[Qgis-user] QGIS project slow to open when too much wms layers

[aperi2007]

Il 05/12/2015 21:52, Brent Wood ha scritto:
> Can we assume a WMS service is unchanging? While some may well be, 
> that is not a safe

Of course no. Is no right assume that a wms service in unchanging.

> assumption to make, so running through the getcapabilities each time a 
> project is opened seems reasonable.
>

I don't understand why.

> I'd assume that within a session, once a layer has been successfully 
> accessed & retrieved it is no longer necessary, but a project may not 
> have been opened for months.
>

The getcapabilites could not help on this.
The wms layer could have change the style and the style actually used is 
no more available.
The wms layer himself could have the name changed and so is no more 
available in the getcapabilities.

How can the getcapabilites don helpin these and in other situation ?

The only real help is to verify if the layer is still available with its 
style.
But is more easy and efficient to wait and when the user Swtich-on the 
wms layer the first getmap if is failing return an xml exception that 
say all the response need to understand that the wms layer in the 
project is no more usable.

Instead of doing a getcapabilitis at the startup always.

> A compromise could be, on opening a project with WMS layers, to 
> (optionally) ask the user whether to validate WxS layers before 
> opening them, allowing them to speed up the operation if they so 
> desire. Or to have this as a project setting the user can toggle, but 
> not something that should be disabled permanently.
>

The issue is when a project has many and more wms layer.
So ask to the user the validate one by one all the wms layer is too 
boring for a user.
Also ask to a user to do a similar ooperation ned to have an user that 
undersand what this mean.
Not all the gis user are capable to understand what mean validate an wms 
layer.

> my 02c...
>
> Brent Wood
>
>
>
> ------------------------------------------------------------------------
> *From:* Andrea Peri <aperi2007 at gmail.com>
> *To:* aperi2007 <aperi2007 at gmail.com>; Jürgen E. <jef at norbit.de>; 
> qgis-user <qgis-user at lists.osgeo.org>
> *Sent:* Sunday, December 6, 2015 9:34 AM
> *Subject:* Re: [Qgis-user] QGIS project slow to open when too much wms 
> layers
>
> Hi Sandro,
>
> I study better the question and perhas this is more a strange issue.
> Infact my doub is why is necessary a getCapability request when open a 
> project ?
>
> The getcapabilities is need for list the layers, choose the style,
> choose the srs and retrieve the bounding-box of the layer.
> All this action are need only when a new wms layer is to add at the
> qgis project.
> So these are all do when I open the WMS add layer windows.
>
> But when I open a project where the wms layer are just added why do a
> getcapabilites request for every wms layer in it ?
>
> This is the question.
>
> A.
>
>
> 2015-12-05 18:32 GMT+01:00 Sandro Santilli <strk at keybit.net 
> <mailto:strk at keybit.net>>:
> > On Sat, Dec 05, 2015 at 06:06:05PM +0100, aperi2007 wrote:
> >
> >> https://lists.osgeo.org/pipermail/qgis-user/2015-December/034593.html
> >
> > [..]
> >
> >> Insteal the problem is on the getcapabilites requests.
> >> They are repeated the same for every single wms layer indipendently
> >> if it is coming from the same wms service or not.
> >
> > [..]
> >
> >> A good enhancement for me could be to do one single getcapabilities
> >> request for every distinct wms service used in the project instead
> >> that one for every layer to avoid this waste redundancy of work.
> >
> > Sounds worth an enhancement ticket.
> > A cache for capabilities request.
> >
> > --strk;
>
>
>
> -- 
> -----------------
> Andrea Peri
> . . . . . . . . .
> qwerty àèìòù
>
>
>
> -----------------
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