Found my notes on doing this. It shows using YUI 3 to load YUI 2 libraries, as well as how to use the loader in general, instead of numerous static javascript references in our Meta classes.

http://jira.icefaces.org/browse/ICE-6273

Some preliminary observations...

The good news is that the YUI3 loader accepts the 'base' attribute that specifies the base path to locate dependencies. So, that resources can be dynamically loaded from the same server the application runs on, and not from Yahoo's servers.

Another good point is that the YUI3 loader has intrinsic support for loading YUI2 dependencies.

Another thing is that it's also possible to declare and load custom modules. So, potentially, we could remove all @ResourceDependency annotations and only load a common, base js file to dynamically load all resources, including css.

The challenging part at this point is that the 'base' attribute assumes that the URL is in the standard format and not in the JSF format. So, we might have to extend the YUI object or maybe modify the source code. The function that generates the resource URLs is declared as a prototype function of YUI.Loader, so, we might get away with wrapping the original function inside our custom function that appends ".jsf" to the URL, etc.

I managed to dynamically load YUI resources from the local server without using @ResourceDependency's and with the correct JSF URL format. It wasn't necessary to modify the original YUI source code. I did this for slider. Now, I'm investigating how to do it for YUI2 components (using the YUI3 loader).

I committed some code, and this is what I've done and found out...

• It's very easy and straight forward to dynamically load YUI3 resources from a local server. This was tested with slider, and all that needs to be done is to specify a path in the 'base' option of the YUI instance.

• In order to produce URLs in the JSF format, it is enough to override YUI.Loader.prototype._url with a function that appends ".jsf" to the original result, as shown in slider.js.

• @MandatoryResourceComponent annotations were commented out from all renderers.

• All YUI @ResourceDependency's (except yui-min) were removed from slider, tabset, and animation.

• Loading YUI2 from YUI3 is not that easy, as explained below.

• First, the YUI3 loader does not really have dependency resolution logic for YUI2. All it has is a pre-configured 'group' for YUI2 that downloads files from Yahoo's servers. The YUI3 loader only contains dependency resolution logic for YUI3 components (in the last part of loader.js). This was checked in versions 3.1.1 and 3.3.0.

• Second, The YUI2 files downloaded from YUI3 (referred to as 2in3), are slightly modified YUI2 source files. The extra code makes sure that YUI2 components also work in a sandboxed way (i.e. there will be no global YAHOO object). Part of those modifications are the actual dependencies for that file. This means that YUI2 dependencies are simply hard-coded in these modified versions. An example of this code looks like this:

YUI.add('yui2-tabview', function(Y) {
if (Y.YUI2)

/* original code */

if (!Y.YUI2)

if (!YAHOO._activ && YAHOO.util.Event)

}, '2.8.0' ,

);

• Thus, the dependency resolution 'logic' for 2in3 only works if the resources are downloaded from Yahoo's servers (because the dependencies are hard-coded.

• It is possible to manually create a custom 'group' setting in the YUI3 loader to download YUI2 resources from a local server, but there would not be automatic dependency resolution. We would have to hard-code all dependencies. The code to do this was committed but is commented out.

These are two possible solutions:

• Do the job of manually downloading from Yahoo server's every 2in3 modified source file and create a new resource library. Then, we can just create a custom 'group' setting in the YUI3 loader to access these files.

• Dynamically load the YUI2 loader from YUI3, and from there let the YUI2 loader automatically resolve dependencies of components, since the YUI2 loader does have dependency resolution logic for YUI2 components (around the middle of yuiloader.js).

The only difference between these two solutions is that in the first solution the YUI2 code would be sandboxed (i.e. no global YAHOO object), while this wouldn't be the case in the second solution.

> Second, The YUI2 files downloaded from YUI3 (referred to as 2in3), are slightly modified YUI2 source files.

re we sure that these modified YUI2 files do not exist in our YUI3 distribution, and are not the same as the version of YUI2 that we currently have? Would we actually have to manually download every file, or is there some archive of them, or cvs/svn access to them?

These modified files do not already exist in our current YUI distributions (i.e. 2.8.1 and 3.1.1) nor in the latest 3.3.0 distribution. The URL used for these wrapper files is something like this

http://yui.yahooapis.com/2in3.1/2.8.0/build/yui2-tabview/yui2-tabview-min.js

...so our distributions would have to have directories named like 'yui2-tabview' at the same level as the other modules, and this is not the case. I also made a full text search of the two distributions and I couldn't find some key strings like "Y.YUI2" that appear in the wrapper files.

I found out that 2in3 is a completely separate project, and the good news is that it's possible to download all these wrapper files in a single zip file. This is the link where we can download the file:

https://github.com/yui/2in3/tree/master/dist/2.8.2/build

I already downloaded the file and noticed that it contains wrapper files for various versions of YUI2, up to 2.8.1. The original code is always the same, I made a careful comparison, and the only things that change are a couple of strings with version information. So, basically the original code is just wrapped inside a snippet of code, like the one shown above, to make it work with YUI3.

So, I suppose that what we have to do is just to add this 2in3 project to our resource library.

I think, when I first read about 2in3, that I mistook their explanation of working with the latest 2.8 to mean that it was in the actual YUI code-base. Looks like these are their private patches. As long as it's all the same license, it should be ok.

Art reports:

These are the issues I'm still working on:

• The calendar component taking a while to re-render after selecting a date when single submit is enabled.
• JS error in the animation page of the showcase in IE.
• Logger issues. This is just a matter of replacing calls to YAHOO.log() with ice.log() if there are no objections.
• Placing YUI loader resources in head or body? I made a test and it's possible to place the YUI loader JS in the body, either at the beginning or at the end of the body. There's just a JS error with our code, but I could see the YUI loader dynamically loading all the needed resources. I'll try to fix that error.
• Implications of 2in3 on skinning.

Since this seems to be working out well we'll go ahead and pull this change into the IF 2.0.1 release, which means we only have a few days to resolve these issues. See my notes below:

• The calendar component taking a while to re-render after selecting a date when single submit is enabled.
  --> I'll review but low priority for now.

• JS error in the animation page of the showcase in IE.
  ---> Needs investigation, Mark will look at this when he can.

• Logger issues. This is just a matter of replacing calls to YAHOO.log() with ice.log() if there are no objections.
  ---> For 2.0.1, just comment out the log statements (Art). We will revisit the log strategy for 2.1.

• Placing YUI loader resources in head or body? I made a test and it's possible to place the YUI loader JS in the body, either at the beginning or at the end of the body. There's just a JS error with our code, but I could see the YUI loader dynamically loading all the needed resources. I'll try to fix that error.
  ---> Deferred to 2.1, for 2.0.1 we'll live with keeping it in the head.

• Implications of 2in3 on skinning.
  ---> Need Art to resolve these asap.

Added test code for using ace-showcase as a single page application, so that testing of postbacks with the YUI loader could happen. Had to re-enable MandatoryResourceComponent annotations for things to work.

Subversion 24170