Article about using hibernate with GWT

I just read this article about the Google Web Toolkit and hibernate, and I’m thrilled that someone wrote this. A few years ago, when I was just starting to use GWT and hibernate, the ORM tool, I thought about writing something similar myself. I could never get over the hump of writing about setting up all the infrastructure necessary, something which the author does quite nicely.

I think this article gives a great overview of some of the complexities of using hibernate with the GWT client. The author essentially talks about three possible solutions to the primary problem when using hibernate objects in a GWT system: hibernate enhances your POJO code, and thus you cannot send objects returned from hibernate queries down the wire to the JavaScript client.  The JRE emulation simply can’t handle it.

I especially enjoyed the explanations of how to use some of the tools, to make mapping between GWT capable objects and hibernate objects easier. I’d heard of hibernate4gwt, now Gilead, but never used it. For most of my RPC calls, I end up using the first approach the author explores, custom DTO creation. Often times, I won’t create a special DTO object, but rather reuse the POJO that represents the domain object. This way, you can scrub subsidiary objects (though you lose lazy loading when you do this) and send those down as well.  As long as the POJO doesn’t have too many extraneous members, this seems to work fine, and removes the need for an extra class.

I was a bit frustrated, however, that the author ignored the delete case. This seems like a situation where tools like Gilead might really shine. I have often run into issues where I have to add a ‘deleted’ boolean flag to the hibernate object.  I do this because when an object gets deleted from a collection on the GWT side, my server-side code has no way of knowing this, without some additional complexity (rerunning the query and doing a comparison of results). Adding such a ‘deleted’ boolean flag, solves one set of problems, but raises additional complexity, because you end up having to check to see whether or not an object exists before you try to insert it in the database.

For example, imagine you have a user with set of CDs, which you display in a grid.  If you want to allow a user to correct the name of one of the CDs, and send it back, the server side has the modified record, hopefully with and ID, and can simply save it.  But if you delete one of the CDs from the collection, the server side does not have the modified object, and so has to figure out which one to delete.  Gilead, with its knowledge of the object graph, seems at first glance like it could solve this problem elegantly (a quick search on the Gilead site shows nothing that I could see).

Also note that, using RPC is fantastic for GWT applications, but if you think about using GWT for widgets, I would suggest using something that gives you a bit more flexibility like JSONP. Because GWT RPC depends on XMLHTTPRequest, it is fundamentally limited to sites where the JavaScript and RPC services are on the same host.  Obviously, since using JSONP serializes hibernate objects to strings, none of these tools are appropriate.  (See my survey of Google Web Toolkit client-server communication strategies for more.)

All that said, if you’re thinking about using hibernate and GWT in the same project, reading this paper and running through the examples will be a worthwhile use of your time.

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Useful Tools: piwik, a worthy web statistics package

I recently installed a open source web analytics tool called piwik.  (You can demo it at that site.) I found out about it via the sourceforge.net mailing list. It was the featured project for July 2009. It bills itself as an alternative to Google Analytics (GA) (actually, right now, the home page states “Piwik aims to be an open source alternative to Google Analytics.”) and I can see why it does so. The architecture is similar, JavaScript executing on every page and sending data to a server; the interface is similar as well, with lots of whizzy Web 2.0, JavaScript heavy features and detailed data.

I had to see been using the Wusage installation that came with my web hosting service. piwik was quite a step up from that, with richer graphs, results and UI. Plus, because it was JavaScript executing and I was assured that every visit was actual visit by an actual person. Since it’s hosted on my server, I control all the data, which was a sticking point for me considering using Google Analytics.

I recently upgraded to 0.4.2, which broke the dashboard, but I’ve been assured a fix is in SVN (Update Aug 4: They no longer plan to fix the bug, but there is a workaround in that thread.).  If you want to get the latest code, go hereYou can download 0.4.1, the last working version I know of, here. I’ll update this to point to the piwik website when they have a release up that works. For some reason they don’t have a release archive that I could find.

So what’s good about piwik?  Well compared to what, Google analytics, or other website analytics tools? This is a fundamental question, because if you are using GA just for the web stats piece, or are using some other static logfile analysis tool, piwik is well worth reviewing.

In comparison to Google Analytics

The downside is

  • you have to maintain another server/database, etc.  I imagine that someone will offer piwik via SAAS sometime soon, though I couldn’t find anyone doing that right now.
  • it’s a beta product and is not as mature as Google Analytics, as evidenced by the 0.4.2 issue above
  • some key GA features are missing (goals, funnels, etc).

In comparison to the other website analytics tools I’ve used, AWstats (which I’ve written about before and is open source) and wusage (not open source, but free with my hosting contract), piwik has

  • a slick user interface
  • JavaScript execution, so you know you’re getting a real browser instead of a bot (the javascript browser guarantee)
  • click outs easier to track
  • easier configuration
  • javascript widgets available

The downside is:

This is obviously not intended to be a full, detailed analysis of all the differences between these tools, but I think that piwik has a lot of promise.  They have a roadmap full of planned features but they definitely aren’t yet an alternative to Google Analytics for anyone who uses some of the more advanced features of that product. Funnels, the click overlay or goals, are all unsupported in piwik as of this version. In the forums, I saw several requests for such richer analysis tools, and in the roadmap I saw a goal tracking plugin as a blocker for version 1.0, so the team is aware of the lack.

When browsing around doing research for this post, I saw a post (sorry, couldn’t find it again) about how piwik features would be developed for smaller websites because it’s an open-source alternative, but I believe that the support of openX (an ad server company that I wrote about in the past), who is funding at least one of the developers, will prevent such feature capture.  In addition, I find that open source projects that have an existing project to model themselves on (like GA), tend to try to reach feature parity.  If piwik continues on its current valid path of replicating Google Analytics features, then I think it will live up to its aim.

If you’re simply using Google Analytics to see who referred traffic to your sites, or for which keywords search engines are showing your site, and you want something more open or more control of your data, piwik is a good fit.  If you use any other web stats tool, and want a slicker admin interface or the javascript browser guarantee, piwik is also worth a look.

Update, 7/31: A friend pointed out this broad survey of the current state of free (as in beer) web analytics options

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Solix website launch

I was able to help launch a revamped website on Monday.  Solix Biofuels is an algal oil producer moving from R&D into production. I’m not really a biology person, but I did enjoy reading about their technology.  To my layperson’s eye, algal energy sources seem much more sustainable than crop fuel sources.

It’s been a while since I’ve been the prime mover behind a deployment–there’s always a bit of nail biting when you finally reveal work to the world–but this one was fairly smooth.

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