Re: [udig-devel] More on catalog

[Justin Deoliveira <jdeolive@xxxxxxxxxxxxx>]

Jody Garnett wrote:
> Hi Justin,
>
> Sorry that nobody has gotten back to you on these questions. You are 
> working on technology that is strategic to uDig and I thank you for 
> talking to us before hacking.
>
> I got a couple ideas of my own ...
> - most of your questions can be answered by looking at the common 
> navigator framework (such as do they allow handle properties on remote 
> resources)
> - mutability is of metadata info is a *pain*, would do much better to 
> resolve to a real class (like an ISO metadata) and hack that, and trust 
> that notification will ripple the changes to the GeoResource handle
>
> > I had another thought for the catalog api. The notion of "refreshing" 
> > a handle. Basically telling the handle to throw away any cached 
> > information such as a capabilities document, authentication 
> > credentials, etc...
>
> This is a tough one, we obviously cannot rely on notification for remote 
> interfaces, so a refresh will be required. But here is the problem, we 
> want uDig at least to be friendly and a refresh button just simply 
> screems "you cannot trust what you see" and sends the wrong message.

I wouldn't expect it to be realized in the user interface. It would be 
stricly for programmatic purposes. However "refresh" might send this 
message but with remote web services you are always subject to elements 
of your environment you cant control, I would rather have a refresh to 
fall back on instead of seeing my app die a cruel death when the 
underlying resources change.
> That said we have a "reset" button in uDig which blows away the handle 
> (and any cached resources) and starts over...
>
> > I had a case for this a while back when I did the PutStyle experiment. 
> > Basically refreshing the style list from the server which is 
> > communicated in the capabilities document. ( although a better a 
> > solution is to do the associated "GetStyles" request, but besides the 
> > point :)).
>
> One thing to do is be tricky ...
> - grab the data you got for putStyles
> - start a background job to fetch a new value
> - return the current value
> - when the job returns check to see if the values are "new" and if so 
> send out notification for the client code to pick up
>
> This idea was the plan for caching GetCapabilities documents locally 
> ..... h2 database anyone?
>
> Jody
>
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--
Justin Deoliveira
The Open Planning Project
jdeolive@xxxxxxxxxxxxx