grails (11) vaadin (11) meteor (6) elasticsearch (3) java (2) centos (1) cloudbees (1) google analytics (1) gradle (1) heroku (1) javascript (1) jdbc (1) jug (1) logback (1) logging (1) mac os (1) mongodb (1) mongolab (1) mysql (1) twitter (1) ubuntu (1)

Tuesday, June 24, 2014

How to install Spark on Mac OS X

  1. Download 
  2. Download (find the version number in README inside spark archive). 
  3. Extract and add on path
    export SCALA_HOME=/Users/ondrej/scala-2.10.4
    export PATH=$PATH:$SCALA_HOME/bin
  4. Go to Spark root directory and run in command line: sbt/sbt clean assembly
  5. Then start up Spark, also from Spark root folder: ./bin/spark-shell

Thursday, January 23, 2014

How to run custom Grails tests

Thanks Jan Rudovský for help with this. The code works with Grails 2.3.x. Use Custom Grails Tests for older versions.

The code below shows how to run your custom tests in functional test environment (so the application is running). For the integration tests you will need to use IntegrationTestPhaseConfigurer instead of FunctionalTestPhaseConfigurer.

Friday, January 10, 2014

Who is using Vaadin plugin for Grails

We are curious who is using the plugin for integration of Vaadin into a Grails application. We could get little info based on 'likes' displayed on, but that is not reliable.
Then we have made page, to provide basic info about the plugin and give a few link to continue with. This page gives us better overview who is interested in the plugin. Drahomir Mach did the editorial work, many thanks for that.
The number of visitors has increased in 2013 probably due to 'Grails integration' chapter that we have included in Vaadin 7 Cookbook.

These people has helped with the plugin and they deserve our thanks. These guys helped with improvements and keeping the plugin updated: Antonio CaiazzoOkram1Christoph Frick and Clemens Schneider. Plus other guys who asked question on stackoverflow, the plugin was improved just because of questions.

Finally, a call for "action" :) 
If you are using the plugin, we would be happy if you let us know what you are building or what you would like to improve in the plugin? 

Monday, October 28, 2013

How to configure JDBC river for ElasticSearch

Updated for new version of ElasticSearch 1.0.0.

JDBC river makes possible to load data from e.g. MySql database to ElasticSearch and provide data much faster. 

Before we start, have a look at the set of jdbc-river parameters. Then you need to pick-up a strategy how to poll data from JDBC. 

How to install ElasticSearch as a service on CentOS

The following steps were tested for ElasticSearch 0.90.5 on CentOS 6.4.

Thursday, August 15, 2013

Grails and Logback: Provide default logback configuration for development environment

The main motivation is to have a custom logger setup, which every developer can easily adjust. Also, we don't want to put logback config, which is meant for developers only, on the class path.

We can place logback.xml into the root folder of our project and then pass it when running up the application
grails -Dlogback.configurationFile=logback.xml run-app
The biggest disadvantage is: it is annoying to always include additional properties in the command line and it also means you need to tell that to the new developers. Also, it is not following Grails principle "convention over configuration".

We need to provide the default configuration for the development mode if logback.configurationFile property is not set.

So we hook after compilation event as follows. Create or open scripts/_Events.groovy file in your project folder.

Here is the content of _Events.groovy file.

In this example logback-config-dev.xml is ment to be stored in the project root folder.

Tuesday, July 30, 2013

Meteor: How to send email from client

  1. Make sure you have got email package in projectfolder/.meteor/packages file.
  2. Create server side code in order to send email (Email.send can be called only on server side). That code you can call from client later on.
  3. Make a template that show a link that invokes client side JavaScript that sends the email.
  4. Make the call from the client in order to send an email.

Sunday, July 21, 2013

Meteor: How to login with Email, GitHub, Twitter, Google and Facebook account and add credentials to an existing user account

When an user has already an account in the Meteor application, we don't want to create another user in MongoDB when he tries to login with other OAuth service. Rather we connect the accounts and add a new login service to the existing user's services collection.

This code doesn't work for Twitter, because Twitter does not return email in the user data. Therefore, there is no way how to to connect Twitter account by email. I propose to exclude Twitter from your application until it is solved by Meteor (requestPermissions).

Also Github can have an account without email. So when user tries to login with GitHub without email, a new account is created.

Just create a new file oauth.js in server folder and copy paste the code below.

Thanks to Gadi Cohen post.

Meteor: Login with Github on Heroku

It is a bit tricky to setup Meteor application to login with external service on Heroku (if you want to use your own domain). You need to do the following:

  1. While creating an application on Github, you have to use the same pattern for URLs. If you choose to use www prefix, use it everywhere.
  2. Then go to the console and set ROOT_URL (heroku config:add ROOT_URL= You need to have it EXACTLY the same as in GitHub application configuration.

Monday, June 3, 2013

Twitter buttons in Meteor

The following steps show how to add Twitter button into a Meteor application.
  1. Add the link which represents Twitter button into the template:
  2. Place the JavaScript provided by Twitter to the .js file for the template:
I took this code from application.

Vaadin 7 and Grails: How to compile widget set

I have promised to publish a tutorial showing how to compile the widget set inside Grails project with Vaadin 7. Here you are.

  1. Create a new widget set definition file AppWidgetSet.gwt.xml in the grails-app/vaadin directory.
  2. Open VaadinConfig.groovy that is inside the grails-app/conf folder and add there a note about the new widgetset file.
    widgetset = "app.AppWidgetSet"
  3. Create a folder libs-widgetset (for example inside the project root folder) for libraries that are needed during the widget set compilation. Download all-in-one archive of Vaadin 7 from and move all the .jar files from the archive into libs-widgetset folder. Do not forgot to move also .jar files from lib folder from the archive.
  4. Create build.xml file with the following content.
  5. Open the console inside the project root and run the ant command. The widget set compilation will start. Before you run the ant command, remove all the content of vaadin-grails-addon/web-app/VAADIN folder. 
This is a short version of tutorial "Adding Vaadin Add-on into Grails project" taken from the Vaadin 7 Cookbook.

Sunday, May 26, 2013

How to deploy Meteor on Heroku with external MongoDB

The case is following, you have made a Meteor application and you want to deploy it on Also, you want to use external MongoDB database provided by
  1. Register at 
  2. Install Heroku Toolbelt from
  3. Register at and create new MongoDB database (they give 500MB for free)
  4. Open the root folder of you Meteor project in console (you need a Git repository in order to deploy applications to Heroku, just set up one or use the one provided by Heroku, it becomes accesible after you create new application)
  5. Login to the Heroku from the command line: $ heroku login
  6. Create new Heroku application: 
    $ heroku create <appname> --stack cedar --buildpack
  7. Setup other than default MongoDB for your Meteor application (you can get all the details for constructing the MONGO_URL from yours Mongolab account): 
    $ heroku config:set MONGO_URL=mongodb://<username>:<password><dbname>
  8. Set the root URL
    $ heroku config:set ROOT_URL=http://<appname>
  9. Or this, in case you have got a domain
    heroku config:add ROOT_URL=
  10. Add the Heroku Git repository as another remote to your git repository and push the code to that remote. The application will be automatically deployed and becomes accesible on <appname> 
    $ git remote add heroku<appname>.git
    $ git push heroku master
When you make changes to your code, just run git push heroku master again and all the commit from your origin/master will be released.

In case you want to see the response times for this setup, you can try it out on or 

Tuesday, May 21, 2013

Meteor with Google Analytics

Trying to get Google Analytics working with Meteor framework is so much fun. It took me quite some after I got this wonderful view:

How to get there: that is the question which is answered in the following gist.

Create new template, so we can hook to Template.googleAnalytics.rendered function. So, when googleAnalytics template is rendered, we can call Google Analytics service.
Insert the template into the HTML page that should be reported to Google Analytics.
Implement the call to Google Analytics service as follows (just replace 'UA-111111-1' with your token).
Thanks to these two sources.

Thursday, May 9, 2013

Vaadin 7 Cookbook

Few things I would like to share about Vaadin 7 Cookbook.
We started writing the book since Vaadin 7 alfa versions - which was hard because we needed to made a lot of changes before releasing the book. But, it gave us a lot of knowledge about Vaadin 7 and we could put it into that book. And that makes the book amazing for those who are starting with Vaadin 7. 
One of the first feedback, was "If I would be a beginner with Vaadin, this is the kind of book I’d like to study - a lot of examples that do a single thing, and everything regarding to that one thing is well explained. ... that’s how I learn new things, not by reading theoretical ramblings regarding things and stuff." - vaadin blog 
Luckily, I could participate a project where we used Vaadin 7 with Grails, which was amazing experience. Many notes are included in the book. 
Jaroslav Holan accepted my offer to be co-author, thanks to him the book is more rich for recipes that I would hardly include. Thank you for that, Jaroslav
Looking forward to hear you reflections.  

Thursday, December 27, 2012

Lazy loaded table in Vaadin 7

There are few options how to make lazy loaded table. When I say lazy loaded table then I mean a table that fetches data lazily from database.

  1. Use standard Vaadin table with scroll bar.

    Client (running in browser) loads items lazily from server (and that is awesome). But there is unfortunately no "lazy container" in Vaadin core and therefore we need to use an add-on. We can use JPAContainer for $299 USD "only". Or LazyQueryContainer for free. I tried LazyQueryContainer and worked well but I noticed that design of that add-on is a bit heavy. Therefore I have decided to build a new LazyContainer.

    Vaadin scrollable table needs to call COUNT of the selected items from a database table when rendering table and also when scrolling. There are also not efficient calls of getItemIds method from container in standard Vaadin table. It is easy to explain. When we scroll in the table then client requests data from the server. Server calls the container method getItemIds(startIndex, numberOfIds) where startIndex and numberOfIds have usually this kind of values. 

    startIndex: 0, numberOfIds: 15
    startIndex: 0, numberOfIds: 55
    startIndex: 10, numberOfIds: 72
    startIndex: 33, numberOfIds: 98


    Then we make SQL or some other kind of query to database that looks like this select * from orders limit 0 offset 15; 
    It is nice that the data is lazy loaded and therefore we don't fetch N thousands of items from database but it is wasting resources on the server. I tried to play with cache rates but I couldn't tune it to this kind of result. 

    startIndex: 0, numberOfIds: 50
    startIndex: 50, numberOfIds: 50
    startIndex: 100, numberOfIds: 50
    startIndex: 150, numberOfIds: 50
  2. We need to use PagedTable add on in order to get that kind of strict fetching data from database. But there are few problems with PagedTable. First it doesn't have good architecture and it not easy to use when we need to do localization or customization of navigation items plus there are some defects. I have fixed some of the defects, converted it to Maven project and made customization of the navigation components easier. It is accesible from forked PagedTable

    When we use PagedTable together with LazyContainer then we get quite efficient lazy loaded table. How the code of that kind of table could look like? 

    Here is the example

Wednesday, November 21, 2012

Hello world in Grails and Vaadin

Download and install Eclipse STS and install the extensions. 

  1. Create new Grails project
  2. Fill in the name of the new project
  3. Try to run the application. The plain Grails application (without Vaadin) should start straight away without any additional configuration.
  4. This is how the started application should look like. 
  5. Install Vaadin plugin. This command will install the latest version of the plugin.
  6. Try to run the application (on this screen I have added option where I run the application on different port... it might be handy for you).
  7. Add Vaadin folder into the source folder list.
  8. Try to run the application again. You will see the Vaadin hello world.
  9. We are done. 

Wednesday, October 3, 2012

Grails and Vaadin 7 beta - first version of the plugin

It is finally out. The first working version of Grails plugin for Vaadin 7.

Vaadin 7 differers from Vaadin 6 a lot and therefore there is no backward compatibility beween the plugins for 6th and 7th version. Actually, the plugin for Vaadin 7 is made almost from scratch. Many things have been simplified and plugin is just handling the connection between Grails and Vaadin. For example dynamic methods getBean and i18n are not injected anymore. 

One thing I have noticed after playing with Grails 2.2.0 and Vaadin 7 - it is fast (actually in two ways). First, I have made localized application with access to database via ORM (Hibernate) and Spring (Services), displaying list of users in a good looking table in just 5 minutes (sometimes, in other frameworks, I don't even setup the project in that short time). Second, it is really responsive user interface. I think the guys in Vaadin did amazing job with the 7th version. 

Let's have a look how to install the latest version and try it out. Setup Grails console before you start or you can just make it in your favorite IDE. 
  1. Create new project and run it.
    grails create-app bookstore
    cd bookstrore
    grails run-app
  2. You can stop the application now. It was just to verify that you have successfully created the project. Download and install the plugin
    grails install-plugin /path/to/plugin/
  3. And run the application
    grails run-app
Quite simple, right? You might be wondering... what about access to database or localization. There is a new class Grails and that one is meant to be used when you need to get the access to the services or i18n. Few examples follows.

Let's create a service class in Grails. It just returns all the users from the database.
class UserService {
   List<User> listUsers() {
      return User.list()
Now get the service and call the method.
List<User> users = Grails.get(UserService).listUsers()

Or just create new Label and pass there localized string. 
String text = Grails.i18n("")
Label label = new Label(text)

If you find an issue, please report it in Jira or preferably in Github

Grails and Vaadin 6 - few changes in the plugin

There are few changes in the plugin. You can find the changed Vaadin plugin under this version number 1.5.5
  • No configuration needed after the plugin installation. 
Previously we had to add a new class that extends Vaadin application, add a reference to VaadinConfig about that class and finally remove content of UrlMapping. This all is automated now. We just create Grails project install the Vaadin plugin and run the application.
  • Versions updated.

Grails updated to 2.2.0 and Vaadin to 6.8.4. 
Follow these steps in case you want to try it out. 
  1. First set Grails console
  2. Create new Grails project and try to run it (so we can verify successful creation of the project + dependencies are downloaded).
    grails create-app bookstore
    cd bookstrore
    grails run-app
  3. Download and install the plugin
    grails install-plugin /path/to/plugin/
  4. Run the application
    grails run-app

Friday, July 27, 2012

Trying to update Grails Vaadin plugin to Vaadin 7

I am quite in a shock. I have tried to update grails-vaadin plugin so I could use the new version of Vaadin 7.0.0alfa3 together with Grails 2.1.0. But what a surprise... alfa3 contains a bit more classes than previous version and it makes it imposible to integrate Vaadin 7.0.0 alfa3 with Grails 2.1.0. 

Have a look how size of Vaadin jars increased...

What does it mean. When I try to add com.vaadin:vaadin:7.0.0.alpha3 as dependency then Grails fails to load with the following error: 
Error Interactive mode exited with error: loader constraint violation: when resolving method "javax.xml.parsers.SAXParser.getXMLReader()Lorg/xml/sax/XMLReader;" the class loader (instance of org/codehaus/groovy/grails/cli/support/GrailsRootLoader) of the current class, groovy/util/XmlSlurper, and the class loader (instance of <bootloader>) for resolved class, javax/xml/parsers/SAXParser, have different Class objects for the type org/xml/sax/XMLReader used in the signature.

I have already complained about it Let's see what happens with the next releases. I still hope it is a kind of a bug or bad joke that there are so many libraries included in the package. 

Here you can find working version of Vaadin 7 (alfa2) for Grails (it is still experimental version, but it worked for few people already):