Hey- Scott Davis wrote: > Bottom line: I need features from a datalayer that has 10k points. Is > WFS what you'd recommend at this point?
A few things to keep in mind: With the current vector formats, you should think on the order of 100s of features client side (not thousands). You can use the maxFeatures parameter with WFS to limit the number of features requested. You can use a combination of WMS and WFS - with min/max resolution on the layers - to limit requests for vector features. You can use WMS with GetFeatureInfo to query feature attributes. There are two ways you take performance hits with vector features (or markers): parsing and rendering. Currently you can't control how many features get rendered - all features within the viewport extent get rendered. In the future, we can improve on this with resolution dependent rendering client-side. In terms of parsing, I've made some improvements to the GML parser. I have not had time to get these in the trunk yet. I've seen a 2-3x improvement in parsing time with the new GML format. This brings GML parsing time close to GeoJSON parsing time (also not in the trunk). Of course, performance varies depending on your setup. I've just run the tests on the following page: http://dev.openlayers.org/sandbox/tschaub/xml/examples/format-test.html And gotten the following parsing times: 5.5 ms per GML feature 4.3 ms per GeoJSON feature (If you run the test - wait until both documents show "loaded" before clicking the links to parse features. The tests take 5-10s to run in FF.) So, without accounting for parsing, you can assume a client will parse a feature (with attributes) in 5-10 ms. You can see how waiting around 100 seconds just to parse 10,000 features is a show stopper. Don't even consider rendering them. I'll work on getting the new GML format tested and into the trunk this week. Even with that, you'll want to take other measures to limit the number of features you deal with on the client side. I hope to experiment with resolution dependent rendering before FOSS4G - if you're going to that, look for updates around that time. Finally, consider WMS GetFeatureInfo for getting feature attributes. I don't have a recipe handy for populating a popup with GetFeatureInfo results, but it's not that hard to put together. Tim _______________________________________________ Users mailing list [email protected] http://openlayers.org/mailman/listinfo/users
