Well, that's a very nice question. I have created 1 jar file that's called commons-exceptions.jar (I like apache commons a lot :-) Then it depends upon your packaging how do you wish to go about it. I generally keep this in my app.war.
>Please provide your input on the directory structure.(at web >layer and also at application layer) or exception classes >should be at root level? Keep any directory structure that you wish. As an example, these base exceptions can be in com/navjot/exceptions. then you can have + web specific exceptions in /com/navjot/web/member/exceptions/ + ejb specific exceptions in /com/navjot/ejb/member/exceptions/ >Also let me know whether your base exception classes (AppException >and AppRuntimeException) extend from Exception or >EJBException or something else? My AppException extends from Exception and AppRuntimeException extends from RuntimeException. >For each different type of exception situation, should >we have different exception classes or just a set of classes >solve the purpose? Ideally, exceptions are bound to some flaw in business logic. So should be kept together. However, if you wish, you may replace DuplicateEmailException & DuplicateUserException with DuplicateKeyException - what /*what is duplicate, email oruser*/ + getWhat():String + setWhat(Stirng) It's just another way that is desired sometimes. Personally, I never followed this staregy ;-) >Thanks Navjot for reply. HTH Navjot Singh -----Original Message----- From: Navjot Singh [mailto:[EMAIL PROTECTED] Sent: Monday, September 01, 2003 6:23 PM To: Struts Users Mailing List Subject: RE: Exception framework Usage hi viral, You are thinking in the right direction. That's the way i do it. I have got 2 base exception classes. AppException and AppRuntimeException. 1. The exceptions that come under the purview of the business logic and these can be handled somehow at the controller/model layer to alter the flow of control MUST extend AppException. 2. The exceptions that does not come under the purview of the business logic and raise because of the system or network problems MUST extend AppRuntimeException. However, one must use some common sense to decide which exception should go where. Say, we are connecting to some URL and it may throw TimeoutException. which is not a checked exception. We must be ready to capture this and throw some checked exception. The caller may catch the exception and try connecting again....may be thrice ;-) and if still no luck the caller passes on the message to PRESENTATION. So your code will not be cluttered with "throws XRuntimeException" and tthese exceptions MUST be handled back at CONTROLLER layer only. MODEL layer should just handle CHECKED exceptions. Examples At Controller => DuplicateEmailException extends AppException (we may display the same form showing error on top) At Model => InsufficientBalanceException extends AppException (we may charge as much as he has got and rest of the amount we will accomodtae in next invoice) DatabaseAccessException extends AppRuntimeException ( as there is hardly anything we can do about this. We MAY show some nice "SORRY" page and/or may LOG this exception somewhere) BTW, there is some nice article on "Exception handling" on IBM Developer site. Do check. hope this helps and suggestions are welcome. Navjot Singh -----Original Message----- From: Viral_Thakkar [mailto:[EMAIL PROTECTED] Sent: Monday, September 01, 2003 5:50 PM To: Struts Users Mailing List Subject: Exception framework Usage Hi, Please suggest the exception framework in a scenario in a following scenario. Struts Action class a Business Delegate --> EJB a OR Mapping (Top link) a Domain classes Please validate the below lines. There will be three layers at which we need to handle the exception. At EJB layer, at business delegate and at struts layer. 1.. EJB layer (session bean) methods will throw the (Application) business exceptions along with RemoteException. In the catch block it will throw the EJBException (in case of checked system exceptions like NamingException). 2.. At business delegate layer, we will throw the application exceptions in the catch block rather than EJBException to decouple the web layer and EJB layer. 3.. At struts layer, in the Action class's execute(), we will catch all these business exceptions. Please provide your valuable inputs. Thanks in advance. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
