Thursday Oct 25, 2012

Centered Content using panelGridLayout

A classic layout conundrum,  which I think pretty much every ADF developer may have faced at some time or other, is that of truly centered (centred) layout. Typically this requirement comes up in relation to say displaying a login type screen or similar.

Superficially the  problem seems easy, but as my buddy Eduardo explained when discussing this subject a couple of years ago it's actually a little more complex than you might have thought. If fact, even the "solution" provided in that posting is not perfect and suffers from a several issues (not Eduardo's fault, just limitations of panelStretch!)

  1. The top, bottom, end and start facets all need something in them
  2. The percentages you apply to the topHeight, startWidth etc. are calculated as part of the whole width.  This means that you have to guestimate the correct percentage based on your typical screen size and the sizing of the centered content. So, at best, you will in fact only get approximate centering, and the more you tune that centering for a particular browser size the more it will fail if the user resizes.
  3. You can't attach styles to the panelStretchLayout facets so to provide things like background color or fixed sizing you need to embed another container that you can apply styles to, typically a panelgroupLayout


For reference here's the code to print a simple 100px x 100px red centered square  using the panelStretchLayout solution, approximately tuned to a 1980 x 1080 maximized browser (IDs omitted for brevity):

<af:panelStretchLayout startWidth="45%" endWidth="45%" 
                       topHeight="45%"  bottomHeight="45%" >
  <f:facet name="center">
    <af:panelGroupLayout inlineStyle="height:100px;width:100px;background-color:red;" 
  <f:facet name="top">
    <af:spacer height="1" width="1"/>
  <f:facet name="bottom">
    <af:spacer height="1" width="1"/>
  <f:facet name="start">
    <af:spacer height="1" width="1"/>
  <f:facet name="end">
    <af:spacer height="1" width="1"/>

And so to panelGridLayout 

So here's the  good news, panelGridLayout makes this really easy and it works without the caveats above.  The key point is that percentages used in the grid definition are evaluated after the fixed sizes are taken into account, so rather than having to guestimate what percentage will "more, or less", center the content you can just say "allocate half of what's left" to the flexible content and you're done.

Here's the same example using panelGridLayout:

  <af:gridRow height="50%"/>
  <af:gridRow height="100px">
    <af:gridCell width="50%" />
    <af:gridCell width="100px" halign="stretch" valign="stretch" 
      <af:spacer width="1" height="1"/>
    <af:gridCell width="50%" />
  <af:gridRow height="50%"/>

 So you can see that the amount of markup is somewhat smaller (as is, I should mention, the generated DOM structure in the browser), mainly because we don't need to introduce artificial components to ensure that facets are actually observed in the final result.  But the key thing here is that the centering is no longer approximate and it will work as expected as the user resizes the browser screen.  By far this is a more satisfactory solution and although it's only a simple example, it will hopefully open your eyes to the potential of panelGridLayout as your number one, go-to layout container.

Just a reminder though, right now, panelGridLayout is only available in and above.

Thursday Oct 18, 2012

ADF Logging In Deployed Apps

Harking back to my series on using the ADF logger and the related  ADF Insider Video, I've had a couple of queries this week about using the logger from Enterprise Manager (EM). I've alluded in those previous materials to how EM can be used but it's evident that folks need a little help.  So in this article, I'll quickly look at how you can switch logging on from the EM console for an application and how you can view the output. 

Before we start I'm assuming that you have EM up and running, in my case I have a small test install of Fusion Middleware Patchset 5 with an ADF application deployed to a managed server.

Step 1 - Select your Application

In the EM navigator select the app you're interested in:

At this point you can actually bring up the context ( right mouse click) menu to jump to the logging, but let's do it another way. 

Step 2 - Open the Application Deployment Menu

At the top of the screen, underneath the application name, you'll find a drop down menu which will take you to the options to view log messages and configure logging, thus:

Step 3 - Set your Logging Levels 

Just like the log configuration within JDeveloper, we can set up transient or permanent (not recommended!) loggers here.

In this case I've filtered the class list down to just oracle.demo, and set the log level to config. You can now go away and do stuff in the app to generate log entries.

Step 4 - View the Output 

Again from the Application Deployment menu we can jump to the log viewer screen and, as I have here, start to filter down the logging output to the stuff you're interested in. 

In this case I've filtered by module name. You'll notice here that you can again look at related log messages.

Importantly, you'll also see the name of the log file that holds this message, so it you'd rather analyse the log in more detail offline, through the ODL log analyser in JDeveloper, then you can see which log to download.

Friday Oct 05, 2012

ADF - Now with Robots!

I mentioned this briefly in a tweet the other day, just before the full rush of OOW really kicked off, so I though it was worth re-visiting. Check out this video, and then read on:

So why so interesting? Well - you probably guessed from the title, ADF is involved. Indeed this is as about as far from the traditional ADF data entry application as you can get. Instead of a database at the back-end there's basically a robot. That's right, this remarkable tape drive is controlled through an ADF using all your usual friends of ADF Faces, Controller and Binding (but no ADFBC for obvious reasons). ADF is used both on the touch screen you see on the front of the device in the video, and also for the remote management console which provides a visual representation of the slots and drives. The latter uses ADF's Active Data Framework to provide a real-time view of what's going on the rack.

SL150 GUI Screen Shot.

What's even more interesting (for the techno-geeks) is the fact that all of this is running out of flash storage on a ridiculously small form factor with tiny processor - I probably shouldn't reveal the actual specs but take my word for it, don't complain about the capabilities of your laptop ever again!

This is a project that I've been personally involved in and I'm pumped to see such a good result and,  I have to say, those hardware guys are great to work with (and have way better toys on their desks than we do).

More info in the SL150 (should you feel the urge to own one) is here


Hawaii, Yes! Duncan has been around Oracle technology way too long but occasionally has interesting things to say. He works in the Development Tools Division at Oracle, but you guessed that right? In his spare time he contributes to the Hudson CI Server Project at Eclipse
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