The use of design patterns in J2EE applications is an exciting new field, adding to the existing wealth of software design patterns. However these patterns do not . Introduction. 1. Chapter 1: Design Patterns Applied to J2EE. 7. Chapter 2: Patterns Applied to the Web Tier. Chapter 3: Patterns Applied to a Persistence. J2ee Design Patterns Applied - [Free] J2ee Design Patterns Applied [PDF] [EPUB ] In software engineering, a software design pattern is a.
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J2EE Design Patterns Applied - Download as PDF File .pdf), Text File .txt) or read online. J2EE Advanced J2EE Platform Development: Applying Integration Tier Patterns DOWNLOAD CHM Designing Enterprise applications with the J2EE platform. Present a catalog of J2EE patterns. – Give an Familiarity with design patterns ( GoF) . allowing them to be applied unobtrusively in a variety of combinations.
Meyer and Arnout were able to provide full or partial componentization of two-thirds of the patterns they attempted. Of particular interest are the Structure, Participants, and Collaboration sections. These sections describe a design motif: a prototypical micro-architecture that developers copy and adapt to their particular designs to solve the recurrent problem described by the design pattern.
A micro-architecture is a set of program constituents e. Developers use the design pattern by introducing in their designs this prototypical micro-architecture, which means that micro-architectures in their designs will have structure and organization similar to the chosen design motif. Domain-specific patterns[ edit ] Efforts have also been made to codify design patterns in particular domains, including use of existing design patterns as well as domain specific design patterns.
Examples include user interface design patterns,  information visualization ,  secure design,  "secure usability",  Web design  and business model design.
Classification and list[ edit ] This section may have been copied and pasted from another location, possibly in violation of Wikipedia's copyright policy. Please review the source and remedy this by editing this article to remove any non-free copyrighted content and attributing free content correctly, or flagging the content for deletion.
Please be sure that the supposed source of the copyright violation is not itself a Wikipedia mirror. August Design patterns were originally grouped into the categories: creational patterns , structural patterns , and behavioral patterns , and described using the concepts of delegation , aggregation , and consultation.
Description Provides a description of the transaction.
Reference Number Specifies the cheque number if the transaction type was a Cheque. The user data store will contain at least the following information: The following table specifies the fields that will be displayed for each transaction: Field Description Date Specifies the time and date the transaction was processed by the back-end system.
Given the scope.
J2EE Design Patterns Applied
For example. By employing the Single Access Point pattern. This pattern is typically represented by a single login prompt to an organization's network or individual server. Security Patterns Let us now identify and discuss security patterns as they apply to this case study.
Rather than developing login pages for each ancillary application.
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J2EE applications. All users or other applications requesting access must first pass through this entryway. Another example is an application that provides a single login page versus separate login prompts for each service.
Only authorized personnel will have access to production. Each network device and application will be hardened and configured with the latest patches. The web-based infrastructure will support high availability HA via load-balancing. A testing and staging environment will be configured to match the production environment as closely as possible.
The J2EE platform natively supports basic authentication. To achieve higher security clearance and access more sensitive information. By employing declarative security in the J2EE web tier.
By centralizing this logic. It is the responsibility of this mechanism to determine if a user has sufficient privileges to grant access to a requested resource. The Check Point pattern can apply to any of the following situations: The pluggable authentication module PAM framework abstracts the application from the underlying authentication code.
Note that a simple application may only employ one or two of these scenarios in a single Check Point whereas a much more complex system may have multiple Check Points and may use each of these scenarios multiple times. JAAS provides both pluggable and stackable authentication.
A gateway can be created to forward requests from these devices to the application but the security will be assured if the requests from the devices are cleared through the Check Point.
When an anonymous user requests a protected resource. It is the function of the Check Point to communicate with. PAM also provides stackable authentication that defines where and when any particular mechanism is 'optional'. The Check Point grants them access to all resources matching this level of security.
Another stronger authentication mechanism could be biometric identification. The Check Point pattern manages the security requirements of the resources. Designers are able to modify and extend these rules without altering the remaining application. To initially gain access.
Our Wrox Web Banking application employs forms-based authentication. In the above discussion of a system with multiple security levels. Even then. To access resources of lower security levels.
Software design pattern
URL patterns. A user can be assigned to. A Preferred Customer has all the privileges of the Regular Customer plus the ability to transfer funds between their accounts and view their account history.
Risk Assessment and Management Security equals risk management. A user is assigned one or more roles and each role is granted one or more privileges.
Regular Customer. Risk assessment and management speak of the "reasonable" and "appropriate" effort required to protect an application and its resources and are the first step in a security analysis. Anonymous User. The business requirement for the Wrox Web Banking application has identified three roles. Simple role-based access control can be achieved by defining roles in declarative syntax within the ejb-jar. The goal is to perform a task in a secure manner.
This approach provides two very important benefits: The J2EE platform incorporates roles into its architecture by way of a declarative security model.
When a protected resource is requested. It can be said that risk is proportional to the following thee factors: A Regular Customer has access to all public pages and can view their account balances. Attempting to duplicate customers' personal and account information locally would present unnecessary technical and procedural issues at this stage. The authoritative source of data for customer account information is the back-end mainframe.
Authoritative Source of Data When an application blindly accepts data from any given source then it is at risk of processing potentially outdated or fraudulent data.
Understanding the authoritative source of data means recognizing where your data is coming from and knowing to what extent you can trust the validity of such information. These will aid us in properly defining the use cases for this application. Wrox Web Banking Use Cases Functional and technical requirements have been identified and a number of security patterns have been discussed.
Of course. At a minimum. In short. Chapter 5 The greater any of these factors. The owner understands better than the application designer or developer the purpose of the information in a larger context.
A model for developing j2ee applications based on design patterns
In most cases. Authoritative source of data also embodies the premise of validating information received from a user or system. Only the information that is relevant to the web banking system. In our case study. Their vulnerability depends on the extent to which the application has been securely written — it could be quite low.
The cost of a breach in the application can include everything from the value placed on stolen code and customer data. A proper risk assessment ensures that not only the application is being properly protected.
Information security groups and application designers. The banking application will therefore be designed to access the mainframe system for all customer account information. Regular Customers.
Use Cases The following use cases have been identified: Anonymous users. On successful validation of their credentials. A more detailed error message is logged to the system log file for inspection. Main Flow of Events The customer is prompted to enter a username and password. Note the same error message is displayed for both invalid username and passwords.
Chapter 5 The diagram attempts to demonstrate how the Preferred Customer has access to all the services of the Regular Customer with the addition of View account activity and Transfer funds. If the password is validated the application creates a user session. View Public Pages This is the trivial use case. The system records this failed login attempt. If this was the third unsuccessful login attempt. This is done to prevent attackers from guessing usernames based on returning error messages.
If not. Main Flow of Events The use case starts when a customer has successfully authenticated to the application. The application retrieves and displays the account balances for all active accounts: The customer selects the logout button and exits the application: The amount is debited from the sending account and credited to the receiving account. A more detailed message is logged.
Chapter 5 Main Flow of Events This use case starts when the Preferred Customer selects an account from the list of account balances. The application verifies that sufficient funds exist in the sending account. The application retrieves account activity and displays the information: The application requests the account activity from the back-end system. The Preferred Customer selects to transfer funds between a sending and a receiving account.
This information is displayed to the customer. If they are not. The back-end system records the transaction and generates a transaction number: Main Flow of Events This use case begins when the Preferred Customer sees a list of account balances.
In this case the roles will represent Regular and Preferred Customers. Implementing the Case Study In the next few sections. String -description: String -referenceNumber: String The diagram above shows the following details: The script below shows the SQL commands for creating the tables and adding some sample data: String -roleName: String 1 AccountDetail -accountDetailId: Date -amount: String 1 -balance: Chapter 5 The diagram below depicts the domain model of the system: UserRole User -userId: String 1 -password: String 1.
The Preferred Customers will also be able to view the account balance. Application Architecture When the users access the system through their browsers.
Once authentication is performed. Chapter 5 The component diagram shown below depicts the high-level application architecture: J2EE enables applications to define security policies declaratively using deployment descriptors. Hence it is possible to implement most of the patterns explained earlier using standard J2EE API and deployment descriptor features. Among these system-level services defined by the J2EE.
The Role Pattern The Command object that handles the initial login will decide the JSP that will display the next view to the user based on the role of the authenticated user. Patterns Applied to Manage Security Single Access Point and Check Point Patterns In the application all public requests will be mapped to a Controller servlet and access to the Controller servlet will be restricted to authenticated users only.
HttpServletRequest returns the currently authenticated user.
EJBContext returns the principal associated with the security credentials of the currently executing thread. The application will use form-based login for authenticating users. HttpServletRequest identifies whether the currently authenticated user belongs to the specified role. EJBContext provides the same functionality. Later in the chapter we will see how we can use the RDBMS-based JAAS module provided by the container provider to implement the security policies defined in the deployment descriptor.
Preferred The first page that is accessed home. Roles Used in the System The system basically utilizes the following roles: URI Role Description index. Chapter 5 Sessions We'll be relying on the server-provided features to manage sessions in the application. HttpSession for sessionbased functionality. Preferred The URI that serves the home page balance. In addition to the features explained above.Rather than developing login pages for each ancillary application, the Single Access Point is used to gather user information once, and forward it along.
Their vulnerability depends on the extent to which the application has been securely written it could be quite low.
Chapter 5 The index. Paulo Silva.
In our case, we have chosen JBoss  as our particular platform, which allows for different sources in order to obtain the data required for the authentication and authorization processes databases, directory services or files , however it does not provide a mechanism to abstract developers from these data sources, in a provider-independent fashion.
Chapter 5 The diagram attempts to demonstrate how the Preferred Customer has access to all the services of the Regular Customer with the addition of View account activity and Transfer funds. In our case study, user input is the form, which contains the username, password, monetary amount; each of these data fields must be validated at least for character type and length. Therefore, when a request arrives to the application, it should pass through a set of verifications before reaching the main processing phase —called the Front Controller—: authentication, session validation, client IP address checking, request authorization, data codification, auditory or browser type used .
The EJB components can use stateful session beans for implementing session-based functionality.