Home > Articles > Programming > Java

  • Print
  • + Share This
This chapter is from the book

Managing Transaction Scope

An application that will interact with any type of data repository can face the somewhat daunting task of managing the transaction scope. Transaction scope is the entire process of establishing a database connection, communicating with the resource at the end of the connection, eventually committing any changes made, and then closing the connection.

Managing transaction scope is more difficult if the scope crosses physical database boundaries. For example, suppose that a transaction must update both an Oracle database and a Microsoft SQL Server database within the scope of one transaction and ensure that both servers are updated at the end of the transaction. This is difficult to do because talking to each database product (Oracle and SQL Server) requires a connection to each that must be managed individually with respect to their individual commit scope. Figure 8-5 depicts a transaction scenario between two database products.

Figure 8-5 Transaction scope with two databases

One solution to this problem is to use a transaction monitor. A transaction monitor, such as BEA's Tuxedo, acts as a watchdog over any utilized resources and is delegated the task of monitoring transaction scope. However, transaction monitors are substantial overkill for small to medium-sized shops.

Another option is to utilize the services of plain JavaBeans coded to utilize JDBC and its ability to control transactions. In JDBC we can quite easily define a unit of work by beginning a transaction: that is, setting the auto-commit parameter of the JDBC connection to false, performing as many update-type transactions as desired, and then issuing a commit or rollback command on the connection. For Remulak Productions, this will be an initial solution that we present in a later chapter.

The final solution discussed here utilizes Enterprise JavaBeans running inside of an application server product. EJB is the framework offered by Sun Microsystems and implemented by many EJB vendors—such as BEA with its WebLogic product, and IBM with its WebSphere product—that provide for true enterprise-level transaction support. There are also open-source (i.e., free!) EJB servers, such as JBoss (found at http://www.jboss.org). For Remulak Productions, an EJB solution will be a second option that we present in a later chapter.

Enterprise JavaBeans

Two primary types of beans are at play in an EJB container. The first type consists of session beans, which can be thought of as workflow coordinators or utility services. The second type consists of entity beans, which represent the entity classes we have already discussed.

Managing transactions is just a small portion of what EJB can do for the application. EJB is reviewed in detail in Chapter 12. For now, the following are some of the many other problems that EJB addresses:

  • Database connection pooling: EJB can pool database connections. Sadly, many developers write poor code and in the scope of just one transaction end up with several database connections open to a database. Not only does this waste precious memory resources on the client and server; it can also increase the project's cost if the database vendor is charging per connection. Pooling keeps used connections intact (to the programmer they appear closed), providing the ability to resurrect them as needed.

  • Thread pooling: Each component can be written as if it were single-threaded. EJB actually disallows thread management by the application, so you may not use the keyword synchronized; EJB will take care of the rest. EJB also leaves threads open, pre-allocated, to allow for quicker response to clients that request thread activation.

  • Reduction of transaction management logic: Without EJB, each transaction must explicitly issue a "begin" transaction and an "end" transaction. In addition, the application must deal with a myriad of return code checks and error handling pertaining to the database with which it is interfacing. EJB takes care of this by virtually connecting transaction components via a common transaction context.

    NOTE

    If bean-managed transactions are used within EJB, the beans can still issue their own commit and rollback requests. With Remulak, however, we will use container-managed transactions.

  • Flexible security model: EJB offers a flexible security model for the application's implementation via its deployment descriptor. Users can be assigned to roles, and then those roles can be assigned to components and interfaces within the components.

  • Container-managed persistence: EJB versions 1.1 and 2.0 support container-managed persistence. Building and managing SQL statements and their interaction with the underlying database require quite a bit of effort on the part of the application team. Container-managed persistence (CMP) delegates the generation of SQL and the management of basic CRUD (create, read, update, delete) functionality to the EJB framework and the application server that implements the framework (e.g., BEA's WebLogic, IBM's WebSphere, Inprise's Application Server, to name a few). For Remulak we will show an EJB 2.0 implementation of CMP.

EJB can obviously assist the application in reducing the amount of overhead logic and transaction management plumbing. So to provide a perspective, Remulak will provide both a bean-managed persistence (BMP) implementation and a container-managed persistence (CMP) implementation. Both the BMP and the CMP examples will use container-managed transactions.

Once you have seen the additional advantages of using CMP in the EJB environment, it will be hard to use anything else. Just the simple fact of not having to write one line of SQL code is reason enough to jump on the CMP bandwagon. Unfortunately, at the time of this writing very few application server vendors support the EJB 2.0 specification. This is the primary reason why we have chosen BEA's WebLogic, because it was one of the early supporters. By the time this book reaches you, most vendors will be in compliance with the EJB 2.0 specification. The direction and emphasis in the Java community and the emphasis that Sun places on the technology attests to the fact that EJB will continue to be integrated into core product architectures.

  • + 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.

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