[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message]

Re: SAXException, checked, buy why?


alan gutierrez


Alan Gutierrez wrote:
> * Karl Waclawek <karl@w...> [2005-01-04 19:30]:
> 
>>
>>Alan Gutierrez wrote:
>>
>>
>>>   If the sender and receiver agree on a class, then they can put
>>>   it in variables map attached to the StrategyError.
>>
>>What about behaviour?
> 
> 
>     Thanks. Yes.
>     
>  ~A On data.
>  
>     I think this is something of a common problem with frameworks.
>     It feels counter intuitive to say that the signature for an
>     event is as simple as.
> 
>     public interface Event {
>         public int getType();
>         public Object getData();
>     }
> 
>     But, what more can the conduit designer know about a particular
>     event? Especially something as generic as an "error" event.

One should not try to make too many assumptions.

>     It seems silly, to me, to have an interface like so:
> 
>     public interface ErrorData {
>     }
> 
>     public interface Error {
>         public ErrorData getErrorData();
>     }
> 
>     This is a common problem I see arrising in frameworks. You want
>     to be extensiable, so you have to forgo some typing, or else use
>     reflection, which also forgos typing.

Or you allow types to be constrained later.
Generics could be a way to achieve that.
Tried it in .NET 2.0. Opens new possibilities.

> 
>     That's why I suggested a map. It seems like after I've worked
>     with this error handler long enough, I'd know what sort of
>     typing to add and how.

> 
>   ? What processing specific data is available.
> 
>     What other data occurs in an error? Do I want to provide a path?
>     A smidge of overhead, and already part of my system. But, if
>     from another SAX filter, that path might not have a real
>     document to reference. 
> 
>     Document location. Again, might not exist, since these might
>     only be events. Imagine a SAX handler that simply watches a socket.
>     Still, good candidate.
> 
>     For SAX Strategy, my library, the current strategy, and the
>     current event (because I create event objects to encasualte
>     event data).

Again, leave it to error producer and consumer.
The API does not have to know.

>  ~B On behavior.
> 
>     That's hard. What behavior is common to all error handling?
>     
>     I'd like to know, really, because I'd like to take some time to
>     develop some error handling best practices, and perhaps, and
>     error event library is a project in itself.

Rolling back to a previous consistent state, then
retry, maybe with a different code path.
Or logging, displaying a message,...

But again, if the Error class is abstract, one
can subclass with appropriate behaviour, known
to the producer and consumer, but not the API
that just forwards the error.

Karl

PURCHASE STYLUS STUDIO ONLINE TODAY!

Purchasing Stylus Studio from our online shop is Easy, Secure and Value Priced!

Buy Stylus Studio Now

Download The World's Best XML IDE!

Accelerate XML development with our award-winning XML IDE - Download a free trial today!

Don't miss another message! Subscribe to this list today.
Email
First Name
Last Name
Company
Subscribe in XML format
RSS 2.0
Atom 0.3
 

Stylus Studio has published XML-DEV in RSS and ATOM formats, enabling users to easily subcribe to the list from their preferred news reader application.


Stylus Studio Sponsored Links are added links designed to provide related and additional information to the visitors of this website. they were not included by the author in the initial post. To view the content without the Sponsor Links please click here.

Site Map | Privacy Policy | Terms of Use | Trademarks
Free Stylus Studio XML Training:
W3C Member
Stylus Studio® and DataDirect XQuery ™are products from DataDirect Technologies, is a registered trademark of Progress Software Corporation, in the U.S. and other countries. © 2004-2013 All Rights Reserved.