exception propagation for a distributed call

exception propagation for a distributed call

[REH]

I need to implement something that has probably already been done
hundreds of times.  I have to implement some distributed calls (i.e.,
across sockets, arinc ports, separate memory partitions, etc.).  I need
to trap any exception that may occur, and re-raise it for the caller,
like CORBA does (though I cannot use CORBA, RPC, etc.).  I also do not
want to replicate a lot of code in each exception block.  What I have
so far is to create a procedure that will take an exception occurence
as a parameter and call it in each exception block at a "when others
=>" arm.  The function returns an enumeration value for the exception
which can be marshalled across and re-raised via a case statement.
What I cannot figure out is how to convert the occurrence in a portable
way so I do not have to use compiler-specific features.  I know I can
convert it to an exception_id, but how do I determine which exception
the id is for?  Is there a way to get the id of an exception without
raising it?  Or, is there a better way 

Thanks,

REH

Re: exception propagation for a distributed call

[REH]

REH wrote:
> I need to implement something that has probably already been done
> hundreds of times.  I have to implement some distributed calls (i.e.,
> across sockets, arinc ports, separate memory partitions, etc.).  I need
> to trap any exception that may occur, and re-raise it for the caller,
> like CORBA does (though I cannot use CORBA, RPC, etc.).  I also do not
> want to replicate a lot of code in each exception block.  What I have
> so far is to create a procedure that will take an exception occurence
> as a parameter and call it in each exception block at a "when others
> =>" arm.  The function returns an enumeration value for the exception
> which can be marshalled across and re-raised via a case statement.
> What I cannot figure out is how to convert the occurrence in a portable
> way so I do not have to use compiler-specific features.  I know I can
> convert it to an exception_id, but how do I determine which exception
> the id is for?  Is there a way to get the id of an exception without
> raising it?  Or, is there a better way
>
> Thanks,
>
> REH

Ah, I should have dug deeper before asking.  I just discovered I can
do: E'Identity on an exception.

Thanks.

REH

Re: exception propagation for a distributed call

[Wilhelm Spickermann]

Hi,

REH wrote:

...
> Iï¿œneed
> to trap any exception that may occur, and re-raise it for the
> caller, like CORBA does
...

Ada does it too.

Wilhelm

Re: exception propagation for a distributed call

[REH]

Wilhelm Spickermann wrote:
> Hi,
>
> REH wrote:
>
> ...
> > I need
> > to trap any exception that may occur, and re-raise it for the
> > caller, like CORBA does
> ...
>
> Ada does it too.
>
> Wilhelm

I don't think you understand what I was asking, unless you are talking
about the distributed systems appendix, which I cannot use.

Re: exception propagation for a distributed call

[Wilhelm Spickermann]

REH wrote:

> you are talking
> about the distributed systems appendix, 

yes

> which I cannot use. 

Sorry -- I didn't notice that.

Wilhelm

Re: exception propagation for a distributed call

[REH]

Wilhelm Spickermann wrote:
> REH wrote:
>
> > you are talking
> > about the distributed systems appendix,
>
> yes
>
> > which I cannot use.
>
> Sorry -- I didn't notice that.

I didn't explicitly state that, so no apology is necessary.  Thanks for
trying to help.

REH

Re: exception propagation for a distributed call

[Martin Krischik]

REH wrote:

> 
> Wilhelm Spickermann wrote:
>> Hi,
>>
>> REH wrote:
>>
>> ...
>> > I need
>> > to trap any exception that may occur, and re-raise it for the
>> > caller, like CORBA does
>> ...
>>
>> Ada does it too.
>>
>> Wilhelm
> 
> I don't think you understand what I was asking, unless you are talking
> about the distributed systems appendix, which I cannot use.

If you can not use all the libraries which have the feature in then you will
have to replicate there functionality. That is: you have to write your own
Annex E or your own CORBA. At least the exception handler part. And since
both PolyORB and GLADE are open source: Why not get inspiration there?

Martin
-- 
mailto://krischik@users.sourceforge.net
Ada programming at: http://ada.krischik.com