2 Feb
2016
2 Feb
'16
3:32 p.m.
On 2 Feb 2016 at 14:56:42, Thomas Mortagne
(thomas.mortagne@xwiki.com(mailto:thomas.mortagne@xwiki.com)) wrote:
On Tue, Feb 2, 2016 at 2:06 PM, vincent(a)massol.net
wrote:
I don’t see how it’s possible since you can have Resource Reference that have no meaning
as EntityResourcReference…
For example “mailto:…”.
Thanks
-Vincent
Hi Edy,
On 2 Feb 2016 at 13:34:49, Eduard Moraru
(enygma2002@gmail.com(mailto:enygma2002@gmail.com)) wrote:
No need to check the resource reference type. The user would use the
EntityReferenceResolver which return the right type
of entity reference based on what is found in the passed
ResourceReference. The the user can check the ResourceReference type
(if it cares about it, in some cases you will just call
XWiki#getDocument(EntityReference)). Hi,
So after an initial implementation we realized there are some issues with
the original approach.
Basically, it is not such a good idea to handle the resolving of untyped
links at the parser level because this is not compatible with the XDOM
caching that we have for XWikiDocuments, i.e. it`s not OK to cache a
document's XDOM that was resolved with links in the context of the *first*
document that resolved them and then to reuse that cached XDOM later or
from a different calling document when/where those links no longer make
sense. We would need to remove the XDOM caching and parse the XDOM every
time we need it in order to make sure that the links are resolved in the
context of the current calling document and that they are the correct
links. Obviously, we don`t want that and we want to keep the XDOM cache
which is vital for performance.
In order to address this issue and to still be able to do the fallback
mechanism (the one that allows us to be backwards compatible at the syntax
level when resolving an untyped link), Thomas suggested that we always
produce a static (cacheable/reusable) parsing result (i.e. URL or DOCUMENT
types, with the DOCUMENT ResourceReference having the isTyped flag set to
false) for untyped links and that the we introduce a new set of
EntityReferenceResolver API to be used on the client
side (i.e. when consuming the XDOM) to get the actual XWiki entities. This
would be used, for example, by the XWikiWikiModel when producing the URLs
and any other places that use DOCUMENT type ResourceReferences. So we pass
the resolving responsibility to this new API and expect the client to use
it.
This second proposal resolves the caching issue but introduces new
requirements on the clients of the rendering result, so in terms of
backwards compatibility, if the clients don`t use this new resolvers API,
some links might be interpreted incorrectly (i.e. assuming it's a document
instead of a space reference). This adds to the backwards compatibility
issues caused by the addition of the new SPACE link type, but there is not
much way around it.
I agree that the XDOM returned by XWikiDocument.getXDOM() should contain exactly what’s
been parsed from the syntax without any interpretation.
We could imagine caching the XDOM along with the Context but it doesn’t make much sense
IMO. I find it better that it’s evaluated at the time it’s needed with the context at that
time.
You propose to provide an Entity Reference Resolver to allow users of getXDOM() to parse
references. So I guess the users would check if the ResourceReference is of type
Attachment, Document or Space and then use that resolver to convert the String into an
EntityResourceReference. > Another idea (don’t know if you thought about it)
would be to implement a Transformation that would take that XDOM and generate a XDOM’ that
is resolved against the current Context (with all the links resolved). I guess there could
be use cases for both needs but having the fine-grained solution is better to start with.
>
>> I`d also like to mention that we are already doing something similar to
>> this when resolving attachment/image references (i.e. the caller needs to
>> resolve the reference since the rendering does not distinguish between
>> "space attachments" or "document attachments") so this new
resolver API is
>> a good/needed addition anyway and expanding this approach to links makes
>> sense, IMO.
>
> I don’t understand "since the rendering does not distinguish between
"space attachments" or "document attachments””, could you provide some
example in wiki syntax?
>
>> Additional note: typed links ([[doc:Doc]], [[space:Space]] etc.) are still
>> supported and not affected by this change of direction, since this is only
>> about (untyped [[Doc]]) links.
>>
>> We`re starting work on this direction.
>>
>> Please let us know what you think about this new approach and if you see
>> any use cases where it creates problems.
>
> Sounds good to me.
>
> Of course we’ll need to document this in the release notes.
>
> I’ve done a quick check of usages of LinkBlock.getReference() since this is where
the problem could happen. I’ve found the following places to check:
> - XWikiDocument.getUniqueLinkedPages()
> - DefaultLinkedResourceHelper
> - PlainTextBlockFilter
>
> Note that the LinkCheckerTransformation is not affected since it only checks
URL-type links.
>
> There are also some matches in xwiki-contrib to check:
>
https://github.com/search?q=LinkBlock+user%3Axwiki-contrib&ref=searchre…
>
> Thanks!
> -Vincent
>
> PS: Good catch Thomas about this!
>
>
>> Thanks,
>> Eduard
>>
>> On Thu, Jan 7, 2016 at 2:03 PM, Eduard Moraru wrote:
>>
>> > Hi Thomas,
>> >
>> > On Wed, Jan 6, 2016 at 7:42 PM, Thomas Mortagne > > > wrote:
>> >
>> >> On Wed, Jan 6, 2016 at 5:57 PM, Eduard Moraru
>> >> wrote:
>> >> > Hi devs,
>> >> >
>> >> > As XWIKI-12920 [1] mentions, we need to hide "WebHome"
references in the
>> >> > wiki syntax for links and images (for now) in order to be
consistent
>> >> with
>> >> > what we did in the UI.
>> >> >
>> >> > What this means is that [[label>>Page.WebHome]] should be
equivalent to
>> >> > [[label>>Page]].
>> >> >
>> >> > The plan is to apply the same logic as we did for URLs and
detailed by
>> >> > Vincent in "Solution 2" in his comment on the issue
[2].
>> >> >
>> >> > In order to achieve this, Vincent proposed to introduce a new
"space:"
>> >> > resource type and make this new type the default instead of
"doc:"
>> >> which is
>> >> > the current default.
>> >> >
>> >> > Before:
>> >> > [[label>>Page]] => [[label>>doc:Page]]
>> >> > After:
>> >> > [[label>>Page]] => [[label>>space:Page]] if
"Page.WebHome" exists,
>> >> > or => [[label>>doc:Page]] if
>> >> ".Page"
>> >> > exists,
>> >> > or => wanted link to create "Page.WebHome" when
>> >> > clicked.
>> >> >
>> >> > Using either the "doc:" or the "space:"
versions manually will resolve
>> >> the
>> >> > requested resource, without doing any fallback resolution (which
is
>> >> applied
>> >> > only for the no-prefix version).
>> >> >
>> >> >
>> >> > For the same consistency reason, we need to apply the same
fallback to
>> >> the
>> >> > "attach:" resource type, e.g:
>> >> > [[attach:Page@file.ext]] =>
[[label>>attach:space:Page@file.ext]] ||
>> >> > [[label>>attach:doc:Page@file.ext]]
>> >> >
>> >> > However, a resource is defined as ((type:) resource) so for
attachments
>> >> we
>> >> > would need to extend the type's definition to allow it to
contain ":" in
>> >> > the type name (i.e. "attach:doc" and
"attach:space") so that more
>> >> > variations are tested when resolving a link reference before
treating
>> >> it as
>> >> > a generic/untyped reference (this is where the fallback mechanism
kicks
>> >> in).
>> >> >
>> >> >
>> >> > There is also the image syntax that needs to be extended to
support the
>> >> > same fallback logic, so something like:
>> >> > image:Page => image:space:Page || image:doc:Page
>> >> >
>> >> >
>> >> > In all these cases:
>> >> > * link space: prefix,
>> >> > * link attach:doc and attach:space prefixes and
>> >> > * image space: and doc: prefix
>> >> > ... we would be breaking backwards compatibility in the sense that
if a
>> >> > wiki with the name "space" (and/or "doc",
depending on which case of the
>> >> > above you are) already existed in the wiki farm, any links
pointing to
>> >> > documents in that wiki from other wikis will be broken, because,
for
>> >> > example [[label>>space:Page]] no longer points to the
document
>> >> > "space:Page.WebHome" (from wiki "space"), but
to the document
>> >> > "Page.WebHome" from the current wiki (where the link is
made). To fix
>> >> this,
>> >> > one would have to write [[label>>space:space:Page]]
instead.
>> >>
>> >> "[[label>>space:Page]]" does not mean
"space:Page.WebHome" right now
>> >> but ":.space:Page"
>> >>
>> >
>> > You are right. Bad example (though I find that behavior a bit odd). It
>> > should have been:
>> >
>> > [[label>>space:Space.Page]] no longer points to the document
>> > "space:Space.Page" (from wiki "space"), but to the
document
>> > "Space.Page.WebHome" from the current wiki (where the link is
made). To fix
>> > this, one would have to write [[label>>space:space:Space.Page]]
instead.
>> >
>> > Thanks,
>> > Eduard
>> >
>> >
>> >> >
>> >> > I guess we could/should write a migrator to try to fix most of
these
>> >> cases
>> >> > automatically (like we fix links to a document that was renamed),
but a
>> >> > couple of links will be unfixable if they are built
programatically
>> >> (e.g.
>> >> > by velocity scripts) and the process could prove to be extremely
lengthy
>> >> > one (due to the parsing, processing, serialization and resaving of
each
>> >> > document).
>> >> >
>> >> >
>> >> > Please feel free to comment on the above described approach.
>> >> >
>> >> > Thanks,
>> >> > Eduard
>> >> >
>> >> > P.S.: I did not mention macro parameter references which would
also
>> >> need a
>> >> > solution for hiding the "WebHome" part, but I`d prefer
it if we handle
>> >> that
>> >> > another time / in another thread.
>> >> >
>> >> > ----------
>> >> > [1] http://jira.xwiki.org/browse/XWIKI-12920
>> >> > [2]
>> >> >
>> >>
http://jira.xwiki.org/browse/XWIKI-12920?focusedCommentId=89129&page=co…
> _________