public interface Context

This interface represents a naming context, which consists of a set of name-to-object bindings. It contains methods for examining and updating these bindings.

Names

Each name passed as an argument to a Context method is relative to that context. The empty name is used to name the context itself. A name parameter may never be null.

Most of the methods have overloaded versions with one taking a Name parameter and one taking a String. These overloaded versions are equivalent in that if the Name and String parameters are just different representations of the same name, then the overloaded versions of the same methods behave the same. In the method descriptions below, only one version is fully documented. The second version instead has a link to the first: the same documentation applies to both.

For systems that support federation, String name arguments to Context methods are composite names. Name arguments that are instances of CompositeName are treated as composite names, while Name arguments that are not instances of CompositeName are treated as compound names (which might be instances of CompoundName or other implementations of compound names). This allows the results of NameParser.parse() to be used as arguments to the Context methods. Prior to JNDI 1.2, all name arguments were treated as composite names.

Furthermore, for systems that support federation, all names returned in a NamingEnumeration from list() and listBindings() are composite names represented as strings. See CompositeName for the string syntax of names.

For systems that do not support federation, the name arguments (in either Name or String forms) and the names returned in NamingEnumeration may be names in their own namespace rather than names in a composite namespace, at the discretion of the service provider.

Exceptions

All the methods in this interface can throw a NamingException or any of its subclasses. See NamingException and their subclasses for details on each exception.

Concurrent Access

A Context instance is not guaranteed to be synchronized against concurrent access by multiple threads. Threads that need to access a single Context instance concurrently should synchronize amongst themselves and provide the necessary locking. Multiple threads each manipulating a different Context instance need not synchronize. Note that the lookup method, when passed an empty name, will return a new Context instance representing the same naming context.

For purposes of concurrency control, a Context operation that returns a NamingEnumeration is not considered to have completed while the enumeration is still in use, or while any referrals generated by that operation are still being followed.

Parameters

A Name parameter passed to any method of the Context interface or one of its subinterfaces will not be modified by the service provider. The service provider may keep a reference to it for the duration of the operation, including any enumeration of the method's results and the processing of any referrals generated. The caller should not modify the object during this time. A Name returned by any such method is owned by the caller. The caller may subsequently modify it; the service provider may not.

Environment Properties

JNDI applications need a way to communicate various preferences and properties that define the environment in which naming and directory services are accessed. For example, a context might require specification of security credentials in order to access the service. Another context might require that server configuration information be supplied. These are referred to as the environment of a context. The Context interface provides methods for retrieving and updating this environment.

The environment is inherited from the parent context as context methods proceed from one context to the next. Changes to the environment of one context do not directly affect those of other contexts.

It is implementation-dependent when environment properties are used and/or verified for validity. For example, some of the security-related properties are used by service providers to "log in" to the directory. This login process might occur at the time the context is created, or the first time a method is invoked on the context. When, and whether this occurs at all, is implementation-dependent. When environment properties are added or removed from the context, verifying the validity of the changes is again implementation-dependent. For example, verification of some properties might occur at the time the change is made, or at the time the next operation is performed on the context, or not at all.

Any object with a reference to a context may examine that context's environment. Sensitive information such as clear-text passwords should not be stored there unless the implementation is known to protect it.

Resource Files

To simplify the task of setting up the environment required by a JNDI application, application components and service providers may be distributed along with resource files. A JNDI resource file is a file in the properties file format (see java.util.Properties), containing a list of key/value pairs. The key is the name of the property (e.g. "java.naming.factory.object") and the value is a string in the format defined for that property. Here is an example of a JNDI resource file:

java.naming.factory.object=com.sun.jndi.ldap.AttrsToCorba:com.wiz.from.Person java.naming.factory.state=com.sun.jndi.ldap.CorbaToAttrs:com.wiz.from.Person java.naming.factory.control=com.sun.jndi.ldap.ResponseControlFactory

The JNDI class library reads the resource files and makes the property values freely available. Thus JNDI resource files should be considered to be "world readable", and sensitive information such as clear-text passwords should not be stored there.

There are two kinds of JNDI resource files: provider and application.

Provider Resource Files

Each service provider has an optional resource that lists properties specific to that provider. The name of this resource is:

[prefix/]jndiprovider.properties

where prefix is the package name of the provider's context implementation(s), with each period (".") converted to a slash ("/"). For example, suppose a service provider defines a context implementation with class name com.sun.jndi.ldap.LdapCtx. The provider resource for this provider is named com/sun/jndi/ldap/jndiprovider.properties. If the class is not in a package, the resource's name is simply jndiprovider.properties.

Certain methods in the JNDI class library make use of the standard JNDI properties that specify lists of JNDI factories:

• java.naming.factory.object
• java.naming.factory.state
• java.naming.factory.control
• java.naming.factory.url.pkgs

The JNDI library will consult the provider resource file when determining the values of these properties. Properties other than these may be set in the provider resource file at the discretion of the service provider. The service provider's documentation should clearly state which properties are allowed; other properties in the file will be ignored.

Application Resource Files

When an application is deployed, it will generally have several codebase directories and JARs in its classpath. Similarly, when an applet is deployed, it will have a codebase and archives specifying where to find the applet's classes. JNDI locates (using ClassLoader.getResources()) all application resource files named jndi.properties in the classpath. In addition, if the file java.home/lib/jndi.properties exists and is readable, JNDI treats it as an additional application resource file. (java.home indicates the directory named by the java.home system property.) All of the properties contained in these files are placed into the environment of the initial context. This environment is then inherited by other contexts.

For each property found in more than one application resource file, JNDI uses the first value found or, in a few cases where it makes sense to do so, it concatenates all of the values (details are given below). For example, if the "java.naming.factory.object" property is found in three jndi.properties resource files, the list of object factories is a concatenation of the property values from all three files. Using this scheme, each deployable component is responsible for listing the factories that it exports. JNDI automatically collects and uses all of these export lists when searching for factory classes.

Search Algorithm for Properties

When JNDI constructs an initial context, the context's environment is initialized with properties defined in the environment parameter passed to the constructor, the system properties, the applet parameters, and the application resource files. See InitialContext for details. This initial environment is then inherited by other context instances.

When the JNDI class library needs to determine the value of a property, it does so by merging the values from the following two sources, in order:

1. The environment of the context being operated on.
2. The provider resource file (jndiprovider.properties) for the context being operated on.

For each property found in both of these two sources, JNDI determines the property's value as follows. If the property is one of the standard JNDI properties that specify a list of JNDI factories (listed above), the values are concatenated into a single colon-separated list. For other properties, only the first value found is used.

When a service provider needs to determine the value of a property, it will generally take that value directly from the environment. A service provider may define provider-specific properties to be placed in its own provider resource file. In that case it should merge values as described in the previous paragraph.

In this way, each service provider developer can specify a list of factories to use with that service provider. These can be modified by the application resources specified by the deployer of the application or applet, which in turn can be modified by the user.

static final String INITIAL_CONTEXT_FACTORY

Constant that holds the name of the environment property for specifying the initial context factory to use. The value of the property should be the fully qualified class name of the factory class that will create an initial context. This property may be specified in the environment parameter passed to the initial context constructor, an applet parameter, a system property, or an application resource file. If it is not specified in any of these sources, NoInitialContextException is thrown when an initial context is required to complete an operation.

The value of this constant is "java.naming.factory.initial".

static final String OBJECT_FACTORIES

Constant that holds the name of the environment property for specifying the list of object factories to use. The value of the property should be a colon-separated list of the fully qualified class names of factory classes that will create an object given information about the object. This property may be specified in the environment, an applet parameter, a system property, or one or more resource files.

The value of this constant is "java.naming.factory.object".

static final String STATE_FACTORIES

Constant that holds the name of the environment property for specifying the list of state factories to use. The value of the property should be a colon-separated list of the fully qualified class names of state factory classes that will be used to get an object's state given the object itself. This property may be specified in the environment, an applet parameter, a system property, or one or more resource files.

The value of this constant is "java.naming.factory.state".

static final String URL_PKG_PREFIXES

Constant that holds the name of the environment property for specifying the list of package prefixes to use when loading in URL context factories. The value of the property should be a colon-separated list of package prefixes for the class name of the factory class that will create a URL context factory. This property may be specified in the environment, an applet parameter, a system property, or one or more resource files. The prefix com.sun.jndi.url is always appended to the possibly empty list of package prefixes.

The value of this constant is "java.naming.factory.url.pkgs".

static final String PROVIDER_URL

Constant that holds the name of the environment property for specifying configuration information for the service provider to use. The value of the property should contain a URL string (e.g. "ldap://somehost:389"). This property may be specified in the environment, an applet parameter, a system property, or a resource file. If it is not specified in any of these sources, the default configuration is determined by the service provider.

The value of this constant is "java.naming.provider.url".

static final String DNS_URL

Constant that holds the name of the environment property for specifying the DNS host and domain names to use for the JNDI URL context (for example, "dns://somehost/wiz.com"). This property may be specified in the environment, an applet parameter, a system property, or a resource file. If it is not specified in any of these sources and the program attempts to use a JNDI URL containing a DNS name, a ConfigurationException will be thrown.

The value of this constant is "java.naming.dns.url".

static final String AUTHORITATIVE

Constant that holds the name of the environment property for specifying the authoritativeness of the service requested. If the value of the property is the string "true", it means that the access is to the most authoritative source (i.e. bypass any cache or replicas). If the value is anything else, the source need not be (but may be) authoritative. If unspecified, the value defaults to "false".

The value of this constant is "java.naming.authoritative".

static final String BATCHSIZE

Constant that holds the name of the environment property for specifying the batch size to use when returning data via the service's protocol. This is a hint to the provider to return the results of operations in batches of the specified size, so the provider can optimize its performance and usage of resources. The value of the property is the string representation of an integer. If unspecified, the batch size is determined by the service provider.

The value of this constant is "java.naming.batchsize".

static final String REFERRAL

Constant that holds the name of the environment property for specifying how referrals encountered by the service provider are to be processed. The value of the property is one of the following strings:

"follow"

follow referrals automatically

"ignore"

ignore referrals

"throw"

throw ReferralException when a referral is encountered.

If this property is not specified, the default is determined by the provider.

The value of this constant is "java.naming.referral".

static final String SECURITY_PROTOCOL

Constant that holds the name of the environment property for specifying the security protocol to use. Its value is a string determined by the service provider (e.g. "ssl"). If this property is unspecified, the behaviour is determined by the service provider.

The value of this constant is "java.naming.security.protocol".

static final String SECURITY_AUTHENTICATION

Constant that holds the name of the environment property for specifying the security level to use. Its value is one of the following strings: "none", "simple", "strong". If this property is unspecified, the behaviour is determined by the service provider.

The value of this constant is "java.naming.security.authentication".

static final String SECURITY_PRINCIPAL

Constant that holds the name of the environment property for specifying the identity of the principal for authenticating the caller to the service. The format of the principal depends on the authentication scheme. If this property is unspecified, the behaviour is determined by the service provider.

The value of this constant is "java.naming.security.principal".

static final String SECURITY_CREDENTIALS

Constant that holds the name of the environment property for specifying the credentials of the principal for authenticating the caller to the service. The value of the property depends on the authentication scheme. For example, it could be a hashed password, clear-text password, key, certificate, and so on. If this property is unspecified, the behaviour is determined by the service provider.

The value of this constant is "java.naming.security.credentials".

static final String LANGUAGE

Constant that holds the name of the environment property for specifying the preferred language to use with the service. The value of the property is a colon-separated list of language tags as defined in RFC 1766. If this property is unspecified, the language preference is determined by the service provider.

The value of this constant is "java.naming.language".

static final String APPLET

Constant that holds the name of the environment property for specifying an applet for the initial context constructor to use when searching for other properties. The value of this property is the java.applet.Applet instance that is being executed. This property may be specified in the environment parameter passed to the initial context constructor. When this property is set, each property that the initial context constructor looks for in the system properties is first looked for in the applet's parameter list. If this property is unspecified, the initial context constructor will search for properties only in the environment parameter passed to it, the system properties, and application resource files.

The value of this constant is "java.naming.applet".

Object lookup(Name name)
       throws NamingException

Object lookup(String name)
       throws NamingException

void bind(Name name,
          Object obj)
   throws NamingException

void bind(String name,
          Object obj)
   throws NamingException

void rebind(Name name,
            Object obj)
     throws NamingException

Binds a name to an object, overwriting any existing binding. All intermediate contexts and the target context (that named by all but terminal atomic component of the name) must already exist.

If the object is a DirContext, any existing attributes associated with the name are replaced with those of the object. Otherwise, any existing attributes associated with the name remain unchanged.

void rebind(String name,
            Object obj)
     throws NamingException

void unbind(Name name)
     throws NamingException

Unbinds the named object. Removes the terminal atomic name in name from the target context--that named by all but the terminal atomic part of name.

This method is idempotent. It succeeds even if the terminal atomic name is not bound in the target context, but throws NameNotFoundException if any of the intermediate contexts do not exist.

Any attributes associated with the name are removed. Intermediate contexts are not changed.

void unbind(String name)
     throws NamingException

void rename(Name oldName,
            Name newName)
     throws NamingException

void rename(String oldName,
            String newName)
     throws NamingException

NamingEnumeration<NameClassPair> list(Name name)
                               throws NamingException

Enumerates the names bound in the named context, along with the class names of objects bound to them. The contents of any subcontexts are not included.

If a binding is added to or removed from this context, its effect on an enumeration previously returned is undefined.

NamingEnumeration<NameClassPair> list(String name)
                               throws NamingException

NamingEnumeration<Binding> listBindings(Name name)
                                 throws NamingException

Enumerates the names bound in the named context, along with the objects bound to them. The contents of any subcontexts are not included.

If a binding is added to or removed from this context, its effect on an enumeration previously returned is undefined.

NamingEnumeration<Binding> listBindings(String name)
                                 throws NamingException

void destroySubcontext(Name name)
                throws NamingException

Destroys the named context and removes it from the namespace. Any attributes associated with the name are also removed. Intermediate contexts are not destroyed.

This method is idempotent. It succeeds even if the terminal atomic name is not bound in the target context, but throws NameNotFoundException if any of the intermediate contexts do not exist.

In a federated naming system, a context from one naming system may be bound to a name in another. One can subsequently look up and perform operations on the foreign context using a composite name. However, an attempt destroy the context using this composite name will fail with NotContextException, because the foreign context is not a "subcontext" of the context in which it is bound. Instead, use unbind() to remove the binding of the foreign context. Destroying the foreign context requires that the destroySubcontext() be performed on a context from the foreign context's "native" naming system.

void destroySubcontext(String name)
                throws NamingException

Context createSubcontext(Name name)
                  throws NamingException

Context createSubcontext(String name)
                  throws NamingException

Object lookupLink(Name name)
           throws NamingException

Object lookupLink(String name)
           throws NamingException

NameParser getNameParser(Name name)
                  throws NamingException

NameParser getNameParser(String name)
                  throws NamingException

Name composeName(Name name,
                 Name prefix)
          throws NamingException

Composes the name of this context with a name relative to this context. Given a name (name) relative to this context, and the name (prefix) of this context relative to one of its ancestors, this method returns the composition of the two names using the syntax appropriate for the naming system(s) involved. That is, if name names an object relative to this context, the result is the name of the same object, but relative to the ancestor context. None of the names may be null.

For example, if this context is named "wiz.com" relative to the initial context, then

composeName("east", "wiz.com")

might return "east.wiz.com". If instead this context is named "org/research", then

composeName("user/jane", "org/research")

might return "org/research/user/jane" while

composeName("user/jane", "research")

returns "research/user/jane".

String composeName(String name,
                   String prefix)
            throws NamingException

Object addToEnvironment(String propName,
                        Object propVal)
                 throws NamingException

Object removeFromEnvironment(String propName)
                      throws NamingException

Hashtable<?,?> getEnvironment()
                       throws NamingException

Retrieves the environment in effect for this context. See class description for more details on environment properties.

The caller should not make any changes to the object returned: their effect on the context is undefined. The environment of this context may be changed using addToEnvironment() and removeFromEnvironment().

void close()
    throws NamingException

Closes this context. This method releases this context's resources immediately, instead of waiting for them to be released automatically by the garbage collector.

This method is idempotent: invoking it on a context that has already been closed has no effect. Invoking any other method on a closed context is not allowed, and results in undefined behaviour.

String getNameInNamespace()
                   throws NamingException

Retrieves the full name of this context within its own namespace.

Many naming services have a notion of a "full name" for objects in their respective namespaces. For example, an LDAP entry has a distinguished name, and a DNS record has a fully qualified name. This method allows the client application to retrieve this name. The string returned by this method is not a JNDI composite name and should not be passed directly to context methods. In naming systems for which the notion of full name does not make sense, OperationNotSupportedException is thrown.