Using Host Access Transformation Server (HATS)

Suppose you want to make all of your host applications available on the Web. Suppose that you also want to create a host application that provides the look, feel, and easy navigation of a Web page, enabling end users to access host application functions using buttons, drop-down lists, links, and option lists. Host Access Transformation Server (HATS) not only enables you to customize host applications to work in this manner, it enables you to customize them without programming.

Using HATS, you can wrap your host application "green screen" with Web-style borders and add headings, company logos, and links to other Web sites. Global text replacement on the host screen enables you to give your application a custom feel. Users can skip unnecessary host screens and be prompted for input. You can also choose to present any host screen element (such as host application function keys) in a fully-interactive, Web-style output (such as links) and define where users will see the output in the application. HATS gives you the control to fully customize your host application and enhance the ways in which users work with applications.

HATS macro support enables you to provide programmed navigation through multiple host screens. For example, a macro can navigate the screens of a host application to display the first screen the end user needs to see, bypassing all the screens in between. You can combine data from multiple host screens into a single HATS screen. HATS global variables can extract data from host screens and enter the data on other screens. You can use business logic to integrate legacy systems with other back-end systems in your company, as well as your business partners' systems. You can also use business logic to perform complex calculations and automatically enter the results into host forms.

The foundation of HATS is the HATS Studio. The HATS Studio provides you with all of the necessary tools to create, assemble, and transfer host applications to the production system for deployment. The resulting host application can be accessed by end users with standard Web browsers.

Understanding HATS application processing

Before creating a HATS project, you should understand how HATS processes host applications. As users access each screen of an application, HATS processes the application as described in the following steps. Figure 1 shows the flow of these steps. Each italicized term in the following steps is a key concept of HATS. Key concepts are described in Understanding HATS key concepts and objects.

1. When the host displays a screen, HATS compares the host screen to each screen recognition criterion defined in the project's enabled screen customizations, in the order defined by event priority, until a match is found.
2. When matched, HATS performs the actions defined for the screen customization. These actions can include:
   • Applying a transformation using the associated template. HATS displays any host components (defined in the transformation) as HTML widgets.
   • Executing business logic
   • Interacting with global variables
   • Showing a URL
   • Playing a macro.
3. If no screen recognition criteria match the host screen, HATS processes the unmatched screen event. The default action of this event is to display the host screen using the default transformation and applying the default template.
4. As the host presents each new screen of an application, HATS begins at Step 1 again and proceeds through these steps.
   Note:
   If a macro uses skip-screen processing, those screens are not subject to these steps.

Figure 1. HATS screen processing

Screen customizations are an important concept in the development of a HATS project. Without screen recognition criteria being defined in a screen customization, HATS would not know what actions to take when the host screen is encountered. You can obtain the greatest level of customization for your host application by applying transformations and displaying host components.

You should familiarize yourself with the basic principles of screen customization before beginning the development process. The core elements of setting screen recognition criteria are discussed in Editing a screen customization.

Understanding HATS key concepts and objects

This section explains key concepts and objects of HATS, some of which are described in Understanding HATS application processing. Many key objects in HATS are created using a wizard, but viewed or modified after creation using an editor.

Project

A collection of HATS resources, created using wizards in HATS Studio and customized using HATS Studio editors, that are assembled into a HATS application.

Event

A list of actions performed when the application has reached a certain state. There are four types of events in HATS applications:

• Connect
• Disconnect
• Unmatched screen
• Matched screen

The first three events are defined by HATS, and you can locate them in the source/profiles/events/session/main directory path of the Navigator tab of the HATS Studio. If you want to modify these events for any reason, you can edit them by double-clicking on the event. The matched screen event is also known as a screen customization.

Screen customization

A HATS resource, an event, with two parts: a set of screen recognition criteria, and a list of actions to be taken.

Screen recognition criteria

During project creation, you set screen recognition criteria that HATS uses to match host screens. Host screens can be recognized by any combination of criteria including how many input fields or total fields are on the screen, the coordinates of the cursor's position, and text strings on the screen within a defined rectangle or anywhere on the screen.

When a host displays a screen, HATS searches to see whether the current host screen matches any of the screen recognition criteria you set in any screen customizations in your project. If HATS finds a match, the defined actions for the screen customization are performed.

For more information on setting screen recognition criteria, see Editing a screen customization.

Action

A step that occurs when a host screen is encountered that matches the screen recognition criteria specified for a screen customization. A list of actions is part of the definition of each screen customization.

Transformation

A transformation is a JSP file that defines how host components should be extracted and displayed in a Web presentation. Applying a transformation is one of the possible actions of a screen customization.

For more information on creating transformations, see Editing a transformation.

Host components

Host components are HATS objects responsible for recognizing elements of the host screen (such as command lines, function keys, menus) that you choose to present to the end user of the HATS application. You can use the set of host components that HATS supplies, or you can create your own host components. For information on creating custom host components, see Creating a custom host component.

For more information on selecting host components to use with your HATS project, see Insert Host Component wizard.

Widgets

Widgets are HATS objects responsible for creating the HTML output for host components in the HATS presentation. For example, you can convert function key host components into button widgets so that the end user sees the function keys as buttons in the HATS application. You can use the widgets that come with HATS, or you can create your own. For information on creating custom widgets, see Creating a custom widget.

For more information on selecting widgets to use with your HATS project, see Insert Host Component wizard.

Template

A template is a JSP file that enables you to enhance the appearance of your project. When creating a HATS project, you select a template to use as the default template for your project. The template can contain company logos and information and links to other Web pages. You can select from the sample templates that are provided with HATS, or you can design custom templates for your projects using the wizards and editors in HATS Studio. You can choose which template to apply to the host screen when a transformation is applied.

In a Web page, the template surrounds the area where the transformation appears. For more information on associating a template with a transformation, see Using templates.

Business logic

Any Java code invoked as an action in an event, such as a screen customization. Business logic is specific to the application and is not provided as part of HATS.

For more information about business logic, see Adding business logic.

Global variable

A variable used to store a value that can be used throughout the lifetime of an application. The value of a global variable can be extracted from a host screen or defined by the developer. Global variables can be used in templates, transformations, screen customization actions, macros, or business logic.

For more information about global variables, see Interacting with global variables.

Macro

An XML script that defines a set of screens and defines certain actions that should be taken on those screens. Macros are used to automate end user interactions with the host. You can record and play macros to skip screens, prompt users for data input, and extract host screen information. A macro that skips screens does not require the user to interact with each screen. Prompt macros request information from the user that is used on other screens, thereby limiting user interaction with the host. An extract macro can be used to retrieve information to present to the user.

A macro can be played as an action of a HATS screen customization. It is the last action defined for a screen customization. For information on playing macros as an action of a screen customization, see Actions tab. For more information on incorporating macros into the HATS environment, refer to Incorporating macros.

HATS terminal

A connection in HATS Studio to a live host. Using the HATS terminal, you can capture screens, create screen customizations and transformations, and record macros. You can also play previously recorded or imported macros.

Screen capture

An XML representation of a host screen, used to create or customize a screen customization or transformation.

Run on Server

A function in HATS Studio that enables you to run your project on the WebSphere Studio internal WebSphere Application Server and see the output. This function is also known as the WebSphere Test Environment (WTE).

Print support

The ability for a developer to specify a printer session to be associated with a host session, and enable the end user to view host application print jobs, send them to a printer, or save them to disk.

For more information on print support, see Enabling print support in projects.

Keyboard support

The ability for a developer to enable an end user to use a physical keyboard to interact with the host when the application is run in a Web browser. The developer also decides whether to include a host keypad, an application keypad, or both, in a project. If the keypads are included, the developer decides which keys are included and how those keys and the keypad appear in the Web browser.

The host keypad is a table of buttons or links that enable the end user to interact with the host as if they pressed the physical keys on a keyboard. However, the end user can still use the physical keys on the keyboard instead of the buttons or links on the host keypad.

The application keypad is a table of buttons or links that enable the end user to perform tasks related to the application, such as viewing their print jobs or refreshing the screen.

For more information on keyboard support, see Enabling keyboard support in projects.