Package nl.tudelft.simulation.naming.context

Interface ContextInterface

All Superinterfaces:
org.djutils.event.EventProducer, Remote, Serializable
All Known Subinterfaces:
EventContext, RemoteContextInterface, RemoteEventContextInterface
All Known Implementing Classes:
FileContext, InitialEventContext, JvmContext, RemoteContext, RemoteEventContext
public interface ContextInterface extends org.djutils.event.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) 2020-2024 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 final org.djutils.event.EventType
    OBJECT_ADDED_EVENT
    OBJECT_ADDED_EVENT is fired whenever an object is added to the Context.
    static final org.djutils.event.EventType
    OBJECT_CHANGED_EVENT
    OBJECT_CHANGED_EVENT can be fired whenever an object present in the Context is changed.
    static final org.djutils.event.EventType
    OBJECT_REMOVED_EVENT
    OBJECT_REMOVED_EVENT is fired whenever an object is removed from the Context.
    static final String
    REPLACE_SEPARATOR
    The replacement string for the separator, in case it is part of a name.
    static final String
    ROOT
    The default root sign for a context.
    static final 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 Details

    • ROOT

      static final String ROOT
      The default root sign for a context.
      See Also:

    • SEPARATOR

      static final String SEPARATOR
      The default separator sign for a context.
      See Also:

    • REPLACE_SEPARATOR

      static final String REPLACE_SEPARATOR
      The replacement string for the separator, in case it is part of a name.
      See Also:

    • OBJECT_ADDED_EVENT

      static final org.djutils.event.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 org.djutils.event.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 org.djutils.event.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 Details

    • 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