote obj)` | Binds a remote reference to the specified `name` in this registry.
    `String[]` | `list()` | Returns an array of the names bound in this registry.
    `Remote` | `lookup​(String name)` | Returns the remote reference bound to the specified `name` in this registry.
    `void` | `rebind​(String name, Remote obj)` | Replaces the binding for the specified `name` in this registry with the supplied remote reference.
    `void` | `unbind​(String name)` | Removes the binding for the specified `name` in this registry.

- - ### Field Detail

    - #### REGISTRY_PORT

          static final int REGISTRY_PORT

      Well known port for registry.
      See Also:
        Constant Field Values

  - ### Method Detail

    - #### lookup

          Remote lookup​(String name)
                 throws RemoteException,
                        NotBoundException,
                        AccessException

      Returns the remote reference bound to the specified `name` in this registry.
      Parameters:
        `name` - the name for the remote reference to look up
      Returns:
        a reference to a remote object
      Throws:
        `NotBoundException` - if `name` is not currently bound
        `RemoteException` - if remote communication with the registry failed; if exception is a `ServerException` containing an `AccessException`, then the registry denies the caller access to perform this operation
        `AccessException` - if this registry is local and it denies the caller access to perform this operation
        `NullPointerException` - if `name` is `null`

    - #### bind

          void bind​(String name,
                    Remote obj)
             throws RemoteException,
                    AlreadyBoundException,
                    AccessException

      Binds a remote reference to the specified `name` in this registry.
      Parameters:
        `name` - the name to associate with the remote reference
        `obj` - a reference to a remote object (usually a stub)
      Throws:
        `AlreadyBoundException` - if `name` is already bound
        `RemoteException` - if remote communication with the registry failed; if exception is a `ServerException` containing an `AccessException`, then the registry denies the caller access to perform this operation (if originating from a non-local host, for example)
        `AccessException` - if this registry is local and it denies the caller access to perform this operation
        `NullPointerException` - if `name` is `null`, or if `obj` is `null`

    - #### unbind

          void unbind​(String name)
               throws RemoteException,
                      NotBoundException,
                      AccessException

      Removes the binding for the specified `name` in this registry.
      Parameters:
        `name` - the name of the binding to remove
      Throws:
        `NotBoundException` - if `name` is not currently bound
        `RemoteException` - if remote communication with the registry failed; if exception is a `ServerException` containing an `AccessException`, then the registry denies the caller access to perform this operation (if originating from a non-local host, for example)
        `AccessException` - if this registry is local and it denies the caller access to perform this operation
        `NullPointerException` - if `name` is `null`

    - #### rebind

          void rebind​(String name,
                      Remote obj)
               throws RemoteException,
                      AccessException

      Replaces the binding for the specified `name` in this registry with the supplied remote reference. If there is an existing binding for the specified `name`, it is discarded.
      Parameters:
        `name` - the name to associate with the remote reference
        `obj` - a reference to a remote object (usually a stub)
      Throws:
        `RemoteException` - if remote communication with the registry failed; if exception is a `ServerException` containing an `AccessException`, then the registry denies the caller access to perform this operation (if originating from a non-local host, for example)
        `AccessException` - if this registry is local and it denies the caller access to perform this operation
        `NullPointerException` - if `name` is `null`, or if `obj` is `null`

    - #### list

          String[] list()
                 throws RemoteException,
                        AccessException

      Returns an array of the names bound in this registry. The array will contain a snapshot of the names bound in this registry at the time of the given invocation of this method.
      Returns:
        an array of the names bound in this registry
      Throws:
        `RemoteException` - if remote communication with the registry failed; if exception is a `ServerException` containing an `AccessException`, then the registry denies the caller access to perform this operation
        `AccessException` - if this registry is local and it denies the caller access to perform this operation