Hi Bill, I must correct me.
more preferable (better) then using the UUID should be use the MD%. You could calculate the MD5 of the single record (or of the single geometry). And when you retry a new record with same MD5 you can understand that it is the same record. Regards. 2012/1/9 aperi2007 <[email protected]> > Hi Bill, > > I guess perhaps you could calculate the > PointOnSurface (don't the centroids) for every single feature received. > > The PointOnSurface (available on spatialite for example) > Will Allow you to understand if a new Features received is the same or is > another. > > Another technics should be calculate the UUID of every feautre received. > > I guess this technics should allow to understand almost pretty well if a > feature is repeated or not. > > Regards, > Andrea. > > > Il 09/01/2012 15:29, Bill Clay ha scritto: > > All, > > > > Thanks to Andrea Peri, I have just discovered that WFS 1.0.0 apparently > > does NOT require a WFS server to report a unique feature ID with every > > feature it transmits (a typical newbie misconception?). > > > > The OGC specs are so nested and versioned, it's hard to be certain I've > > understood them correctly. Could someone be kind enough to enlighten me > > on the following? > > > > 1. Can you confirm or correct the following understandings: > > > > a. Every WFS server (versions 1.0.0 and 1.1.0) must have a permanent > > unique identifier for every feature. > > > > b. WFS GetFeature responses version 1.0.0 may or may NOT provide a > > unique "fid" attribute with each <feature> element, provided the layer > > is not editable (WFS-T). > > > > c. WFS GetFeature responses version 1.1.0 MUST provide a unique "fid" > > attribute with each <feature> element. > > > > 2. Are you aware of any common implementation of WFS 1.0.0 that does NOT > > always report a "fid" attribute with every <feature> element? (I > > understand TinyOFS can be configured not to do so.) > > > > 3. Do you believe that WFS services that do not always provide a "fid" > > with every feature are unusual enough that the QGIS WFS client can > > simply disable all feature caching for such servers? > > > > The proposal at item 3 would require GetFeatures to be requested for the > > entire canvas extent every time any previously un-fetched area is > > exposed on the canvas. Practically speaking, this means potentially long > > delays on every pan and zoom-out on maps containing WFS layers with many > > features that are hosted by such servers. > > > > Doubtless this is old news to everyone but me. Sorry for the static. > > > > Bill Clay > > > > > > -- ----------------- Andrea Peri . . . . . . . . . qwerty àèìòù -----------------
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