Automatic exception handling in conditions

Rule variable

If a definition is unknown, the condition part is automatically unknown regardless of the remaining conditions.

If the rule variable 'statusIsNew' is unknown, the condition is considered unknown and no rule action is taken.

definitions
   set 'statusIsNew' to the status of 'the borrower' starts with “New";

if it is not true that 'statusIsNew' and  the comment of 'the loan' contains "similar"
then
   reject 'the loan' ;
   add "duplicate detected" to the messages of 'the loan' ;
else 
   add "no duplicate found" to the messages of 'the loan' ;

All rule variables should be resolved differently from unknown to allow the evaluation of the condition part. If the rule variable statusIsDuplicate is unknown, the condition is considered unknown and no rule action is taken, even if there an or condition and part of it is true. For example, in the following rule the comment of 'the loan' does contain "similar":

set 'statusIsDuplicate' to the customer status of 'the borrower' starts with "Duplicate";

if 
   'statusIsDuplicate' or  the comment of 'the loan' contains "similar"
then
   reject 'the loan' ;
   add "duplicate detected" to the messages of 'the loan' ;
else
   add "no duplicate found" to the messages of 'the loan' ;
	
    

Conditions that use collections

When the rule engine assembles collections of objects, the objects for which the where clause is unknown or false are ignored. Consequently, the test on the number of objects in a collection reflects this behavior: Only objects that have a where clause evaluated true are counted.

The following example shows a condition that uses collections and tests the number of objects. In the example, the collection (the borrowers) contains only borrowers for whom the attribute values are known. So, when the count operation is performed (is less than 3), any borrower for whom an attribute is unknown is not included in the count. In other words, if 3 borrowers are evaluated and the name of one borrower is unknown while the name of the two other borrows is the name of the 'borrower', then the condition is True and the then action is taken.

if  
   the number of borrowers where the name of each borrower is the name of 'the borrower', 
   is less than 3,
then
   add "less than 3 similar barrowers found" to the messages of 'the loan' ;
else	
   add "duplicate detected" to the messages of 'the loan' ;   
   reject 'the loan' ;

In the following example, if the where clause is true for two borrowers and unknown for two borrowers, then the rule engine considers that the rule condition is false. The else action is taken:

If there are more than 3 borrowers in the past borrowers of 'the loan' where the name of each borrower is the name of 'the borrower', 
then
   reject 'the loan';
   add "more than 3 similar borrowers found" to the messages of 'the loan' ;
else
   add "3 or fewer similar borrowers found " to the messages of 'the loan' ;

Adding exception types

You can customize the list of exception types automatically handled by creating a BOM with the corresponding classes and by adding specific properties, de.autoCatchExceptionInConditions and de.doNotAutoCatchExceptionInConditions, to each class where appropriate. When automatic exception handling is enabled in Rule Designer, the behavior is to handle automatically exceptions that occur in the condition parts of rules for exceptions that belong to the following subclasses:

You can customize the default behavior to add more exception types to be automatically handled by setting a property named de.autoCatchExceptionInConditions to the corresponding class using the BOM editor:

package java.lang;
      public class ClassCastException
        extends java.lang.RuntimeException
        property "de.autoCatchExceptionInConditions" "true"
{
    public ClassCastException();
    public ClassCastException(string arg);
}

Excluding exception types

You can exclude exception types from automatic exception handling in one of the handled classes by overriding the definition of the class in the BOM with the property named de.autoCatchExceptionInConditions. For example, you can remove arithmetic exceptions from automatic exception handling by removing the de.autoCatchExceptionInConditions property from the ArithmeticException class:

public class ArithmeticException
        extends java.lang.RuntimeException
{
    public ArithmeticException();
    public ArithmeticException(string arg);
}

You can exclude a subclass of the four default classes from automatic exception handling by setting a property named de.doNotAutoCatchExceptionInConditions (in bold):

public class StringIndexOutOfBoundsException
        extends java.lang.IndexOutOfBoundsException
       property "de.doNotAutoCatchExceptionInConditions" "true" 
{
    public StringIndexOutOfBoundsException();
    public StringIndexOutOfBoundsException(string arg);
    public StringIndexOutOfBoundsException(int arg);
}

Logging

Automatic exception handling uses the standard Java™ logger logging service, so that you can log messages based on message type and level and control how these messages are formatted and stored at runtime.

In Rule Designer, to capture activity traces that occur in automatic exception handling, you must first define a logging.properties file and make it available to the JVM that is used in the rule execution run or debug configuration. Then, in the Run Configurations window, under the Parameters & Arguments tab of your decision operation, enter one of the following VM arguments: -Djava.util.logging.config.file=file_path/logging.properties or -Djava.util.logging.config.file="${workspace_loc}/your_project/logging.properties".

handlers = java.util.logging.ConsoleHandler
############################################################
# Handler specific properties.
# Describes specific configuration info for Handlers.
############################################################
# Limit the messages that are printed on the console to INFO and above.
java.util.logging.ConsoleHandler.level = FINE
java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter
com.ibm.rules.engine.aeh.level = FINE

To enable automatic exception handling logs in a server environment, define a logging.properties file and make it available to the JVM by configuring your application server, the log level for the Logger name com.ibm.rules.engine.aeh should be set to FINE.

For an introduction to the Java Logging API, see Java Logging Overview. For more information about the java.util.logging Java logger, see java.util.logging in the Oracle documentation.