Home > Articles > Security > Network Security

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

3.2 J2EE Applications

A J2EE application, an enterprise application that conforms to the J2EE specification, is structured as shown in Figure 3.2 and consists of the following:

  • Zero or more EJB modules

  • Zero or more Web modules

  • Zero or more application client modules

  • Optionally, JAR files containing dependent classes or components required by the application

  • Any combination of the preceding, as long as it contains at least one module

03fig02.gifFigure 3.2. Contents of a J2EE Application

A J2EE application is represented by, and packaged in, an Enterprise Archive (EAR) file. The modules that comprise the EAR file are themselves packaged in archive files specific to their types. For example, a Web module is packaged in a Web Archive (WAR) file, and an EJB module, containing one or more enterprise beans, is packaged in a JAR file. WAR files can exist as independent deployment units from EAR files.

EAR files also contain a deployment descriptor file—an XML document describing the contents of the application and containing instructions for the deployment of the application. In particular, the deployment descriptor specifies the security settings to be enforced by the runtime environment. Each WAR file packaging a Web module, JAR file packaging enterprise beans, or JAR file packaging an application client module contains its own deployment descriptor as well.

3.2.1 EJB Modules

An enterprise bean is a Java component that can be combined with other resources to create distributed client/server applications. Instantiated enterprise beans reside in enterprise bean containers, or EJB containers. An EJB container provides an interface between the enterprise beans and the application server on which the enterprise beans reside. An enterprise bean is typically accessed using Java RMI-IIOP. An ORB manages the interaction between clients and enterprise beans, using IIOP. ORBs enable clients to make requests and receive responses from servers in distributed computing environments. Alternatively, enterprise beans are accessible through JMS. It is also possible to invoke an enterprise bean as a Web service via SOAP, as explained in Chapter 14 on page 497.

There are three types of enterprise beans: entity beans, session beans, and message-driven beans. Entity beans store persistent data and typically use database connections. Entity beans are of two types: CMP entity beans and BMP entity beans.

  • Entity beans with container-managed persistence (CMP) let the EJB container transparently and implicitly manage the persistent state. The enterprise bean developer does not need to code any database access functions within the enterprise bean class methods.

  • Entity beans with bean-managed persistence (BMP) manage persistent data in a manner defined by the application developer in the bean code. This usually includes writing to databases.

Session beans do not require database access, although they can obtain it indirectly, as needed, by accessing entity beans. Session beans can also obtain direct access to databases and other resources through the use of resource references, which include the use of JDBC. Session beans can be either stateless or stateful.

  • A session bean is said to be stateless if it provides a stateless service to the client. A business method on a stateless session bean is similar to a procedural application or static method; there is no instance state. Therefore, all the data needed to execute a stateless session bean's method is provided by the method arguments.

  • A session bean is said to be stateful if it acts as a server-side extension of the client that uses it. A stateful session bean is created by a client and will work for only that client until the client connection is dropped or the bean is explicitly removed. Unlike a stateless session bean, a stateful session bean has state or instance fields that can be initialized and changed by the client with each method invocation.

Message-driven beans are enterprise beans accessible asynchronously via JMS rather than synchronously through such protocols as RMI-IIOP. The EJB V2.1 specification expands the scope of message-driven beans beyond JMS to support any messaging system.

An EJB module is one or more enterprise beans assembled into a single deployable unit. As we have observed, an EJB module is stored in a standard JAR file, commonly referred to as ejb-jar. This file contains

  • One or more deployable enterprise beans

  • A deployment descriptor, stored in an XML file

Specifically, an EJB module's deployment descriptor file declares the contents of the module, specifies the structure and external dependencies of the enterprise beans in the module, explains how the enterprise beans are to be used at runtime, and defines the security policies applicable to the enterprise beans within the module. The format of the security policy is defined by the EJB specification (see Chapter 5 on page 157).

3.2.2 Web Modules

A Web module represents a Web application—an application that can be accessed over the Web using HTTP. A Web module is used to assemble servlets and JSP files, as well as static content, such as HTML pages, into a single deployable unit. As we said earlier, Web modules are stored in WAR files, which are enhanced JAR files with a .war file extension, and contain

  • One or more servlets, JSP files, and other supporting files

  • A deployment descriptor, stored in an XML file

The deployment descriptor file, web.xml, declares the contents of the Web module. This file contains information about the structure and external dependencies of the components in the Web module and describes the components' runtime use. In addition, the deployment description file is used to declare the security policies applicable to the universal resource identifiers (URIs) that are mapped to the resources within the Web module. These security policies include both the authorization policy and the login configuration information. The format of the security policy is defined by the Java Servlet specification.

Servlets are Java programs running on a WAS and extend the Web server's capabilities. For example, servlets support generation of dynamic Web page content, provide database access, concurrently serve multiple clients, and filter data by MIME type. Servlets use the Java Servlet API. By analogy, servlets are the server-side equivalent of client-side browser applets.

JSP files enable the separation of the HTML coding from the business logic in Web pages, allowing HTML programmers and Java programmers to more easily collaborate in creating and maintaining pages. This process is described in greater detail in Section 4.1.2 on page 104.

3.2.3 Application Client Modules

Application clients are first-tier Java-based client programs. Even though it is a regular Java application, an application client depends on an application client container to provide system services. An application client module packages application client code in a JAR file. This JAR file includes a deployment descriptor XML file, which specifies the enterprise beans and external resources referenced by the application.

The security configuration of an application client determines how the application will access enterprise beans and Web resources. If the J2EE components that the client application accesses are secured, the client will be authenticated accordingly. In order for an application client to retrieve authentication data from an end user, configuration information must be specified in a deployment descriptor XML file, application-client.xml, associated with the client application. Application clients typically run in an environment that has a Java 2 security manager installed and the security policies enforced based on the J2SE security policy framework (see Chapter 8 on page 253).

  • + 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