[OpenAjaxIDE] IDE Issue 1: Toolkit identification, configuration, loading, and initialization

Jon Ferraiolo jferrai at us.ibm.com
Thu Dec 13 07:51:08 PST 2007


At the Gadgets TF meeting yesterday, we looked at the IBM Widgets proposal:

* http://www.openajax.org/member/wiki/IBM_Widgets_proposal

where there is (what I think) an interesting idea for how to address some
of the problems associated with this issue. Here is a snippet:

<widget xmlns ="http://openajax.org/widget" ...>
      <require library='dojo' version="0.9">
            <config>
                   "parseOnLoad: false, isDebug: true, extraLocale:
['en-us', 'ar-sy', 'es-es', 'zh-cn']"
            </config>
      </require>
...
</widget>

This has some similarities with Adobe's <assetfile> and Jonathan's
<resource>, but I like a couple of particular things with the above
proposal. First, it is explicit in its name by saying that the key semantic
is that it is identifying a resource that is *required*. Second, it bundles
any customization information (i.e., <config>) with the resource reference.

Also, we need to take into account the fact that some leading
mashup-oriented gadget formats, such as Google Gadgets, only allow you to
identify the snippet that belongs in the BODY (but not the HEAD), whereas
others, such as Apple Dashboard, have you provide an entire HTML file that
can include the HEAD.

Here is a derivative proposal that builds on the above:

<widget xmlns ="http://ns.openajax.org/widget" ...>
      <requires>
            <require [type=""] [name=""] [min_version=""] [src=""]
[target=""] [head=""]>
                  <preload>
                        parseOnLoad: false, isDebug: true, extraLocale:
['en-us', 'ar-sy', 'es-es', 'zh-cn']
                  </preload>
            </require>
      </requires>
...
</widget>

* 'type' is an an enum: library | javascript | css | xsl | folder | other
(we can add other options in the future) where
** 'library' indicates an Ajax library. If provided, then either ('name'
and 'min_version') or ('src') must be provided. If ('name' and
'min_version') are provided, then look to the OpenAjax Registry to find the
'src' for the standard download place for the given library. (Note that
there are three options to reference a library such as Dojo. Either use
<require type="library" name="dojo".../> or <require type="javascript"
src="../lib/dojo1.0/dojo.js"/> or if the widget system allows for complete
HTML files (as in Apple Dashboard) then simply include a <script
src="../lib/dojo1.0/dojo.js"/> line in your HTML file.)
** 'javascript' indicates a single JavaScript file that is needed by the
widget
** 'css' indicates a single CSS stylesheet file that is needed by the
widget
** 'xsl' indicates a single XSLT stylesheet file that is needed by the
widget
** 'folder' indicates a folder whose entire contents are needed by the
widget
** 'other' is for other single file resources such as images that need to
be deployed
* 'name' - see 'library'
* 'min-version' - see 'library'
* 'src' holds the relative URL for the given resource, where the base
folder is the location of the widget metadata file
* 'target' holds the relative URL within the deployed package where the
resource should be placed. Defaults to the same as 'src'.
* 'head' is an enum that says whether the resource needs to be referenced
at the top of the document (in HTML, within the HEAD):
** 'auto' requires a complete definition, but here is a start. For 'css',
'xsl' and 'javascript', auto=true. For 'folders' and 'other', auto=false.
** 'true' says that the given resource must be included in the HEAD. (Tools
SHOULD notify the user if there the given request cannot be performed.)
** 'false' says that the given resource must not be included in the HEAD.

If unsufficient attributes are provided for the tool to understand what it
needs to do (e.g., the <require> element has no attributes at all), then
the tool SHOULD notify the user.

I added the above proposal to the bottom of Issue 1:
* http://www.openajax.org/member/wiki/IDE_Issue_1

Jon



                                                                           
             Jon                                                           
             Ferraiolo/Menlo                                               
             Park/IBM at IBMUS                                             To 
             Sent by:                  ide at openajax.org                    
             ide-bounces at opena                                          cc 
             jax.org                                                       
                                                                   Subject 
                                       [OpenAjaxIDE] IDE Issue 1: Toolkit  
             12/05/2007 02:54          identification, configuration,      
             PM                        loading, and initialization         
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




URL: http://www.openajax.org/member/wiki/IDE_Issue_1

IDE Issue 1: Toolkit identification, configuration, loading, and
initialization

Original write-up


Most of the widgets that we are looking to use with IDEs are built on top
of an Ajax toolkit. For example, in 3 early samples, we looked into the
date picker widget (built on Dojo), a menu widget (built on YUI), and a
Google Map widget (built on Google-developed JavaScript). In most cases,
one or more Ajax libraries need to be sourced into the HTML application via
a <script> tag and (in some cases) some sort of library configuration and
initialization must occur for the widget to work properly when deployed
with the HTML page.


The question is what information will we include within our IDE standards
around toolkit identification, configuration, loading and initialization.
On one extreme, we could decide to steer clear of defining any standards in
this area and decide that the various IDEs must take care of this somehow
or other. On the other extreme, we could decide to define an industry
standard for how widgets identifier the Ajax libraries that they need and
how those libraries are configured, loaded and initialized.



Existing industry practice


jMaki's widget.json file includes a config property that provides
information about toolkits and how they should be initialized. Here is a
snippet from the information within jMaki for the Dojo date picker widget:


    'config' : {
         'type' :
          { 'id' : 'dojo',
            'libs' : [
                  '../resources/libs/dojo/v0.4.3/djd43.js'
              ],
              'preload' : 'if (typeof djConfig ==\'undefined\') djConfig =
{ parseWidgets: false, searchIds: [] };',
              'resources' : [
                '../resources/libs/dojo/v0.4.3/src'
              ]
   },


The jMaki engineers need to explain this in more detail, but a good guess
is that libs: points to the root JavaScript file to load for Dojo, preload:
provides configuration settings that are used once the Dojo file is loaded
via a dynamic <script> tag, and resources: is the root folder for finding
other resources needed by Dojo.


Adobe Dreamweaver proposes an <assetfile type="javascript"
location="<url>"> tag to identify JavaScript files that need to be loaded.



Complexities that we might want (or not) to address


Here are some sub-issues about various complexities that we might want to
address:
            Shared use of Ajax libraries - If two widgets use the same Ajax
            library, we might want to (or in fact need to) ensure that the
            Ajax library is loaded only once and that the two widgets share
            the same instance of the given library. This begs the following
            question:
                        What happens if widgets use different variations of
                        the same Ajax library? - Suppose one widget
                        requires jQuery 1.5 and another one jQuery 2.3 and
                        there is a major incompatibility between jQuery 1.x
                        and 2.x. Suppose one widget ships with a custom
                        version of Dojo 1.0 that only supports the features
                        needed by that widget and another widget uses a
                        different custom version of Dojo. (Most likely we
                        will have to have some reasonable behavior rules on
                        Ajax toolkits, such as what we see in the
                        introduction chapter to the OpenAjax Hub 1.0
                        Specification.)
            Dynamic loading standards for Ajax libraries - There have been
            at least two recent proposals to OpenAjax Alliance about having
            us define a standard JavaScript loader. OpenAjax Alliance
            hasn't taken a run at that issue yet.

Analysis


It seems like an IDE loses much of its value as a visual UI tool if it
cannot automatically insert <script> tags for the necessary Ajax libraries
automatically into the Web page on behalf of the user. (Same argument for
other resources such as <link> tags pointing to CSS files.) For a
reasonable user experience, one would hope that a user does not need to do
any more than:
            Identify an Ajax library that they want to use with their
            application, and thereby have the IDE make all of the widgets
            from that library available to the user
            Import specific widgets from that library into the HTML
            document, such as via drag-and-drop
            Customize those widgets, such as with a property inspector
Therefore, due to a strong user requirement, we are strongly inclined to
provide some automation in the area of automatic loading of Ajax libraries
from within the IDE.


Many common Ajax libraries have an architecture that would allow some level
of automation in this area. It is common that a library has a base set of
JavaScript such that it is possible to:
            first load the base set of JavaScript for a given library
            then load the specific JavaScript for each widget used on the
            Web page
(Note: some Ajax libraries have packaging features, such as dojo.require,
that allow consolidation of JavaScript into a single file.)


Both jMaki and Dreamweaver have had some degrees of successful with popular
Ajax libraries in this area.


Given the strong benefit to the user and the fact that many Ajax libraries
have a reasonably desirable architecture in this area, it seems like we
should pursue standardization.



Alternative approaches

Strawman widget metadata


The strawman proposal simply identifies a library by name and version.


<widget
   libraryName="dojo"
   libraryVersion="0.4.3"
 >


jMaki widget metadata


jMaki identifies the library by name and points to the JavaScript files.
jMaki also includes configuration information (i.e., djConfig).


    'config' : {
         'type' :
          { 'id' : 'dojo',
            'libs' : [
                  '../resources/libs/dojo/v0.4.3/djd43.js'
              ],
              'preload' : 'if (typeof djConfig ==\'undefined\') djConfig =
{ parseWidgets: false, searchIds: [] };',
              'resources' : [
                '../resources/libs/dojo/v0.4.3/src'
              ]
   },


Adobe Dreamweaver metadata


Adobe proposes an <assetfile location="..." referenceType="javascript"/>
tag to identify the JavaScript that needs to be loaded"


  <assetfiles>
   <!--  the following asset files will get copied to the users's site when
they save their document and the paths will be adjust to point to them -->

   <!-- Specifing referenceType (link, import, or javascript) will create a
reference to the associated asset file in the <head> -->
   <!-- not specifying a referencetype copies the file but adds no
reference to it -->
   <assetfile location="yui/2.3.1/build/menu/assets/skins/sam/menu.css"
referenceType="link"/>
   <assetfile location="yui/2.3.1/build/fonts/fonts-min.css"
destination="yui/build/fonts/fonts-min.css" referenceType="link"/>
   <assetfile location="yui/2.3.1/build/yahoo-dom-event/yahoo-dom-event.js"
referenceType="javascript"/>
   <assetfile location="yui/2.3.1/build/container/container_core-min.js"
referenceType="javascript"/>
   <assetfile location="yui/2.3.1/build/menu/menu-min.js"
referenceType="javascript"/>
   <assetfile location="yui/2.3.1/build/menu/map.gif" />
 </assetfiles>


Jon's proposed resolution


Specific recommendations:
            Only focus on workflows where there is only a single version of
            a given Ajax library used within a particular HTML page. For
            example, our primary target workflow would be situations where
            the entire page uses a single version of a particular library
            (e.g., Dojo 3.1 or YUI 1.9), but don't attempt to define
            metadata markup that address the ability to mix Dojo 0.4
            widgets with Dojo 1.0 widgets. Assume that if a user needs a
            new widget from a newer version of a given library (e.g., Dojo
            1.0's grid widget), then the user has to upgrade the entire
            page to the newer version of the library.
                        NOTE: By saying only focus, that just means where
                        we focus. It doesn't necessarily mean that we don't
                        allow other workflows.
            Choose a markup approach similar to Adobe's <assetfile> that
            lists various widget-specific files (including the library's
            core JavaScript) that need to be loaded within the <head> of
            the HTML page. The idea is that, in general, each <assetfile>
            would result in the addition of a single line of code to the
            HTML page, such as a <script> tag or <link> tag.
                        NOTE: This simple approach neither requires that
                        Ajax libraries and IDEs support this metadata nor
                        restricts Ajax libraries and IDEs from supporting
                        other similar mechanisms. If this simple approach
                        is not sufficient for particular requirements, Ajax
                        libraries and IDEs are fully free to invent their
                        own mechanisms.
                        NOTE: If multiple widgets point to the same asset
                        files, assume the IDEs will be smart enough to only
                        load the given assets once.
                        NOTE: We might consider a feature where
                        OpenAjaxLibrary.xml also supports something similar
                        to <assetfile> for any files that must be loaded in
                        order for any of the widgets to work.
                        NOTE: We need to think through how this might
                        relate to a possible future OpenAjax standard
                        around centralized JavaScript loading.
            Define XML metadata markup that provides similar hooks to
            jMaki's libs, preload, and resources, which means markup that
            identifies the location of the JavaScript files to load for a
            given library, any JavaScript to execute before loading that
            library, and the location of the root directory for that
            library.
                        NOTE: Regarding resources, perhaps that belongs in
                        OpenAjaxLibrary.xml instead.
                        NOTE: Regarding preload, maybe we need a
                        library-level preload instruction within
                        OpenAjaxLibrary.xml along with widget-level preload
                        instructions within the widget metadata.
Here is some markup that would address the bullets listed above:


Within OpenAjaxLibrary.xml:


<library xmlns="http://ns.openajax.org/library"
 ...
 baseDirectory="...relative URL to root folder for library..."
 ...
 >
 ...
 <assetfiles>
   <assetfile type="javascript|css|..." location="<url>"/> <!-- from Adobe
-->
   <!-- etc -->
 </assetfiles>
 ...
 <preload> <!-- from jMaki -->
   ...javascript logic...
 </preload>
 ...
</library>


Within OpenAjaxWidget.xml:


<widget xmlns="http://ns.openajax.org/widget" ...>
 ...
 <assetfiles>
  <assetfile type="javascript|css|..." location="<url>"/> <!-- from Adobe
-->
   <!-- etc -->
 </assetfiles>
 ...
 <preload> <!-- from jMaki -->
   ...javascript logic...
 </preload>
 ...
</widget>_______________________________________________
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