Manage Exception Conditions

Exception Group classes manage exception conditions. Connect:Direct® generates Exception Group classes if an exception condition is encountered while a request is being processed. Following is an exception scenario where a message is pushed into the exception before the initial throw.

Function A calls Function B, and Function B calls Function C. Function C is a helper routine called by many routines so it does not include information specific to a task. Since the exception occurred in C, it throws the exception. A message describing the error is added and flagged as a technical message.

Function B traps the exception. A message describing the error is added and flagged as a user message. User messages are displayed in dialog boxes. For example, a user message reads: Communication with the server has been lost.

The CDMsgException class stores the messages as an array of strings. The messages are stored in a last-in first-out (LIFO) order because messages added later are more general as the exception moves up the call stack.

Following is a description of the Exception Group classes:

Class Description
CDMsgException The base exception class for all Connect:Direct exception objects. It provides a message stack for troubleshooting.
CDConnectionException This exception is generated when communication with the node is lost or cannot be established.
CDCommandException Generated when an object cannot be executed because parameters are invalid, including a submitted Process containing errors.
CDLogonException Generated if the Connect:Direct node rejects the user ID and password supplied in the logon attempt. You can respond to this exception by prompting the user for the correct logon information.