Home > Articles

Naming and Directory Services

This chapter is from the book

Days 1 and 2 introduced you to enterprise computing concepts and J2EE technologies such as EJBs and Servlets. This chapter will show how the Java Naming and Directory Interface (JNDI) supports the use of many of the J2EE components.

In its simplest form, JNDI is used to find the resources (such as EJBs) that you have registered via the J2EE server. Advanced use of JNDI supports sophisticated storage and retrieval of Java objects and other information.

This day's work will include

  • Using Naming and Directory Services

  • JNDI and X.500 names

  • Obtaining a JNDI Initial Context

  • Binding and looking up names

  • Name attributes

  • Objects and References

  • JNDI events and security

Naming and Directory Services

A Naming Service provides a mechanism for giving names to objects so you can retrieve and use those objects without knowing the location of the object. Objects can be located on any machine accessible from your network, not necessarily the local workstation.

A real-world example is a phone directory. It stores telephone numbers against names and addresses. To find people's phone numbers is simply a matter of using their name (and possibly address) to identify an entry in the phone book and obtaining the stored phone number. There are a few complications, such as finding the right phone book to look in, but it is essentially a simple process.

Incidentally, naming services have a similar problem to that of finding the right phone book. This is known as obtaining a context. A name can only be found if you examine the right context (phone book).

A Directory Service also associates names with objects but provides additional information by associating attributes with the objects.

The yellow pages phone directory is a simple form of a directory service. Here, businesses often include advertisements with additional information such as a list of products sold, professional qualifications, affiliated organizations, and even maps to their premises. These attributes add value to the name entry. A directory service will normally provide the ability to find entries that have particular attributes or values for attributes. This is similar to searching the yellow pages for all plumbers running a 24-hour emergency service within a certain area.

Yellow page style phone books also store names under categories—for example, hairdressers or lawyers. Categorizing entries can simplify searching for a particular type of entry. These categorized entries are a form of sub-context within the directory context of the local phone book.

Why Use a Naming or Directory Service?

Naming Services provide an indispensable mechanism for de-coupling the provider of a service from the consumer of the service. Naming services allow a supplier of a service to register their service against a name. Users, or clients, of the service need only know the name of the service to use it.

Think of the phone book once more, and how difficult it would be to find someone's phone number without it. Obtaining your friend's phone number would mean going to their home and asking, or waiting until you meet up with them again—which may be difficult to organize because you can't phone them to arrange the meeting.

At the end of the day, it is very difficult to imagine a world without naming services.

What Is JNDI?

JNDI is a Java API that defines an interface to Naming and Directory Services for Java programs. JNDI is just an API and not, in itself, a Naming and Directory Service. To use JNDI, an implementation of a Naming and Directory service must be available. JNDI provides a service-independent interface to the underlying Service Provider implementation.

Figure 3.1 shows how the JNDI layer interfaces between the Java program and the underlying naming services. Additional naming services can be plugged into the JNDI layer by implementing the Service Provider Interface (SPI) for JNDI.

Figure 3.1Figure 3.1 JNDI Architecture.

JNDI has been a standard component of J2SE since version 1.3. JNDI is available as a standard Java extension for JDK 1.2 and earlier. JNDI has always been a required component of J2EE.

Common Naming Services

Figure 3.1 shows that JNDI supports plug-in Service Providers for several well-known naming services, including the following:

  • Lightweight Directory Access Protocol (LDAP) is the approved standard for an Internet naming service. LDAP is a true directory service and supports attributes as well as names for objects. LDAP is fast becoming the de facto directory service for the enterprise.

  • Domain Name System (DNS) is the Internet naming service for identifying machines on a network.

  • Novell Directory Services (NDS) from Novell provides information about network services, such as files and printers. NDS is found primarily in environments where the main networking software is Novell.

  • Network Information Service (NIS) from Sun Microsystems provides system-wide information about machines, files, users, printers, and networks. NIS is primarily found on Solaris systems, but Linux and some other Unix platforms also support it.

JNDI also supports some more specialized naming systems. For example, CORBA for distributed component programming and RMI for distributed Java programming.

Although there is no named Service Provider for Windows Active Directory within JNDI, it is supported. Windows Active Directory supports an LDAP interface, and you can access it via the JNDI LDAP Service Provider Interface.

Naming Conventions

Each naming service has its own mechanism for supplying a name. Perhaps the most familiar naming convention is DNS, where every machine connected to the Internet has a unique name and address. Most readers will recognize the following as a host name used by DNS:

http://www.samspublishing.com

In contrast, LDAP names are based on the X.500 standard and use distinguished names that look like the following fictitious example:

cn=Martin Bond, ou=Authors, o=SAMS, c=us

This format will also be familiar to users of Microsoft's Active Directory service, whose naming system is also based on X.500 but uses a forward slash to separate the various name components:

cn=Martin Bond/ou=Authors/o=SAMS/c=us

These last two naming conventions have similarities in that they are both hierarchically structured with the more specific names (such as cn=Martin Bond) being qualified by a general name (such as o=SAMS).

JNDI applies minimal interpretation to names specified as String objects. JNDI uses the forward slash character (/) as a name separator to provide a simple name hierarchy called a Composite Name. It is conventional for these composite names to be used to group related names (such as plumbers in the phone book). As an example, JDBC data sources take names of jdbc/XXX and EJBs the form ejb/XXX. While this is only a convention, it does help separate different sorts of named objects within the JNDI name space.

Composite names can span different naming systems. An LDAP name can combine with a file system name to get a composite name:

cn=Martin Bond, ou=Authors, o=SAMS, c=us/agency/agency.ldif

Here a filename (agency/agency.ldif) is appended to an LDAP name. How JNDI interprets this is up to the individual Service Provider.

Incidentally, JNDI calls structured names like the DNS and LDAP names Compound Names. JNDI does not interpret compound names, but simply passes them through to the Service Provider.

In addition to forward slash (/), JNDI also treats backslash (\), single quote ('), and double quote (") characters as special. If a compound name or a component of a name contains any of these characters, they must be escaped using the backslash character (\). Remember that backslash and double quotes are also special characters in Java string literals and must be escaped. Therefore to insert a double quote into a JNDI name you must place \\\" into the string literal. For example the following is how to insert the name jdbc/"Agency"—avoid this if you can.

"jdbc/\\\"Agency\\\""

If the underlying Service Provider uses the forward slash as a name separator (as does the CORBA name service for example), there appears to be a conflict between JNDI and the Service Provider. In practice, this is unlikely to be a problem because JNDI recognizes two sorts of name separation—weak and strong. JNDI always passes the entire name to the Service Provider. A strong name separation implementation (such as LDAP or DNS) simply processes the first part of the composite name and returns the remainder to the JNDI Naming Manager to pass on to other name services. A weak name separation implementation will process the entire composite name. This is not something you need to worry about unless you are writing a Service Provider.

For those programmers who need to do more than use names to look up and bind objects, JNDI provides several classes for manipulating and parsing composite and compound names. The JNDI name support classes in the javax.naming package are Name, CompositeName, and CompoundName.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020