Logical to phycal data source mapping

Question

Hi,
I am new to OracleAS. Every other server I worked with has this and it seems like it's a big part of J2EE, but I can't seem to find anywhere how to do this in OracleAS.
I am trying to find a place to map my logical JNDI name that would be specified, say in web.xml in <resource-ref> tag to a physical JNDI name in the server.
Where is the place to tie these two?
Thanks,
Yaakov.

Answer 1

By default, the files are generated into the
j2ee/home/application-deployments/<app-name>/<module-n&gt;
&gt; > me>
directory of your OC4J instance.
They will be named along the lines of
orion-web.xml
orion-ejb-jar.xml
orion-application.xmlSo, you are saying that it takes the contents of
<resource-ref> from web.xml and BYITSELF maps it to
the physical JNDI name. Hmm... How would it know
WHICH JNDI name I want to map a particular logical
JNDI??? Sounds a bit strange to me.
For resource-ref entries, it doesn't do a default mapping. What is does is provide the XML tags that need to be filled in. You just need to specify the actual JNDI location as an attribute of one of the XML tags.
It will endeavour to lookup and find a physical resource of the same name if no explicit mapping is provided.
>>
You can also provide copies of these files withthe
settings you with to give to OC4J at deploymenttime
by placing the orion-*.xml file in the samedirectory
as it's corresponding J2EE standard deployment
descriptor file.Well, that's what I was asking... Where in these
files is the place to map the logical JNDI to the
physical. For <resource-ref> in web.xml, I assume the
place to do this would be in orion-web.xml. However,
I can't find any normal documentation where it would
tell me where to do this. In Weblogic, for example,
there is a clear way to map your logic JNDI names you
use in your web.xml to your physical JNDI names that
are stored on the server. The place to do this in the
web component is in weblogic.xml.
Lets get to an example:
If you put the following resource-ref in your web.xml file:
<resource-ref>
<description>Default DataSource</description>
<res-ref-name>jdbc/MyDefaultDS</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
then when the application gets deployed, the auto-generated deployment descriptor orion-web.xml contains the following line
<resource-ref-mapping name="jdbc/MyDefaultDS" />
If you want to map this to the physical datsource jdbc/ThePhysicalDS then you'd just need to add a location attribute to the tag as follows:
<resource-ref-mapping name="jdbc/MyDefaultDS"
location="jdbc/ThePhysicalDS" />
That will then complete the the mapping.
If you don't provide the location details, then OC4J will try and locate a physical datasource of the same name as the logical one that was supplied. If jdbc/MyDefaultDS exists as a physical datasource within the namespace of the application, it will use that.
I'd recommend that you just deploy the Web application, then go and look in the orion-web.xml that gets generated to see specifically what happens to your files.
One nice thing about OC4J is that you don't need to provide these files to do the initial deployment -- OC4J will detect what needs to be mapped and include thos elements within the files it generates. You just need to fill them in.
>>
I'd recommend having a quick flick through the
OC4J/J2EE documentation which is available on OTN--
the various developer guides and user's guidestouch
on this.I looked through all of it and it doesn't say a
thing. So, I was hoping the developers knew this.
The J2EE Services guide on OTN does cover this type of information.
A quick look at the index showed:
For JMS mappings -- http://download-west.oracle.com/docs/cd/B10464_02/web.904/b10326/jms.htm#1037919
For Datasource mappings --
http://download-west.oracle.com/docs/cd/B10464_02/web.904/b10326/datasrcs.htm#1005963
The EJB and Servlet Developer's Guides also have some coverage of this.
I have an example which does doing security logical role-name mapping on my blog, see http://radio.weblogs.com/0132383/stories/2004/04/23/usingFormBasedAuthentication.html
Also, we ARE talking about the regular Oracle AS, not
the standalone one, right? Because I read in the docs
that only the standalone one allows you to use
"expert mode" where you modify those xml files
yourself. The regular server wants you to use the
Enterprise Manager to do this. In any case, this is
supposed to be a J2EE server and there has got to be
a way to map logical names to physical.
It's basically the same model irrespective of which way you actually specify the mappings.
The final source of truth always comes from the same orion-*.xml file.
If you are using OracleAS installation with Enterprise Manager, you can directly edit the configuration files. You just need to be aware that you must inform the server that the files have been updated using the dcmctl command.
dcmctl -updateConfig In the EM console, we're working on making this more task oriented, so you can actually specify the physical mappings as you run through the deployment wizard. I'm sure the 904 release has some support for this today.
Hope someone can help me with this.
I hope this information I've provided here helps you with the questions you have.
-steve-