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Donnerstag Mrz 25, 2010

Roolastic - Part Four

Part One

Part Two

Part Three

Since the last part I've added Spring security to Roolastic (it's not really used yet) but it helped me understand a bit more about Roo. So while it is still early days, I'd like to come up with some general notes and opinions on Roo and ElasticSearch.

Notes

Database

I've chosen to use H2 as it comes with a handy little web console. If you start that (as I do here) you can then point your browser to http://localhost:8082/and have a look at and modify what's in your db - neat!

IDE

I've been using STS and it's nice enough even though a bit lacking in the responsiveness department. If you use 'plain' Eclipse make sure you have a least m2eclipse installed (and you probably want to have the AspectJ plugin as well). Also if you use any of those - do yourself a favor and rightclick on the 'target' folder in Navigator view and check the Derived box in Properties to prevent files in target from popping up when you do an 'Open Resource...'

Serialization

I've been using Jackson to serialise my entities to JSON which I then feed into ElasticSearch and I really like it. What's a bit annoying is that Jackson serialises some fields named 'ajc$interField$...' which AspectJ is responsible for and which are not needed really. The only way to turn that off that I found was to specify every single of these fields in the @JsonIgnoreProperties annotation which is a bit painful - some pattern matching would be helpful here

Opinion

Spring Roo

What I like

  • You must love the speed with which you can setup a fully functional webapp and start toying with your ideas. And once you accept the AspectJ stuff it is actually all fairly transparent
  • The scaffolding is cool. I think it was one of the most envied feature of Ruby on Rails in the Java community. While I think it isn't really that important in a project in the long run (because you will deviate from the generated stuff) it is really useful at the beginning of a new project.
  • I really like the whole 'shell/console' idea. It comes natural (to me at least) and feels very lightweight
  • I know that Maven had to take quite a lot of criticism recently, but I like it and I like the fact that it standardises the project layout and so I'm quite happy that Roo makes use of Maven as well (even though there is talk of switching to ivy)
  • I'm also very happy with Tiles being used in the view layer. I think it's quite a clean and clever way to keep your views mean and lean

What I'm not sure about

  • My main gripe is with JSP actually. I never really got into JSPs and have always preferred Velocity and Freemarker - so getting Freemarker as an alternative view technology would be perfection. I'm also at odds with the way javascript is woven into the scaffolded views. The fact that the script tags get sprinkled all across the file rather than in one place in some sort of document.ready listener is not to my liking (even though I can imagine the generation would get more complicated that way)
  • I also have the feeling that the aspectJ weaving adds a couple of seconds to the app startup time (having embedded database, JMS and ElasticSearch doesn't help there either) and a couple of seconds for every restart quickly add up over a days work - but I guess that's the price you pay (and it can serve as an excuse to get a new MacBook)

Overall Roo is growing on me quickly and I think it will become a permanent part of my toolbox. It gives you part of that RAD feeling that Rails and Grails are all about while letting you stay in beloved Java land and also feeling more transparent (to me at least - I was frightened by Grails' stacktraces)

ElasticSearch

While I haven't spent as many words on ES as on Roo, I really think ES rocks! Even though it's such a new project, it already feels really very useful. The flexibility it gives you is great, the effortless clustering is a boon and the JSON driven interface makes it easy to intergrate with almost anything (modern) you care to think of. The fact that you don't need to define a schema really makes it so easy to get started with (unlike Solr - which I never the less also really like). And it's getting new features almost on a daily basis. I will keep an eye on it and hopefully find the time to advance my little project over the coming months while blogging about my findings. (I especially need to research the facetting capabilities)

Posted at 05:06PM Mrz 25, 2010 by joerg in Allgemein  | 

Roolastic - Part Three

Part One

Part Two

Part Four

Now that we have our little webapp running and we can add images to it and they get indexed, we need a way to query the index.
So we quickly create a SearchController by running 

controller class --class ~.web.SearchController
then we add a little search form to the index view, create a new view for the results (don't forget to adapt the tiles config in views.xml) and implement the controller logic for stuffing the result in our model like here.
I've done a couple of things here:
  1. I put a JSON expression into the search field to give you a head start
  2. I implemented two different controller methods linked to the two different search buttons. One just stuffs the json coming back from elasticsearch into the model and one deserialises the returned results back into entity instances and stuffs those into the model
That is all still very primitive but it is sufficient I think to get started and experiment with ElasticSearch's possibilities. You should be aware though, that I currently shave off all search metadata from the results and just return the results source in the order they come back from ElasticSearch.

Posted at 01:35PM Mrz 25, 2010 by joerg in Allgemein  |