Hello Mats,
In HTML 5 there is the Web Worker object, and it should be possible to
leverage this to perform the calculation in a background thread
client-side.
XSLTForms is not yet using Web Worker but Google Chrome is already
complaining about XMLHttpRequest being called in main thread... ;-)
I guess it is possible to implement the long running calculation in a
javascript function that may be called via xf:load and where the
result is returned via call to XForms DOM API
(model.getInstanceDocument(), model.recalculate()...).
However, it would be nice if the operation could be kept more "XFormy"
and as declarative as in the "non-async" example above.
I'm currently considering two possible options:
1) XForms extension attribute, like so:
<xf:setvalue ref="mynode" value="..." @ext:async="true"/>
2) Implementing the operation as an xf:submission, but proxying the
underlying XMLHttpRequest object to intercept selected submission URLs
and handle them client-side:
<xf:submission resource="http://client/myfunction?param1=...";
serialization="...".../>
and
XMLHttpRequest.registerHandler("http://client/myfunction";, myhandler)
XSLTForms supports xf:setnode as an extension. So, with both xf:setvalue
and xf:setnode, at first glance, I prefer a
@mode="synchronous/asynchronous" implementation (as in xf:submission).
Both options seem to have their unique merits and possible usages.
While the second option is probably quite straight-forward to
implement, the second option may require some more work, like:
1) Porting XSLTForms XPath implementation, as well as some other
objects (XSLTTransform), to work in a Web Worker context.
I have not been working with Web Workers yet but I read that there are
limitations like these. XSLTForms already has its own XPath engine but
is currently using native XML engines (an independent XML engine, fully
written in Javascript, is already in good progress!). Why do you think
that XSLT would also be required or is just it that XSLT would be nice
to have available too?
2) Finding a way to efficiently transfer relevant data (XForms
instances) to the Worker context
2) Making modifications to the relevant action implementations in
XSLTForms to handle asynchronous execution of the action
Seems doable to me, but would be interested to hear if someone has
experience to tell whether that'a crazy idea or not. Obviously, would
be cool if such features could become native features of XSLTForms!
I will be happy to add such features in XSLTForms even if only recent
browsers will support them!
What do you think?
--Alain
------------------------------------------------------------------------------
_______________________________________________
Xsltforms-support mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/xsltforms-support
