A Comprehensive Guide to IBM WebSphere Host Publisher Version 3.5

Chapter 18. XML Legacy Gateway 583

18.6.2 The xmlAppData JavaBean

This JavaBean communicates with the host application using XML data

formatting. A JavaDoc for this JavaBean is included with the Host Publisher

installation and can be accessed starting with the following file:

install_dir\SDK\XLGW\xmlAppData\AllNames.html

where install_dir is the directory in which Host Publisher is installed.

The following functionality is provided by the xmlAppData JavaBean:

򐂰 It provides Java classes and events for sending and receiving host windows.

򐂰 It provides an XML interface for representing and manipulating these host

windows.

The xmlLegacyGatewayServlet uses XSL processing to convert the XML host

window data to the HTML output, which is then sent to the Web browser.

The HTML output that the Web browser receives contains JavaScript, which

resides in a Host Publisher directory that the WebSphere Application Server is

configured to access.

Refer to Figure 18-2 on page 572 to see how the xmlAppData JavaBean relates

to the other components of the XML Legacy Gateway. The xmlAppData

JavaBean contains properties that describe the Host Publisher, HOD, and

TN3270 or TN5250 parameters used to instantiate a host session.

The xmlAppData JavaBean also contains properties that describe the host data

as XML records. These records contain the text of the fields displayed in the

window and the attributes of the fields. Methods are supplied for reading the

fields so they can be manipulated as an XML document.

The xmlAppData JavaBean contains methods for sending a new window of data

to the host. This new window is described by an XML document, which will often

be the previous host data transformed into an XML document, with the user input

fields updated, or a user action specified, or both.

The xmlAppData JavaBean sends xmlDataEvents to all xmlDataEvent listeners.

The data events are sent when the host window has changed.

The xmlAppData JavaBean interacts with the IBM Host On-Demand (HOD)

session JavaBean using PSEvents. When a PSEvent is received by the

xmlAppData JavaBean, the JavaBean updates its internal objects to reflect the

new status of the host window. The xmlAppData JavaBean sends an

xmlDataEvent to inform its listeners of the change.

584 IBM WebSphere Host Publisher Version 3.5

The xmlAppData JavaBean sends xmlErrorEvents to all xmlErrorEvent listeners

when a processing error has been detected. The xmlAppData JavaBean sends

xmlLegacyTraceEvents to all xmlLegacyTraceEvent listeners for appropriate

tracing of the xmlAppData JavaBean activity. The xmlAppData JavaBean listens

for HODTraceEvents and sends the HODTraceEvents to all xmlHODTraceEvent

listeners.

Interfaces

The xmlAppData JavaBean provides for the following interfaces that you can use

when writing a servlet that invokes this API.

1. xmlDataListener

This interface is used for receiving notification of host window changes. It

requires you to include the following method:

xmlDataEvent(xmlDataEvent)

This is an abstract method to receive notification of host window changes.

2. xmlErrorListener

This interface is used for receiving notification of xmlAppData errors. It

requires you to include the following method:

xmlErrorEvent(xmlErrorEvent)

This is an abstract method to receive error notifications.

3. xmlTraceListener

This interface is used for receiving notification of xmlAppData trace events. It

uses the following methods:

– xmlHodTraceEvent(TraceEvent)

This is an abstract method of the xmlTraceListener event handler.

– xmlLegacyTraceEvent(String)

This is an abstract method of the xmlTraceListener event handler.

Classes

The following classes are available with this API:

1. xmlAction

This class extends the Hashtable class and contains the host window action

information for XML host data parsing and generation.