viernes, 26 de agosto de 2016

How to get ORE to work with APEX by Brendan Tierney

This blog post will bring you through the steps of how to get Oracle R Enterprise (ORE) to work with APEX.

The reason for this blog posts is that since ORE 1.4+ the security model has changed for how you access and run in-database user defined R scripts using the ORE SQL API functions.

I have a series of blog posts going out on using Oracle Text, Oracle R Enterprise and Oracle Data Mining. It was during one of these posts I wanted to show how easy it was to display an R chart using ORE in APEX. Up to now my APEX environment consisted of APEX 4 and ORE 1.3. Everything worked, nice and easy. But in my new APEX environment (APEX 5 and ORE 1.5), it didn't work. This is the calling of an in-database user defined R script using the SQL API functions didn't work. Here is the error message that is displayed.

NewImage

So something extra was needed with using ORE 1.5. The security model around the use of in-database user defined R scripts has changed. Extra functions are now available to allow you who can run these scripts. For example we have an ore.grant function where you can grant another user the privilege to run the script.

But the problem was, when I was in APEX, the application was defined on the same schema that the r script was created in (this was the RQUSER schema). When I connect to the RQUSER schema using ORE and SQL, I was able to see and run this R script (see my previous blog post for these details). But when I was in APEX I wasn't able to see the R script. For example, when using the SQL Workshop in APEX, I just couldn't see the R script.

NewImage
Something strange is going on. It turns out that the view definitions for the in-database ORE scripts are defined with
owner=SYS_CONTEXT('USERENV', 'SESSION_USER');
(Thanks to the Oracle ORE team and the Oracle APEX team for their help in working out what needed to be done)

This means when I'm connected to APEX, using my schema (RQUSER), I'm not able to see any of my ORE objects.

How do you overcome this problem ?
To fix this problem, I needed to grant the APEX_PUBLIC_USER access to my ORE script.
ore.grant(name = "prepare_tm_data_2", type = "rqscript", user = "APEX_PUBLIC_USER")
Now when I query the ALL_RQ_SCRIPTS view again, using the APEX SQL Workshop, I now get the following.

NewImage


Great. Now I can see the ORE script in my schema.

Now when I run my APEX application I now get graphic produced by R, running on my DB server, and delivered to my APEX application using SQL (via a BLOB object), displayed on my screen.

NewImage

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