Accessing the ExceptionList tree using ESQL

This tree is created with the logical tree when an input message is parsed. It is initially empty, and is only populated if an exception occurs during message flow processing. It is possible that more than one exception can occur; if more than one exception occurs, the ExceptionList tree contains a subtree for each exception.

You can access the ExceptionList tree in Compute, Database, and Filter nodes, and you can update it in a Compute node. You must use the appropriate correlation name; ExceptionList for a Database or Filter node, and InputExceptionList for a Compute node.

You might want to access this tree in a node in an error handling procedure. For example, you might want to route the message to a different path based on the type of exception, for example one that you have explicitly generated using an ESQL THROW statement, or one that the integration node has generated.

The following ESQL shows how you can access the ExceptionList and process each child that it contains:

-- Declare a reference for the ExceptionList
-- (in a Compute node use InputExceptionList)
DECLARE start REFERENCE TO ExceptionList.*[1];

-- Loop through the exception list children
WHILE start.Number IS NOT NULL DO 
   -- more ESQL

   -- Move start to the last child of the field to which it currently points 
   MOVE start LASTCHILD;
END WHILE;         

The following example shows an extract of ESQL that has been coded for a Compute node to loop through the exception list to the last (nested) exception description and extract the error number. This error relates to the original cause of the problem and normally provides the most precise information. Subsequent action taken by the message flow can be decided by the error number retrieved in this way.

CREATE PROCEDURE getLastExceptionDetail(IN InputTree reference,OUT messageNumber integer,
OUT messageText char)	
    /****************************************************************************
	 * A procedure that will get the details of the last exception from a message
	 * IN InputTree:  The incoming exception list
	 * IN messageNumber:  The last message numberr.
	 * IN messageText: The last message text.
	 *****************************************************************************/
   BEGIN
   	    -- Create a reference to the first child of the exception list
   	    declare ptrException reference to InputTree.*[1];
   	    -- keep looping while the moves to the child of exception list work 
		WHILE lastmove(ptrException) DO
			-- store the current values for the error number and text
			IF ptrException.Number is not null THEN
        		SET messageNumber = ptrException.Number;
        		SET messageText = ptrException.Text;
  			END IF;
  			-- now move to the last child which should be the next exceptionlist
			move ptrException lastchild;
		END WHILE; 
	END;

DECLARE tmp ROW;                                                
CREATE LASTCHILD OF tmp DOMAIN('XMLNSC') NAME 'XMLNSC';         
SET tmp.XMLNSC.ExceptionList = InputExceptionList;              
SET tmp.BLOB = ASBITSTREAM(tmp.XMLNSC.ExceptionList OPTIONS     
FolderBitStream CCSID 1208);
DECLARE FULLEXCEPTION CHAR CAST(tmp.BLOB AS CHAR CCSID 1208);
LOG USER TRACE VALUES('FULLEXCEPTION got is ',FULLEXCEPTION);

For information on accessing the ExceptionList tree using Java™, see Accessing the ExceptionList tree using Java.