RavenclawDev: returning frame from a back end

[Svetlana Stenchikova]

Thanks Dan,

this generally makes sense, but I am not sure how to do this in the java
server.

The operation function in the java galaxy service returns a GFrame.

I can set properties of this frame in any way, but I must return a GFrame, I
think. I tried declaring an operation that returns String and it causes
runtime exception:
java.lang.ClassCastException: java.lang.String


This is how a RoomLine return from a perl back end looks like:

{
        suggested_refine        none
        error   false
        results :1
        {
                {
                        date_time       {
                                time    {
                                        start_time      1700
                                        end_time        1800
                                }
                                date    {
                                        valid_date      true
                                        year    2006
                                        month   10
                                        day     11
                                        weekday 3
                                }
                        }
                        room_size       30
                        room_projector  true
                        room_whiteboard true
                        room_computer   true
                        room_network    true
                        room_location   Wean Hall
                        room_size_spec  large
                        room_number     4625
                }
        }
}


And here is how my java back end frame looks like:

Server environment sending frame:
{c java_be.add_event
   error "false"
   :hub_opaque_data {c admin_info
                       :reply_requested 1
                       :session_id "Default"
                       :tidx 70
                       :scriptless 1
                       :timestamp [array: type GAL_FLOAT_64, 1 elements]
                       :provider_id "[8]"
                       :invoked_stype "java_be" } }

Please make a suggestion on how to return a string from a java server.

thank you,
Svetlana

On 10/10/06, Dan Bohus <dbohus at cs.cmu.edu> wrote:
>
>  Hi Svetlana,
>
>
>
> I think this is the same problem with "Ravenclaw frames" and "galaxy
> frames" but on the output side. Basically what you're doing in the code
> below is constructing a galaxy frame. Instead ravenclaw expects a single
> string in that galaxy frame which contains the information in a single
> string in the "string Ravenclaw frame" format…
>
>
>
> If this message is too cryptic, let me know and I can send you more
> details,
>
> Dan
>
>
>  ------------------------------
>
> *From:* ravenclaw-developers-bounces at LOGANBERRY.srv.cs.cmu.edu [mailto:
> ravenclaw-developers-bounces at LOGANBERRY.srv.cs.cmu.edu] *On Behalf Of *Svetlana
> Stenchikova
> *Sent:* Tuesday, October 10, 2006 5:41 PM
> *To:* ravenclaw-developers at cs.cmu.edu
> *Subject:* RavenclawDev: returning frame from a back end
>
>
>
> Hi,
>
> How should a  back-end function of a ravenclaw dialog manager format a
> frame?
>
> For example,  I am expecting to get a "error" parameter from:
>
> CALL("java_be.add_event <event_add error>backend_error")
>
> backend_error is declared as:
> BOOL_SYSTEM_CONCEPT(backend_error)
>
> In the java back-end:
>
> public GFrame serverOpAddEvent(GFrame f) {
> ...
>
>     GFrame eventAdded = new Clause("event_add");
>
>     eventAdded.setProperty("error", "false");
>
>     return eventAdded;
> }
>
>
> But the backend_error in DM does not get initialized.
>
> Is there a particular way that the return GFrame from the backend server
> has to be generated?
>
> Thank you,
> Svetlana
>
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