Registry (Java SE 26 & JDK 26)
Description: declaration: module: java.rmi, package: java.rmi.registry, interface: Registry
Keywords: java.rmi.registry.Registry interface

# 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 final int`
  `REGISTRY_PORT`
  Well known port for registry.

- ## Method Summary

  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 Details

  - ### REGISTRY_PORT

    static final int REGISTRY_PORT
    Well known port for registry.
    See Also:
      - Constant Field Values

- ## Method Details

  - ### 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