Customized Styles for Application Development

PowerVista Bridge introduces Regeneratable Styles - a unique innovation in application design. It's unique for two reasons: 

• layout and behavior are created for each window 

• regeneration supports preserving manually coded changes when new style elements are added to a window. 

PowerVista Styles create a customized development environment for your company and/or application. 

What is a "Style"?
A Style is composed of a set of 'generators' for the various window designs/behaviors that make up an application. Most applications have 5 to 8 basic window types. For example, application entities such as Customer, Vendor or Employee are displayed for user manipulation on one standard window type. Search windows, dialogs, report selection windows and wizards have a different (but internally standard) layouts. A PowerVista Style automates the process of creating windows --both widget layout and behavior -- for the different sections of an application. A Style specifies not just how an edit field is placed but also its validation. A Style specifies not just the columns for a grid or spreadsheet, but also sort, drill-down, validation, record selection and navigation. Activity that may not be associated with a control is also specified. These actions include event processing such as setting initial values, window close processing, validating database update, delete and new record functionality... whatever the window style requires, you get both the layout and the activity.

Using a Style to code an application window is very fast. The developer completes a four step process to specify data and behavior. When the developer presses the "Finish" button, each window generator creates an entire, working window for the application. The Tutorial Walkthrough shows how styles are used to speed up the development process.

Why use Styles?
The underlying theory is that a 'good' application has a specific and consistent way of presenting data to the user. For example, an accounting system has windows for entering a Customer. The same basic window format is used for entering a Product, a Vendor, a Ledger Account. A well designed application presents the different data in similar ways. This is done to maximize the comfort level of the user. A consistent 'look and feel' and behavior is important for creating excellent database applications.   

The fastest and most consistent way to build an application is to standardize all the repeated parts of an application - whether that standard is to have field labels in bold text or to separate 'add record' functionality from 'update record' functionality. Then, the developer wants to manually specify just the parts of a window that are different. For example, let's say one window contains a dropdown list of customer names, and another window has a dropdown of product descriptions. It's faster to specify 'use customer data' or 'use product data' - rather than have to write the logic to return an existing record for the Customer window, and write it again for the Product window.

How are PowerVista Styles different?
Other application development languages, word processors and web page design tools use Styles and Templates. Most serious developers find them either too simplistic or too restrictive. 

PowerVista Styles are different. You can specify event processing AND regenerate the window at any time and preserve manual changes.

A generated window can be altered and customized in any manner using the  editors inside PowerVista. At any time, that same window can be re-opened in the Style generator, and new elements added. The regenerated window retains every manual change - in addition to the changes in generation. The developer can even reject or retain alterations on a case-by-case basis. 

In a 'real-life' situation, this ability makes all the difference. 

Let's say that an application needs to be enhanced to set every edit control in every window to read-only if the user is "Guest". With PowerVista Regeneratable Styles, the style is altered and all the windows regenerated. The enhancement can be delivered in a fraction of the time associated with other development environments. 

Let's say the database schema changes, and additional fields need to be added to all the 'Customer' windows. Even if you've made hundreds of manual changes to customize the customer window, you simply open the window in its generator, and add the new fields. 

What if all the 'support' windows for an application are similar, but a customized ActiveX control on one of them to provides a unique market-edge? Using a style, generate all the other windows - even the one that hosts the ActiveX control. Then, add the connection manually using normal programming techniques. Any window can be regenerated any number of times, preserving all of the manual changes. 

Customized Styles 
Often, the most difficult part of database application design is the initial work of creating the layout for the various windows and standardizing the processing and functionality.

We are able to participate in these initial design sessions, and create a customized style for an organization. The Style becomes the property of the organization for developing future applications or application modules. The normal application has between 5 and 8 window styles that are used throughout an application. It generally takes between 40 and 100 hours for our staff to create a Style for an organization. The benefits realized in the reduction of development time using a Style are enormous.

The PowerVista development environment comes with two styles: the Tutorial Style and the Generic Style. In addition, all styles for released PowerVista applications, such as RollCall are included. The Tutorial Style is an abbreviated version of the Generic style and is used as an instruction tool for the Tutorial. The Generic Style is less consistent than those we normally use for a particular application. It is a repository for examples and source designs for the other Styles we use. The RollCall style was used to generate the RollCall membership/student management application.

There are several Shareware applications, for example HireMe!, that use example Styles. The intent of PowerVista Shareware applications is to allow anyone to purchase the software, download the source, and then easily modify the applications to suit their particular needs - a Personal Application development system.

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Last Modified: 04/20/04