Hello, While beginning to refactor the rewriter APIs I've discovered that there unfortunately is one semantic difference inherent to moving getContent() and setContent() methods into the Gadget object (replacing View.get/setRewrittenContent()): BasicGadgetSpecFactory no longer caches rewritten content.
I've written a discussion of this in issue SHINDIG-500, which tracks this implementation sub-task: https://issues.apache.org/jira/browse/SHINDIG-500 To summarize: 1. Is this change acceptable for the time being? 2. I suggest that we can, at a later date, move fetching of gadget specs into GadgetServer while injecting a Gadget(Spec) cache there as well, offering finer-tuned control over caching characteristics. Thanks, John On Mon, Aug 11, 2008 at 2:20 PM, John Hjelmstad <[EMAIL PROTECTED]> wrote: > I understand these concerns, and should be clear that I don't (despite my > personal interest in experimenting with the idea, agreed that we don't have > time for it at the moment) have any plans to introduce this sort of RPC > anywhere - certainly not in Shindig itself, as any such call would be hidden > behind an interface anyway. > > Putting the RPC hypothetical aside, I still feel that there's value to > implementing HTML parsing in terms of an interface: > * Clearer separation of concerns/boundary between projects. > - Corollary simplicity in testing. > * Clearer API for content manipulation (that doesn't require knowledge of > Caja). > > I could be convinced otherwise, but at this point the code involved seems > of manageable size, so still worth doing. Thoughts? > > John > > > > On Mon, Aug 11, 2008 at 1:00 PM, Kevin Brown <[EMAIL PROTECTED]> wrote: > >> I agree with Louis -- that's just not practical. Every rewriting operation >> must work in real time. Caja's existing html parser is adequate for our >> needs, and we shouldn't go out of our way to tolerate every oddity of >> random >> web browsers (especially as it simply wouldn't work unless you farmed it >> out >> to *every* browser). Any new code needs to be grounded in practical, >> current >> needs, not theoretical options. We can always change code later if we find >> a >> real need for something like that. We have real work to do in the >> meantime. >> >> On Mon, Aug 11, 2008 at 12:06 PM, Louis Ryan <[EMAIL PROTECTED]> wrote: >> >> > John, >> > >> > From a practicality standpoint I'm a little nervous about this plan to >> make >> > RPCs calls out of a Java process to a native process to fetch a parse >> tree >> > for transformations that have to occur realtime. I don't think the >> > motivating factor here is to accept all inputs that browsers can. Gadget >> > developers will tailor their markup to the platform as they have done >> > already. I would greatly prefer us to pick one 'good' parser and stick >> with >> > it for all the manageability and consumability benefits that come with >> that >> > decision. Perhaps Im missing something here? >> > >> > -Louis >> > >> > On Mon, Aug 11, 2008 at 11:59 AM, John Hjelmstad <[EMAIL PROTECTED]> >> wrote: >> > >> > > On Fri, Aug 8, 2008 at 6:10 AM, Ben Laurie <[EMAIL PROTECTED]> wrote: >> > > >> > > > [+google-caja-discuss] >> > > > >> > > > On Thu, Aug 7, 2008 at 9:27 PM, John Hjelmstad <[EMAIL PROTECTED]> >> > wrote: >> > > > > On Thu, Aug 7, 2008 at 3:20 AM, Ben Laurie <[EMAIL PROTECTED]> >> wrote: >> > > > > >> > > > >> On Wed, Aug 6, 2008 at 11:34 PM, John Hjelmstad < >> [EMAIL PROTECTED]> >> > > > wrote: >> > > > >> > This proposal effectively enables the renderer to become a >> > > multi-pass >> > > > >> > compiler for gadget content (essentially, arbitrary web >> content). >> > > Such >> > > > a >> > > > >> > compiler can provide several benefits: static optimization of >> > gadget >> > > > >> content >> > > > >> > (auto-proxying of images, whitespace/comment removal, >> > consolidation >> > > of >> > > > >> CSS >> > > > >> > blocks), security benefits (caja et al), new functionality >> > > (annotation >> > > > of >> > > > >> > content for stats, document analysis, container-specific >> > features), >> > > > etc. >> > > > >> To >> > > > >> > my knowledge no such infrastructure exists today (with the >> > possible >> > > > >> > exception of Caja itself, which I'd like to dovetail with this >> > > work). >> > > > >> >> > > > >> Caja clearly provides a large chunk of the code you'd need for >> this. >> > > > >> I'd like to hear how we'd manage to avoid duplication between the >> > two >> > > > >> projects. >> > > > >> >> > > > >> A generalised framework for manipulating content sounds like a >> great >> > > > >> idea, but probably should not live in either of the two projects >> > (Caja >> > > > >> and Shindig) but rather should be shared by both of them, I >> suspect. >> > > > > >> > > > > >> > > > > I agree on both counts. As I mentioned, the piece of this idea >> that I >> > > > expect >> > > > > to change the most is the parse tree, and Caja's .parser.html and >> > > > > .parser.css packages contain much of what I've thrown in here as a >> > > base. >> > > > > >> > > > > My key requirements are: >> > > > > * Lightweight framework. >> > > > > * Parser modularity, mostly for HTML parsers (to re-use the good >> work >> > > > done >> > > > > by WebKit or Gecko.. CSS/JS can come direct from Caja I'd bet) >> > > > > * Automatic maintenance of DOM<->String conversion. >> > > > > * Easy to manipulate structure. >> > > > >> > > > I'm not sure what the value of parser modularity is? If the >> resulting >> > > > tree is different, then that's a problem for people processing the >> > > > tree. And if it is not, then why do we care? >> > > >> > > >> > > IMO the value of parser modularity is that the lenient parsers native >> to >> > > browsers can be used in place of those that might not accept all >> inputs. >> > > One >> > > could (and I'd like to) adapt WebKit or Gecko's parsing code into a >> > server >> > > that runs parallel to Shindig and provides a "local RPC" service for >> > > parsing >> > > semi-structured HTML. The resulting tree for WebKit's parser might be >> > > different than that for an XHTML parser, Gecko's parser, etc, but if >> the >> > > algorithm implemented atop it is rule-based rather than >> strict-structure >> > > based that should be fine, no? >> > > >> > > >> > > > >> > > > >> > > > > >> > > > > I'd love to see both projects share the same base syntax tree >> > > > > representations. I considered .parser.html(.DomTree) and >> .parser.css >> > > for >> > > > > these, but at the moment these appeared to be a little more tied >> to >> > > > Caja's >> > > > > lexer/parser implementation than I preferred (though I admit >> > > > > AbstractParseTreeNode contains most of what's needed). >> > > > > >> > > > > To be sure, I don't see this as an end-all-be-all transformation >> > system >> > > > in >> > > > > any way. I'd just like to put *something* reasonable in place that >> we >> > > can >> > > > > play with, provide some benefit, and enhance into a truly >> > sophisticated >> > > > > vision of document rewriting. >> > > > > >> > > > > >> > > > >> >> > > > >> >> > > > >> > c. Add Gadget.getParsedContent(). >> > > > >> > i. Returns a mutable GadgetContentParseTree used to >> manipulate >> > > > Gadget >> > > > >> > Contents. >> > > > >> > ii. Mutable tree calls back to the Gadget object indicating >> > when >> > > > any >> > > > >> > change is made, and emits an error if setContent() has been >> called >> > > in >> > > > the >> > > > >> > interim. >> > > > >> >> > > > >> In Caja we have been moving towards immutable trees... >> > > > > >> > > > > >> > > > > Interested to hear more about this. The whole idea is for the >> > gadget's >> > > > tree >> > > > > representation to be modifiable. Doing that with immutable trees >> to >> > me >> > > > > suggests that a rewriter would have to create a completely new >> tree >> > and >> > > > set >> > > > > it as a representation of new content. That's convenient as far as >> > the >> > > > > Gadget's maintenance of String<->Tree representations is >> concerned... >> > > but >> > > > > seems pretty heavyweight for many types of edits: in-situ >> > modifications >> > > > of >> > > > > text, content reordering, etc. That's particularly so in a >> > > > single-threaded >> > > > > (viz rewriting) environment. >> > > > >> > > > Never having been entirely sold on the concept, I'll let those on >> the >> > > > Caja team who advocate immutability explain why. >> > > > >> > > >> > >> > >
