Code Generation with JDeveloper
I've written about Jack Herrington's Code Generation in Action before; it is a great book for stimulating your thinking on how you go about producing code.
JDeveloper has evolved into one of the strongest IDEs when it comes to code generation. It's not explicitly mentioned in the book however. That's not a criticism of the book, but it does beg a review of how JDeveloper stacks up against the concepts covered.
Integrating code generation into your IDE
Writing a code generator can be difficult-but convincing your fellow engineers to use [it] can be even more difficult. The key .. is to make it as simple as possible to use.IDE integration is one approach to address this problem, and the common techniques supported are external tool invocation and filtering.
JDeveloper only directly supports external tool invocation (see the Tools menu). For instance, you can call simple Ruby scripts like the following to perform file-level processing (this example simply comments each line of the file that is currently open in the editor pane).
fh = File.open( ARGV[0] )
text = fh.read()
fh.close
text.gsub!( /^/, "// " )
File.open( ARGV[0], "w" ).write( text )
 |  |
NB: in the 11.1 preview, it seems the "Availability" conditions are still a little broken and it is not possible to make commands available only when a file (or certain type of file) is open.
Filters are not directly supported by JDeveloper, however implementing a filter is a fairly straight-forward project using the JDeveloper Extension API.
JDeveloper Extension API
Herrington does not directly address the topic of IDE APIs, which is understandable given the scope of his book. However if you are looking to implement complex and very specific code generation approaches you will probably want to look into this topic further.
JDeveloper comes with a comprehensive Java-based extension API which was significantly revamped in (I think) 10.1.3 to bring it into line with the standardisation efforts of JSR-198.
I must say documentation of the extension development process is a little thin. And it is only in 11.1 that JDeveloper has explicit project support for extension development (although I find it a little broken and mysterious in the preview edition). The best approach at present seems to be good ol' copy-and-modify the extensive set of samples provided by Oracle at the Extensions Exchange. There is a growing number of 3rd party open source extensions that are even available through the JDeveloper Check for updates menu.
Still, no filter add-in is available, and you are of course stuck with developing in Java. It of course puts me in mind of a little project: a simple filter add-in that then allows you to invoke a filter process developed in the language of your choice such as perl, ruby or python. Maybe I'll be able to follow-up this post with an example;-) PS: yes I did; you can read about it here.
JDeveloper's Generation Credentials
I've been hedging around the fact that JDeveloper is very significantly geared towards code generation itself. It is one of the main drawcards for why you would use it over your favourite text editor.
In the back cover of the book, Herrington includes a very illustrative Generator Tree which provides a taxonomy of generators, with of course references back to what is covered in the book. I thought I'd experiement with mapping JDeveloper into the taxonomy. I doubt if I'll manage to cover all of JDeveloper's features (or get it all right), but here goes:
| Class | Platform | Technology | Herrington | JDeveloper |
| Database Access | MS | ASP | ASP Generator | n/a |
| ASP.NET | ASP.NET Generator | n/a | ||
| Java | EJB | EJB Generator | EJB Entities from Tables | |
| JDBC | JDBC Generator | ADF Business Components | ||
| JDBC | n/a | Toplink O-R Mapping | ||
| PHP | PHP | PHP Generator | n/a | |
| Perl | DBI | Perl DBI Generator | n/a | |
| User Interface | Java | JSP | JSP Generator | JSP/struts/JSF wizards |
| Swing | Swing Generator | Swing wizards; ADF Swing wizards | ||
| MS | MFC | MFC Generator | n/a | |
| Documentation | SQL | SQL | SQL Documentation Generator | n/a |
| Java | Java | JavaDoc | JavaDoc | |
| Unit Tests | C | Tests | Augmented C Unit Test Generator | n/a |
| Ordered Tests | Ordered Test Generator | n/a | ||
| Test Data | n/a | Test data generator | n/a | |
| Test Robots | n/a | Test robot generator | n/a | |
| File Formats | Java | CSV | CSV file Reading Java Generator | File Adapter |
| Java | Data Adapter | Data Adapter Generator | (arguably) File Adapter; Toplink | |
| Java | Binary | Binary File Reader Generator | n/a | |
| Web Services | Java | XML-RPC | XML-RPC Generator | n/a? |
| Java | SOAP | SOAP Generator | Java Web Service from WSDL | |
| PL/SQL | n/a | PL/SQL Web Service | ||
| JMS | n/a | JMS Web Service | ||
| Various | n/a | Technology Adapters | ||
| Business Logic | Java | Math | Equation Generator | n/a |
| Java | Reports | Report Logic and Interface Generator | n/a | |
| External Libraries* | C++ | DLL | DLL Wrapper Generator | n/a |
| Scripting Languages | C++ | External Language Wrapper Generator | n/a | |
| Configuration* | Firewall | any | Firewall Configuration Generator | n/a |
| Reference Data* | any | Lookup Function Generator | n/a | |
| any | Macro Lookup Table Generator | n/a |
*I've reclassified these items from the original table in the book.
NB: I generated the table above using an OpenOffice Calc spreadsheet [generator-taxonomy.ods]. Good example of dog-fooding perhaps;-) I've always found Excel/Calc to be really useful tools for rapidly generating scripts, SQL or HTML fragments like this.
With so much capability in JDeveloper, you might expect instant adoption. But there are of course two classic issues still to be addressed:
- There's quite a steep learning curve until you get comfortable with what features are available, and when they are appropriate to use. The rapid enhancement of JDeveloper and all the technology over the past few years means that your average dev shop probably doesn't have the luxury of many gurus who can coach the team either
- It seems to be an inherent trait of developers (arguably a good one), that generators and wizards are not fully trusted and accepted until you've had the chance to dig down under the covers. That's simply a lot of work for all of JDeveloper's features, and there isn't a great deal of information available to help your short-cut the process.
Postscript:
- Shay Shmeltzer just posted a useful summary of How Do I Start Learning JDeveloper and ADF?
- Olaf Heimburger has started a new blog series demonstrating ADF In Action
- Eduardo Rodrigues has a great post on his favourite JDeveloper extensions with some good recommendations of what you should install or at least have a closer look at.
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2007 In Review
Picking up the idea to present "my blog-year in review", by taking just the first complete sentence each month's post (remembering not to make this the first post for Jan;-)
Hmm, very geek. What's not listed is the post that generated the swiftest, strongest reaction: Ballmer Peak and the Programmers' Paradox, which probably goes to show that frat humour is the surest way to internet fame;-)
During the year I also started blogging quick reviews of all the books I read over at PrataLife. So as a variation on the meme, here's my Book-Year In Review:
July | The Extraordinary Adventures of Arsène Lupin, Gentleman-Burglar (audiobook) |
| August | The Ambler Warning |
| September | A Different Point of View (audiobook) |
| October | The Warden (audiobook) |
| November | Code Generation In Action |
| December | Quarter Share (audiobook) |
The number of audiobooks is a bit misleading, as I'm sure I actually read at least as many on paper (although Neal Stephenson is slowing me down a bit at the moment!). And ye gads, only one tech book! But this is to be expected: with fiction its easy to read and do a quick blog entry, whereas technical non-fiction is generally not suited to blogging an instantaneous reaction. They'll tend to stay on my desk/shelf for a probationary period;-)
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Backup your WebCenter Wiki. Yikes!
Previously I wrote about installing Oracle WebCenter Wiki, and also had my 2c worth.
One of the surprises is that it uses file storage by default. Database storage seems to be a work-in-progress (Toplink, hibernate and HSQLDB are all involved somehow), but not a documented option at this point.
Now if you are going to run WebCenter Wiki for real, that means as a dilligent system admin you want to be pretty sure you really understand how the file storage is working so you can have good backup and recovery procedures in place.
The documentation on Backing Up and Restoring Wiki Content sounds straight-forward. Just make a backup of the OC4J_HOME/applications/application_name/owc_wiki/pages folder.
But BEWARE!
Gotcha #1: Don't Forget Your Toothbrush!
A little poking around, and it is clear that this is NOT all you need to backup. I've noted content modifications in at least the following locations also:
OC4J_HOME/applications/application_name/owc_wiki/attachments [any uploaded attachments]The jzwiki backup/restore instructions also tell you to backup WEB-INF/classes/yawikiDB.script (WebCenter wiki is based on jzwiki)
OC4J_HOME/applications/application_name/owc_wiki/templates [added/changed page templates]
So to be sure you haven't left anything behind, I'd suggest you probably want to be backing up the entire OC4J_HOME/applications/application_name/owc_wiki directory structure no matter what the doc says, and practice some restores!
Gotcha #2: Beware of EAR Re-deployments!
If you've worked with OracleAS/OC4J deployment before, and also noticed that the wiki content is stored in the application directory structure, I hope it rang an alarm!
Yes, if you touch or replace the owc_wiki.ear, then say goodbye to your wiki content and pray your backup is good and not too old! OC4J will redeploy the application and give you a nice fresh install, deleting all your wiki content and customisations;-)
I have always had a sneaking suspicion that there can be other circumstances in which OracleAS/OC4J may choose to redeploy an EAR. I can't really substantiate this, but I have had situations in production where EARs are redeployed for no immediately apparent reason.
This is of course very hairy for any non-trivial production deployment. The obvious first step would be to configure wiki content storage to some other location. This isn't documented however, and I'm not sure if its even possible with the product as it is.
So for now, it seems just backup or rsync deep and often, and enjoy the view as you walk the edge of the abyss;-)
WebCenter Wiki Future?
So far, there's no real news on what is planned for WebCenter Wiki in 11g. If you've read my posts, it will come as no surprise that my view is the 10g wiki is far from production-ready.
Which makes the question of what is in store for 11g so interesting. Maybe a significant revamp of the 10g (jzwiki) wiki? Maybe an internally developed replacement based on Content DB or UCM?
Or maybe something completely different? A collegue pointed me to Jive Clearspace today .. "discussions, blogs, files, instant messaging, and wiki documents under one unified umbrella" .. and since Oracle already have Jive Forums integrated in WebCenter it raises interesting possibilities!
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Talking Heads
For some reason, there's a common fixation on making computers take on a character and actually talk to us. Like another human. Or dog, seal or animated sponge....
Why? Can't think of any deeper reason than its just a bit of fun.
The state of the art is not quite Toy Story, but its certainly come a long way. I remember playing with (now defunct?) JavaHead a few years back: impressive demo, but it was hard work to get good results with your own images. You needed to be a techie/animator/audio engineer.
I've just been playing with PQ Talking Photo, and it's great to see not only a pretty good, synchronised animation but also a great, anyone-can-do-it UI. My little test is below, hopefully earning me a promo copy by blogging about it. Shameless!
Edit: pqdvd is defunct, the embed above no longer works.
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