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From ja...@hookom.net
Subject Re: AJAX functionality in MyFaces
Date Tue, 02 May 2006 18:52:36 GMT
With the XML solution, how would you capture content written directly to the response vs. content
from multiple components?  We're really interested in providing a prototype for this for JSF
1.2, so if you guys think the XML body will work better, let us know.  I'm just wondering
how you would still get around needing to capture/buffer content written to the responsewriter
in relation to the possibility of content from other UIComponents.

>well, I wouldn't say that generally. If we can work around this
>without a major downside, we should, I suppose.
>
>@Being Advantageous: Hmm.... Don't think there is any difference for
>the end developer - if you have a client side javascript library doing
>the parsing anyways...
>
>regards,
>
>Martin
>
>On 5/2/06, jacob@hookom.net <jacob@hookom.net> wrote:
>> That's a good point, but AJAX requests are much smaller so the buffering of 
>the response isn't as dramatic as it would otherwise be on initial page load.  
>It's tricky to implement, but the trade-off to the end developer, I believe, 
>would be extremely advantagous.
>>
>> >The only problem I see with the header approach is that everything
>> >needs to be processed and buffered upfront again.
>> >
>> >If you have a component that is processed at the end of a very, very
>> >long component tree, it might as well be that you can't store the
>> >response data in memory in the meantime.
>> >
>> >regards,
>> >
>> >Martin
>> >
>> >On 5/2/06, jacob@hookom.net <jacob@hookom.net> wrote:
>> >> I originally tried XML, but never gave much clarity to the CDATA route 
>(good
>> >idea IMHO).  The real upside of exploring the use of response headers 
>though
>> >is that you can have a specific action or event in mind that may have it's 
>own
>> >response, but at the same time you may utilize observers to update other
>> >parts.
>> >>
>> >> With splitting up the body, you can run into issues since any
>> >valuechangelistener, actionlistener, method, etc could write directly to 
>the
>> >body-- and we should let them do that, so we push this multiple encodes out 
>of
>> >the body and into the headers, allowing some methodexpression to actually
>> >write back JSON or do reverse JS function invocation on the client *while*
>> >updating 5 other parts of the page.
>> >>
>> >> An example would be an order entry system where you assign JS event
>> >listeners to quantity changes that invokes a ValueChangeListener on the
>> >server, which does two things:
>> >>
>> >> 1) Tells JSF to re-render the div for order total
>> >> 2) Possibly report/re-render issues with that line item, such as B/O 
>status
>> >> 3) Push JavaScript to the client to highlight the quantity area
>> >>
>> >> In the case of 1 and 2, they would be written to the response headers,
>> >allowing the ValueChangeListener to write whatever JS, JSON, XML, or HTML 
>it
>> >wants to without being tied to the rules of UIComponent's encoding 
>strategy.
>> >>
>> >> -- Jacob
>> >>
>> >> >Jacob (as he pointed out above) came up with what I think a rather
>> >> >clever idea - using multiple HTTP response headers to embed
>> >> >the multiple response sections.  Very untraditional, but I think it'll
>> >> >work very well and scale nicely.
>> >> >
>> >> >-- Adam
>> >> >
>> >> >On 5/2/06, Travis Reeder <treeder@gmail.com> wrote:
>> >> >>
>> >> >>
>> >> >> > > Good point, this could easily be moved into
>> >> >AjaxRendererUtils.encodeAjax
>> >> >> > > since most of the form components just call back to that
anyways 
>to
>> >> >> handle
>> >> >> > > common cases.  I was heading in a different direction
with the
>> >generic
>> >> >> > > listener update, where it would send the response wrapper
and put
>> >the
>> >> >> pay
>> >> >> > > dirt in a cdata section, but it may be easier to just
return
>> >different
>> >> >> types
>> >> >> > > of responses depending on the component.
>> >> >> >
>> >> >> > I'm not enthused about that - for one thing, it makes
>> >> >> > it essentially impossible to send responses from two different
>> >> >> > components in response to one request.  And that's so
>> >> >> > incredibly useful that you really shouldn't shut the door
on it.
>> >> >> >
>> >> >> > IMO, MyFaces should just pick a blessed format for sending
>> >> >> > responses that is flexible enough to support multiple responses
>> >> >> > per request (and sending back at least both XML and HTML
>> >> >> > content, and preferably also embedded JSON), and just tell
>> >> >> > people to stick with that.
>> >> >> >
>> >> >> > Regards,
>> >> >> > Adam
>> >> >> >
>> >> >> >
>> >> >>
>> >> >> You are absolutely correct Adam, and you reminded me why it is
the 
>way
>> >it
>> >> >> is.  The current way *does* support a response containing multiple
>> >> >> components, which is the case with the CommandButtonAjax component

>that
>> >> >will
>> >> >> return multiple errors or multiple successes for all the components

>in
>> >the
>> >> >> corresponding form.  The client side script also supports this
too.
>> >> >>
>> >> >> So as you suggested, it may be best to put HTML and JSON responses
in
>> >CDATA
>> >> >> sections and stick to the standard response format.
>> >> >>
>> >> >> Travis
>> >> >>
>> >> >>
>> >>
>> >
>> >
>> >--
>> >
>> >http://www.irian.at
>> >
>> >Your JSF powerhouse -
>> >JSF Consulting, Development and
>> >Courses in English and German
>> >
>> >Professional Support for Apache MyFaces
>>
>
>
>--
>
>http://www.irian.at
>
>Your JSF powerhouse -
>JSF Consulting, Development and
>Courses in English and German
>
>Professional Support for Apache MyFaces

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