For what it's worth, I've used that same weird SCRIPT hack to insert
dynamically generated code onto my OPAC screen for other purposes too.
It was initially suggested to me by Dave Pattern. It's a useful hack.
Jonathan
Altay Guvench wrote:
> Hi Godmar-
>
> Tim asked me to join the list and discussion on the LibraryThing widgets.
>
> You're right that, with Ajax, we're bound by the same-origin restriction.
> But we can dynamically change the page content after loading, by
> eschewing
> traditional Ajax. New content is delivered through dynamically-inserted
> <!cript> tags. For example, you can set an onclick that adds a tag like
> this to the <head>:
>
> <!cript src="http://www.libarything.com/get_content.php?tag=foo"
> type="text/javascript"></script>
>
> Server-side, get_content.php generates the response on the fly, e.g.
> echo "
> document.getElementById('tagbrowser').innerHTML = 'books tagged
> foo'". As
> long as the response header in get_content is set to javascript, the
> browser
> should interpret it correctly.
>
> As for the hardwired DOM finagling you saw in Danbury's OPAC, in most
> cases,
> the table[3] stuff isn't necessary. Typically, a library will simply
> edit
> their OPAC's html template to include empty widget divs ( e.g. <div
> id="ltfl_tagbrowse" class='ltfl'></div> ) wherever they'd like the
> widgets.
> Then a single script tag finds those divs and inserts the contents
> onload.
>
> However, there were some permissions issues with the Danbury OPAC that
> didn't allow for this. (They could only edit the OPAC footer.) The
> workaround was to dynamically insert the LTFL <div>s using custom
> javascript
> in the footer. That said, like I mentioned, this isn't necessary in most
> cases. We've tested it in a few systems, and generally speaking, our
> widgets are DOM-agnostic.
>
> Altay
>
>
> ---------- Forwarded message ----------
> From: Tim Spalding <[log in to unmask]>
> Date: May 14, 2007 1:50 PM
> Subject: Fwd: [CODE4LIB] A new generation of OPAC enhancements
> To: Altay Guvench <[log in to unmask]>
>
> ---------- Forwarded message ----------
> From: Godmar Back <[log in to unmask]>
> Date: May 14, 2007 1:44 PM
> Subject: Re: [CODE4LIB] A new generation of OPAC enhancements
> To: [log in to unmask]
>
>
> Interesting. A few questions/comments.
>
>> From what I can see, you will not be able to dynamically change the
> page's content after it has finished loading, due to the same-origin
> restriction. Is this correct? In other words, you'd have to pre-plan
> for any user interactivity and send the necessary data along.
>
> We're pursuing a similar approach with the most recent version of
> MAJAX. Instead of using <div>, we're using COinS-style <span> tags
> currently. (*) We tried to keep the JavaScript to a minimum - the user
> shouldn't include anything more than the <!cript> to pull the
> processing JavaScript. Then only plain HTML would be used. (By
> contrast, your approach relies on hardwiring knowledge of the page
> layout into your Javascript, such as "table[3]" to find out where to
> insert your information - and at librarything.com at that!)
>
> My comment, I suppose, is that it may be nice to agree on a set and
> syntax of features that people could use to include into their web
> offerings - not only the catalog, but other library and even
> non-library offerings as well. For instance, a new book list or a list
> of resources prepared by a professor for a particular class are
> example applications we have prepared for Majax, and they could
> certainly be implemented for/with LTFL as well.
>
> - Godmar
>
> (*) See http://libx.org/majax/majaxtalk.html - BTW, Annette will talk
> about this in San Jose Wednesday afternoon at the IUG meeting.
>
>
> On 5/14/07, Tim Spalding <[log in to unmask]> wrote:
>>
>> I expect many of you will object that both are kludges. We need
>> genuinely open and extensible systems.
>>
>> Of course, I agree with you. All the LTFL widgets are also available
>> as XML feeds. And I can't wait to plug them into Evergreen, or
>> whatever. But, for now, and for most people, the exsiting OPACs exist.
>> There's a lot we can do with them, even so.
>>
>> I hope that LTFL can inspire a new generation of light-weight OPAC
>> enhancements. If anyone wants to talk architecture, I'm more than
>> happy.
>>
>> Tim
>>
>
--
Jonathan Rochkind
Sr. Programmer/Analyst
The Sheridan Libraries
Johns Hopkins University
410.516.8886
rochkind (at) jhu.edu
