Friday, 26 September 2014

APEX 5 imminent?

It seems the release of APEX 5 is due within hours - just in time for OOW weekend.

To quote Anton here
Apex 5.0 is going to be released in a couple of hours
It's a long weekend here in Perth, and I have a footy grand final to watch - but no doubt I'll be installing it somewhere soon!

All that being said, is still on 4.2.5, so don't hold your breath for too long.

Stay tuned...

Monday, 22 September 2014

Leisure Suit Larry Ellison

Larry Ellison 1978
So at 70 years of age, the man who's been heading Oracle since before I was born is stepping down.

While I admit I'm far removed from the reality of the situation, I find it a little amusing how it's been deemed as a 'shake up' when a few paragraphs before he's quoted as saying this (referring to new co-CEOs)
“I am going to continue to do what I have been doing the past several years and they are going to continue doing what they have been doing the past several years,” 

So I bet he's probably going to be working in the same office, just the title under his name on the door will read "CTO". So for us at the coal face, surely this means he will spend more time directing the nature of the beast and leave operations to those who specialise. That sounds to me like a good thing.

I enjoyed this New York Times article, but writer Quentin Hardy made me read one of the last paragraphs a few times
Mr. Ellison does not leave his company entirely untroubled. Besides continuing challenges in cloud computing, including acquisitions and new competition, the company faces a raft of new types of databases, first developed inside Google and Yahoo, that also threaten the dominance of the relational database.

I've been thinking recently what the next generation of databases will be like. The relational model was revolutionary at the time, but bigger data and intelligent networking will surely one day reach another punctuated equilibrium. No doubt it will come from somewhere like contemporary giant Google.

If I was a passionate billionare I think I would have left the business behind long ago, along with the suit.
Circa 1993 - no eyebrows then either

Monday, 8 September 2014

Using Post-Authentication to run process after APEX login

A frequent requirement, and hence frequent question on the forums is
How do I run procedure x after the user has logged in?
This is often required for such tasks as determining user access, such as populating a restricted Application Item relating to a role like F_IS_ADMIN based on the username defined in substitition string APP_USER

Those new to APEX and unfamiliar with certain concepts may consider using an Application Computation, firing "On New Instance (new session)"
Application Computation Frequency

It sounds fair enough, and I remember doing the same thing when I was first learning APEX. The documentation on understanding page computations states
The computation point On New Instance executes the computation when a new session (or instance) is generated
This still isn't clear, but this actually fires when you first navigate to a page in your application - any page. This means when you first open a page like /apex/f?p=100:1, which may redirect you to the login page - the 'on new instance' event has already fired since APEX needed to provide you with a new session to render the home/login page.

In other words, these events can be generally described in the following order:
  • Open home page
    1. On New Instance (new session) - APP_USER is 'nobody'
    2. Redirect to login page
  • User enters username/password and submits
    1. Pre-Authentication 
    2. Validate credentials - APP_USER now set
    3. Post-Authentication
    4. Redirect to relevant page

I think I've only used 'On New Instance' once or twice, possibly to prime content of application items - but I use 'Post-Authentication' all the time to calculate values based on the user who just logged in.

Post-Authentication is defined in the Authentication Scheme, and expects the name of a stored procedure.
Shared Components -> Authentication Scheme
This stored procedure can be defined within the Authentication Scheme -> Source -> PL/SQL code as an anonymous block:
PROCEDURE post_authentication IS
  -- do stuff here


For better performance and code management you should place it within a PL/SQL package. That way it doesn't need to be interpreted dynamically every time a user logs in.

The Post-Authentication Procedure Name attribute just needs the name of the stored procedure, no semi-colon.

The PL/SQL may run something like:
I understand changes are coming in APEX 5 regarding when these events fire as you navigate between applications that share authentication.

This also reminds me of a little experiment I wrote ages ago to determine the order of page/application events.