RE: [wsrp-interfaces] Applet resources through WSRP

The spec says the following about portlet markup (not resources): “If a Portlet is unable to completely write the portlet URLs for its markup, it MUST set the requiresUrlRewriting flag in the returned MarkupContext structure to “true”.”

However, the same is not said of resources, naturally, since they will not often include “portletURLs” (URLs back into the portlet). While it may be underspecified for resources, the way I would view it is that there must not be any relative URLs, but absolute URLs which point outside the consumer are allowed – After all we would not want to prevent a portlet/resource from containing a direct link to Google, right?

In other words, I agree with your 1-3, but with the definition of “final” as “pointing to the consumer or a third party web site”.

Yossi.

From: Spector, Artem [mailto:artem.spector@sap.com]
Sent: Monday, March 28, 2005 1:51 PM
To: Yossi Tamari; wsrp-interfaces@lists.oasis-open.org
Subject: RE: [wsrp-interfaces] Applet resources through WSRP

Would it be correct to summarize the Producer responsibility in rewriting of URLs inside resources as follows?

If the Producer returns the resource URL with wsrp-requiresRewrite=true, then the URLs in this resource must be ready for the Consumer side rewriting (contain wsrp-rewrite tokens).
If the Producer returns the resource URL with wsrp-requiresRewrite=false, then the URLs in this resource must be final (pointing to the Consumer).
Any other option is not compliant.

Artem

From: Yossi Tamari [mailto:yossi@giloventures.com]
Sent: Sunday, March 27, 2005 7:52 PM
To: wsrp-interfaces@lists.oasis-open.org
Subject: RE: [wsrp-interfaces] Applet resources through WSRP

I do not see why the current situation is confusing, but could you please explain what are you suggesting? To remove either producer or consumer side rewriting from the spec? (Which one?) Only for resources?

I guess your confusion may be result of the fact that in 1, you deal with resources that are not WSRP compliant to begin with. In a “pure” WSRP world, the resources would already include the “wsrp-rewrite?” URLs (at least in the sense that they are dynamic and add use URLs when called in a certain way). Because of legacy resources, you encounter the need to actually parse the resource for other tokens and replace them with rewritable links. This is not something the spec deals with at all, since there is no general solution for it (e.g. if the resource contains JavaScript, it is possible that the URL is constructed dynamically in such a way that the parser will not recognize the URL). The filter that was suggested here earlier is a best-effort attempt to solve this, which is an acceptable implementation, but it is not part of the spec, or even suggested by it.

Yossi.

From: Spector, Artem [mailto:artem.spector@sap.com]
Sent: Sunday, March 27, 2005 7:27 PM
To: wsrp-interfaces@lists.oasis-open.org
Subject: RE: [wsrp-interfaces] Applet resources through WSRP

Yes, I can see your point, and it’s a good opportunity to return to the real question:

What should be the Producer role in rewriting URLs within a resource? I can see two options:

the Producer wraps the resource and “prepares” the URLs for the Consumer-side rewriting (or uses the resource templates)
the Produce does not wrap the resource and the Consumer does the rewriting by itself

IMO the situation when both options are possible is confusing, because the Consumer implementation will have to rely on the Producer implementation (and not on the spec as it should be). Shouldn’t the spec be more explicit here and allow only one of these options?

Artem

From: Yossi Tamari [mailto:yossi@giloventures.com]
Sent: Sunday, March 27, 2005 6:19 PM
To: wsrp-interfaces@lists.oasis-open.org
Subject: RE: [wsrp-interfaces] Applet resources through WSRP

Hi Artem,

If I understand you correctly, you suggest that the consumer will parse the resource looking for text like “url(images/bcg,gif)” and rewrite it.

While it is compliant to the spec to do so (the spec does not forbid it), the portlet/producer that returned this resource is not compliant. It cannot assume that the consumer will parse the resource for anything other than “wsrp-rewrite?”.

This can be implemented as a vendor specific extension, so the producer does not need to parse when serving consumer from that vendor, but in “normal operation” the producer has to assume the consumer does exactly what the spec requires, and not more.

Yossi.

From: Spector, Artem [mailto:artem.spector@sap.com]
Sent: Sunday, March 27, 2005 4:58 PM
To: wsrp-interfaces@lists.oasis-open.org
Subject: RE: [wsrp-interfaces] Applet resources through WSRP

Assume the Producer doesn’t rewrite the content of the CSS and the Consumer gets the original content:

backimage{

background-image:url(images/bcg.gif);

}

The point is that this happens in the context of consumer serving the client request

http://consumer/portal/resources/my.css?wsrpUrl=http://producer/portal/applications/MyPortlet/css/my.css&requiresRewrite=true

This means that at time of parsing of the style sheet content the Consumer knows its absolute URL (wsrp-url parameter of the current request).

Knowing the absolute URL of the style sheet and having a URL relative to this style sheet, the consumer can transform images/bcg.gif to

http://producer/portal/applications/MyPortlet/css/images/bcg.gif

That’s what I mean saying “enough information”. Wrapping this result with the Consumer URL and requiresRewrite=false(or true) is relatively straightforward, so the Client will get

backimage{

background-image:url(/portal/resources/bcg.gif?wsrpUrl=http://producer/portal/applications/MyPortlet/css/images/bcg.gif &requiresRewrite=false);

}

An advantage of this approach is better performance (because the resource content is parsed only on the consumer side) and simplicity (because there’s no need to define producer-side wrapper).

I don’t think that this approach is “less compliant” to the v1.0 spec than producer-side resource wrapper.

Artem

From: Mike Caffyn [mailto:mike@netunitysoftware.com]
Sent: Thursday, March 24, 2005 8:36 PM
To: wsrp-interfaces@lists.oasis-open.org
Subject: Re: [wsrp-interfaces] Applet resources through WSRP

I see how the consumer would rewrite the url in the portlet markup

and then the stylesheet itself contains

backimage {

background-image:url(wsrp-rewrite?wsrp-url=http://producer/portal/applications/MyPortlet/images/bcg.gif&requiresRewrite=false);

}

but not if the stylesheet contains

backimage {

background-image:url(wsrp-rewrite?wsrp-url=images/bcg.gif&requiresRewrite=false);

}

This is the bit I don't get "The consumer has has enough information to convert relative URL images/bcg.gif"

This part I do not see as being part of the WSRP spec and consumers required to process relative to absolute urls.

If the producer has a wrapper for resource css stylesheet that takes the

backimage{

background-image:url(images/bcg.gif);

}

and converts it to

backimage {

background-image:url(wsrp-rewrite?wsrp-url=http://producer/portal/applications/MyPortlet/images/bcg.gif&requiresRewrite=false);

}

before it is sent back to the consumer then everything works fine.

Mike

----- Original Message -----

From: Spector, Artem

To: wsrp-interfaces@lists.oasis-open.org

Sent: Thursday, March 24, 2005 11:11 AM

Subject: RE: [wsrp-interfaces] Applet resources through WSRP

Please note that in my example the wsrp-url is absolute (step 4), though the Portlet code operates with relative URLs.

As for the relative urls contained in other resources, they can be rewritten by the Consumers without any assistance from the Producers.

I’ve tried to show that when the Consumer processes the request

GET  http://consumer/portal/resources/my.css?wsrpUrl=http://producer/portal/applications/MyPortlet/css/my.css&requiresRewrite=true

and parses the input stream, it has enough information to convert relative URL images/bcg.gif into something like

“/portal/resources/bcg.gif?wsrpUrl=http://producer/portal/applications/MyPortlet/images/bcg.gif&requiresRewrite=false”

Doesn’t the spec require the Consumers to respect the wsrp-requiresRewrite flag?

Artem

From: Mike Caffyn [mailto:mike@netunitysoftware.com]
Sent: Thursday, March 24, 2005 5:08 PM
To: wsrp-interfaces@lists.oasis-open.org
Subject: Re: [wsrp-interfaces] Applet resources through WSRP

Currently the spec says wsrp-url for a resource must be an absolute address, so I would guess not many consumers would support this relative address as you specify. I have also noticed not many consumers support rewriting of resources that are referenced in another resource. For example an CSS stylesheet that contains another CSS stylesheet reference.

Currently the producers would have to be involved in the generating the urls for images within the markup and in the resource processing of a css stylesheet (unless they contained absolute addresses, this would be a nightmare in deployment). All they would be doing is replacing the relative address with an absolute address so it is wsrp specific when required ie not running in local mode.

Mike

----- Original Message -----

From: Spector, Artem

To: wsrp-interfaces@lists.oasis-open.org

Sent: Thursday, March 24, 2005 9:15 AM

Subject: RE: [wsrp-interfaces] Applet resources through WSRP

Let’s look into the flow for a simple example, when a Portlet MyPortlet was deployed with a style sheet (relative path “css/my.css”) which contains a URL of a background image “images/bcg.gif”.

The Portlet begins with the local path and outputs to the response stream the string: “css/my.css”.

The response wrapper constructs a relative URL which contains the servlet path (based on the request). The result looks like this: “/portal/applications/MyPortlet/css/my.css”

Now we have two different scenarios: local portal and WSRP.

Local Portal scenario:

The page content includes the URL as it was created on step 2: “/portal/applications/MyPortlet/css/my.css”

Note that the image URL inside the css is still “images/bcg.gif”.

Now for these two resources the browser issues the following requests:

GET      http://producer/portal/applications/MyPortlet/css/my.css

GET      http://producer/portal/applications/MyPortlet/images/bcg.gif

Everything is OK in this case.

WSRP scenario:

Here we have some additional steps before the content gets to the browser:

The Producer response wrapper converts the URL to absolute (based on the request) and the result is: “http://producer/portal/applications/MyPortlet/css/my.css”

The Producer embeds the absolute URL into the resource template (or the Consumer rewrites the URL): “/portal/resources/my.css?producerUrl=http://producer/portal/applications/MyPortlet/css/my.css&rewriteUrl=true”

When the page is downloaded to the browser, it issues the following request:
GET            http://consumer/portal/resources/my.css?producerUrl=http://producer/portal/applications/MyPortlet/css/my.css&rewriteUrl=true

Now the Consumer must parse the content of the resource being downloaded and rewrite the URLs.

Obviously the result of rewriting of “images/bcg.gif” should be:

“/portal/resources/bcg.gif?producerUrl=http://producer/portal/applications/MyPortlet/images/bcg.gif&rewriteUrl=false”

But the Consumer cannot compose it because it doesn’t know the producer-side servlet path (highlighted).

On the second thought the Consumer can compose the result URL using the producer servlet path taken from the current request, assuming the inside URLs are relative. This could work! I’ll try it out…

Artem

From: Rich Thompson [mailto:richt2@us.ibm.com]
Sent: Wednesday, March 23, 2005 9:29 PM
To: wsrp-interfaces@lists.oasis-open.org
Subject: Re: [wsrp-interfaces] Applet resources through WSRP

If people don't mind, lets walk into this carefully (I am certainly not an expert on how portals manage urls).

Consider, for the local portlet case, how the eventual urls gets constructed:
1. The Portlet begins with a local/relative URL; example: relative path to a CSS file
2. The Portal adds to the URL items such as host and context path to form an absolute url
3. The loaded resource contains a local/relative URL; example: a style specifies a background gif
4. The xxx forms the absolute url.

If xxx in step #4 is the browser, I would think it would use the baseURL of the page and therefore construct an absolute url which failed to point at the gif. If instead it uses the url of the css file, I would suspect the relative reference to work (including working with WSRP).

if xxx in step #4 is the Portal, I would think it already has a facility for preprocessing resources that could be leveraged to generate WSRP type urls using either Consumer url rewriting or Producer template processing.

Rich

"Spector, Artem" <artem.spector@sap.com>

03/23/05 11:31 AM

To

<wsrp-interfaces@lists.oasis-open.org>

cc

Subject

RE: [Fwd: Re: [wsrp-interfaces] Applet resources through WSRP]

Yes, the “entire user experience” was our purpose. From that point of view the URL string of some resource should be the same whether this URL “originates” from a Portlet code or from a resource text.

Usually building of Portlet-originated URL takes 3 steps:
1. The Portlet begins with a local/relative URL
2. The Producer adds to the URL the servlet path (including host and context path)
3. The Consumer wraps the producer-side URL with its own servlet path (using templates or consumer-side rewriting).

Now let’s consider a resource file containing some local URL. If the Producer just indicates wsrp-requiresRewrite, then the Consumer has to deal with this local URL directly. Returning to the 3-step example, the step 2 is missing.

Honestly I don’t see how the Consumer-side parsing/rewriting of resource content can be implemented without any Producer assistance.

Artem

From: Rich Thompson [mailto:richt2@us.ibm.com]
Sent: Wednesday, March 23, 2005 5:28 PM
To: Subbu Allamaraju
Subject: Re: [wsrp-interfaces] Applet resources through WSRP

I agree with the issues you raise. However, if the Producer is doing the url production, it must do it in a manner that will work for the entire user experience ... including resources. The idea would be to point out these issues to implementers and provide some guidance on how they could be addressed. One of the options could be to use templates for url production in the markup and then mark resource as needing Consumer url rewriting, but Artem points out that other options exist if the Producer is willing to manage things properly.

Rich

Subbu Allamaraju <subbu@bea.com>

03/23/05 10:17 AM

To

wsrp-interfaces@lists.oasis-open.org

cc

Subject

Re: [wsrp-interfaces] Applet resources through WSRP

I agree with that. I'm referring to your comment "the Producer must also
use the templates on the relevant urls within the resource". Such a
requirement, if placed, would assume that the Producer has control over
resource serving, and that it has the templates handy. Both of these may
not be true in most cases.

Subbu

Rich Thompson wrote:
>
> Section 10.2.1.1.3.2 of WSRP v1 lays the burden on the Consumer to parse
> and rewrite urls for resources that set wsrp-requiresRewrite to true.
> Discussion of this requirement within the TC limited the burden to
> string parsing with a replacement of matching substrings. As such, all
> textual types, including CSS, should be parsed. It is likely best if the
> Consumer is agnostic to the resource's mimetype other than a
> determination of what, if any, of the rewritten url needs to be escaped
> in order for it to be valid within the containing document.
>
> Rich
>
>
> *Subbu Allamaraju <subbu@bea.com>*
>
> 03/23/05 09:58 AM
>
>
> To
> wsrp-interfaces@lists.oasis-open.org
> cc
>
> Subject
> Re: [wsrp-interfaces] Applet resources through WSRP
>
>
>
>
>
>
>
>
> Rich Thompson wrote:
> >
> > It sounds like you are mixing two issues here:
> >
> > 1. You have validated that applet use has the same issues as any
> > other url, but not a large set of new issues. As a special note;
> > resource urls require full name preservation, whether it be a .gif
> > or a .jar.
> > 2. When Producers use templates for url production and referenced
> > resources also contain urls, the Producer must also use the
>
> Can you confirm if the spec requires Producers to rewrite resources it
> is serving over HTTP? AFAIR, this is only a requirement on Consumers
> when the MIME type of the resource is text/xml-like. I think the
> requirement on Producers has implications that we've not discussed in
> detail.
>
> > templates on the relevant urls within the resource. This will
> > become easier with the new getResource operation (important pieces
> > of data are passed on the invocation), but can be also done by
> > providing a resolver and passing any required info on the url (or
> > in cookies, though I would prefer to not explicitly name that
> > option). Note: this includes namespace resolving as well as url
> > rewriting.
> >
> >
> > Rereading your post, is there also an issue with not all Consumers
> > rewriting urls within resources (as per the specs requirements)?
> >
> > I think a couple of additions to the FAQ and Primer from this
> > information might be in order.
> >
> > Rich
> >
> >
> > *"Spector, Artem" <artem.spector@sap.com>*
> >
> > 03/23/05 05:03 AM
> >
> >
> > To
> > <wsrp-interfaces@lists.oasis-open.org>
> > cc
> >
> > Subject
> > RE: [wsrp-interfaces] Applet resources through WSRP
> >
> >
> >
> >
> >
> >
> >
> >
> > Yes, we’ve found a solution (we work together with Avi) and I’d like to
> > share it with you.
> >
> > Actually there are two challenges when composing consumer-side URLs for
> > producer-side resources:
> > 1. In some cases the resource name must be preserved in the
> > consumer-side URL (like .jar for applets)
> > 2. Nested resources – if a css contains URLs, they must be
> > rewritten as well.
> >
> > The solution includes the following aspects:
> > 1. The Consumer modifies the URLs so that they will end up with
> > the resource names.
> > 2. The Portlets use a standard API to output resource URLs. In
> > WSRP scenario these calls are intercepted by the Producer, which does
> > the necessary conversions (for example, URL writing using templates).
> > 3. If the URL references a resource containing other URLs (like
> > css or js), the producer replaces the resource URL with a URL pointing
> > to a special producer-side servlet. This servlet acts as a filter when
> > downloading the resource, and rewrites all the URLs it contains.
> >
> > For illustration imagine a Portlet called *ExamplePortlet* which was
> > deployed with image resource */images/r1.gif*. Its consumer-side URL
> > will look like this:
> >
> _http://consumer.com/portal/consumer/resources/r1.gif?producerUrl=http://producer.com/portlets/ExamplePortlet/images/r1.gif_
>
> >
> >
> > If the Portlet has a style sheet resource */css/r2.css*, its URL will
> > look like this:
> >
> _http://consumer.com/portal/consumer/resources/r2.css?producerUrl=http://producer.com/producer/resources/r2.css?resourceUrl=http://producer.com/portlets/ExamplePortlet/css/r2.css_
>
> >
> >
> > Now if r2.css contains a reference to r1.gif, then the producer-side
> > servlet (producer/resources) will invoke the Producer URL writing logic
> > for this URL. So eventually the image URL returned to the client within
> > the style sheet will exactly as in the first example.
> >
> > Regards,
> > Artem
> >
> >
> >
> > ------------------------------------------------------------------------
> >
> > *From:* Rich Thompson [mailto:richt2@us.ibm.com] *
> > Sent:* Tuesday, March 22, 2005 9:58 PM*
> > To:* wsrp-interfaces@lists.oasis-open.org*
> > Subject:* Re: [wsrp-interfaces] Applet resources through WSRP
> >
> >
> > I have been asked this question now by several people ... has anyone
> > tried referencing an applet in markup from a WSRP portlet? If so, any
> > guidelines that should be shared with portlet developers?
> >
> > Rich
> >
> > *Subbu Allamaraju <subbu@bea.com>*
> >
> > 01/26/05 08:07 AM
> >
> >
> > To
> > wsrp-interfaces@lists.oasis-open.org
> > cc
> >
> > Subject
> > Re: [wsrp-interfaces] Apptel resources through WSRP
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > Is the Producer returning the Content-Type header? I've not tried applet
> > downloading, but if Content-Type does not work, I would try the
> > Content-Disposition header, e.g. with a "inline; filename=foo.jar"
> > value. In any case, the Consumer has to proxy these headers to the
> browser.
> >
> > Regards,
> >
> > Subbu
> >
> > Klein, Avi wrote:
> > > Hi,
> > >
> > >
> > >
> > > I wonder if someone has dealt with fetching of applet as resource.
> > >
> > >
> > >
> > > Whenever rewriting the URL of the applet, the browser fails to
> fetch it
> > > since it expects the URL to end with *.jar and not with the
> consumer URL
> > > (result of the rewriting).
> > >
> > >
> > >
> > >
> > >
> > > Thanks,
> > >
> > >
> > >
> > > Avi.
> > >
> >
>
>

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