Wednesday, December 11, 2013

Vaadin TextFields in a Table empty/null value not propagated for required field



When you create a table in Vaadin with a .setTableFieldFactory(), and you have a Field which is set to .setRequired(true), and a user puts in an empty value for that field after first putting in a non-empty value, the field won't be set to that empty value when iterating through the table to read the current values.


Make sure you invoke .setInvalidCommitted(true) on that field to have the empty value also be passed through; i.e "committed" even though validation fails.

For example:

urlTable.setTableFieldFactory(new DefaultFieldFactory() {

    public Field createField(final Container container, final Object itemId, final Object 
                    propertyId, Component uiContext) {

    if (URL_PROPERTY_ID.equals(propertyId)) {
        final TextField urlText = new TextField();

        // Add the below line to have also the empty string be
        // passed on!!
        // See:!/thread/1129126
        urlText.setInputPrompt("Enter a URL");
        return field;


Note the bold line.

And for completeness here an example of the iterating over the table to get the current entered values:

List result = new ArrayList();
int sequence = 1;
for (Iterator iterator = urlTable.getItemIds().iterator(); iterator.hasNext();) {

    // Get the current item identifier
    String itemId = (String);

    // Now get the actual item from the table.
    Item item = linksTable.getItem(itemId);
    Property urlProperty = item.getItemProperty(URL_PROPERTY_ID);
    String url = urlProperty.getValue();

    // Fill the object
    UrlInfo urlInfo = new UrlInfo();
    // ... set other stuff

return result;

Related resources

The forum thread that put me on the right track can be found here.
Long thread related to required vs validation problems can be found here.
@NotNull bean validator annotation combined with setRequired() also has some issues.

Wednesday, August 21, 2013

Migrating from MySQL 5.5 to 5.6.4 to have milliseconds/fractional seconds support

Before MySQL version 5.6.4, MySQL does not support milliseconds (more precise: fractional seconds) in TIME, TIMESTAMP and DATETIME!

In a project I was on, timestamps are used for versioning of entities via the JPA @Version annotation. So it's essential for correct optimistic locking, otherwise changes with a millisecond or bigger difference won't get a stale data exception. Since MySQL 5.6.4 milliseconds (fractional seconds) are supported by the newly introduced type TIMESTAMP(fsp), where fsp stands for fractional seconds precision. fsp ranges from 0 to 6 with 0 indicating there's no fractional part.

This blogpost describes how to migrate your current MySQL 5.5 version to 5.6.4, get it working correctly with fractional seconds support and problems that occurred.


- MySQL 5.5
- JPA 2.0
- Spring 3.1.2
- Hibernate 4.2
- Ubuntu 12.04
- Tomcat 7

JPA @Version annotation used for all entities:
@Column(nullable = false)
private Date version;

Possible solutions

  1. Put in an interceptor for Hibernate such that milliseconds are removed before inserting. But then you only have optimistic locking correctly working for updates that don't occur within a second. More details here
  2. Change the version field into a long, so don't store it as a TIMESTAMP. 
  3. Try to put something else smart in the application logic itself. 
  4. Put in a columnDefinition on the column:
  5. Upgrade to 5.6.4.

Selected Solution

Together with the Product Owner it was decided to go for option 5. That means the minimal MySQL requirement for the application had to be upped to 5.6.4. That was acceptable; if a company is a MySQL shop, then usually they don't mind using a new(er) version of MySQL.
Option 4 was dismissed because that introduced a MySQL database dependency, which that project tries to avoid as much as possible.


  1. Upgrade MySQL from 5.5 to 5.6.4. Basically following the steps from here:
    The exact MySQL version I used was:

  2. But a few more things are needed. For one thing, you need an up-to-date Connector/J, at least 5.1.24. Follow these steps to upgrade it:
    1. Download it from:
    2. Stop Tomcat
    3. Remove the old version:

      sudo rm /usr/share/tomcat7/lib/mysql-connector-java-5.0.8-bin.jar
    4. Put in the new version:

      sudo cp mysql-connector-java-5.1.26/mysql-connector-java-5.1.26-bin.jar /usr/share/tomcat7/lib/
    5. Restart Tomcat
    6. Done.

  3. Now you need to make sure columns are created as TIMESTAMP(fsp) to get the fractional precision, instead of TIMESTAMP which Hibernate uses by default. Decided was to go for millisecond accuracy, so TIMESTAMP(3). For that, a Hibernate dialect resolver was put in place that registers another column type for java.sql.Types.TIMESTAMP:

    public class FixMysql5Dialect extends MySQL5Dialect {

        public FixedMysql5Dialect() {
            registerColumnType(java.sql.Types.BOOLEAN, "bit");
            registerColumnType(java.sql.Types.TIMESTAMP, "timestamp(3)");

    Note also the boolean fix :)

    The resolver:
    private final DialectResolver standardDialectResolver = new StandardDialectResolver();


    public Dialect resolveDialect(DatabaseMetaData metaData) throws JDBCConnectionException {

    Dialect dialect = standardDialectResolver.resolveDialect(metaData);

    if (dialect instanceof MySQL5Dialect) {

    return new FixedMysql5Dialect();

    return dialect;

  4. Configure it in the Spring JavaConfig:

    map.put("hibernate.dialect_resolvers", MyHibernateDialectResolver.class.getName());

  5. Done


  • Problem: After restarting the application and loading the pre-existing testdata, an exception started occuring:

    java.sql.SQLException: Value '0000-00-00 00:00:00.000' can not be represented as java.sql.Timestamp
  • Cause: the SQL import scripts were using:

    INSERT INTO ct (ID, VERSION, NAME) VALUES (1, '1970-01-01 00:00:00.001', 'a');

    Looking in the database, it turns out the import wasn't able to be converted correctly anymore! They all appeared as:

    | 1 | 0000-00-00 00:00:00.000 | a

    After trying out a couple of combinations, it turns out that "it" definitely doesn't like 1 january 1970!! All below inserts do work:

    '2013-08-05 12:32:34.233'
    '2000-01-01 00:00:00.233'
    '1999-01-01 00:00:00.233'
    '1999-01-01 00:00:00.001'
    '1990-01-01 00:00:00.001'
    '1971-01-01 00:00:00.001'

    Also failing are '1970-01-01 00:00:00.000' and '1500-01-01 00:00:00.001'.

    If you watch carefully on the (incorrect) inserts, you see there's a warning (put in red for clarity):

    INSERT INTO ct (ID, VERSION, NAME) VALUES (19, '1970-01-01 00:00:00.001', 'Test19');
    Query OK, 1 row affected, 1 warning (0.01 sec)

    To see the exact warning execute:

    show warnings\G
    Then you see:

    *************************** 1. row ***************************
    Level: Warning
    Code: 1264
    Message: Out of range value for column 'VERSION' at row 1

    So the entered values are just not valid. Couldn't find out why they are not accepted, if you find it, leave it in the comments!!

    In the scripts we decided to use '1971-01-01 00:00:00.001' for the inserts.

Thursday, August 15, 2013

Refactor/rename package in Eclipse with Subclipse and SVN

Refactoring a package by giving it a new name can give quite annoying problems when trying to commit it from within Eclipse using the Subclipse plugin.

You can get (tree) conflicts, maybe even causing you to rollback all your changes and then step by step committing them.
Below is a set of steps you can follow that should not cause any problems if executed in this order :) In short: you do your refactor, then first commit only the deletions, and only then commit the additions (which are the moved files in their new package location).

Detailed steps

Set up and tested with: Eclipse Juno version, Subclipse plugin, SVN 1.6:

  1. Rightclick on your project and select Team --> Synchronize with Repository
  2. Select the incoming view
  3. Now note in the incoming view, it shows conflicts on some/most directories (packages) that were renamed. Just do an update on those.
  4. Go to the outgoing view
  5. If you now select all items with a '-' (the deleted ones) and then try to commit, you get an error on the commit: Tree remains in conflict. Notice the red/green icons on several directories (actually the ones that had a conflict in step 3), see screenshot:

    So those need to be resolved first.
  6. Right click on one of those entries (multiple select not supported for the Show Tree Conflicts operation) and select Team --> Show Tree Conflicts. That shows something like:

  7. Rightclick and select Resolve...
  8. On that next screen:

    select only Mark conflict resolved.
  9. Click Finish
  10. Now the entry is not marked red/green any more, and only shown with a '-' in the Synchronize screen! 
  11. Do that for all red/green arrows (conflicts)
  12. When done, right-click on all items marked with a '-' and select Commit. And that succeeds!
  13. Finally, commit now the ones marked with '+' (so the added ones)
  14. Really final step: note that sometimes some empty packages with the old name stay around. Deleting them in Eclipse and then trying to commit gives again conflicts(!). Those I just delete directly from the Repository perspective and do an update on those.
Bonus tip: sometimes when another team member has commited a new module, the Synchronize perspective will show the (compiled) /target dir and its items as needing to be committed. Even though the directory is already in the .svnignore file, since right-clicking on it won't allow you to add it. Solution: do an update on that target directory. After this it should be fine and it should not show up anymore on the next Synchronizes.

Saturday, July 27, 2013

JPA @Version annotation: when is the version updated?

In JPA you can annotate a field of an entity with @Version to specify that property as its optimistic lock value.
But the above documentation does not say when the version number is validated and updated (increased).
The short answer is: at commit time!

I came across this because I was having trouble passing on the updated version number back to the caller, after a merge() operation.

The setup

Example and the solution

A client class (not in a transaction) invokes the method 

    * Updates the order and returns the new version number for the order
    * @param order the entity to update. Must be provided with the current version of the order.
    *             If not provided, StaleObjectStateException will be thrown
   Date updateMe(Order orderWithNewValues);

on a service class, which is annotated with Spring @Service and Spring @Transactional

That method invokes 

    * Similar java doc
   Date updateMe(SomeEntity orderWithNewValues)

in a DAO which is annotated with Spring @Transactional(propagation = Propagation.MANDATORY) and @Repository.  The DAO searches for the entity to update using its name, sets the version number to the currently known version number, updates it and should return the new version number.

The class Order is annotated (amongst other things) with @Version as follows:

   @Column(nullable = false)
   private Date version;
   DateTime getVersion() {
       return version;

The implementation of the DAO method implementing the update originally was:

   Order order = orderDao.findByName(name);
   if (order == null) {
       throw new IllegalArgumentException("No order with name '" + name + "' exists");

   Order updatedOrderNotManaged = new Order(order);

   Order updatedOrderManaged = orderDao.merge(updatedOrderNotManaged);

   return updatedOrderManaged.getVersion();

Expecting that the last line (return updatedOrderManaged.getVersion()) would return the new version number, since the non-managed entity was now managed.

But it isn't! What seems to be the reason is that:
  • The JPA implementation (in this case Hibernate) can do some caching, deferring the actual database access to a later moment, causing the changes to not hit the database yet.
  • Not hitting the database also doesn't cause the @Version to be "triggered" (it seems).
  • So the version is still at its old value!
But after the service method had returned the (old) version to the client calling it (so the transaction was committed), in the database you can see the new increased timestamp in the version column.

The solution is to force the JPA implementation to flush() to the database, such that the @Version annotation gets triggered and thus the version gets updated.
Therefor the following was added, just before the "return"  statement: 


That did it, now return updatedOrderManaged.getVersion()) is returning the updated version number. Should the transaction commit fail later, then no harm is done since the whole transaction is rolled back and the client should get an exception or similar so it knows it should ignore the returned version number.

Wednesday, July 10, 2013

Vaadin error: A connector with id 7 is already registered!

This post describes a short analysis and possible solution when getting the error java.lang.RuntimeException: A connector with id 7 is already registered!


  • Vaadin 7.0.4 with Spring using the SpringVaadinIntegration plugin 1.6.5 and Shiro 1.2.1
  • The UI class has @Component en @Scope("prototype") as annotations
  • All components extend CustomComponent
  • All components but one component also have the @Scope("prototype") annotation
  • One component, let's call that the HelpWindow, it extends Window, has no @Scope annotation, and thus is a Spring singleton. The reason for it being a singleton is that it seemed the only solution to always have a sub-window on top of another sub-window (using UI.addWindow()). At least one situation in the project made the sub-window appear beneath another sub-window sometimes...
  • No @VaadinView used anywhere.
  • Spring 3.1.2
  • Tomcat 7 as application server.


This is the reproducible scenario that causes the A connector with id 7 is already registered! error to appear: 
  1. Log in for first time, so authentication is via Shiro: all fine, the HelpWindow is shown.
  2. Log out.
  3. Log in again. I can see the UI constructor and its init() getting invoked.
  4. Exception in the logfile:

    java.lang.RuntimeException: A connector with id 7 is already registered!
    ....... stuff deleted.....

    java.lang.RuntimeException: A connector with id 7 is already registered!
    at com.vaadin.ui.ConnectorTracker.registerConnector(
    at com.vaadin.server.AbstractClientConnector.attach(
    at com.vaadin.ui.AbstractComponent.attach(
    at com.vaadin.ui.Label.attach(
    at com.vaadin.server.AbstractClientConnector.setParent(
    at com.vaadin.ui.AbstractComponent.setParent(
    at com.vaadin.ui.Table.registerComponent(
    at com.vaadin.ui.Table.parseItemIdToCells(
    at com.vaadin.ui.Table.getVisibleCellsNoCache(
    at com.vaadin.ui.Table.refreshRenderedCells(
    at com.vaadin.ui.Table.getVisibleCells(
    at com.vaadin.ui.Table.beforeClientResponse(
    at com.vaadin.server.AbstractCommunicationManager.writeUidlResponse(
    at com.vaadin.server.AbstractCommunicationManager.paintAfterVariableChanges(
    at com.vaadin.server.AbstractCommunicationManager.handleUidlRequest(
    at com.vaadin.server.VaadinServlet.service(
    at com.vaadin.server.VaadinServlet.service(
    at javax.servlet.http.HttpServlet.service(
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(
    at org.apache.shiro.web.servlet.AbstractShiroFilter.executeChain(
    at org.apache.shiro.web.servlet.AbstractShiroFilter$
    at org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(
    at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(
    at org.apache.catalina.core.StandardWrapperValve.invoke(
    at org.apache.catalina.core.StandardContextValve.invoke(
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(
    at org.apache.catalina.core.StandardHostValve.invoke(
    at org.apache.catalina.valves.ErrorReportValve.invoke(
    at org.apache.catalina.valves.AccessLogValve.invoke(
    at org.apache.catalina.core.StandardEngineValve.invoke(
    at org.apache.catalina.connector.CoyoteAdapter.service(
    at org.apache.coyote.http11.AbstractHttp11Processor.process(
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(
    at java.util.concurrent.ThreadPoolExecutor.runWorker(
    at java.util.concurrent.ThreadPoolExecutor$

    The exception occurs at the moment UI.addWindow(helpWindow) is invoked (not included in this exception-dump).
  5. After this, even appending ?restartApplication to the URL won't save you anymore. Only a full restart of the application server (Tomcat) fixes the problem.
  6. BUT: if after the log out I press ctrl-F5 (so full browser refresh) once, the problem still occurs after logging in again.
  7. BUT: if after the log out I press ctrl-F5 twice, the problem does not occur! All works fine. 

Investigation and Solution

So very strange that Vaadin's ConnectorTracker thinks/sees the HelpWindow's connectorId already registered, because the user logged out and the UI's constructor and its init() method were invoked, so a completely new UI is created.
After pressing ctrl-F5 twice, I did see that the HelpWindow's connectorId is cleared (null).
Also changing the HelpWindow's scope to prototype fixed the problem, no exception; but prototype isn't an option for the project for above mentioned reason.

So something somewhere doesn't get fully cleared at logout time. Potentially the reasoning could be: since the HelpWindow is a singleton, Spring won't re-instantiate it (it's a singleton), Vaadin won't clear its connectorId either for some reason, so the ConnectorTracker (see the stacktrace) detects that it is already registered --> exception!

Several posts on the Vaadin forum indicated that the singleton vs prototype might be the problem. Like this one which indicates a potential problem right there. And in this one another caching-like problem is mentioned.

Also not "everything" getting cleared at logout was pointed out as a potential problem. So for that, the code invoked when logging out I changed from only doing currentUser.logout() and the setLocation() to:

// currentUser.logout() might also clear the Vaadin session, but better safe than sorry...

Subject currentUser = SecurityUtils.getSubject(); // Shiro
currentUser.logout(); // Shiro

// It's apparently essential to do the redirect too

For readability, the try/catch around each statement is omitted. And, as mentioned in the first comment, currentUser.logout() might already be sufficient to clear the session, did not further investigate this.

Together with a colleague another solution came to mind: try @Scope("request")! Using that as scope, within an HTTP request the HelpWindow bean exists only once, but a new one is created for each new HTTP request.
And yes, that did it! And it also keeps the 'sub-window on top of a sub-window' problem away.

Sufficient work-around for now!

PS: note that there might be something not 100% ok regarding scope in the SpringVaadinIntegration add-on; see this discussion on what the scope of the UI should be. The last comment (from the user pointing out this potential issue) also refers to using this post as a reference to integrating Spring with Vaadin....

Tip: talking about injection/CDI: integration Vaadin with JEE 6? This might be a good one to read.

Wednesday, July 3, 2013

Integrating Twitter 1.1 api in Android with oauth including app-only authentication


One major change is that all API calls now have to be authenticated (and authorized) via OAuth: "user authorization (and access tokens) are required for all API 1.1 requests". That means any action on Twitter that is related to a user has to happen this way.

Luckily there is also a so called application-only (app-only) authentication for actions that don't require a user as a context. Those are requests on behalf of an application. Think about search and getting a timeline for a user. One thing that's definitely different from the other calls is that this app-only authentication has to use OAuth 2.0, while the user-context based authentication has to use OAuth 1.0a!

In this post I'll describe how to implement both, including a full working Android code example.

App-only Twitter 1.1 Authentication OAuth 2.0

Information about this principle can be found here. As said above, you can use it for accessing the Twitter API 1.1 endpoints that do not require a user action. For example searching for tweets falls in this category; just like getting a tweet from a user's timeline. Tweeting a status update does not fall in this category, because a user has to give permission for this. You can see if a Twitter API call supports application-only authentication if there's a rate-limit specified with it. E.g for the search it says on the right: 450/app. So that's accessible via the app-only API. But getting a user's direct messages isn't, it only has 15/user specified.

The problem with this userless-context API solution I had was my app was using the Signpost library for the Twitter 1.0 API. I preferably would have used that lib for this app-only authentication too, but the Signpost still does not support OAuth 2 yet...
Then I tried to use the Scribe library, which supports OAuth 2.0, but I couldn't get that working quickly. 
Therefore I went back to the basics and used plain HTTP POST and GET methods, using this blogpost as a starting point. All pieces to get it working are in that post, but not available as one complete code set, that's why I made this post. Plus you might come along a few problems too... also described below.

Making it work

Easiest is to refer to the above mentioned Crazy Bob's blogpost to get started and what's happening why.
In my attached example code (see bottom of this post) most of the logic occurs in In OnCreate() the UI is set up, including the consumer, provider and client for the OAuth 1.0a using Signpost (see next section for details on that part).

When a user clicks on the top button of the application, named '1a) Request bearer-token via app-only oauth2') the getBearerTokenOnClickListener.onClick() method is invoked. There you see the bearer token getting retrieved via requestBearerToken(), as described in Crazy Bob's blogpost.
That should give the bearer token which you need as mentioned here
Then to get a tweet from a Twitter user (in the code I'm using 'twitterapi'), click on the second button named '1b) Get tweet from user via app-only oauth2'. That invokes its listener which invokes fetchTimelineTweet(), which in turn gets the tweet using the bearer token, after which the tweet is displayed on the screen.


I ran into a few issues:
  1. When fetching the tweet, the getInputStream (in readResponse()) was giving a FileNotFoundException. Turns out that since Android 4 ICS (Ice Cream Sandwich), this can occur because the conn.setDoOutput(true) causes the request to be turned into a POST even though the specified request method is GET! See here. The fix is to remove that line.
  2. When invoking requestBearerToken() two times in a row on Android 1.5, the responseCode showed as -1 sometimes; mainly when waiting about 30 seconds before invoking it again. That turned out to be a known issue for Android before 2.2 Froyo. For that the method disableConnectionReuseIfNecessary() is put in place. 
  3. It seems a bearer token lasts "forever", until it is revoked/invalidated. Twitter can do that but you can do it yourself too, via the invalidate_token API call.
PS 1: no the code is not optimal, for example the error handling can be done a lot better
PS 2: and no the UI won't win any "Best Interface" prizes
PS 3: yes all network calls should be done on a non-UI thread really. Yup that's some homework for you too :)

User Context Twitter 1.1 Authentication OAuth 1.0a

For updating a user's status (i.e. tweeting), you have to be authenticated and the user has to have authorized you to perform those type of actions. Usually the user authorization happens by switching to a browser in which the user has to log in to Twitter and say whether the application is allowed to perform the requested actions.
Luckily, for this type of authentication still the Signpost library can be used since its based on OAuth 1.0a.

Making it work

After upgrading to the signpost-core- and signpost-commonshttp4-, everything almost worked immediately. Especially make sure to use CommonsHttpOAuthProvider as it says on the Signpost homepage in the Android section.

Since my app still runs on Android SDK 1.5 (yes!) I tested the solution on a 1.5 emulator.
But then I ran into my first problem, authentication failed with: Not trusted server certificate.
To get this working, I had to make sure all the Twitter Root CA certificates are known. For that I used this blogpost. See the class CrazyBobHttpClient for the implementation. After putting in all VeriSign certificates one by one (search for the string 'class 3 Public Primary Certification Authority - G' in the .pem file mentioned in this Twitter Developers Forum post to find all 5 of them).
In short, issue the following command to have each one added to your own keystore:

C:\>C:\jdk1.7.0_17\jre\bin\keytool -import -v -trustcacerts -alias 3 -file verisign_cert_class3_g5.cert -keystore twitterkeystore.bks -storetype BKS -provider org.bouncycastle.jce.provider.BouncyCastleProvider -providerpath bcprov-jdk16-145.jar -storepass ez24get

So in the above I'm adding the VeriSign G5 certificate. The -alias 3 you have to increase each time. And notice the password used: 'ez24get', you'll find that in the CrazyBobHttpClient class.

If you see:

Certificate already exists in system-wide CA keystore under alias
Do you still want to add it to your own keystore? [no]:  

answer with: yes

And do the same for the DigiCert certificates, you only need the 3 Root ones. You can find the separate certificates and keystore in the res/raw directory of the example application. The separate certificates don't have to be provided, I just left them there for reference.

After performing all these steps, I was able to authenticate and even tweet. Just as a test I switched back to the DefaultHttpClient(). And the authentication now goes fine using that implementation too! Strange, because AFAIK that one just uses the default system keystore, and before it gave the "not trusted server certificate error"... Strange to me. If anybody knows the reason why, please leave it in the comments!

PS: maybe even cleaner is to add your own created keystore to the existing keystore(s). See the comments at the top in the

Outstanding Issues

Well, issues.... more like questions: 
  • Why does the DefaultHttpClient() suddenly work (see previous section)?
  • It would be nice to have an example for app-only authentication using an OAuth 2.0 library like Scribe instead of using this low level POST/GET code.
  • In the LogCat I see these messages appear after each API call:

    07-01 18:59:03.575: W/ResponseProcessCookies(732): Invalid cookie header: "set-cookie: guest_id=v1%3A137270514572832152;; Path=/; Expires=Wed, 01-Jul-2015 18:59:05 UTC". Unable to parse expires attribute: Wed, 01-Jul-2015 18:59:05 UTC
    Why do these appear?
  • It should be possible to get the Twitter Timeline for a given user using your application's private access tokens (and thus not requiring the app-only authentication). Of course this is not recommended, because that would mean you'd have to put these tokens in your application. But for some situations it could be an option. See this PHP code on how that can be done.

The Sample Code Application

You can find the complete source code here
It should run on anything from Android 1.5 and higher.
It has been tested by me on:
  • Android 1.5 emulator
  • Android 4.0 Samsung S2
  • Android 4.0 emulator
You might want to remove the scribe-oauth2.0-1.3.0.jar from the libs directory, just left it there for reference. Same goes for the certificates in the res/raw/ directory. Removal is not necessary, it just uses unnecssary storage.

How to run it

  1. Load the project in your favorite IDE or whatever you use to build Android applications.
  2. In OAuthTwitterClient change the values of CONSUMER_KEY and CONSUMER_SECRET to your own application keys.
  3. Also modify the CALLBACK_URL to your application's callback URL. Note: you can also make an OOB (out-of-bounds) call that doesn't require a callback URL, but that's for you to figure out, didn't spend time on that.
  4. Deploy it. You should see a screen like this:

  5. Press button 1a) to get a bearer token. After pressing it should look like:

  6. Press 1b) to get the tweet. That should look like:

  7. Press button 2a) to get authenticated and authorized to post a tweet on behalf of a user. When the browser opens, enter the credentials under which account the tweet should be performed (no screenshot for that one). Then authorize the app (click Authorize app):

    It should get back to:

    Note: I am getting a message that the certificate is not ok. This is I think because the quite old 1.5 emulator does not have that root certificate:

    Because the certificate looks fine: 
  8. Enter a tweet text.
  9. Press button 2b) to tweet the text above it. That should give you:

  10. At the bottom of the screen you can see some statuses of what's going on. If you see any error message, check the LogCat.
  11. That's it!
And here two examples of what it can look like after integration in an app, here in the free Android SongDNA app.
Showing all tweets with the words 'shakira' and 'underneath your clothes' in it.

And the different actions possible on each tweet:

Wednesday, April 17, 2013

Vaadin Charts add-on showing custom properties in tooltip hover

Recently I had to investigate if it is possible to show other data than the X and Y value when hovering over a stacked bar graph in the Vaadin Charts add-on. And yes it is possible!
Nowhere I could find an example on how to do this, so that's why I wrote this blogpost. Hope it helps some people :)

- Vaadin 7.0.1
- Charts add-on 1.0.1. In version 1.0.0 you can't set the color of the stacked bars using PlotOptions and ContainerDataSeries. This version has a fix for that.
- Note: I had to manually modify some labels of the hover in the screenshot since I can't use the real data used in the project. Same goes for the code, did not check if it still compiles. Let me know if something essential is missing :) Oh yeah and this is all demo-code so no quality complaints please....

- Be able to add a custom field to the hover. And even better: be able to add an array to the hover tooltip.

Here's a screenshot of what the goal was. Click on it for a larger image:

The code:
Notice the Grapes ok: 7 Total: 16 in the hover text. These are the standard x and y values you can show easily via:

        Tooltip tooltip = new Tooltip();
        tooltip.setFormatter("function() { return ''+ this.x +'"+ " '+ +': '+ this.y 
+' '+'Total: '+ this.point.stackTotal;}");


But also note the extra this.point.custom = 708. That's an example of adding a custom value. The tooltip code then looks like:

tooltip.setFormatter("function() {"return ''+ this.x +'"+ " ' +': '+ this.y +' '+
'Total: '+ this.point.stackTotal + ' this.point.custom = ' + this.point.custom + "''"

And then below that line you see a set of table-like data: Quality 1: 2 Stored: 3 Interesting: 4. This is the data that comes from three arrays. The tooltip code then looks like this:

tooltip.setFormatter("function() { var qualityValuesArray = JSON.parse(this.point.qualities); " +
        "var storedValuesArray = JSON.parse(this.point.stored); " + 
        "var interestingValuesArray = JSON.parse(this.point.interesting); " + 
        "return ''+ this.x +'"+ " ' +': '+ this.y +' '+
        'Total: '+ this.point.stackTotal + ' this.point.custom = ' + this.point.custom + " +
Quality 1: ' + qualityValuesArray[0]  + " + "'Stored: ' + storedValuesArray[0]  + " + "'Interesting: ' + interestingValuesArray[0]  + " +
Quality 2: ' + qualityValuesArray[1]  + " + "'Stored: ' + storedValuesArray[1]  + " + "'Interesting: ' + interestingValuesArray[1]  + " +
Quality 3: ' + qualityValuesArray[2]  + " + "'Stored: ' + storedValuesArray[2]  + " + "'Interesting: ' + interestingValuesArray[2]  + " +
Quality 4: ' + qualityValuesArray[3]  + " + "'Stored: ' + storedValuesArray[3]  + " + "'Interesting: ' + interestingValuesArray[3]  + " +
Quality 5: ' + qualityValuesArray[4]  + " + "'Stored: ' + storedValuesArray[4]  + " + "'Interesting: ' + interestingValuesArray[4]  + " +
Quality 6: ' + qualityValuesArray[5]  + " + "'Stored: ' + storedValuesArray[5]  + " + "'Interesting: ' + interestingValuesArray[5]  + " +
Quality 7: ' + qualityValuesArray[6]  + " + "'Stored: ' + storedValuesArray[6]  + " + "'Interesting: ' + interestingValuesArray[6]  + " +
Quality 8: ' + qualityValuesArray[7]  + " + "'Stored: ' + storedValuesArray[7]  + " + "'Interesting: ' + interestingValuesArray[7]  + " +

The span can also be replaced by a HTML b tag of course.
Too bad you can't use the setHTML() for better formatting, like putting in a HTML table tag. This is a known issue, see here.

Essential in constructing the data is to use the BeanItemContainer, ContainerDataSeries and the addAttributeToPropertyIdMapping() in which you can put custom class (bean) OrderChartItem:

  * Class with custom value and 3 arrays to be displayed in tooltip
    public class OrderChartItem {

     private static final int NR_QUALITIES = 8;
     private final String name;
  private final int x;
  private final Number y;
  private final int someValue;
  private final Number[] quality = new Number[NR_QUALITIES];
  private final Number[] stored = new Number[NR_QUALITIES];
  private final Number[] interesting = new Number[NR_QUALITIES];

  public OrderChartItem(String name, int x, Number y, int someValue) { = name;
   this.x = x;
   this.y = y;
   this.someValue = someValue;
   for (int i = 0; i < NR_QUALITIES; i++) {
    quality[i] = i + 2;
    stored[i] = i + 3;
    interesting[i] = i + 4;

  public String getName() {
   return name;

  public int getX() {
   return x;

  public Number getY() {
   return y;

  public int getSomeValue() {
   return someValue;

  public List getQualities() {
   return java.util.Arrays.asList(quality);
  public List getStored() {
   return java.util.Arrays.asList(stored);
  public List getInteresting() {
   return java.util.Arrays.asList(interesting);

I made the arrays the same size because of its table data, but that doesn't have to be of course.

The basic mechanism is:
  1. Set up a BeanItemContainer with values of OrderChartItem. Take special care when putting in 0 values. The graph then shows the number 0. To avoid that, put in 'null' as a value.

    BeanItemContainer containerGood = new BeanItemContainer(OrderChartItem.class);
    containerGood.addBean(new OrderChartItem("some name good", 1, null, 701));

     So the OrderChartItem has the properties that can be reached from the tooltip Javascript. Note the OrderChartItem just gets some name, later it is overwritten by setting the ContainerDataSeries names:


  2. Then wrap each BeanItemContainer in a ContainerDataSeries:

    ContainerDataSeries seriesGood = new ContainerDataSeries(containerGood);

  3. Then add the custom properties for each container. First the one value:

    seriesGood.addAttributeToPropertyIdMapping("custom", "someValue");

    Then the arrays:
    seriesGood.addAttributeToPropertyIdMapping("qualities", "qualities");

  4. And add the series to the configuration:


In summary: the OrderChartItem is used as data-provider by adding them to the ContainerDataSeries. The properties-mappings of the custom OrderChartItem are then added to the series, after which they are accessible in the tooltip Javascript. Note the "trick" of using JSON.parse() in the formatter and the List getQualities() to get the arrays in the correct format.

Full source code can be found here.
The widgetsets directory has been cleared out because of distribution issues.

Wednesday, February 27, 2013

Vaadin add-on Timeline vs Vaadin Charts add-on comparison


For a recent project I had to evaluate the Vaadin Charts and Timeline add-ons for their capabilities.

- Vaadin 7.0.1
- Vaadin Charts 1.0.0
- Vaadin Timeline which is included in Vaadin Charts since Vaadin 7.0

- Be able to see data for 90 days, and the same data but then per week (same graph, just other view).
- Be able to click on a bar and perform some action like retrieving other data based on the selected bar.
- Customizable three code coloring stacked bars.
- Display more details when hovering over a bar.



This type of graph is very flexible and elaborate in the ways it can display data. It has a "selection bar" below the actual graph so you can determine the values being displayed in the graph above it. See below for a screenshot:

You can try it out yourself in an online demo here and here.


- The graph is scrollable thus no worries about the bars/lines getting too close to each-other.
- You can zoom in and out, also with your mouse.
- Different charts (graph modes) provided by default, changeable in one click: line, bar and scatter.
- A quick zoom per period (1d, 5d, 1w, 5m etc).


- Can't attach any action to clicking on a bar. What you can do is react on the area selected with the selection bar, so a work-around might be to have the user select exactly one bar to mimic a kind of "clicking" on that bar. And then take the appropriate action.
- You can only show days on the x-axis it seems. You can't show a bar per week for example (thus one bar representing 1 week). A work-around might be to create your own Zoom period for 1 week, which is quite easy to do.
- Currently as of this writing there are at least two bugs regarding hovering: the timeline moves down a few pixels when hovering for the first time, and the stacked bars have a hovering problem.


- Can you also add an hover-over tooltip to the bars?

This type of graph does not have the fancy zooming possibilities, but has more possibilities regarding customization and reacting to events. See below screenshot for an example:

You can try it out yourself here.


- The bars are clickable and that event can be handled, indicating the x and y of the item clicked.
- The graph is more customizable; for example the numbers in the bars can be removed.
- Different values (like week number) on the x-axis is probably possible (still out for investigating).
- All data is always visible in the current view.
- Customizable hover-over tooltip.
- Does not have the two (smaller) timeline bugs.


- No horizontal scrollbar or similar, thus for example showing 90 days looks quite "cramped", see the above screenshot. When making the browser smaller, day numbers start to overlap. Do-able, but not optimal. A horizontal scrollbar would be great!
- No space for showing a full date at the bottom. As a work-around the actual date could be added to the tooltip when hovering over a bar (in the screenshot it only says 26).
- No zooming.
- No out-of-the-box other graph modes (i.e like in the Timeline those are provided with it always).


For the project we chose the chart because it is a bit more customizable and the ability to click on a bar and do something with that event was most important requirement.

What's crap about my new Dell Precision M4700 laptop (+ the few good things)

Just got my new Dell Precision M4700 laptop in, which is the top model of their range for 15" screens.
My last laptop was also a Dell Precision, the M4400. Having looked around to see if there's another brand I'd rather take, I still came to the conclusion that a Dell seems to be the best fit for heavy development.

So online I ordered it, with changing the default low 4G or 8G RAM to a more reasonable 16G. That's the first place where I noticed they are really overcharging for the additional RAM: 200 euro (about 261 dollars) for having put in 16G of RAM, while if you buy it seperately it's only about 100 euro. But since I don't like messing around with a brand new laptop (mainly because of warranty) I decided to pay the extra.

Here's a list of pros and cons of the laptop after using it for a few weeks:

- The power plug is straight, so it fits better in a block of power plugs, see the image below:

- It feels sturdy and solid.

- The power cord is still quite short. Why not just add 1 meter more?
- The plug that goes into the laptop is straight and at the back. Lots of times when you've got the laptop on your lap it will just fall out. Much better solution: an angled plug and plug it in on the side of the laptop.
- The keyboard has a numeric keypad. Why would you need that on a laptop? How often will data entry people use such a high end laptop? And it forces me to sit more to the left of the keyboard to be able to type... And I know I'll never ever use that numeric keypad... See image below:

- The Page Up and Page Down are placed at such a weird position. And it feels like they should be the other way around anyway: Page Down left, Page Up right...

- Right after I started it up for the very first time, I wanted to search in the Windows configuration screen. The whole machine just froze, I couldn't do anything else but hard-shutdown the machine via the power button. Ok this might be a Windows problem but still it shouldn't happen within 5 minutes...

- It's really hard to turn off the built-in webcam. Out of the box it will switch on automatically if a video stream comes in (or something like that). This should be the other way around by default. You can only turn it really off via system devices, not via the annoying pre-installed webcam control app.

- For creating a VMWare image of the same Windows 7 Professional OS as on this new laptop, you have to enter the Windows COA product key. And guess where they put it on the laptop? No not on the side or the bottom..... it is inside the battery compartment!! So when you're right in the middle of installation, you have to shutdown the laptop, take out the battery, write down the long key, put the battery in, start it all up again.... Djeezzz!!

- Multiple times I've had now that I put a VMWare guest in suspend-mode and that after that the light of the harddisk stays on "forever". I can hear it spin too. Even if after that I close the VMWare application, the harddisk keeps on going. When after that I put the laptop to sleep via the power button, it stops spinning. When I then turn it on again, the harddisk directly starts spinning again. In Windows Task Manager I can't find any process that is supposed to be reading or writing. So what is going on? Who is reading and/or writing? Is the disk crappy? After running diagnostics (during bootup) no problems are found. Is VMWare causing it? I can't reproduce it everytime, so can't really make a support call for it. But all 'n all it doesn't give me much confidence in the machine + setup combinatino.... I'm planning on re-installing the whole OS, so no Dell Recovery manager and other Dell software is on it anymore. Hope that makes it more stable...
- When I plug in a headphones cable on the left, my mouse keeps on bumping into the cable.

Well, that about sums up this "rant".... Next time I'll definitely re-consider whether I should purchase a Dell again....

Saturday, February 2, 2013

Lessons learned Spring 3.0 project

Another quick post with some bullet points of lessons learned during my last Spring 3.0 project.
Tools used were:

  • Spring 3.0 (3.1.2 when moving to Hibernate 4)
  • Spring MVC
  • Spring WebFlow 2
  • Spring Batch
  • Spring Agent Framework
  • Hibernate 3.2.6
  • Apache CXF
  • JBehave (Behavior Driven Development)
  • Tiny bit of GXT, which is a Google Web Toolkit extension based on GWT and ExtJS technology. Formally known as Ext GWT, GXT is a Java library for building rich internet applications with the Google Web Toolkit (GWT)
  • JBoss jBPM 5.2.0
  • JBoss Drools 5.3.1
  • Jenkins for CI
  • Crucible for code reviews
  • Jira for issue tracking en sprint user stories and tasks and progress tracking
  • SpringSource Tool Suite 2.9.1 as Eclipse based IDE
  • JUnit 4.8
  • EasyMock 2.5.2, EasyMockSupport
  • Java 6
  • Cargo-itest (introduction here) for integration testing
  • Tomcat 6
  • Oracle SQL Developer (free version)
Besides learning new tools like JBehave an Cargo-itest, below are some things picked up using above tools.

Spring MVC
Had some issues getting REST-like services available, mainly from inexperience, but good to know what's working and what not:

    Response getSomeOtherUrlParams(@PathParam(value = "roleId") final String roleId);
    // Unable to call it, because PathParam is not existing (it's not really part of the path)

    Response getSomeOtherUrlParamsNotAsRequest(@PathParam(value = "roleId") final String roleId);
    // Works

    Response getSomeOtherUrlParamsAsQueryParam(@QueryParam("role") final String roleId);
    // Works, will have clients of this service (like SoapUI) already generate a ?role= parameter

    Response getSomeOtherUrlParamsAsRequestParam(@RequestParam("role") final String roleId);
    // Won't generate a ?role= parameter for clients, the WADL also looks different for this method/parameter

Don't use @FormParam for submitting XML because if the mediatype is text/xml for example, the mapping on the REST method fails because JAXRS expects HTML (default if not specified at the service definition).
So suppose the service is defined as:

    Response sendMessage(@PathParam(value = "messageCode") final String messageCode, 
                                         @FormParam("moduleName") String moduleName,
                                         @FormParam("userId") String userId, 
                                         final MessageContentsRequest messageContents);

When invoking the above method by POSTing to 


with as POST body parameters moduleName and userId + the MessageContentsRequest XML, that gives the following error in the log:

2013-01-05 11:24:38,491 WARN  [http-8890-1] JAXRSUtils#processFormParam - An application/x-www-form-urlencoded form request is expected but the request media type is text/xml;charset=UTF-8. Consider removing @FormParam annotations.
2013-01-05 11:24:38,493 WARN  [http-8890-1] WebApplicationExceptionMapper#toResponse - WebApplicationException has been caught : no cause is available

The same error occurs when invoking: ..../send/?moduleName=abc&userId=ttl  (so adding them as POST URL name/value parameters).

So make sure you use in that case:

    Response sendMessage(@PathParam(value = "messageCode") final String message ode, 
                                         @QueryParam("moduleName") String moduleName,
                                         @QueryParam("userId") String userId, 
                                         final MessageContentsRequest messageContents);

The moduleName and userId can then be passed in via the POST URL name/value parameters.

Use replayAll() and verifyAll() instead of replay(mock) and verify(mock) for each mock seperately. Requires extending EasyMockSupport.

SQL Developer
The free SQL Developer can't export clob column values. Nor can it import clob values larger than 4K.


Saturday, January 12, 2013

Got my Kickstarter BERO remote controlled robot in

Last year I funded one of the BERO robots via Kickstarter. And last week the matte finish black Basshead arrived! This is wat it finally looks like:

Quite a sturdy little robot, remote controllable via an Android and iOS app. Biggest challenge was to switch it on! In the supplied instructions it said to turn it on and off, but I just couldn't find the on/off switch! Almost sent out a question for this to the support, but then I found it! Below a picture, should you come across the same problem.
And some Android app screenshots with which you can control the Bero: Splash screen
Home screen
Control screen to let Bero react (dance) to sound/music
Eight programmable modules for its movement/lights/sound
So, quite funky!