jpspan-discuss

[Jpspan-discuss] Exceptions and JPSpan?

[Markus W. <wo...@21...>]

Hey guys,

I'm trying to throw Javascript exceptions in JPSpan from the server side 
using JPSpan_Error like this:

if (PEAR::isError($obj)) {
     $err = new JPSpan_Error($obj->getCode(), "get_record_by_criteria()",
                             $obj->getMessage());
     return $err;
}

This doesn't seem to work though, JPSpan just opens an alert window with 
the error text and that's it, no catchable exception is fired.

Is there a way to throw actual exceptions from the server-side, which I 
can use in a try...catch block on the client-side?

CU
  Markus

Re: [Jpspan-discuss] Exceptions and JPSpan?

[Markus W. <wo...@21...>]

Hi Harry,

thanks for answering ;-)

Okay, so it's quite straightforward when dealing with async calls, but 
what about synchronous ones, where I don't have a handler object for 
callbacks?

CU
  Markus

Harry Fuecks wrote:
> OK - the reason for the alert is the default client-side error handling 
> mechanism - unless you override it you get an alert.
> 
> The fundamental problem with exceptions and async calls is how to 
> transmit the exception to the callback function that handles the 
> response, given that it's not the caller. In JPSpan this is basically 
> done by special callback functions for errors, using a naming convention.
> 
> The basic choice you have to "catch" your exception is either "locally" 
> in your handler or "globally" for all calls through a specific "remote 
> object" class.
> 
> To do this "locally", create a function in your handler with the same 
> name as the remote method but with the string "Error" as the end of the 
> function name. For example, if your remote method is something like;
> 
> math.divide(x,y)
> 
> In your MathHandler, you would define a function called "divide" to 
> handle a non-error responses and a function "divideError" which will be 
> passed the exception object if an exception happens. This function 
> "divideError" will only be passed exceptions you specifically "threw" 
> from PHP, not other exceptions like network errors etc.
> 
> The other option you have is to redefine some special functions in your 
> remote object class in Javascript. If you look the script 
> "remoteobject.js" in the source, the functions you need to look at are 
> clientErrorFunc, serverErrorFunc and applicationErrorFunc - see the 
> comments in the source for their purpose. You would want to redefine 
> applicationErrorFunc to "globally" handle all exceptions you throw from 
> PHP e.g.;
> 
> var myErrorHandlingFunc = function(e) {
>     // do something here
> }
> 
> var m = new math(MathHandler);
> m.applicationErrorFunc = myErrorHandlingFunc;
> 
> If you look at the "examples/postoffice_client_generated.php" script, 
> you'll see some more examples.
> 
> Regards,
> 
> Harry
> On 9/6/05, *Markus Wolff* <wo...@21... <mailto:wo...@21...>> wrote:
> 
>     Hey guys,
> 
>     I'm trying to throw Javascript exceptions in JPSpan from the server side
>     using JPSpan_Error like this:
> 
>     if (PEAR::isError($obj)) {
>          $err = new JPSpan_Error($obj->getCode(),
>     "get_record_by_criteria()",
>                                  $obj->getMessage());
>          return $err;
>     }
> 
>     This doesn't seem to work though, JPSpan just opens an alert window with
>     the error text and that's it, no catchable exception is fired.
> 
>     Is there a way to throw actual exceptions from the server-side, which I
>     can use in a try...catch block on the client-side?
> 
>     CU
>       Markus

Re: [Jpspan-discuss] Exceptions and JPSpan?

[Harry F. <hf...@gm...>]

Hmmm - looking at the code again, looks like sync calls will always pass=20
exceptions to applicationErrorFunc rather than letting them bubble through.=
=20
In retrospect that seems like a mistake but I've bias against sync calls (
http://ajaxblog.com/archives/2005/05/25/synchronous-requests-bad) so that=
=20
code is old. You'd basically have to redefine applicationErrorFunc to=20
re-throw the exception in Javascript, then you'd get it coming back at you.

On 9/7/05, Markus Wolff <wo...@21...> wrote:
>=20
> Hi Harry,
>=20
> thanks for answering ;-)
>=20
> Okay, so it's quite straightforward when dealing with async calls, but
> what about synchronous ones, where I don't have a handler object for
> callbacks?
>=20
> CU
> Markus
>=20
> Harry Fuecks wrote:
> > OK - the reason for the alert is the default client-side error handling
> > mechanism - unless you override it you get an alert.
> >
> > The fundamental problem with exceptions and async calls is how to
> > transmit the exception to the callback function that handles the
> > response, given that it's not the caller. In JPSpan this is basically
> > done by special callback functions for errors, using a naming=20
> convention.
> >
> > The basic choice you have to "catch" your exception is either "locally"
> > in your handler or "globally" for all calls through a specific "remote
> > object" class.
> >
> > To do this "locally", create a function in your handler with the same
> > name as the remote method but with the string "Error" as the end of the
> > function name. For example, if your remote method is something like;
> >
> > math.divide(x,y)
> >
> > In your MathHandler, you would define a function called "divide" to
> > handle a non-error responses and a function "divideError" which will be
> > passed the exception object if an exception happens. This function
> > "divideError" will only be passed exceptions you specifically "threw"
> > from PHP, not other exceptions like network errors etc.
> >
> > The other option you have is to redefine some special functions in your
> > remote object class in Javascript. If you look the script
> > "remoteobject.js" in the source, the functions you need to look at are
> > clientErrorFunc, serverErrorFunc and applicationErrorFunc - see the
> > comments in the source for their purpose. You would want to redefine
> > applicationErrorFunc to "globally" handle all exceptions you throw from
> > PHP e.g.;
> >
> > var myErrorHandlingFunc =3D function(e) {
> > // do something here
> > }
> >
> > var m =3D new math(MathHandler);
> > m.applicationErrorFunc =3D myErrorHandlingFunc;
> >
> > If you look at the "examples/postoffice_client_generated.php" script,
> > you'll see some more examples.
> >
> > Regards,
> >
> > Harry
> > On 9/6/05, *Markus Wolff* <wo...@21... <mailto:wo...@21...>> wrote:
> >
> > Hey guys,
> >
> > I'm trying to throw Javascript exceptions in JPSpan from the server sid=
e
> > using JPSpan_Error like this:
> >
> > if (PEAR::isError($obj)) {
> > $err =3D new JPSpan_Error($obj->getCode(),
> > "get_record_by_criteria()",
> > $obj->getMessage());
> > return $err;
> > }
> >
> > This doesn't seem to work though, JPSpan just opens an alert window wit=
h
> > the error text and that's it, no catchable exception is fired.
> >
> > Is there a way to throw actual exceptions from the server-side, which I
> > can use in a try...catch block on the client-side?
> >
> > CU
> > Markus
>=20
>

Re: [Jpspan-discuss] Exceptions and JPSpan?

[Harry F. <hf...@gm...>]

OK - the reason for the alert is the default client-side error handling=20
mechanism - unless you override it you get an alert.

The fundamental problem with exceptions and async calls is how to transmit=
=20
the exception to the callback function that handles the response, given tha=
t=20
it's not the caller. In JPSpan this is basically done by special callback=
=20
functions for errors, using a naming convention.

The basic choice you have to "catch" your exception is either "locally" in=
=20
your handler or "globally" for all calls through a specific "remote object"=
=20
class.

To do this "locally", create a function in your handler with the same name=
=20
as the remote method but with the string "Error" as the end of the function=
=20
name. For example, if your remote method is something like;

math.divide(x,y)

In your MathHandler, you would define a function called "divide" to handle =
a=20
non-error responses and a function "divideError" which will be passed the=
=20
exception object if an exception happens. This function "divideError" will=
=20
only be passed exceptions you specifically "threw" from PHP, not other=20
exceptions like network errors etc.

The other option you have is to redefine some special functions in your=20
remote object class in Javascript. If you look the script "remoteobject.js"=
=20
in the source, the functions you need to look at are clientErrorFunc,=20
serverErrorFunc and applicationErrorFunc - see the comments in the source=
=20
for their purpose. You would want to redefine applicationErrorFunc to=20
"globally" handle all exceptions you throw from PHP e.g.;

var myErrorHandlingFunc =3D function(e) {
// do something here
}

var m =3D new math(MathHandler);
m.applicationErrorFunc =3D myErrorHandlingFunc;

If you look at the "examples/postoffice_client_generated.php" script, you'l=
l=20
see some more examples.

Regards,

Harry
On 9/6/05, Markus Wolff <wo...@21...> wrote:
>=20
> Hey guys,
>=20
> I'm trying to throw Javascript exceptions in JPSpan from the server side
> using JPSpan_Error like this:
>=20
> if (PEAR::isError($obj)) {
> $err =3D new JPSpan_Error($obj->getCode(), "get_record_by_criteria()",
> $obj->getMessage());
> return $err;
> }
>=20
> This doesn't seem to work though, JPSpan just opens an alert window with
> the error text and that's it, no catchable exception is fired.
>=20
> Is there a way to throw actual exceptions from the server-side, which I
> can use in a try...catch block on the client-side?
>=20
> CU
> Markus
>=20
>=20
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