Category Archives: JavaRanch

Subversion, Subversion – what client shall I pick?

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Since I’m using Eclipse at home for development, it seemed logical to go with Subclipse or Subversive – two of the top three clients listed on the Subversion homepage.  I also tried TortoiseSVN the the other of the top three.  Below are my experiences with the three.  (I haven’t tried branching yet in any of them.)  All have had a release within the past month.  My comments for Subclipse and Subversive are largely from slightly earlier versions though.

Note: See If you tried Subversive before, it’s time to try it again for an update.

Subclipse 1.4.8 (released February 27, 2009)
Pros:

  • It seemed faster to checkout a large project with Subclipse than Subversive.  I can’t prove this as my internet connection varies, but I did notice this a few times.   Another person had the same observation though.
  • Has been around longer.

Cons:

  • No tag awareness!  When I want to commit a file, I need to think about copying the directory to the tags directory.  This is a mental jump as I’m really just thinking I want to create a version – not about how Subversion data is stored.  I also worry that it is too easy to accidentally create the version in the wrong place.  Why invite trouble?  The CVS Eclipse plugin just asked for the name of the tag.
  • Similarly, I have to think about where the tags are stored when comparing to a past version.
  • One common thing I do in Eclipse is awkward – I want to compare the contents of a file to tagged versions.  If I do “compare with revision” I see all the revision numbers and commit comments, but the tag column is blank.  If I do “compare with branch/tag”, I see all the tags, but can only select one to see the compare before starting the whole process again.  Also, you can only compare with branch/tag on a project level – which takes forever – at least over my internet connection.  As a clumsy workaround, we’ve been storing the tag name and revision number on our “release notes” wiki page.  This is an extra manual step that I feel should be unnecessary.  If the tool would just show the tag in the “compare with revision” view like Eclipse does, it would be perfect.
  • The proposal to become an Eclipse project has been withdrawn.

How long I used before switching
A few months.  It wasn’t until the project got into the tagging phase when the tag awareness feature became problematic.

Subversive 0.7.7 (release February 24, 2009)
Pros:

  • Can compare file with “working copy” (last checked out) without connecting to network
  • Since November 2007, has been an incubator project on eclipse.org.  This reset the version number which is why .7 is newer than 1.0/1.1 on polarion.org.

Cons:

  • Installing requires two parts.  The connectors are a separate install for licensing purposes.
  • As in Subclipse, I want to compare the contents of a file to tagged versions.  Using “compare with revision” is worse than in Subclipse.  it doesn’t attempt to show the tags.  More importantly, you must pick which revision you want to compare to, wait a while, view it and then repeat the entire process to pick another revision.  Not nearly as easy to use as the Eclipse version.  (If you think to open the SVN history view first, you get the Eclipse/Subclipse based view where you see them all at once.  It still takes forever though for large projects as it is seeing what else changed in that revision.  Turning off “deep copy” didn’t help matters.)  I didn’t try compare to with branch/tag because I didn’t see the option.

How long I used before switching
I started with Subversive.  After a few months a switched to Subclipse.  Then I switched back to Subversive where I have been since December.

I wasn’t thrilled with either of these so I then tried a standalone client. Tortoise SVN 1.5.9 (released February 27, 2009)
Pros:

  • Checking out one project wasn’t hard.
  • I like the GUI – very intuitive.
  • Committing was simple from Windows.
  • A very cool graphical release view for tags and branching.
  • I really like the log viewer letting you filter by date and or message.  It makes it easy to find out which version you want to compare with.

Cons:

  • It’s not in the IDE.  If not using an IDE, this isn’t a problem of course.
  • Windows only.
  • To tag a project, you need to be aware of the directory structure.  (See my comments about Subclipse for why this scares me.)  There is a graphical explorer to find the tags directory.

How long I used before switching
I just tried it for a few days.  I really wanted an Eclipse based plugin – was just looking to see if this was better.  If I wasn’t using Eclipse, this would be fine.

Conclusion

Both Subclipse and Subversion are usable Eclipse plugins for Subversion.  I prefer Subversive a bit and am going with that at home.  The main reason being tag awareness (I tend to deploy/tag on a weekday evening when I am tired and more likely to mess things up.)  I am keeping TortoiseSVN on my machine for the non-Java code checkins I need to do.  Note that you do have to pick one or the other.    You can’t point to both Tortoise and an Eclipse plugin for the same directory.  As a result, the last week of development on my home computer for Javaranch looked like:

  1. Sunday – Do a bit of Java development in JForum project using Eclipse.  Check out/commit using Subversive.
  2. Monday night – Generate the book promotion materials in PickWinners project by updating the build.properties and running an Ant build script.  (I don’t check these in on Monday since they are so easy to regenerate if something happens to my computer over the course of the week.)
  3. Wednesday night – Production deployment.  I wanted to get in some changes that would make sending private messages to the winners a two click operation.  (It took six clicks for each winner last time it was my turn.)  Tag JForum project using Subversive.
  4. Friday night – Pick winners for book promotion copying winners from web page into one of the files generated on Monday.  Commit using TortoiseSVN.  I like that I didn’t need to open Eclipse on Friday – picking winners is now a web page and the commit happened in Windows.

Many weeks I do less Subversion work at home.  It so happens last week was representative of the breadth of SVN operations I do.  I liked the split between Subversive for JForum (Java development) vs TortoiseSVN for PickWinners (Ant build and text files) and plan to continue that way. I’ll be interested to hear what my co-promotion coordinator uses to commit when it is his turn.  I’m not overly thrilled with either Subversion Eclipse plugin.  I’m thinking of pulling in the JForum project into another directory in Tortoise to use it for file comparison too!

This analysis isn’t so useful for recommending a tool in a corporate scenario where network connections are more reliable and projects are huge.  My suspicion is that Subclipse is better in that environment.  Especially if the majority of tagging operations are done through an automated build.

Why JDBC + JSP = Bad

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Over years of moderating at The JavaRanch, I’ve seen one type of question spring up on a weekly basis: that asked by people who need help with JDBC code inside of Java Server Pages (JSPs). As much as we may want to help this individual fix their particular problem, the overriding thought of “STOP WHAT YOU’RE DOING” often prevents us from doing so. The purpose of this post is to explain why putting JDBC code inside a JSP file is akin to shooting yourself in the foot. With a shotgun. While not wearing shoes.

Don't use JDBC inside of JSP pages

1. You cannot reuse the code
First and foremost is the issue of code reusability. While importing java classes is quite common, importing code from a JSP is not. While you can write JSP functions, although I never recommend doing so for reasons I won’t get into now, you’re basically writing code that you cannot be used anywhere else, particularly in non-JSP java classes. The most common counter response to this is “Well, I don’t need to use it anywhere else”. Yes, you do. Whether its just reusing code for making the connection to database or the code for performing a query and reading the results, it will be used again at some point in the future in a way you have not thought of yet. Unless you are being paid by the line and prefer this sort of thing, it’s a bad move, and I guarantee your code base will be much larger than someone who put all their JDBC code into normal Java classes. Larger code base means more difficulty to maintain and more headaches for you down the road.

2. You are mixing business logic with the presentation layer
Probably the most overlooked issue for inexperienced developers is the fact that you’re mixing the business/data layers with the presentation layer. I’ll put it another way, if your boss comes in one morning and says we’re throwing out the JSP front end and replacing it with a web service, Java Swing, Flash, or some other interface, there is virtually no way for you to reuse the database code without going through every line of every JSP file by hand. If the database code had been placed in plain java files, then you would have a path for packaging the JDBC code into a single JAR and making it available as a service to a different front-end client such as a web service, Flash, etc.

In enterprise development, the presentation JSP layer and the database are often separated by multiple layers of indirection such as described by the commonly used three-tier architecture pattern. Those who are just starting out programming often do not know why mixing these layers is bad, but I promise you if you stay with software development you’ll understand one day.

3. But it’s just this once!
Often times, JDBC code enters JSPs by developer lying to themselves saying “Well, it’s just this once” or “I just need to test something”. Instead of being removed when the developer is done ‘testing’, the code often persists for a long time afterward. Furthermore, putting your JDBC code inside of reusable Java classes makes testing go faster! Spending 10 minutes setting up a single reusable Java JDBC class will save you hours down the road. Then, if you want to test more than one JSP page with JDBC logic, you already have your Java class file to start with. Proponents of test-driven development tend to understand this better than anyone.

4. It’s really hard to maintain
Code maintenance is another topic that new developers do not fully appreciate since they have not spent years maintaining the same code base. Unless you write the most beautiful JDBC code imaginable, its very difficult to read through huge JSP files looking for bugs and/or making enhancements. It’s a lot easier if all the JDBC access is restricted to a set of files much smaller in size than the JSP code base.

5. It’s a really bad practice
If after reading this article you still do not fully understand why you should not put JDBC code inside of JSPs, let me simplify the issue by saying “Just Don’t Do It”. Whether or not developers understand the reasons against doing so is not as important as stopping them from doing so in the first place. In short, you create code someone else (possibly yourself) will have the misfortune of maintaining down the road.

javaranch’s forum migration – want to know more?

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The JavaRanch Journal about the forum migration is out.

Since I was involved in the details of the project, I wrote quite a bit.  It contains:

  • My overview of why we did it, what technologies we used, the timeline and process
  • Pauline’s interview with Ulf, Ernest, Bear, Amit and myself
  • My article on the data migration including analysis.
  • A cute interview where Ernest talks in elvish along with a cute extended analogy he wrote comparing the forum migration to a physical farm move.
  • A Lucene article from the Lucene in Action authors.  (JForum uses Lucene making it relevant to the migration.)