Monday May 07, 2012

Looking Through the Telescope From the Big End: Four Small Java Developments that Pack a Punch!

There are a LOT of exciting developments in Java, almost on a daily basis. Most of them make a big splash, and for good reason! But sometimes, it's the little things...

There have been a lot of small developments in Java that are pretty exciting, too. I'll pick out four of my favorites - each at a different level and/or stage of development or detail - and explain why they're a big deal. Let's get started!

Home automation

I had the privilege of watching Vinicius and Yara Senger give a presentation at Jfokus (available below at Parleys.com) on Java EE and home automation. The Sengers developed the jHome platform and run it on GlassFish, controlling Arduino-based appliances in their home, office, and boat. I won't give away all the spoilers, and it isn't Java end-to-end...but the Sengers are demonstrating a compelling, fully open source (hardware and software!) package for Java working in harmony with even the tiniest of devices.

Robotics

FIRST, or "For Inspiration and Recognition of Science and Technology", was founded by world-renowned inventor Dean Kamen. In his words:

"Our mission is to inspire young people to be science and technology leaders, by engaging them in exciting mentor-based programs that build science, engineering and technology skills, that inspire innovation, and that foster well-rounded life capabilities including self-confidence, communication, and leadership."

FIRST's vehicle for doing this is robotics. Teams of various ages use available technology components and their brains to develop and program robots to compete in some pretty tricky challenges. This isn't Robot Wars (no Real Steel destructive matches here), but it's just as engaging - for the teams and spectators alike.

The 2012 FIRST International Championship was held in St. Louis, MO, USA, and teams representing several countries participated. I was able to attend for awhile - with an event like this, you just can't see it all! - and chanced upon a team in the pit area with a homemade sign saying "We use JAVA!". I was directed to the 15 year-old programmer who proudly informed me that they use NetBeans and Java to program their robot. We had a nice conversation, and I was left with the realization that Java's original "embedded" mission is still being realized in ways that we don't often think about.

Raspberry Pi

Simon Ritter recently posted about his work with the Raspberry Pi and JavaFX 2. I had seen others relate their victories getting OpenJDK onto the little Pi, a small-but-capable computer the size of a deck of cards...but Simon (and those who provided assists in whatever form) took the bar and threw it up onto the roof. It won't win any supercomputer awards (well, not alone anyway!), but the Raspberry Pi's small size and low price now make a host of formerly-unrealistic uses possible. Even before much optimization is done, JavaFX 2 is already running. If you've ever migrated existing software (of any kind) to a new platform, you know that that first "clean" run can be elusive. I can't wait to see how far we can take this...just as I can't wait for my pre-ordered Pi to hurry up and get here!

Harmonization of Java ME, SE

Henrik Stahl was on the Java Spotlight podcast recently (link below) presenting a clear vision for the harmonization of Java Micro Edition (ME) and Standard Edition (SE). The devil is in the details, of course, but here's the good news:

1) There is a plan
2) The plan makes sense
3) The plan is being worked...diligently!

Without getting into those details or the challenges surrounding them (API synchronization, Jigsaw, etc.), a modern, consistent set of APIs and a modular architecture should excite Java developers wherever they may fall along the spectrum.

The Bottom Line

It's an exciting time to work with Java at any level, and that includes in the crevices where small and/or embedded devices often lie hidden from view. If you haven't already been involved in "Java in the small", check it out. And if you have a favorite I've missed, drop me a line or comment below! If you like it, chances are the rest of us will, too.  :-)

All the best,
Mark



free counters


Sunday Apr 29, 2012

Performance Test: DriverManager vs. DataSource

I was troubleshooting some well-traveled Java code the other day and hit an intriguing set of circumstances. The original developer(s) of this code -- a web application using JSP/servlets -- had written a data wrapper construct using DriverManager. After several upgrades of JDK and JVM, some minor cracks were starting to show.

We tried doing a direct transplant of DataSource-based code into the wrapper mechanism, effectively a one-for-one swap of the minimum number of lines of code without any real refactoring. Yes, I know...not a good idea for the long-term. But one has to start somewhere.  :-)

Interestingly, performance tanked. When things like that happen, it's time to get curious and dig deeper.

Why DataSource?

The DataSource approach to data connectivity brings numerous benefits with it (connection pooling, distributed transactions, etc.), but does it also carry a hefty performance penalty? I had never heard that it did. Either way, it's always good to do a little first-person testing to verify/refute findings. So off we go!

Testing Methodology

I put together a pretty simple test and ran it several times to factor out normal variations in environmental conditions. Using NetBeans, I created a plain-vanilla web application, sans frameworks. Next, I asked NetBeans to generate JPA entities from some tables in our database, and then an EJB (see this recent article for a refresher on connecting a basic EJB to underlying data via a DataSource) to provide the DataSource-based baseline. I then created an EJB that used DriverManager to build a connection and SQL statements for comparison.

Oh, and one last necessity: I created a couple methods to capture start/stop times using System.currentTimeMillis() for a timekeeper. That covered all the essentials.

And the Winner Is...

Well, there really wasn't a runaway winner strictly from a performance perspective. Results varied from run to run, but these two horses were neck and neck, often trading the lead by only a few milliseconds in consecutive runs...which is great news, considering that DataSource offers so much more and yet manages to retain the expected level of performance.

The bad news? Well, it's clear I have a lot of rework to do on this old code.

Sigh.  :-)

For more fun with Java, click here to follow Mark on Twitter.

Thursday Apr 19, 2012

Basic Bean Building: How to Quickly Create a JSF Managed "Look-up" Bean

If you're called upon to build a JSF application (large or small), NetBeans is a great tool to help you gain traction, and fast. I've mentioned previously how much I like the ability to do a quick first cut by creating your data structures and using NetBeans to generate a basic web app as a starting point. You go from nothing to working web application in short order, albeit a bit bare-bones. Still, what a great time-saver!

Let me toss out a few reminders and disclaimers. First, I'm a firm believer in rapid, iterative, and thoughtful development. No "paralysis of analysis" allowed, but OTOH, each step should be considered carefully as you go. Plan, execute, evaluate. Lather, rinse, repeat.  :-)

Second, build from small to large. Plan ahead, but make things work on a small scale and build out. This goes hand-in-hand with point #1, but it bears mentioning separately.

With those points in mind, I created a small sample project for use in this and future discussions: The Mighty Bean Coffee Company. Java is a wonderful thing in almost any form, so why not double our pleasure?

For the first iteration of our new project, I created an initial set of tables in a new MySQL database. These are the ones we'll be considering on our quest to create a JSF managed "look-up" bean:

Next, I created a new Java Web project, Web Application in NetBeans called MightyBeansWeb. Defaults were fine for our purposes here with the exception of selecting JavaServer Faces under Frameworks.

With the project created, I right-moused on MightyBeansWeb in the tree browser, chose "New Entity Classes from Database", and made the connections to the data source. Selecting the two tables modeled above, NetBeans provided us a couple of nicely-formed entity classes: Customer.java and CoffeeOrder.java.

Creating the JSF pages was also a snap. Right-moused again on the app, chose "New JSF Pages from Entity Classes", selected the classes and specified destination packages, and clicked finish. Et voila! We now have a working JSF web app. Go ahead, try it out. I'll be right here when you get back.  :-)

(Side note: Please feel free to a) update the toString() methods for more meaningful contents - this will come in very handy later! - and b) to refer to our recent article NetBeans, JSF, and MySQL Primary Keys using AUTO_INCREMENT to enable primary key auto-generation within MySQL.)

"That's great!" you say. But wouldn't it be nice to see which customer we've selected for our order? That brings us to the topic of this article. Let's whip up a look-up bean and make that happen now.

Right-mouse once more on the web app and choose "New JSF Managed Bean". Pick a name (I called this one "CustomerLookupBean") and a package and click finish. No need to do anything else on that panel since we're using Java EE 6.

Opening the class, we see it has annotations for @ManagedBean and @RequestScoped which serve our needs nicely. We just need to add a couple of very small things to wrap up our bean-work.

Since EJBs are non-reentrant, we can simply inject an instance of EntityManager into our lookup bean by adding the following lines to the class definition:
    @PersistenceContext(unitName = "MightyBeansWebPU")
    EntityManager em;
Clicking on the warnings in the left column prompts you to let NetBeans fix the imports. Yes, please!

Next and finally, we need to create a method to return the desired customer, something along the order of this:


This method issues a named Customer query using the ID provided and returns a single result. Since createNamedQuery returns a generic object, we cast it to what we know is coming back to us (a Customer object), then return the customer's full name. Not pretty, but good enough for a first cut.

Editing the appropriate list.xhtml file to display the customer's name instead of number is as simple as replacing <h:outputText value="#{item.customer}"/> with <h:outputText value="#{customerLookupBean.getName(item.customer.id)}"/> to query and receive the full customer name, taking us from this:

To this:

"Pretty" comes later, but this is a start. Any thoughts, comments, or questions? Please drop me an email or comment below!

All the best,
Mark

Wednesday Apr 11, 2012

How to Plug a Small Hole in NetBeans JSF (Join Table) Code Generation

I was asked recently to provide an assist with designing and building a small-but-vital application that had at its heart some basic CRUD (Create, Read, Update, & Delete) functionality, built upon an Oracle database, to be accessible from various locations. Working from the stated requirements, I fleshed out the basic application and database designs and, once validated, set out to complete the first iteration for review.

Using SQL Developer, I created the requisite tables, indices, and sequences for our first run. One of the tables was a many-to-many join table with three fields: one a primary key for that table, the other two being primary keys for the other tables, represented as foreign keys in the join table. Here is a simplified example of the trio of tables:


Once the database was in decent shape, I fired up NetBeans to let it have first shot at the code. NetBeans does a great job of generating a mountain of essential code, saving developers what must be millions of hours of effort each year by building a basic foundation with a few clicks and keystrokes. Lest you think it (or any tool) can do everything for you, however, occasionally something tosses a paper clip into the delicate machinery and makes you open things up to fix them. Join tables apparently qualify.  :-)

In the case above, the entity class generated for the join table (New Entity Classes from Database) included an embedded object consisting solely of the two foreign key fields as attributes, in addition to an object referencing each one of the "component" tables. The Create page generated (New JSF Pages from Entity Classes) worked well to a point, but when trying to save, we were greeted with an error: Transaction aborted. Hmm.

A quick debugger session later and I'd identified the issue: when trying to persist the new join-table object, the embedded "foreign-keys-only" object still had null values for its two (required value) attributes...even though the embedded table objects had populated key attributes. Here's the simple fix:

In the join-table controller class, find the public String create() method. It will look something like this:

    public String create() {
        try {
            getFacade().create(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("JoinEntityCreated"));
            return prepareCreate();
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
            return null;
        }
    }

To restore balance to the force, modify the create() method as follows (changes in red):

    public String create() {

        try {
            // Add the next two lines to resolve:
            current.getJoinEntityPK().setTbl1id(current.getTbl1().getId().toBigInteger());
            current.getJoinEntityPK().setTbl2id(current.getTbl2().getId().toBigInteger());
            getFacade().create(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("JoinEntityCreated"));
            return prepareCreate();
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
            return null;
        }
    }

I'll be refactoring this code shortly, but for now, it works. Iteration one is complete and being reviewed, and we've met the milestone. Here's to happy endings (and customers)!

All the best,
Mark

Wednesday Apr 04, 2012

Extreme Portability: OpenJDK 7 and GlassFish 3.1.1 on Power Mac G5!

Occasionally you hear someone grumble about platform support for some portion or combination of the Java product "stack". As you're about to see, this really is not as much of a problem as you might think.

Our friend John Yeary was able to pull off a pretty slick feat with his vintage Power Mac G5. In his words:

Using a build script sent to me by Kurt Miller, build recommendations from Kelly O'Hair, and the great work of the BSD Port team... I created a new build of OpenJDK 7 for my PPC based system using the Zero VM.

The results are fantastic. I can run GlassFish 3.1.1 along with all my enterprise applications.

I recently had the opportunity to pick up an old G5 for little money and passed on it. What would I do with it? At the time, I didn't think it would be more than a space-consuming novelty. Turns out...I could have had some fun and a useful piece of hardware at the same time. Maybe it's time to go bargain-hunting again.

For more information about repurposing classic Apple hardware and learning a few JDK-related tricks in the process, visit John's site for the full article, available here.

All the best,
Mark

About

The Java Jungle addresses topics from mobile to enterprise Java, tech news to techniques, and anything even remotely related. The goal is to help us all do our work better with Java, however we use it.

Your Java Jungle guide is Mark Heckler, an Oracle Java/Middleware/Core Engineer with development experience in numerous environments. Mark's current work pursuits and passions all revolve around Java and leave little time to blog or tweet - but somehow, he finds time to do both anyway.

Mark lives with his very understanding wife, three kids, and dog in the St. Louis, MO area.



Stay Connected

Search

Archives
« April 2014
SunMonTueWedThuFriSat
  
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
   
       
Today