--- Sylvain Wallez <[EMAIL PROTECTED]> wrote:
Error-handlers are not invoked on internal requests, which is what the flow uses behind sendPage[AndWait](). In that case, the exception are propagated.
How do you catch these exceptions in a flowscript? I tried a simple
try{sendPageAndWait(some-page-with-an-error)}
catch(){sendPageAndWait(some-custom-error-page}
but the catch never caught an exception. Instead I just got the standard
error page in the browser.
That's because processing of the page occurs outside of the scope of the flowscript. There's no way to catch this in the flow.
Internal requests are created in 2 circumstances :
- use of SitemapSource: SourceResolver.resolveURI("cocoon:/blah")
- use of internal redirects: <map:redirect-to uri="cocoon:/blah"/> or Redirector.redirect("cocoon:/blah")
The flow uses an internal redirect to handle an external request. This means that the propagated exception is only catched by the top-level Cocoon object which outputs the default error page (if configured to do so). So we can say that the behaviour of not executing error handlers for internal requests is not suitable for internal redirects.
Does this mean that we cannot catch the exception from the flowscript? That would be bad.
Yep. We cannot for two reasons :
- we cannot catch exceptions after an internal redirect (in e.g. an action) because the redirection is handled when going back in the sitemap engine from the component having done the redirect,
- we cannot because sendPageAndWait() creates a continuation that halts execution of the flow script.
There are 2 solutions to solve this :
1/ apply the same policy for internal redirects than the one that was active before the redirect (i.e. handle errors on internal redirects resulting from external requests)
2/ let the user choose the behaviour through the a new attribute such as handle-internal="true" on <handle-errors>.
Thinking further, these 2 solutions are complementary if we consider that 2/ applies only to internal requests produced by the SitemapSource.
What do you think ?
I personally would be happy if the flowscript could catch errors as exceptions and create its own responses, such as sending an alternate page or an error page.
It would be nice to also have the option of letting the sitemap handle-errors pipeline take care of it, but I am not too worried about this if I can get my first wish. I guess this last part is asking for a way to make solution 1 optional, possibly per call to sendPage[AndWait](), but I am not sure since my current use case gives me no hints.
Yep. But you can't get your first wish...
I would say that 1/ is required as it can be considered as a bug. For 2/ this is a new feature that has to be discussed.
Sylvain
-- Sylvain Wallez Anyware Technologies http://www.apache.org/~sylvain http://www.anyware-tech.com { XML, Java, Cocoon, OpenSource }*{ Training, Consulting, Projects } Orixo, the opensource XML business alliance - http://www.orixo.com
