I wanted to try out a persistence API for Cassandra. There’s a JPA implementation for Cassandra: Kundera, as well as JDO implementation, on top (or using) datanucleus: datanucleus-cassandra.

Just to clarify why I would want such a thing: nosql solutions such as Cassandra are, in essence distributed key-value stores. I know, from following a few classes on databases and distributed databases when attending the university that’s a whole lot more complicated to implement then it may seem.
Nevertheless, to do anything useful with that you need a layer on top of the key-value store. Basically all SQL databases like Oracle or MySQL have SQL layer around there key-value store. But the nice thing about stuff like Cassandra you can put something more convenient on top.

I wanted to try out both, starting with the JDO version, as that seemed more like a natural fit, and I once started ORM with JDO 1.0 many years ago.
I’d need a git client on Windows, and apparently there’s already a Tortoise Git client, based on the truly great TortoiseSVN, on of the tools I really miss on my Mac. The client version of git first had to be installed, but that was quite easy as well, just download and install msysgit.
The tortoisegit client looks very well, and seems easy to use. At least I got the code of datanucleus-cassandra in a breeze. Well now it’s kind of late, I’ll try out later.

Other stuff I want to try out: creating a Rest service using Restlet on Google AppEngine. Just to find out how that works. But later.

Finally I saw a demo on VMForce. Looks very promising, as I like Spring for development and that’s what you’d use. Nothing is released however, now there’s just articles and a demo.

Of course Oracle has something like SQLPlus, but that would mean SQLPlus has to be installed on the machine from where the package is installed. Another problem with SQLPlus is that it’s not so userfriendly.

Using JDBC and some programming I can easily create something that would check what current version of my application is installed, and then run the needed SQL scripts to upgrade the database. However, even easy things take some time and I’d think there are already some existing solutions.

I was about to ask a question on stackoverflow, but before I finished typing my question stackoverflow already came up with a similar question: Update a backend database on software update with Java. I’ll have to try out on of the suggested solutions, Liquibase, dbmigrate and maybe Autopatch.

There’s a lot of talk about the IPhone 4 supposedly having bad reception. Well, the Motorola Milestone has a problem too. When calling, I very often incidentally put the telephone to mute, which causes the other party not to hear me anymore. This is caused by the mute button in the middle of the touch screen. I often press is that area with my hear while calling, as I have the habit of putting my telephone to my ear… Well apparently few people in Motorola though of that.

The Motorola Milestone has a proximity sensor that supposed to turn of the screen while calling. However, for me, that doesn’t work. I searched for a solution on the Motorola forum. There a quite a few threads about this issue, like this, this one, this on long hair and this one saying it’s a hardware problem.
Many answers are infuriating rather than useful. Most of them have tips on how to properly hold the phone (in your right hand, below ear lob, under your hair). Arg, that’s not what I want to hear. Apart from the fact that doesn’t work, I don’t want a whole instruction who to hold my phone when I’m using a mobile phone for over 10 years.
Some idiots even say they have the problem, but still love the Droid.

At least some sort of official person who sorts of answers to the problem. People at Motorola are working on an update.  That’s not of much help. Finally, in this thread I found a more useful answer. There’s an application called Screen Suite, which allows you to lock the screen while calling. It only costs $1.99. Bought it already, I have the phone to long to get my money back. I just installed the application, Screen Suite seems to work.

Well bottom line, Apple isn’t the only one with a problematic telephone. And avoid the Motorola Droid and Milestone, at least when you also want to make phonecalls with your smartphone.

My company, Xebia, has started a master-apprentice program in the Netherlands. See Apprenticeship Program for more information.

What would like is integration with my electronic calendar of Google Calender (personal) and MS Exchange (work). That way, almost automatically available dates could be picked. Both Google Calendar as the latest version of Exchange can make there calender available via ical – so integration should be quite easy. When all people you want to make an appointment with have there calenders integrated as well with the appointment tool, an appointment could be created automatically – just like a secretary would do by calling other people’s secretaries.

Furthermore, besides entering emailaddresses, picking contacts from my address book from either google or MS Exchange would be more convenient.

I was thinking, such an application shouldn’t be hard to make. I wasn’t the only one with that idea. Recently someone suggested another website: Doodle. From what I can see, that website seems a whole lot better than there Dutch counterparts. Integration with Google Calendar and Contacts. Integration with Exchange and possibility to add ical calenders. Looks good, saves me from creating a startup .

German electric car, 1904, with the chauffeur on top

(Above picture from Wikipedia – of course electric cars aren’t actually new, just as the idea dependency injection or reversion of control existed long before spring)

Also, this allows for fine-grained security at database level: Virtual Private Database.

(c) Oracle

As described in the above image and referenced article, the user identified by userid 106 (let’s say that’s user john) will access the database using a private database connection. The user can only access rows that have that userid as primary or foreign key.  John can’t see the passwords, orders, credit card data or anything of other users even if he would somehow hack the webapplication. How to set up this finegrained securiy is beyond this article, but I hope the above example explains what the purpose VPD is.

If you develop your JEE software using Oracle software  proxy authentication requires only a bit of configuration, for example, see the following article how to setup proxy authentication using JHeadstart.

However, what if you’re JEE applicication consists of non-oracle software? Can you still use proxy authentication when you use software like JBoss, Hibernate, IBatis, MyFaces, Wicket etc? Yes you can! I’ll explain below how to set up proxy authentication using JBoss in such a way you don’t have to modify any of the code that uses JDBC, directly or indirectly.

• First a way is needed to set a username for each (JDBC) database connection retrieved. It-eye weblog explains how to open a connection to a database using java, and then switch to another username.
• Secondly, in your application users should authenticate them self using the default mechanism of J2EE 1.4 (and higher) application, using JAAS. Usually creating a security policy inside your web.xml or inside your ear is enough. Here’s the information how to do this under JBoss: Secure a webapplication.
  Since we’re using a database, the best option would be to use database based authentication, meaning user information comes out of a database table. There’s a lot of documentation on the web how to do add security, so I won’t repeat that here.
• Database connection in JBoss are retrieved using connection pooling, as is custom in any JEE server.  You can create a custom connection pool, that changes the switches to the user name that is currently logged in at the webapplication. That way, every action on the database is done under a database user that is currently logged in.Do to be able to do that, first, you’ll need a custom connection factory that extends the default connection factory. Our connection factory will return a customized datasource that modifies code.Here’s a code listing:

  package nl.gerbrandict.dbconnaudit;
  
  import java.sql.SQLException;
  import javax.resource.ResourceException;
  import javax.resource.spi.ConnectionManager;
  
  import org.apache.log4j.Logger;
  import org.apache.commons.lang.StringUtils;
  import org.jboss.resource.adapter.jdbc.local.LocalManagedConnectionFactory;
  
  /**
   * An extended connection factory, that uses the Oracle feature to change the username of an existing connection
   *
  
   * When a user authenticated on the application server, the database connection will switch to that username.
   * This allows for better auditing and potentially for improved security.
   *
   * Properties (get'ers and set'ters) can be set via the configuration section of the -ds file
   * @author gvdieijen
   */
  public class DBConnAuditConnectionFactory extends LocalManagedConnectionFactory {
  
      private String defaultProxyUser;
  
      public DBConnAuditConnectionFactory() throws SQLException {
          super();
  
      }
  
      @Override
      public Object createConnectionFactory(ConnectionManager cm) throws ResourceException {
          return new OracleWrapperDataSource(this, cm);
      }
  
      public void setEnableProxySession(Boolean enableProxySession) {
          this.enableDbConnAudit = enableProxySession;
      }
  
      public void setDefaultProxyUser(final String defaultProxyUser) {
          if (StringUtils.isEmpty(defaultProxyUser)) {
              this.defaultProxyUser=null;
          } else {
               this.defaultProxyUser = defaultProxyUser;
          }
      }
  
      /**
       * Default db user to open proxy session for, when no authenticated user is active
       * @return
       */
      public String getDefaultProxyUser() {
      	return this.defaultProxyUser;
      }
  }

  As you can see, the file returns a OracleWrapperDatasource. That’s custom class, that extends the default WrapperDatasource of JBoss, and changes the user of jdbc connection just before the connection is handed of to the application. To speak in terms of the fine book

• Now, How can you use that new class? They have to be packed into a rar file. Functionally, that’s a Resource Adapter, a module that allows a J2EE application to use resources. Technically (and practically), it’s just a jar-archive similar to a war, with a different extension. Maven can create these files automatically for you, if you set the packaging type to rar instead of jar (which is the default).
• When you download JBoss, you’ll get a sample connection pool for a in-memory database: default-ds.xml, located in the server/default/deploy directory of jboss. To use the custom classses, copy the file into (for example) myoracleproxy-ds.xml and create a minor modification so a custom connection factory is used – update the managedconnectionfactory property, that a custom connectionfactory is used, that returns the proxied connections:

  <managedconnectionfactory-class>nl.gerbrandict.dbconnaudit.DBConnAuditConnectionFactory</managedconnectionfactory-class>

All in all, after some tweaking, all queries and updates to your Oracle database are done under the J2EE username. This means when user Joe logs in, all his database access will be logged under user Joe as well. This can improve auditing as well as security.