Hi, OpenLayers have grown to a quite large library (877kB minified), and my guess is that most sites only use a small portion of the classes. Of course you could hand pick the classes you need to build a smaller library, but you have to modify the build script to exclude everything except what you explicitly define in your config. This process is quite difficult, and you would have to update the config if you want to use new classes. The changes might change the API slightly, so now is a good time to investigate. So here are a few suggestions to make it easier to load code on demand, create custom packages and improve minifying. All users will benefit from these improvements, but they are probably most noticeable on mobile devices and computers connected to internet through mobile connections.
Unfortunately I'm not working with OL right now (back full time Sept. 1st), but I hope to start some interesting discussions, and I'll start playing around in a sandbox in Sept. === Load on demand === First configure a minimal OpenLayers package with only what's needed to show a map with no controllers. Then load other classes when they're needed. The classes in OpenLayers already have @requires annotations for it's dependencies, so hopefully it's not such a big job to rewrite. It's not very difficult to write code that loads code async on demand, but there are also well tested libraries, like RequireJS (BSD, MIT, and GPL). This method won't complicate anything for developers that don't care, since they could include bundles with what they need like before. But it would be easy to include a minimal version, and load the rest on demand. You could even see what classes normally loads on demand and create bundles of those to load async. It would also be possible to improve it further without changing the API. With a short timer we could buffer classes that are required into one request, and bundle the files server side. Yahoo has this service for YUI: http://yuiblog.com/blog/2008/10/17/loading-yui/, and there are open source projects that can do this for you: http://code.google.com/p/minify/ Google Maps v3 also does something similar to give the user a lower perceived latency: http://www.stevesouders.com/blog/2010/07/07/velocity-google-maps-api-performance/ === JavaScript minifying === Google released their javascript compiler last autumn. It does a lot to reduce the size of the scripts, but to use the advanced optimizations the code has to be prepared for it. I'm not sure if Google Closure is the right way to go, but I think it's worth a discussion. Does anyone have experience with Google Closure or other compilers? http://code.google.com/closure/compiler/docs/api-tutorial3.html#enable - Google Closure removes unused methods. This can cause a lot of problems for unaware developers, but it could also reduce the size significantly if used right. I think you have to build your own code in the same process of building OpenLayers for this to work, and the resulting script might be difficult to split and load parts on demand. So maybe not worth it? - When compiling, add an extra file to the beginning and end so that OpenLayers is in a private scope. This allows the compiler to obfuscate all methods and properties to shorter names. Then expose references to the privates in the script at the end. Sounds easy in theory, but might be difficult to find an easily maintained and generic solution. OpenLayers["Layer"] = OpenLayers.Layer would work, but I guess we don't want to hard-code each method and property. Maybe use the NaturalDocs annotations in combination with a perl script? Suggestions? Regards, Gregers _______________________________________________ Dev mailing list Dev@openlayers.org http://openlayers.org/mailman/listinfo/dev
