Target Skill:

Describe the role of front-end objects, and how to customize them  

Object Interactions

When a user logs into an application, by default, BillerXpert displays a form that contains fields for the user name and password. The following diagram illustrates the actions BillerXpert takes when the user submits this form. 


The diagram illustrates the following interactions, numbered from 1 to 5,  which occur between the front-end objects (application logic), the back-end objects (component business objects), and the data server tier: 

  1. The AppLogic retrieves the user name and password from the form. It creates a validation object that verifies that these fields are filled in and that the constraints (such as minimum and maximum lengths) were met.
  2. The AppLogic creates an application business object containing the data with which it performs authentication. 
  3. The application business object creates a component business object; in this case, the component business object represents a customer’s profile. 
  4. The application business object uses the component business object to retrieve the customer’s profile from a data repository; in this case, the Directory Server (LDAP). 
  5. The AppLogic uses the data to populate fields in the next form and outputs the HTML to display the form. The AppLogic creates template data and template map objects, which define the rows of data or individual data to be displayed. In the case of the Sign On AppLogic, the data is simply a template map object that contains the verified user name from the data repository. 

  6. If an error occurs, either as a result of validation or during retrieval of the customer’s profile, the AppLogic outputs HTML that describes the error instead of the normal processing described above. 
The following table summarizes the role of each of the objects that are involved in this process: 
 
OBJECT
FUNCTION
AppLogic Represents the processing of a request to BillerXpert
validation object Represents the validation logic for input data
application business object Represents the data manipulated by the AppLogic and methods that operate on the data
component business object  Represents data in a data repository and the methods that control access to the repository
template data object Represents rows of data to be displayed by an AppLogic
template map object  Represents name-value pairs of data to be displayed by an AppLogic

With the exception of the component business objects, all objects in this table are part of the BillerXpert front end. BillerXpert provides source code for front-end classes, which are the classes that you can modify. BillerXpert provides class libraries for component business object classes; however, you can implement your own component business object classes, as needed. 

 

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