On Tue, Mar 31, 2009 at 5:30 PM, loic devaux <devl...@gmail.com> wrote: > > Hi List, > > I am implementing a new OpenLayers layer type ( using existing WMS layer > code) to display data from CartoWeb (3.5) Web-GIS with OpenLayers. Because > CartoWeb's architecture can be divided in two servers ( one dealing with the > user interface and another dealing with the GIS processes) I need to make a > cross browser POST request to fetch data but that's not possible with > Xmlhttprequest . I don't want to user OpenLayers Proxyhost capability because > that will increase traffic and complexity for deployment. > There are some solutions with GET requests but the one that works fine for me > for POST requests is submitting a dynamically generated form inside a dynamic > iframe. I read Google Maps has something similar. > Now my problem is that I rely on the onLoad event of the iframe that tells me > when the fetched data is available in the browser. Because this is an > asynchronous execution I haven't found a way to feed OpenLayers with the data > because there is no way (?) in javascript ( without doing ugly cpu intensive > javascript loops or waiting for javascript 1.7 ) to halt execution and resume > it once the callback function (which retrieves the data) associated to the > onLoad event of my iframe has been triggered. > I managed however to make things work for the layerswitcher control but the > other openlayers controls are far more complex and I try to be the less > intrusive as possible so I don't want to modify the source code of each > control (which wouldn't be a solution for custom controls anyway). > The only solution I see would be to be able to specify the execution order of > the callbacks so I could execute my callback first which woud : > - store the event context > - stop the other callbacks from executing > - fetch the CartoWeb data > - recall the stopped callbacks using the stored context > > I don't know if this is feasible as it seems that each browser might handle > the execution order of browser events differently but maybe OpenLayers has > more control on his own events. > > Sorry for the necessary verbosity. I'd be glad to see alternative solutions. > I believe that by solving this problem we would at the same time extend > OpenLayers interoperability since cross domain requests inside the browser > might more and more belong to the future of the web even though this raises > legitimate security concerns. > > Loïc
Hi Loïc Just a quick comment. I fail to see why you need synchronous behavior here, e.g. why would the LayerSwitcher need to know when the data has been received? -- Eric Lemoine Camptocamp France SAS Savoie Technolac, BP 352 73377 Le Bourget du Lac, Cedex Tel : 00 33 4 79 44 44 96 Mail : eric.lemo...@camptocamp.com http://www.camptocamp.com _______________________________________________ Dev mailing list Dev@openlayers.org http://openlayers.org/mailman/listinfo/dev
