import scala.xml._
import java.io._
import java.net.{URLEncoder, URL}
 
def getCoords(query:String, countryCode:String):(String, Double, Double) = {
  val geonames = XML.loadString(readUrl(
    "http://ws.geonames.org/search?featureClass=P&q=" + URLEncoder.encode(query) +
            (if (countryCode != null) ("&country=" + countryCode) )))
 
  if ((geonames \ "geoname").size  > 0) {
    var firstGeoname = (geonames \ "geoname").first
 
    ((firstGeoname \ "name").first.text + " (" +
          (firstGeoname \ "countryCode").first.text + ")",
     (firstGeoname \ "lat").first.text.toDouble,
     (firstGeoname \ "lng").first.text.toDouble)
  } else {
    null
  }
}
 
def readUrl(url:String) = {
  val in = new BufferedReader(new InputStreamReader(new URL(url).openStream(), "utf-8"))
  val response = new StringBuilder
  var inputLine:String = null
  do {
    inputLine = in.readLine
    if (inputLine != null) response.append(inputLine)
  } while (inputLine != null)
  in.close
 
  response.toString
}

Calling getCoords(“Neuchatel”, “CH”) returns a triple (Neuchâtel (CH),46.99179,6.931).

Just improving the python script which I had been using for few years for backing up Picasa albums would not be an option, because this new tool would need a UI. The user needs first to have an overview over the albums and the disk space they consume, and then decide which one to archive.

So I decided to make a tool which would help me with it. On Saturday evening I started to code and have fun with the good old Swing, and finished it late on Sunday. And then the tool helped me to remove tens of thousands of non-starred photos which I didn’t want to have on my laptop (after backing them up) and free precious gigabytes just in few minutes.

Here it is: Picback. If you are an extensive Picasa user and photographer, I hope it can be useful for you too.

But there are few problems which I experienced:

1. The most frustrating is in fact described in the Hibernate docs. An object returned by session.load() isn’t necessarily an object of the expected class:

   Cat cat = (Cat) session.load(Cat.class, id);  // instantiate a proxy (does not hit the db)
   if (cat.isDomesticCat()) {                  // hit the db to initialize the proxy
       DomesticCat dc = (DomesticCat) cat;       // Error!
       ....
   }

2. No inheritance mapping for value objects: here is the JIRA issue that never gets fixed, and a workaround.
3. The strong suggestion in the Hibernate documentation to use a join table for every unidirectional one-to-many association (in the section 2.2.5.3.2.2. “Unidirectional”). Another suggestion is discussed here.
4. 2nd level caching should be used with caution: after deleting an object the stale version can still stay in cache which can lead to an ObjectNotFoundException. I found no other solution except disabling the 2nd level cache for the class.

The most impressive part of the talk was when Armin demonstrated the “online” debugging feature on a standard error page generated by Werkzeug. Upon each error the context in which it happens is stored on the server (only if the app is in the debug mode). Thus on the error page itself you can directly interact with the Python interpreter which is “frozen” in the very state in which the error happened. So you can use the full power of the interactive Python interpreter directly on the standard error page. That’s awesome.