com.bea.wlpi.common.plugin
Interface PluginField

public interface PluginField

extends java.io.Serializable

The interface that a plugin has to implement to define a new field. Fields are used by the expression evaluator to extract information from an incoming EventData object.

Since:

WebLogic Process Integrator 2.0

Author:

Copyright © 2000, 2001 BEA Systems, Inc. All Rights Reserved.

See Also:

FieldInfo

Method Summary

java.lang.Object	evaluate(EvaluationContext context) Evaluate the field.
void	init(java.lang.String name, java.lang.String eventDescriptor) Set the name and event descriptor associated with this field.
void	setQualifier(PluginField qualifier) Set the field qualifier.

Method Detail

init

public void init(java.lang.String name,
                 java.lang.String eventDescriptor)
          throws PluginException

Set the name and event descriptor associated with this field. This method provides plugin fields the opportunity to access external data dictionary information to retrieve column details to be saved as part of the compiled expression.

Parameters:

name - The field name.

eventDescriptor - The event descriptor.

Throws:

PluginException - if the field is unable to initialize itself.

setQualifier

public void setQualifier(PluginField qualifier)
                  throws PluginException

Set the field qualifier. This method is called when the expression parser encounters a qualified field reference; it provides plugin fields the opportunity to access external data dictionary information to retrieve column details to be saved as part of the compiled expression.

Parameters:

qualifier - The field qualifier, of the same class as this object.

Throws:

PluginException - if the qualifier is invalid, for example.

evaluate

public java.lang.Object evaluate(EvaluationContext context)
                          throws PluginException

Evaluate the field. The expression evaluator calls this method when it needs to retrieve the value of the field referenced by this object from the event datum contained within the context parameter. The plugin field must take account of any field qualifiers it has when calculating its value.

Parameters:

context - The evaluation context. The plugin field can call the the EvaluationContext.getEventData() to access the event datum.

Returns:

The result of evaluating this field against the event data contained in the context parameter.

Throws:

PluginException - if an exception occurs during field evaluation.