On 01/30/09 09:59, glassfish_at_javadesktop.org wrote:
> I guess I'm confused.
>
> Why aren't you simply letting GF serve the images for you? i.e. why are you streaming at all? Are the images not part of your application?
>
> How is mod_jk et al relevant to this issue?
>
> Glassfish has "alternate doc roots" which will let you "mount" directories within your web app.
>
> Let's take a simple example.
>
> Let's say that you want to have a directory in your Webapp for external images.
>
> We'll place that directory at /ext_images.
>
> So, http://example.com/yourapp/ext_images/picture.png would be the URL for an image.
>
> On your disk, you will create the directory "/var/altdocroot/ext_images" and simply copy your image files in to that directory.
>
> Then, you would add the following to your sun-web.xml:
>
> [code]
> <property name="alternatedocroot_1" value="from=/ext_images/* dir=/var/altdocroot">
> <description>External Image mapping</description>
> </property>
> [/code]
>
> Trust me on this, this is the most aggravating bit of configuration, but it does work.
>
> Let me explain.
>
> First, "alternatedocroot_1" is a key word for the property that GF looks for. If you want more mappings, just use _2, _3, etc.
>
> Value is the point, WITHIN YOUR WEB APP that you want to "mount" the external directory.
>
> Dir is the "root" of that external directory.
>
> And here's the nut.
>
> What folks think is happening is that the web app directory "/ext_images" (in this case) is the same as "/var/altdocroot". And that's not the case, and it's not obvious either.
>
> Rather, "/var/altdocroot" is exactly that -- a DOC ROOT. When GF get a URL for /ext_images, it will prepend the alternate docroot, /var/altdocroot, to the URL. Thus /ext_images becomes /var/altdocroot/ext_images.
>
> So, for our example of http://example.com/yourapp/ext_images/picture.png, that in fact gets mapped to "/var/altdocroot/ext_images/picture.png".
>
> When first playing with this everyone (everyone!) gets it wrong right out the gate, and it can be tricky to debug.
>
Thanks for your great response to the user, Will!
I've also blogged about this common "misconception", see
http://blogs.sun.com/jluehe/entry/alternate_docroots_and_local_resource
Hopefully, the blog entry and your response on the forum will help clear any
misunderstandings.
Jan
> So, hopefully this will explain how to set it up and how it works so that you can use it first time.
>
> Once you've mounted this external directory using the alternatedocroot, then GF will simply serve those files up for you just like any other static resource. It's a great facility to let you separate your WAR application from a large amount of static data that you don't want to have to constantly recopy and redeploy.
> [Message sent by forum member 'whartung' (whartung)]
>
> http://forums.java.net/jive/thread.jspa?messageID=329272
>
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