The Web DataWindow server component and client control – PB Docs 126

The Web DataWindow server component and client control

The Web DataWindow has two main components: the server component
and the client control.

Web DataWindow server component

The Web DataWindow server component retrieves data from a
database and returns JavaScript and XSLT, XHTML, or HTML that represent
the data and the DataWindow object definition to the page server.
The server component is a PowerBuilder custom class user object
that uses a DataStore to handle retrieval and updates and is deployed
as an EAServer component. You
can use the generic component provided with PowerBuilder or a custom
component.

The generic EAServer component,
HTMLGenerator126, is preinstalled in EAServer in
a package named DataWindow.

note.png Using an older version of the generic component

Earlier versions of the generic HTMLGenerator component are
also installed in the EAServer DataWindow
package. Because EAServer supports
multiple PowerBuilder VMs, you can continue to run older Web DataWindow applications
that use this component.

The generic component has methods that you call in your Web
page template to instantiate and configure the component. The generic
component also provides most of the methods available on the PowerBuilder
DataWindow control. You should probably use the generic component
when you are getting started with the Web DataWindow. Later you
might want to build and deploy a custom component that uses the
methods of the generic EAServer component interface
or that uses only the methods you design for the component. For information,
see “Using a custom server component”.

Types of server components and platforms

The following table describes all the types of Web DataWindow
server components and their supported platforms:

Table 6-1: Web DataWindow server components and platforms

Web DataWindow server component

Platform

(server component name)

Description

Generic

EAServer (DataWindow::HTMLGenerator126)

Prebuilt EAServer component.
No generation or compiling of stubs required.

Container
(can include multiple DataWindow definitions)

EAServer (PackageName::ComponentName using
generic DataWindow::HTMLGenerator126 interface)

Deploy with Web DW Container project
wizard. Increases performance by reducing calls to server. No generation
or compiling of stubs required.

Custom (hybrid)

EAServer (PackageName::ComponentName using
generic DataWindow::HTMLGenerator126 interface)

Use to increase flexibility of generic
component. Can build and deploy with PB object or project wizard. Generic
methods remain available.

Custom
(user-designed)

EAServer (PackageName::ComponentName)

Potentially best for performance and scalability.
Can use to avoid downloads of unneeded generic methods to client.

Web DataWindow client control

Embedding client-side scripts

The Web DataWindow client control is the JavaScript plus XML,
XSLT, and CSS; the JavaScript plus XHTML; or the JavaScript plus
HTML that is generated by the server component and embedded in the
page returned to the Web client. Client-side scripts that you add
to your Web page template and wrap in SCRIPT tags are embedded as JavaScript
in the client control.

JavaScript caching

Some features available on the client control are optional:
events, methods, data update and validation, and display formatting for
newly entered data. The size of the generated JavaScript increases
as you add more client-side functionality. You can cache client-side
methods in JavaScript files on your Web server to reduce the size
of the markup generated for Web DataWindow pages and, if the browser
is configured to use cached files, improve the performance on the
client machine.

For information about enabling JavaScript caching, see “Using JavaScript caching
for Web DataWindow methods”
. You can find
additional information about client-side caching, HTMLGen properties,
and other generation properties in the DataWindow Reference.

Using client-side events

Events that are triggered on the client control and several
of the client control methods do not require the server component
to reload the page, so processing on the client is typically much
faster than processing performed on the server.

For more information about enabling features on the client,
see “Web DataWindow properties” and “Controlling what is generated “. For more
about writing scripts, see “Writing client-side scripts”.

For complete documentation of the events and methods available
on the server component and the client control, see the DataWindow
Reference
or the PowerBuilder online Help.


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