Avrom’s Java EE and Oracle ADF Blog

This is an (obviously) late post in a series of posts about ODTUG Kaleidoscope 2009. Monday was the least busy day for me at Kaleidoscope–I only attended two presentations, “That’s Rich! Putting a smile on ADF Faces,” by Lucas Jellema, and “Fusion Design Fundamentals,” by Duncan Mills. But it was perhaps the most thought-provoking of my days there. In fact, I have a full three posts worth of stuff to say about just these two talks. Today, I’m going to talk about a dramatic contrast: the two talks, among other things, represented opposite ends of a debate I consider quite important: the advisability, or lack thereof, of using ADF Faces RC client-side components.

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So, I submitted a presentation, “The Rich Get Richer: Ultimate RIA with Oracle ADF Faces RC Client-Side Objects” to Oracle OpenWorld 2009, in San Francisco this October. The presentation is about performing tasks that usually require a partial round-trip, such as cascading dropdowns, conditionally visible content, etc., with no server round-trip at all. I talk a bit about this, on a very theoretical level, here (in the section, “Consider a Javascript-Only Solution,”) but I plan to go into considerably more detail, giving practical examples and advice, in the presentation.

The presentation did not make the cut of abstracts selected by Oracle. But if you want to see it at OOW, there’s still a chance! Just vote for the presentation on Oracle Mix (you’ll need to create an Oracle Mix account if you don’t already have one, but it’s free and a good way to meet people in the ADF community).

See you at ODTUG and/or OOW!

I’m back from the wilds of December, and to my regular schedule. I had intended to talk about view links this week, but I realized there were two important things about tuning view objects that I forgot to discuss in Part 1 or Part 2: View link consistency and in-memory filtering.

View Link Consistency

Like association consistency, view link consistency affects whether new rows appear in the query collections for accessors (view link accessors this time, rather than association accessors). But it does something more: It affects how new entity rows appear in the query collections of view objects.

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Continuing on from the last post, we’re looking at ways to tune ADF view objects for optimal performance and resource management.

Forward-Only Mode

In most applications, the user needs to be able to scroll through data both forwards and backwards–to return to a previous row in addition to simply being able to scroll forward, or to find rows an earlier view row after finding a later one. Because of this, by default, once rows from a view object’s query result are read into the view cache, they stay there. If your JDBC fetch size is 18, then initially, only 18 rows will be in the view cache, but when request rows outside the first 18, that number goes up to 36, then 54, then 72, and so on.

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Now that we’ve looked at tuning entity objects and associations, we’ll turn to talking about tuning your ADF view objects for good performance and memory management. There’s a lot to say about tuning view objects (more than for any other business component, in my opinion), so I’m going to break this topic up over two posts. This week, we’ll discover the reasons for and against basing read-only view objects on entity objects, learn how to control how much data is fetched into the middle tier at one time (and how to optimize this for your particular case), and talk about what passivation of view objects is and how to control whether and how much of it happens. Next week, we’ll talk about query-level range paging, forward-only mode, and the spill-to-disk feature for handling very large caches.

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