Can OracleXE's APEX access another Oracle Database (10g) on the same Server, or is it Restricted to those Users/Tablespaces in the XE Database? - oracle

Question

My work uses Oracle 10G and is planning on installing Apex. In the meantime, I have downloaded Oracle XE and have taught myself APEX on it; however, I can only access users/tablespaces that I have made in the XE database. What I would like to do is use the XE's Apex to access the users/tablespaces in the production databases of my work.
My colleague says that this should be possible because my workstation is connected to the server, and that there should be a way to configure access from my XE's Apex to the 10g's databases, such as by setting up an appropriate DAD.
I see nothing in the Apex user interface to allow this. I've read every word of the Apex documentation but nothing registered.
XE uses the embedded PL/SQL gateway, as opposed to 10/11G which uses either an Apex Listener or an HTTP Server with the mod_plsql plugin.
Thank you,
Matthew Moisen

Answer 1

I have done this before where we didn't have access to the actual database hosting the data to be worked with save for the standard port 1521 listener access. Apex at the time was new enough to the organization that the DBA's also had a voodoo taboo on using their database server as a webserver gateway as well. You can use your database instance with APEX installed as a "middle tier" or app server with the following steps:
Set up an account on your 10g database that is accessible remotely via dblink.
Set up dblinks to your 10g database table on your workstation with XE installed, use the account and connection information for the 10g database as set up in (1). Note, you may have to update a TNS names file or explicitly indicate your host/networking settings within the dblink itself.
For simple sanity and simplicity in coding your apex projects, set up synonyms for all your dblinked objects (i.e., table1 for table1#dblink) so you're not referencing the dblinks directly in your apex code. Making changes later will be easier if you adhere to this.
That's it. One proviso is that you need to know that LOBs will not work with the out-of-the-box functionality of APEX driven DML operations while using dblinks. This may have changed with the newest version. One workaround you may consider is trying to use a stored procedure which passes your LOB data as a input parameter which will do your DML operation for you.
Otherwise, this approach works nicely. The place where I implemented this model has several production level apps, a test and a development tier all using servers hosting APEX separately from the actual data sources. We used Oracle Standard Edition One (for the support), but Oracle XE should work as well since APEX is the platform in common between either Oracle version.