Re: ParsedURL and Virtuals Filesystems

On 10/20/2011 05:41 AM, Jeremias Maerki wrote:
> I've looked into this some time ago. My idea was to add support for JAXP
> URIResolvers like we did in Apache FOP. But ParsedURL seems to be so
> knit into Batik that it's difficult to do that (without major
> refactoring and API changes). Since I didn't have enough time, I
> resorted to a URL protocol handler that is globally registered. You
> could also implement a ParsedURLProtocolHandler but they are maintained
> in a static variable in ParsedURL, so they, too, are global. No
> connection with the user agent. For me, the normal URL protocol handler
> works well enough for now, but I'm not entirely happy.
>

I did use a ParsedURLProtocolHandler, adding files to a global registry 
(Weak map) and using UserAgent.get*Security() methods in order to not 
allow one SVG to use files of another one. Still not the solution I 
liked because this is server side code, and I am not very happy in 
having a global synchronized store for those linked files

> On 19.10.2011 23:00:20 Robert Marcano wrote:
>> Greetings.
>>
>> I have been using Batik for a few years and I love its extensibility. I
>> even use the CSS Engine directly for a non SVG dialect document without
>> needing to add another library.
>>
>> My problem right now is that I need to run/paint the SVG file inside
>> some kind of virtual filesystem. The linked files inside the SVG
>> (xml-stylesheet processing instructions, images...) are not on a real
>> filesystem, they are on RAM isolated from any other SVG loaded. I tried
>> using ParsedURL to define a new protocol but despite the advantages of
>> it over the standard URL class, It still has the problem that protocol
>> handlers are global, I haven't found a way to isolate a protocol for
>> only a SVG document (I set the ParsedURL on the document directly
>> because there is no real URL for it). I tried using ThreadLocal to
>> create a ParsedURL protocol handler context aware, but I found many
>> problems with this approach, Batik is not single threaded, some external
>> to the svg resources are loaded with parsing, some of them are loaded on
>> threads created by Batik out of my control (script on the document that
>> add elements linking to external resources), so there is no easy way to
>> use a ThreadLocal for that.
>>
>> It would be nice if Batik could be extended with a VFS layer in order to
>> be able work with svg files that resides on things not directly mapped
>> to a virtual protocol, but that is something that I could hack a little
>> later, in the short them I need to solve this problem with something
>> less intrusive in the Batik codebase. Any help is really appreciated.
>>
>> Note: I thought about registering those virtual files on some kind of
>> global registry and then create a protocol handler accessing that
>> registry but I am trying to avoid anything with globals because I need
>> very good isolation between docs.
>>
>> Thanks in advance
>
>
>
> Jeremias Maerki
>
>
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