Contextpublic 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 {@link #lookup(Name) 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
{@link java.util.Properties#load 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
{@link ClassLoader#getResources 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.
Application resource files are available beginning with the Java 2
Platform, except that the file in
java.home/lib may be used on earlier Java platforms as well.
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:
- The environment of the context being operated on.
- 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. |
| Fields Summary |
|---|
| String | INITIAL_CONTEXT_FACTORYConstant 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". | | String | OBJECT_FACTORIESConstant 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". | | String | STATE_FACTORIESConstant 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". | | String | URL_PKG_PREFIXESConstant 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". | | String | PROVIDER_URLConstant 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". | | String | DNS_URLConstant 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". | | String | AUTHORITATIVEConstant 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". | | String | BATCHSIZEConstant 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". | | String | REFERRALConstant 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". | | String | SECURITY_PROTOCOLConstant 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". | | String | SECURITY_AUTHENTICATIONConstant 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". | | String | SECURITY_PRINCIPALConstant 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". | | String | SECURITY_CREDENTIALSConstant 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". | | String | LANGUAGEConstant 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". | | String | APPLETConstant 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". |
| Methods Summary |
|---|
| public java.lang.Object | addToEnvironment(java.lang.String propName, java.lang.Object propVal)Adds a new environment property to the environment of this
context. If the property already exists, its value is overwritten.
See class description for more details on environment properties.
| | public void | bind(javax.naming.Name name, java.lang.Object obj)Binds a name to an object.
All intermediate contexts and the target context (that named by all
but terminal atomic component of the name) must already exist.
| | public void | bind(java.lang.String name, java.lang.Object obj)Binds a name to an object.
See {@link #bind(Name, Object)} for details.
| | public void | close()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.
| | public javax.naming.Name | composeName(javax.naming.Name name, javax.naming.Name prefix)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".
| | public java.lang.String | composeName(java.lang.String name, java.lang.String prefix)Composes the name of this context with a name relative to
this context.
See {@link #composeName(Name, Name)} for details.
| | public javax.naming.Context | createSubcontext(javax.naming.Name name)Creates and binds a new context.
Creates a new context with the given name and binds it in
the target context (that named by all but terminal atomic
component of the name). All intermediate contexts and the
target context must already exist.
| | public javax.naming.Context | createSubcontext(java.lang.String name)Creates and binds a new context.
See {@link #createSubcontext(Name)} for details.
| | public void | destroySubcontext(javax.naming.Name name)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.
| | public void | destroySubcontext(java.lang.String name)Destroys the named context and removes it from the namespace.
See {@link #destroySubcontext(Name)} for details.
| | public java.util.Hashtable | getEnvironment()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().
| | public java.lang.String | getNameInNamespace()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.
| | public javax.naming.NameParser | getNameParser(javax.naming.Name name)Retrieves the parser associated with the named context.
In a federation of namespaces, different naming systems will
parse names differently. This method allows an application
to get a parser for parsing names into their atomic components
using the naming convention of a particular naming system.
Within any single naming system, NameParser objects
returned by this method must be equal (using the equals()
test).
| | public javax.naming.NameParser | getNameParser(java.lang.String name)Retrieves the parser associated with the named context.
See {@link #getNameParser(Name)} for details.
| | public javax.naming.NamingEnumeration | list(javax.naming.Name name)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.
| | public javax.naming.NamingEnumeration | list(java.lang.String name)Enumerates the names bound in the named context, along with the
class names of objects bound to them.
See {@link #list(Name)} for details.
| | public javax.naming.NamingEnumeration | listBindings(javax.naming.Name name)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.
| | public javax.naming.NamingEnumeration | listBindings(java.lang.String name)Enumerates the names bound in the named context, along with the
objects bound to them.
See {@link #listBindings(Name)} for details.
| | public java.lang.Object | lookup(javax.naming.Name name)Retrieves the named object.
If name is empty, returns a new instance of this context
(which represents the same naming context as this context, but its
environment may be modified independently and it may be accessed
concurrently).
| | public java.lang.Object | lookup(java.lang.String name)Retrieves the named object.
See {@link #lookup(Name)} for details.
| | public java.lang.Object | lookupLink(javax.naming.Name name)Retrieves the named object, following links except
for the terminal atomic component of the name.
If the object bound to name is not a link,
returns the object itself.
| | public java.lang.Object | lookupLink(java.lang.String name)Retrieves the named object, following links except
for the terminal atomic component of the name.
See {@link #lookupLink(Name)} for details.
| | public void | rebind(javax.naming.Name name, java.lang.Object obj)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.
| | public void | rebind(java.lang.String name, java.lang.Object obj)Binds a name to an object, overwriting any existing binding.
See {@link #rebind(Name, Object)} for details.
| | public java.lang.Object | removeFromEnvironment(java.lang.String propName)Removes an environment property from the environment of this
context. See class description for more details on environment
properties.
| | public void | rename(java.lang.String oldName, java.lang.String newName)Binds a new name to the object bound to an old name, and unbinds
the old name.
See {@link #rename(Name, Name)} for details.
| | public void | rename(javax.naming.Name oldName, javax.naming.Name newName)Binds a new name to the object bound to an old name, and unbinds
the old name. Both names are relative to this context.
Any attributes associated with the old name become associated
with the new name.
Intermediate contexts of the old name are not changed.
| | public void | unbind(javax.naming.Name name)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.
| | public void | unbind(java.lang.String name)Unbinds the named object.
See {@link #unbind(Name)} for details.
|
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