Package nl.tudelft.simulation.naming.context

Interface ContextInterface

All Superinterfaces:

EventProducer, Remote, Serializable

All Known Subinterfaces:

EventContext, RemoteContextInterface, RemoteEventContextInterface

All Known Implementing Classes:

FileContext, InitialEventContext, JVMContext, RemoteContext, RemoteEventContext

public interface ContextInterface
extends EventProducer, Serializable

ContextInterface is the lightweight and simplified version of the JNDI EventContext interface in the standard Java distribution. It just contains the services for binding and unbinding of objects, for retrieving objects and Context trees, and for creating an initial context and creating and removing subcontexts. As it extends the EventProducer, it is able to fire events for adding and removing of elements in the Context.

A name for a Context can be compound, i.e. consisting of parts separated by a separator string. Usually the separator string is the forward slash. As an example, when the name is "sub1/sub2/ref", sub1 and sub2 must be pointing to a Context, whereas ref can be either another Context, or a regular Object.

The context names support absolute addresses that start with a forward slash. For an absolute address, the context tree is traversed to the root, and the (compound) name is resolved from the root context. For relative addresses that start with any character but the forward slash, the (compound) name is resolved from the current context.

Values that are stored in the context are required to be Serializable. Both the FileContext and the RemoteContext need to serialize the values when storing them, so serializability of the Context's content is a necessary property.

Copyright (c) 2020-2023 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See for project information https://simulation.tudelft.nl. The DSOL project is distributed under a three-clause BSD-style license, which can be found at https://https://simulation.tudelft.nl/dsol/docs/latest/license.html.

Author:

Alexander Verbraeck

Field Summary

Fields

Modifier and Type	Field	Description
static EventType	OBJECT_ADDED_EVENT	OBJECT_ADDED_EVENT is fired whenever an object is added to the Context.
static EventType	OBJECT_CHANGED_EVENT	OBJECT_CHANGED_EVENT can be fired whenever an object present in the Context is changed.
static EventType	OBJECT_REMOVED_EVENT	OBJECT_REMOVED_EVENT is fired whenever an object is removed from the Context.
static String	REPLACE_SEPARATOR	The replacement string for the separator, in case it is part of a name.
static String	ROOT	The default root sign for a context.
static String	SEPARATOR	The default separator sign for a context.

Fields inherited from interface org.djutils.event.EventProducer

FIRST_POSITION, LAST_POSITION

Method Summary

Modifier and Type	Method	Description
void	bind(String name, Object object)	Binds an object into the Context using the name.
Map<String,Object>	bindings()	Returns a (raw) map of bindings in the current context, mapping the name on the registered objects.
void	bindObject(Object object)	Binds an object into the Context using the toString() method of the object as the key.
void	bindObject(String key, Object object)	Binds an object into this Context using the key.
void	checkCircular(Object newObject)	Check whether a circular reference would occur when the object would be inserted into the current context.
void	close()	Closes the context and removes all content from the context.
ContextInterface	createSubcontext(String name)	Creates and binds a new context into the current Context using the name.
void	destroySubcontext(String name)	Removes the binding for an existing, empty subcontext with the given name, and recursively unbinds all objects and contexts in the context indicated by the name.
boolean	exists(String name)	Indicates whether an object with the given name has been registered in the Context.
void	fireObjectChangedEventKey(String key)	Fire an OBJECT_CHANGED_EVENT for an object with the given key in the current context.
void	fireObjectChangedEventValue(Object object)	Fire an OBJECT_CHANGED_EVENT for an object within the current context.
Object	get(String name)	Retrieves the named object from the Context.
String	getAbsolutePath()	Returns the absolute path for this context, or an empty string when this is the root context.
String	getAtomicName()	Retrieves the atomic name of this context.
Object	getObject(String key)	Retrieves the named object from the Context.
ContextInterface	getParent()	Retrieves the parent context for this context, or null when this is the root context.
ContextInterface	getRootContext()	Retrieves the root context for this context, or the current context when this is the root context.
boolean	hasKey(String key)	Indicates whether the key has been registered in the current Context.
boolean	hasObject(Object object)	Indicates whether the object has been registered (once or more) in the current Context.
boolean	isEmpty()	Indicates whether the current context is empty.
Set<String>	keySet()	Returns a set of registered keys in the current context.
void	rebind(String name, Object object)	Replaces an object in the Context with the given name, or registers the object when a registration with the name does not exist yet.
void	rebindObject(String key, Object object)	Replaces an object in this Context with the given key, or registers the object when a registration with the key does not exist yet.
void	rename(String oldName, String newName)	Replaces the name under which an object has been registered in the Context.
String	toString(boolean verbose)	Return a String with the hierarchical content of the Context in case verbose is true; otherwise return the atomic name.
void	unbind(String name)	Removes the binding for an object in the Context with the given name.
void	unbindObject(String key)	Removes the binding for an object in this Context with the given key.
Collection<Object>	values()	Returns a (raw) collection of registered values in the current context.

Methods inherited from interface org.djutils.event.EventProducer

addListener, addListener, addListener, addListener, fireEvent, fireEvent, fireEvent, fireTimedEvent, fireTimedEvent, fireTimedEvent, fireUnverifiedEvent, fireUnverifiedEvent, fireUnverifiedTimedEvent, fireUnverifiedTimedEvent, getEventListenerMap, getEventTypesWithListeners, getListenerReferences, hasListeners, numberOfListeners, removeAllListeners, removeAllListeners, removeListener

Field Detail

ROOT

static final String ROOT

The default root sign for a context.

See Also:

Constant Field Values

SEPARATOR

static final String SEPARATOR

The default separator sign for a context.

See Also:

Constant Field Values

REPLACE_SEPARATOR

static final String REPLACE_SEPARATOR

The replacement string for the separator, in case it is part of a name.

See Also:

Constant Field Values

OBJECT_ADDED_EVENT

static final EventType OBJECT_ADDED_EVENT

OBJECT_ADDED_EVENT is fired whenever an object is added to the Context. The implementations of the ContextInterface in the nl.tudelft.simulation.naming.context package take care of firing this event.
Payload: Object[] - the absolute path of the context in which the object was bound, the relative key in the context, and the bound object.

OBJECT_REMOVED_EVENT

static final EventType OBJECT_REMOVED_EVENT

OBJECT_REMOVED_EVENT is fired whenever an object is removed from the Context. The implementations of the ContextInterface in the nl.tudelft.simulation.naming.context package take care of firing this event.
Payload: Object[] - the absolute path of the context in which the object was bound, the relative key in the context, and the removed object.

OBJECT_CHANGED_EVENT

static final EventType OBJECT_CHANGED_EVENT

OBJECT_CHANGED_EVENT can be fired whenever an object present in the Context is changed. The object making changes has to fire this Event itself, because the Context has no way of knowing that the content of the object has changed. The method fireObjectChangedEvent(...) in the ContextInterface can be used to fire this event.
Payload: Object[] - the absolute path of the context in which the object is bound, the relative key in the context, the object after change.

Method Detail

getAtomicName

String getAtomicName()
              throws RemoteException

Retrieves the atomic name of this context.

Returns:

String; the atomic name of this context

Throws:

RemoteException - on a network error when the Context is used over RMI

getParent

ContextInterface getParent()
                    throws RemoteException

Retrieves the parent context for this context, or null when this is the root context.

Returns:

ContextInterface; parent context for this context, or null when this is the root context

Throws:

RemoteException - on a network error when the Context is used over RMI

getRootContext

ContextInterface getRootContext()
                         throws RemoteException

Retrieves the root context for this context, or the current context when this is the root context.

Returns:

ContextInterface; the root context for this context

Throws:

RemoteException - on a network error when the Context is used over RMI

getAbsolutePath

String getAbsolutePath()
                throws RemoteException

Returns the absolute path for this context, or an empty string when this is the root context.

Returns:

String; the absolute path for this context, or an empty string when this is the root context

Throws:

RemoteException - on a network error when the Context is used over RMI

get

Object get(String name)
    throws NamingException,
           RemoteException

Retrieves the named object from the Context. The name may be a compound name where parts are separated by separation strings indicating subcontexts. All intermediate subcontexts must exist. When name is the empty String or "/", the current Context is returned.

Parameters:

name - String; the name of the object to look up; may be a compound name

Returns:

Object; the Context or Object indicated by the name

Throws:

NamingException - as a placeholder overarching exception

NameNotFoundException - if an intermediate context or the reference does not exist

NullPointerException - when name is null

RemoteException - on a network error when the Context is used over RMI

getObject

Object getObject(String key)
          throws NamingException,
                 RemoteException

Retrieves the named object from the Context. The key is not compound. Key cannot be empty or contain "/".

Parameters:

key - String; the name of the object to look up; NOT a compound name

Returns:

Object; the Context or Object indicated by the key

Throws:

NamingException - when key is the empty string or when key contains "/"

NameNotFoundException - if the key does not exist in the current context

NullPointerException - when key is null

RemoteException - on a network error when the Context is used over RMI

exists

boolean exists(String name)
        throws NamingException,
               RemoteException

Indicates whether an object with the given name has been registered in the Context. The name may be a compound name where parts are separated by separation strings indicating subcontexts. All intermediate subcontexts must exist. When name is the empty String or "/", the method returns true.

Parameters:

name - String; the name of the object to look up; may be a compound name

Returns:

boolean; whether an object with the given name has been registered

Throws:

NamingException - as a placeholder overarching exception

NameNotFoundException - when an intermediate context does not exist

NullPointerException - when name is null

RemoteException - on a network error when the Context is used over RMI

hasKey

boolean hasKey(String key)
        throws NamingException,
               RemoteException

Indicates whether the key has been registered in the current Context. The name is not compound. When name is the empty String or "/", the method returns an exception.

Parameters:

key - String; the name of the object to look up; NOT compound

Returns:

boolean; whether an object with the given key has been registered in the current context

Throws:

NamingException - when key is the empty string or when key contains "/"

NullPointerException - when key is null

RemoteException - on a network error when the Context is used over RMI

hasObject

boolean hasObject(Object object)
           throws RemoteException

Indicates whether the object has been registered (once or more) in the current Context. The object may be null.

Parameters:

object - Object; the object to look up; mey be null

Returns:

boolean; whether an object with the given key has been registered once or more in the current context

Throws:

RemoteException - on a network error when the Context is used over RMI

isEmpty

boolean isEmpty()
         throws RemoteException

Indicates whether the current context is empty.

Returns:

boolean; whether the current context is empty

Throws:

RemoteException - on a network error when the Context is used over RMI

bind

void bind(String name,
          Object object)
   throws NamingException,
          RemoteException

Binds an object into the Context using the name. The name may be a compound name where parts are separated by separation strings indicating subcontexts. All intermediate subcontexts must already exist. The object will be registered using the terminal atomic reference in the deepest subcontext provided. Name cannot be empty or "/". An OBJECT_ADDED_EVENT is fired containing an object array with a pointer to the context, the relative key, and the object when a new binding has taken place.

Parameters:

name - String; the name under which the object will be stored; may be a compound name with the terminal reference indicating the key under which the object will be stored

object - Object; the Context or Object to be stored into the given context; a null object is allowed

Throws:

NamingException - when the reference is "/" or empty

NameAlreadyBoundException - if name is already bound to an object

NameNotFoundException - when an intermediate context does not exist

NullPointerException - when name is null

RemoteException - on a network error when the Context is used over RMI

bindObject

void bindObject(String key,
                Object object)
         throws NamingException,
                RemoteException

Binds an object into this Context using the key. The key is not compound. The key cannot be empty or "/". An OBJECT_ADDED_EVENT is fired containing an object array with a pointer to the context, the relative key, and the object when a new binding has taken place.

Parameters:

key - String; the key under which the object will be stored; NOT a compound name

object - Object; the Context or Object to be stored into this Context using the given name; a null object is allowed

Throws:

NamingException - when key is the empty string or when key contains "/"

NameAlreadyBoundException - if key is already bound to an object

NullPointerException - when key is null

RemoteException - on a network error when the Context is used over RMI

bindObject

void bindObject(Object object)
         throws NamingException,
                RemoteException

Binds an object into the Context using the toString() method of the object as the key. All "/" characters in the toString() result will be replaced by "#" characters. An OBJECT_ADDED_EVENT is fired containing an object array with a pointer to the context, the relative key, and the object when a new binding has taken place.

Parameters:

object - Object; the Context or Object to be stored into this Context using the toString() result as the key; a null object is not allowed

Throws:

NamingException - when the toString() of the object results in an empty string

NameAlreadyBoundException - if key is already bound to an object

NullPointerException - when object is null

RemoteException - on a network error when the Context is used over RMI

unbind

void unbind(String name)
     throws NamingException,
            RemoteException

Removes the binding for an object in the Context with the given name. The name may be a compound name where parts are separated by separation strings indicating subcontexts. Name cannot be empty or "/". It is not a problem when there is no object registered with the given name. An OBJECT_REMOVED_EVENT is fired containing an object array with a pointer to the context, the relative key, and the removed object when a binding has been removed.

Parameters:

name - String; the name of the object that has to be removed; may be a compound name with the terminal reference indicating the key under which the object is stored

Throws:

NamingException - when the reference is "/" or empty

NameNotFoundException - when an intermediate context does not exist

NullPointerException - when name is null

RemoteException - on a network error when the Context is used over RMI

unbindObject

void unbindObject(String key)
           throws NamingException,
                  RemoteException

Removes the binding for an object in this Context with the given key. The key is not compound. The key cannot be empty or "/". It is not a problem when there is no object registered with the given key. An OBJECT_REMOVED_EVENT is fired containing an object array with a pointer to the context, the relative key, and the removed object when a binding has been removed.

Parameters:

key - String; the key of the object that has to be removed; NOT a compound name

Throws:

NamingException - when key is the empty string or when key contains "/"

NullPointerException - when key is null

RemoteException - on a network error when the Context is used over RMI

rebind

void rebind(String name,
            Object object)
     throws NamingException,
            RemoteException

Replaces an object in the Context with the given name, or registers the object when a registration with the name does not exist yet. The name may be a compound name where parts are separated by separation strings indicating subcontexts. All intermediate subcontexts must already exist. The object will be (re)registered using the terminal atomic reference in the deepest subcontext provided. Name cannot be empty or "/". An OBJECT_REMOVED_EVENT is fired containing an object array with a pointer to the context, the relative key, and the removed object when a binding had to be removed, followed by an OBJECT_ADDED_EVENT containing an object array with a pointer to the context, the key, and the new object when a new binding has taken place.

Parameters:

name - String; the name of the object to be replaced, or under which the object will be stored; may be a compound name with the terminal reference indicating the key under which the object will be stored

object - Object; the Context or Object to be replaced or stored into this Context using the given name; a null object is allowed

Throws:

NamingException - when the reference is "/" or empty

NameNotFoundException - when an intermediate context does not exist

NullPointerException - when name is null

RemoteException - on a network error when the Context is used over RMI

rebindObject

void rebindObject(String key,
                  Object object)
           throws NamingException,
                  RemoteException

Replaces an object in this Context with the given key, or registers the object when a registration with the key does not exist yet. The key is not a compound name. Name cannot be empty or "/". An OBJECT_REMOVED_EVENT is fired containing an object array with a pointer to the context, the relative key, and the removed object when a binding had to be removed, followed by an OBJECT_ADDED_EVENT containing an object array with a pointer to the context, the key, and the new object when a new binding has taken place.

Parameters:

key - String; the key of the object to be replaced, or under which the object will be stored; NOT a compound name

object - Object; the Context or Object to be replaced or stored into this Context using the given name; a null object is allowed

Throws:

NamingException - when key is the empty string or when key contains "/"

NullPointerException - when name is null

RemoteException - on a network error when the Context is used over RMI

rename

void rename(String oldName,
            String newName)
     throws NamingException,
            RemoteException

Replaces the name under which an object has been registered in the Context. Both names are relative to the current Context, and may be compound names where parts are separated by separation strings indicating subcontexts. All intermediate subcontexts of the new name must already exist. The object will be deregistered under the old name, and reregistered using the terminal atomic reference in the deepest subcontext of the newName. Nether the oldName, nor the newName can be empty or "/". An OBJECT_REMOVED_EVENT is fired containing an object array with a pointer to the old context, the old relative key, and the object when a binding had to be removed, followed by an OBJECT_ADDED_EVENT containing an object array with a pointer to the new context, the new relative key, and the object when a new binding has taken place. When the new name is illegal or occupied, the object will not be renamed.

Parameters:

oldName - String; the (compound) name of the object to be moved to a new location

newName - String; the (compound) name with the terminal reference indicating where the object will be stored

Throws:

NamingException - when the reference of oldName or newName is "/" or empty

NameNotFoundException - when an intermediate context of oldName or newName does not exist, or when there is no registration at the oldName reference

NameAlreadyBoundException - if newName is already bound to an object

NullPointerException - when oldName or newName is null

RemoteException - on a network error when the Context is used over RMI

createSubcontext

ContextInterface createSubcontext(String name)
                           throws NamingException,
                                  RemoteException

Creates and binds a new context into the current Context using the name. The name may be a compound name where parts are separated by separation strings indicating subcontexts. All intermediate subcontexts that do not yet exist, will be created. The new context will be registered using the terminal atomic reference in the deepest subcontext provided. Name cannot be empty or "/". On success, OBJECT_ADDED_EVENTs are fired for the created context and each new intermediate context, containing an object array with an object array with a pointer to the embedding context, the local key in the embedding context, and the newly created (intermediate) context.

Parameters:

name - String; the name under which the new context will be stored; may be a compound name with the terminal reference indicating the key under which the new context will be stored

Returns:

ContextInterface; a pointer to the newly created subcontext

Throws:

NamingException - when the terminal reference is "/" or empty

NameNotFoundException - when an intermediate context does not exist

NameAlreadyBoundException - if name is already bound to an object or context

NullPointerException - when name is null

RemoteException - on a network error when the Context is used over RMI

destroySubcontext

void destroySubcontext(String name)
                throws NamingException,
                       RemoteException

Removes the binding for an existing, empty subcontext with the given name, and recursively unbinds all objects and contexts in the context indicated by the name. The name may be a compound name where parts are separated by separation strings indicating subcontexts. Name cannot be empty or "/". A context has to be registered with the given name. For all removed objects and contexts, OBJECT_REMOVED_EVENT events are fired containing an object array with a pointer to the context from which content has been removed, the key of the binding that has been removed, and the removed object. The OBJECT_REMOVED_EVENT events are fired in depth-first order.

Parameters:

name - String; the name of the object that has to be removed; may be a compound name with the terminal reference indicating the key under which the object is stored

Throws:

NamingException - when the reference is "/" or empty

NotContextException - if the name is bound but does not name a context

NameNotFoundException - when an intermediate context does not exist, or when no object is registered with the terminating atomic reference

NullPointerException - when name is null

RemoteException - on a network error when the Context is used over RMI

fireObjectChangedEventValue

void fireObjectChangedEventValue(Object object)
                          throws NameNotFoundException,
                                 NullPointerException,
                                 NamingException,
                                 RemoteException

Fire an OBJECT_CHANGED_EVENT for an object within the current context. Look up if the the object exists using the toString() method of the object as the key. All "/" characters in the toString() result will be replaced by "#" characters. When the object does not exist directly in the context, a NameNotFoundException is thrown.

Parameters:

object - Object; the object that has changed and for which an event should be fired

Throws:

NamingException - on general error in the method, e.g., a problem with remote connections

NameNotFoundException - when no object is registered with object.toString() as the key

NullPointerException - when object is null

RemoteException - on a network error when the Context is used over RMI

fireObjectChangedEventKey

void fireObjectChangedEventKey(String key)
                        throws NameNotFoundException,
                               NullPointerException,
                               NamingException,
                               RemoteException

Fire an OBJECT_CHANGED_EVENT for an object with the given key in the current context. If the the key does not exist directly in the context, a NameNotFoundException is thrown. The key should not be the empty String or contain "/" characters.

Parameters:

key - String; the key within the context of the object that has changed and for which an event should be fired

Throws:

NamingException - when key is the empty string or when key contains "/", or on a general error in the method, e.g., a problem with remote connections

NameNotFoundException - when no object is registered with the key in the given context

NullPointerException - when key is null

RemoteException - on a network error when the Context is used over RMI

keySet

Set<String> keySet()
            throws RemoteException

Returns a set of registered keys in the current context.

Returns:

Set<String>; a set of registered keys in the current context

Throws:

RemoteException - on a network error when the Context is used over RMI

values

Collection<Object> values()
                   throws RemoteException

Returns a (raw) collection of registered values in the current context.

Returns:

Collection<Object>; a raw set of registered objects in the current context

Throws:

RemoteException - on a network error when the Context is used over RMI

bindings

Map<String,Object> bindings()
                           throws RemoteException

Returns a (raw) map of bindings in the current context, mapping the name on the registered objects. Both regular objects and subcontexts are returned. Mappings to null objects can exist.

Returns:

Map<String, Object>; a map of registered names and their bound (possibly null) object in the current context

Throws:

RemoteException - on a network error when the Context is used over RMI

checkCircular

void checkCircular(Object newObject)
            throws NamingException,
                   RemoteException

Check whether a circular reference would occur when the object would be inserted into the current context. Insertion potentially causes a problem when the object to be inserted is a Context.

Parameters:

newObject - the object to be inserted

Throws:

NamingException - when a circular reference would occur

RemoteException - on a network error when the Context is used over RMI

close

void close()
    throws NamingException,
           RemoteException

Closes the context and removes all content from the context. No events will be fired that the content of the context has been removed. Some contexts, such as the FileContext could have to be really closed as well.

Throws:

NamingException - when a problem occurs during closing (e.g., of a FileContext)

RemoteException - on a network error when the Context is used over RMI

toString

String toString(boolean verbose)
         throws RemoteException

Return a String with the hierarchical content of the Context in case verbose is true; otherwise return the atomic name.

Parameters:

verbose - boolean; whether the information is exhaustive or very brief

Returns:

String; formatted content of the context when verbose is true; otherwise the atomic name

Throws:

RemoteException - on a network error when the Context is used over RMI