Building Web applications
PowerBuilder provides several tools that you can use to build
Web applications. This section provides a brief overview of these
tools and points to where you can find more information.
Web Deployment Kit The PowerBuilder Web Deployment Kit is a utility that allows
browser-based access to existing PowerBuilder two-tier client/server
applications. For more information see the Sybase web site
.
Web services
Web services are
loosely defined as use of Internet technologies to make distributed
software components talk to each other without human intervention.
Those software components might perform such business logic as getting
a stock quote, searching the inventory of a catalog on the Internet,
or integrating the reservation services for an airline and a car
rental agency. You can reach across the Internet and use preexisting
components, instead of having to write them for your application.
A PowerBuilder application can act as a client consuming a
Web service that is accessed through the Internet. Through use of
SOAP and WSDL, a collection of functions published remotely as a
single entity can become part of your PowerBuilder application.
A Web service accepts and responds to requests sent by applications
or other Web services. You can also use Web services in a JSP target.
For more information about Web services, see Chapter 30, “Building a Web Services
Client” and the manual Working
with Web and JSP Targets
.
Web targets
A Web target is a collection of files and components used
to create a Web site. Web targets can deliver dynamic, interactive
content by integrating database data, scripting for client- and
server-side events, and calling methods on components stored on
middle-tier servers.You can build standard HTML pages or complex
Web pages that can include client- and server-side scripting, Web
DataWindows, EAServer components (including
Enterprise JavaBeans), and ActiveX components.
The Web Target object model supports server-side programming
for multiple application servers so that you can deploy Web targets
to multiple servers. To provide dynamic content for your Web applications,
you can create scripts in JavaScript or any ECMA-compliant script
(DynaScript, VBScript, JScript, and others).4GL extensions to the
Web Target object model are specific for applications that you deploy
to EAServer. They provide server-side
event processing and generate server-side code automatically from
selections you make in the Web target user interface.
For more information about Web targets, see Working
with Web and JSP Targets
.
JSP targets
JavaServer Pages (JSP) technology provides a quick, easy way
to create Web pages with both static and dynamic content. JSPs are
text-based documents that contain static markup, usually in HTML
or XML, as well as Java content in the form of scripts and/or
calls to Java components. JSPs extend the Java Servlet API and have
access to all Java APIs and components.
You can use JSPs in many ways in Web-based applications. As
part of the J2EE application model, JSPs typically run on a Web
server in the middle tier, responding to HTTP requests from clients,
and invoking the business methods of Enterprise JavaBeans (EJB)
components on a transaction server.
JSP pages built with PowerBuilder support version 1.2 of the
JavaServer Pages specification, version 2.3 of the Java Servlet
specification, and JDK 1.3 and later. PowerBuilder also supports
custom tag libraries that use the JSP 1.2 format. You can choose
to deploy a JSP target as a Web application to EAServer, Apache Tomcat, or any
JSP 1.2 server for which you can configure command line deployment
capabilities.
For more information about Web targets, see Working
with Web and JSP Targets
.
Web DataWindow
The Web DataWindow is a thin-client DataWindow implementation
for Web applications. It provides most of the data manipulation,
presentation, and scripting capabilities of the PowerBuilder DataWindow
without requiring any PowerBuilder DLLs on the client.
The Web DataWindow uses the services of several software components
that can run on separate computers:
- Web DataWindow
server component running in an application or transaction server - Dynamic page server
- Web server
- Web browser
- Database
The server component is a nonvisual user object that uses
a DataStore to handle retrieval and updates and generate HTML. You
can use the generic component provided with PowerBuilder or a custom
component.
There are several ways you can take advantage of the capabilities
of the Web DataWindow:
- Web DataWindow
design-time control In a Web target, you can use the Web DataWindow design-time
control to generate server-side scripts that access the Web DataWindow
component. This is the easiest way to use the Web DataWindow. - Hand coding against the Web Target
object model In a Web target, you can write server-side scripts that use
the Web Target object model to access the Web DataWindow component.
The Web Target object model provides a set of predefined objects
and methods that simplify coding against the Web DataWindow component. - Hand coding against the Web DataWindow
component itself You can write server-side scripts that access the Web DataWindow
component directly. - Writing your own HTML generator Using a sample PBL provided with PowerBuilder as a starting
point, you can create your own HTML generator that provides the
methods you need for your application.
For more information about the Web DataWindow, see the DataWindow Programmer’s
Guide
.
DataWindow Web control for ActiveX
The DataWindow Web control for ActiveX is a fully interactive
DataWindow control for use with Internet Explorer. It implements
all the features of the PowerBuilder DataWindow except rich text.
The DataWindow Web control for ActiveX supports data retrieval
with retrieval arguments and data update. You can use edit styles,
display formats, and validation rules. Most of the PowerBuilder
methods for manipulating the DataWindow are available. Several functions
that involve file system interactions are not supported, allowing
the Web ActiveX to be in the safely scriptable category
of ActiveX controls.
Included with the DataWindow Web control is the DataWindow
Transaction Object control for making database connections that
can be shared by several DataWindow Web controls.
The Web ActiveX is provided as a CAB file, which allows the
client browser to install and register the control. When the user
downloads a Web page that refers to the CAB file, the browser also
downloads the CAB file if necessary, unpacks it, and registers the
control.
For more information about the DataWindow Web control for
ActiveX, see the DataWindow Programmer’s Guide
.
DataWindow plug-in
The DataWindow plug-in displays Powersoft reports (PSRs) that
have been generated previously and stored on the Web server. Because
the PSR files have been generated previously, database access is
not necessary. The plug-in supports only read-only access—users
can view, print, and save the reports, but they cannot modify them.
The plug-in works with any browser that supports Netscape
plug-ins, including Netscape Navigator (Microsoft Internet Explorer
5.5 Service Pack 2 and later versions do not support Netscape plug-ins).
Only the DataWindow plug-in DLL is required on the client browser.
For more information, see Chapter 31, “Using the DataWindow Plug-in”
PowerBuilder window plug-in
The PowerBuilder window plug-in runs a PowerBuilder application
that displays a PowerBuilder window in an HTML page on a client
workstation. It works with any browser that supports Netscape plug-ins,
including Netscape Navigator (Microsoft Internet Explorer 5.5 Service
Pack 2 and later versions do not support Netscape plug-ins). A secure
version of the plug-in ensures that PowerBuilder applications downloaded
over the Internet will not damage a client system or access information
on a client workstation.
An application in the PowerBuilder window plug-in can execute
most PowerBuilder functionality as long as the application begins
with a child window. The application can run any PowerBuilder windows,
display information, accept data input, and update databases. Database
access is initiated on the client workstation using the client’s
connections.
A major disadvantage of the plug-in is that it requires a
fat client—the browser client requires the PowerBuilder
runtime DLLs or shared libraries and the PowerBuilder window plug-in
DLL or shared library.
For more information, see Chapter 32, “Using the PowerBuilder
Window Plug-in”
PowerBuilder window ActiveX
The PowerBuilder window ActiveX lets you provide a graphical
interface inside HTML pages when using a Web browser that supports
ActiveX. It provides all the capabilities of the window and DataWindow
plug-ins, plus the ability to use JavaScript or VBScript to access
a subset of a PowerBuilder child window’s events and functions.
It includes methods you can call to invoke functions and events
in the child window contained in the window ActiveX control.
An application in the PowerBuilder window ActiveX can execute
most PowerBuilder functionality as long as the application begins
with a child window. The application can run any PowerBuilder windows,
display information, accept data input, and update databases. Database
access is initiated on the client workstation using the client’s
connections.
Like the window plug-in, the major disadvantage of the window
ActiveX is that it requires a fat client—the browser client
requires the PowerBuilder runtime DLLs and the PowerBuilder window
ActiveX.
For more information, see Chapter 33, “Using the PowerBuilder
Window ActiveX”