[AG-TECH] questions for September Townhall

Susanne Lefvert lefvert at mcs.anl.gov
Wed Sep 8 10:13:51 CDT 2004

On Mon, 6 Sep 2004, Dioselin Gonzalez wrote:

> Hello, I have a couple of questions about programming shared 
> applications I would like to discuss:
> 1. GetApplicationID() in sharedApplicationClient:
> This functions makes a call to its appProxy.GetId and passes an 
> argument, however the server returns an error because this function 
> doesn’t take an argument. A comment in the file says: “Check GetState 
> instead of GetId; GetId exists on old servers but with no private id as 
> argument”. What should developers do?

This becomes an issue when connecting to old servers (2.1.2) since the 
interface changed. I will make sure this case is taken care of in the 
SharedAppClient class so developers don't have to worry about it. 

> 2. sharedAppClient.GetData():
> This function reads data from the venue server and stores it in a local 
> cache. When reading from the cache, it doesn’t check whether the data 
> has changed, and so it always returns the first value it ever gets. When 
> a client makes an update using SetData, other clients will still get the 
> old one. What should I use if my application has one client constantly 
> updating data and other clients need to read the latest value of this data?

The data cache is updated when the SetData call is first made and after 
that when 'update data' events are received.  I am guessing you are 
connecting to a 2.1.2 server which doesn't distribute this event. To solve 
the problem I will add an UpdateDataCache() method to the SharedAppClient 

> 3. Shared applications need to maintain a lot of info about the session, 
> participants, application-specific data, etc. For the wish list, I would 
> like to have a more complex data store, something like a database server 
> that lets me execute queries :o) How can I approach this?

I have added this as a feature request in bugzilla (#1148) 
(http://bugzilla.mcs.anl.gov/accessgrid/).  If you have more feature 
requests/bugs please feel free to add them to our bugzilla, that way you 
will receive emails with information regarding your bug report and you 
have a chance to add more comments later.

Thank you very much for your comments.

Susanne Lefvert

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