slide2- Introduction of PowerBuilder. скачать в хорошем качестве

slide2- Introduction of PowerBuilder.

What PowerBuilder is PowerBuilder is an enterprise development tool that allows you to build many types of applications and components. It is one of a group of Sybase products that together provide the tools to develop client/server, multitier, and Internet applications. What’s in a PowerBuilder application? A PowerBuilder client application can contain: A user interface Menus, windows, and window controls that users interact with to direct an application. Application processing logic Event and function scripts in which you code business rules, validation rules, and other application processing. PowerBuilder allows you to code application processing logic as part of the user interface or in separate modules called custom class user objects. What is a PowerBuilder component? In a multitier application, modules containing application processing logic (that you deploy to a server) are called components. You can design, build, and deploy custom class user objects as application server components. PowerBuilder applications are event driven In a client application, users control what happens by the actions they take. For example, when a user clicks a button, chooses an item from a menu, or enters data into a text box, one or more events are triggered. You write scripts that specify the processing that should happen when events are triggered. Windows, controls, and other application components you create with PowerBuilder each have a set of predefined events. For example, each button has a Clicked event associated with it and each text box has a Modified event. Most of the time, the predefined events are all you need. However, in some situations, you may want to define your own events. PowerScript language You write scripts using PowerScript, the PowerBuilder language. Scripts consist of PowerScript commands, functions, and statements that perform processing in response to an event. For example, the script for a button’s Clicked event might retrieve and display information from the database; the script for a text box’s Modified event might evaluate the data and perform processing based on the data. The execution of an event script can also cause other events to be triggered. For example, the script for a Clicked event in a button might open another window, triggering the Open event in that window. PowerScript functions PowerScript provides a rich assortment of built-in functions that can act on the various components of your application. For example, there is a function to open a window, a function to close a window, a function to enable a button, a function to update the database, and so on. You can also build your own functions to define processing unique to your application. Object-oriented programming with PowerBuilder Each menu or window you create with PowerBuilder is a self-contained module called an object. The basic building blocks of a PowerBuilder application are the objects you create. Each object contains the particular characteristics and behaviors (properties, events, and functions) that are appropriate to it. By taking advantage of object-oriented programming techniques such as encapsulation, inheritance, and polymorphism, you can get the most out of each object you create, making your work more reusable, extensible, and powerful