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From Thorsten Scherler <scher...@gmail.com>
Subject Re: blockcontext protocol (part 2) (was Re: [jira] [Created] (COCOON3-107) ...)
Date Fri, 28 Sep 2012 12:29:24 GMT
On 09/28/2012 07:24 AM, Jos Snellings wrote:
> Dear all,
>
> Noticing that is very interesting discussion is getting silent, I'd 
> like to ask a question.
> First of all, pardon me my ignorance. (blonde, can't help it).
> So from just a high-level understanding, can I rephrase the problem?
> What we seek to accomplish is:
> * in a sitemap, being able to load resources from another sitemap,
>   according to the scheme:
>   <map:generate src="cocoon://{relative-url}"/>
> * within an xslt calling
>     <xsl:variable name="var" select="'cocoon://{relative-url}'" />
> * within controller logic:  redirect, or send the reference of a 
> ModelAndView

Well the cocoon:/ is/was never a java.net handler but resolved via 
avalon/excalibur. Further the c3 correspond  would be more servlet:/

>
> So now, in C3, we want to address resources cross-block to accomplish 
> modularity, right?
>
>     <map:generate src="{someBlock}://{relative-url}"/>

well yes and no. blockcontext:/ refers to static (resources) and not 
matches in the blockcontext sitemap. If you would want to call the block 
sitemap you would request servlet:${blockId}:/...

>
> This should be restricted to the instance of the cocoon servlet 
> itself, so it can peacefully coexist with another cocoon servlet in 
> the same JVM.

The blockcontext protocol once installed only will work for the first 
called servlet. With the change of Fran. we do what you describe but on 
a specific point in the app. BUT we never install the protocol which 
makes it unusable outside the java route where you can pass a URLHandler 
to the context.

> So you would like to avoid tweaking "URL" for the servlet without 
> interfering with the rest.
>
> - something less invasive than URL.setURLStreamHandlerFactory ?
> - mechanism that keeps track of wich cocoon servlet deployed wich blocks?
>
> Is that a correct way of stating it? Not even my 10 cents, just a 
> question.

If we want to keep using blockcontext protocol, the handler needs a 
central place where the different paths are resolved. However due to the 
nature of the problem we can have the same name for a block in 2 
different servlet but if we resolve the url in the connection we will 
have the problem deciding which path to return to the caller, since it 
can happen that the underlying request has no servlet context associated 
meaning it is impossible to determine which block to use.

Thanks for keeping the thread alive.

salu2

>
> Cheers,
> Jos
>
>
> On Wed, Sep 26, 2012 at 3:05 PM, Thorsten Scherler <scherler@gmail.com 
> <mailto:scherler@gmail.com>> wrote:
>
>     On 09/26/2012 10:10 AM, Francesco Chicchiriccò (JIRA) wrote:
>
>         Francesco Chicchiriccò created COCOON3-107:
>         ----------------------------------------------
>
>                       Summary: With latest cocoon-block-deployment and
>         cocoon-service-impl SNAPSHOTs, integration tests fail
>                           Key: COCOON3-107
>                           URL:
>         https://issues.apache.org/jira/browse/COCOON3-107
>                       Project: Cocoon 3
>                    Issue Type: Bug
>                    Components: cocoon-sample-webapp, cocoon-servlet,
>         cocoon-sitemap
>              Affects Versions: 3.0.0-beta-1
>                      Reporter: Francesco Chicchiriccò
>                      Priority: Critical
>                       Fix For: 3.0.0-beta-1
>
>
>         This is happening as a consequence of COCOON3-105.
>
>         Basically, since there is no more an installed
>         URLStreamHandlerFactory, every "new URL()" should include an
>         instance of BlockContextURLStreamHandler.
>
>         This makes every other URL loading (including XSLT sheets in a
>         separate block, like happening for cocoon-sample-webapp)
>         unaware of "blockcontext://" URLs.
>
>
>     Meaning we are back to square one.
>
>     Andreas Hartman is ATM in our office and we had a small chat about
>     the underlying problem.
>     We think that blockcontext cannot work as protocol as it is for now.
>
>     The above report shows that we need to use a
>     URLStreamHandlerFactory to be able to resolve this protocol.
>
>     {myblock2=file:/home/thorsten/src/apache/apache-tomcat-6.0.20/work/Catalina/localhost/mywebapp2-1.0-SNAPSHOT/blocks/myblock2/}
>
>     Now if we look on the above and how we defined it, we have:
>
>     in block-servlet-service.xml
>
>     <servlet:context mount-path="/${blockId}"
>     context-path="blockcontext:/${blockId}/"/>
>
>     will then produce the following blockcontext object:
>     ${blockId}=${tomcat.work}/${servlet_which uses the
>     block}/blocks/${blockId}/
>
>     Meaning that blockcontext:/ will be resolved to
>     "${tomcat.work}/${servlet_which uses the block}/blocks/"
>
>     There are various problematic parts:
>
>     As of the looks of it a block is treated as "servlet" mounted to a
>     context.  Problematic is that the mount-path in some cases needs
>     to become ="" to catch all incoming request, which means root context.
>     Blocks are treated as servlets meaning you can only mount once a
>     block (in a specific version of that block). If another block use
>     this blockId it is not possible to use the same mount point.
>     However that has the ultimate consequence that you need to manage
>     the name of your block manually or ideally the ${blockId} is
>     unique and contains the version of the block!
>     However blocks are more servlets within a servlet, since without a
>     servlet that has deps on them they would be not reachable.
>
>     This leads to to the "real" mount point "${servlet_which uses the
>     block}/{@mount-path_as defined in the block}" in the servlet
>     context and the path as above. For example "blockcontext:/test"
>     could refer to  "${tomcat.work}/${servlet1}/blocks/test" or
>     "${tomcat.work}/${servlet2}/blocks/test", depending from which
>     servlet the request is issued. Meaning the blockcontext protocol
>     does not resolve url (Uniform (or universal) resource locator)
>     since the resources it describes are not universal (due to the
>     fixed connection to the underlying servlet).
>
>     With all the above said the logical consequence is that the
>     pattern of blockcontext would need the ${servlet_which uses the
>     block} in it somewhere, but that would render the whole block
>     concept useless if used within the block. That however would force
>     a url rewritting on the fly where the ${servlet_which uses the
>     block} prefixed would be injected prior of resolving.
>
>     We tested to push the resolving logic into the handler but that
>     failed since some calls have no resolvable servlet context while
>     they issue the call. We succeed to inject the handler in the
>     servlet context but never declared an UrlFactory so xsl imports
>     e.g. are failing now since they do not know about our handler.
>
>     In the old days (2.1.x) we had our avalon/exaclibur source
>     resolver for creating custom protocols within a specific context -
>     with them above would not have been a prob.
>
>     Anyway, how can we refactor the blockcontext so we can deploy more
>     then one c3 webapp? Any ideas?
>
>     salu2
>
>     -- 
>     Thorsten Scherler <scherler.at.gmail.com
>     <http://scherler.at.gmail.com>>
>     codeBusters S.L. - web based systems
>     <consulting, training and solutions>
>
>     http://www.codebusters.es/
>
>
>
>
> -- 
> The doctrine of human equality reposes on this: that there is no man
> really clever who has not found that he is stupid.
>         -- Gilbert K. Chesterson
>
>


-- 
Thorsten Scherler <scherler.at.gmail.com>
codeBusters S.L. - web based systems
<consulting, training and solutions>

http://www.codebusters.es/


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