Using the Sybase Web DataWindow DTC
The Web
DataWindow DTC (design-time control) lets you add database-driven
content to your Web applications.
Brief history of the DataWindow DTC The Sybase Web DataWindow DTC was previously called the HTML DataWindow
DTC, which replaced the original DataWindow DTC. The original DataWindow
DTC is not provided and should not be used with PowerBuilder 9.
Thin-client implementation
The Web DataWindow DTC provides support for the features available
in the Web DataWindow, a thin client DataWindow implementation.
As a thin client, the Web DataWindow does not require any runtime components
on the client–only a standard Web browser.
Security setting requirements
The Web DataWindow DTC is an ActiveX control. To use the Web DataWindow
DTC, you must be able to run ActiveX controls on the development
machine and script ActiveX controls marked safe for scripting.
You can change your machine’s ActiveX security settings
in the Internet Options dialog box that you access from the Control
Panel or from the Tools menu of the Internet Explorer browser. Changing
the Default Level settings to Medium is all that is required to
enable you to use the Web DataWindow DTC.
Since the DTC is used only at design time, client security
settings do not require modification. Web DataWindow pages are still
visible to client browsers with High security settings.
Use existing DataWindow objects
The Web DataWindow DTC lets you create Web applications that
include DataWindow objects created in PowerBuilder or InfoMaker.
When you add a Web DataWindow DTC to a Web page, the Sybase Web
DataWindow DTC Properties dialog box displays.
From this dialog box you can select the DataWindow object
you want, the location and connection information required by the
server, and bindings for any retrieval arguments. The script to
access the Web DataWindow is automatically inserted in your page.
What happens in an application
Here is what happens when a client browser requests a page
with a Web DataWindow on it:
- The user’s
browser requests the URL for the page template. - Server-side scripts in the template run, calling
the server component methods that generate the Web DataWindow code. - The Web page with the Web DataWindow is delivered
to the browser. - The user interacts with the DataWindow.
- Actions by the user cause the URL, with added action
parameters, to be sent to the server. The actions are communicated
to the server component which causes modifications to the regenerated
DataWindow and the cycle continues again with step 2.
Server-side environment
The Web
DataWindow works
with a server component hosted in any of these environments:
- EAServer
- Microsoft Internet Information Server
- Microsoft Transaction Server
For information about specific configurations, see the DataWindow Programmer’s
Guide
.
The Web DataWindow retrieves and manipulates data from your
enterprise database. When you create a DataWindow object, you can
set properties that determine how the DataWindow object appears
in HTML. The server component generates the HTML for your DataWindow
object.
Additional EAServer support
When you set up EAServer, the DataWindow HTMLGenerator90 is installed for
you as a default server component. It contains many methods that
you can display on the Components tab of the System Tree and that
you can invoke in server-side method calls.
You can also create a custom DataWindow server component and
deploy it to your component server for greater flexibility. However,
if your custom component does not implement the HTMLGenerator90 interface,
you cannot use the Sybase Web DataWindow DTC. (You must manually
code the DataWindow connection information in a server script on
your page.)
You can use the Web DataWindow Container component wizard
to create a custom component that implements the HTMLGenerator90 interface.
The main advantage of the wizard-created component is that it deploys
all the DataWindow objects in a selected target with the connection
information encoded in the component.
For information on creating and deploying a custom server
component or a Web DataWindow Container component, see the DataWindow
Programmer’s Guide
. For information on DataWindow
methods, see the DataWindow Reference
.
Benefits of using the Web DataWindow DTC
The
Web DataWindow DTC provides an easy way to access a database from
a Web page. The DTC offers the following benefits:
- Enhanced productivity Using the Web DataWindow with the Web DataWindow DTC decreases
the amount of code you need to write. A Web DataWindow DTC generates
the scripts that access a DataWindow server component, as well as
the scripts and HTML to render the page. It also generates the scripts
that allow the server component to access a database. - Reusability You can use a DataWindow object in as many Web pages as you
like. - Ease of maintenance Whenever the data-driven requirements for a Web page change,
you do not need to rewrite the server scripts in the page; instead
you can simply modify the DataWindow object and update the properties
for the DTC if needed.