Home > Articles > Operating Systems, Server > Solaris

  • Print
  • + Share This
Like this article? We recommend

Considering Purpose and Design

Our purpose is to design a framework for triggers in the Sun Java System Directory Server using its Plug-in API as a foundation. We might call them LDAP triggers. With triggers, we mean an abstraction that allows us to define an action that must be invoked when an event occurs. The action might be simply recording an entry in a change log, sending a notification to an administrator, or changing an attribute of another logically associated entry. Computer scientists like to remark that by means of triggers, a data repository is turned into an active database; that is, the repository's state transactions are not only a consequence of external actions, but also the result of internal events.

Overall a framework for triggers does the following:

  • Supports an administrator's manipulation of triggers (creation, deletion, inactivation, and so on.)

  • Supports predefined actions (for example IGNORE, skip the LDAP operation, LOG to log the action, and so on)

  • Supports custom actions (for example, the ability to execute user functions loaded from external libraries)

  • Allows user interaction based on a SQL-like language

In our example, triggers are administrator's objects (replication agreements are an example of administrator's objects), and they cannot be instantiated by non-privileged users. To enable this feature, a non-trivial effort is required to manage permissions and rights.

To design a trigger framework, initially consider the following requirements:

  1. The administrator, through a client console or command line application, can manipulate triggers through simple commands (create, delete, enable, and so on).

  2. The framework asks predefined actions that an administrator can choose from when creating triggers.

  3. The framework asks for custom actions, possibly implemented by externally, user-provided libraries.

  4. A language for the trigger manipulation, that is, a collection of trigger instructions (such as CREATE TRIGGER, DELETE TRIGGER, and so on) that simplify user interaction with trigger objects.

After we are certain that we know what the customer wants, we ask: "Do we have the right tool or technologies to realize this framework in Sun Java System Directory Server?" and "Is the solution feasible?"

A UNIX expert would easily figure out which tool is needed to create a small language in C: YACC. It allows you to specify a grammar for your language, that, with a lexical analyzer specification provided by you, greatly simplifies the task of writing a compiler. In fact, the YACC task is to generate a compiler for you; it is the kind of tool often referred to as the compiler of compilers.

We have the parser that parses the trigger instructions, but we need a client command-line-based application to accept administrator commands to be parsed. At first we might be tempted to embed the parser in the client application, but this approach is not a good solution. Instead, it's better to run the parsed commands directly in the server, embedding them into a plug-in. This approach permits third parties to write their own client applications. The database server follows a similar architectural solution: third parties embed the SQL parser component in the server itself, and allow client applications, written in different languages and for various platforms, to send plain SQL text.

How do you send the commands the administrator enters in the client application to the LDAP server? Let's put it into context with an extended operation. We could pass the trigger statements to the server-side parser through an extended operation invocation, with the invocation argument being the trigger commands.

In our design, the parser is responsible only for parsing the instructions it turns into statements, like CREATE TRIGGER, in a data structure for an internal LDAP operation. That is, if an administrator issues a command such as DELETE TRIGGER mytrigger, we program the parser to produce a data structure, for example, ParserOutput, which is passed down to a routine that performs the actual data operation.

Intuitively, in a directory server we could record the triggers as LDAP entries. Standard schema, however, does not have an object class suitable for our objects (triggers), therefore we need to extend it.

The object class definition chosen for triggers as it might appear in the 99user.ldif user schema file is as follows:

objectClasses: ( trigger-oid NAME 'trigger' SUP top STRUCTURAL MUST ( cn $ enabled ) 
 MAY ( action $ actiondn $ before $ explain $ externallib $ on ) X-ORIGIN 'user defined' )

The information we choose to store about triggers is as follows:

TABLE 1 Storing Trigger Information




Its name, as typed by the user


Flag that indicates if the trigger is active


The trigger run on this LDAP operation (ADD, DELETE, etc.)


The DN of the entry for which the trigger is registered


Action code that specifies which action to perform


For some actions, it indicates on which DN the action must be performed


1 if this is before a trigger; 0 is it is after a trigger


When the action is external, this attribute contains the name of the library to load


As the name suggests, it stores the instruction that created this trigger (it is retrievable by using the explain trigger <trgname> command

Triggers are stored flatly under a specific branch, ou=triggers,o=sunblueprints in the previous code example.

Of course when a data event occurs, for example, deleting an entry, nothing happens unless we override the default LDAP operation. That's why we need a pre-operation (before triggers) and post-operation (after triggers) plug-in, which is merged in a single plug-in. We address this in the next section. The pre- and post-operation plug-in is the most important component of the framework, because it is where the trigger runs.

Now we have all the pieces to start building a solution. First, let's summarize how the various components functionally cooperate and concur to serve user requests. The logical flow is as follows:

  • The administrator enters trigger statements at the client application prompt.

  • The client application issues an extended operation call, passing as argument the trigger statements verbatim.

  • On the server side, the extended operation routine invokes the parser to parse the user commands, which turns them into trigger data structures and executes all the trigger operations.

  • The client application receives a response and reports it to the user.

  • When an event occurs (an LDAP operation is issued by a user), the pre- and post-operation plug-in searches for triggers registered with the DN of the entry being affected by the data event. If found, it applies the actions associated with the triggers.

In this article, we implement the framework in our code example to provide an advanced example of implementing and using extended operations and directory plug-ins.

  • + Share This
  • 🔖 Save To Your Account

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.


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.


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.


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.


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


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


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.


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.


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