September 30, 2011

Play Framework CookBook - Book Review - worth buying

It has been a while I got hold of new book on Play framework from Packt publications - Play Framework Cookbook. I just completed reading this book.
Play online documentation is itself awesome - explaining the basics and leaving the readers to explore complex features on these basics. This book complements the online documentation and digs deep on some of the great features of the framework - providing practical techniques with source code.
The book is written by Alexander Reelsen. 

This book is intended for experienced Play users -  not the beginners. By experienced I mean, users who understand the basics, high level architecture of Play and who have worked on few examples. There is very less introductory stuff. 

The book covers the Play 1.2 version, whereas the current online version available online is 1.2.3. One of the technical review member is none other - Guillaume Bort - the creator of the Play framework. There is no question of technicalities and correctness of the code examples.
There are 7 chapters with an Appendix covering about 60 recipes.

The most useful chapters that I found where:
1. Leveraging Modules - This chapter covers dependency injection with Spring and Guice. There is a recipe of using MongoDB module which I found useful. The recipes are useful and gives a good insight into how modules can provide powerful extensions to Play’s core functionality.
2. Introduction to Writing Modules - This is another useful chapter - which is not easily found on the web. When the project size increases, it is best to split into modules and manage the complexity. This covers Play plugins, understanding events, managing module dependencies.
3. Running in Production - This is an very important chapter which will be most useful for any project team. Almost all the recipes presented in this chapter like - Test automation,  SSL for certain controllers, running jobs in distributed environment are very useful and clearly explained.

1.  The code examples span multiple pages and not very well formatted.  This is nothing to do with the content but with more of formatting and presenting. Just look at any O'reilly book, their editors do an awesome job
2. Few recipes lack good explanation - it could have been improved - For e.g. - "Understanding events" in the "Introduction to Writing Modules"
3. The reader can make out that English is not the first language of the Author. This is some room for improvement in this area.

Conclusion: It is definitely a very useful book for teams who have already started using the framework. As I said earlier - it complements the online documentation. It is a good buy - worth the investment.

Disclosure: I was provided with an eBook copy of the Play Framework Cookbook by Packt Publishing for the purposes of this review.

September 28, 2011

Software Architecture Review

Software Architecture Review  - in my opinion happens at two levels

1.  Macro Level 
2.  Micro Level 

To review an existing system for any recommendations or trouble shooting - is not a one man job especially for complex Enterprise systems. This is simply not feasible. This is a team effort -at least a team of 3 to 4 - you need strong developers, architects, designers, database architects, domain architects etc.
But for simple to medium complex applications - one person can do the review - provided he networks and seeks help in areas which he is not hands-on.

Coming to the review part, first and foremost - the reviewer (or the review team) should understand from the stakeholders: 
Why this review is being conducted? 
What are the existing concerns?
What measures have they taken already to address the issues? What have they learned till now?
Or is it a pro-active measure by the management?

These questions would set the right direction for the reviewer. He should exercise his personal judgment and be unbiased.

At Macro Level - the focus should be on the 
At the Micro level - it gets interesting because at the Macro level things can be misleading - the code would give the true picture. The reviewer should start digging into the code. 
At the end of this exercise the review team should produce a diagnostic report highlighting recommendations and best practices.

    September 26, 2011

    Installed Scala...the journey begins..

    Scala has caught my interest lately. It has been due on my learning list.
    Also - Play Framework (which I'm currently using) has got awesome Scala support (I see lot of answers and questions of Play and Scala on the Google groups).
    I've read the primer..looks very interesting. Now to do code something concrete.

    To download Scala (latest as of today) and install on Mac (Snow Leopard 10.8) is quite easy:
    curl -O
    After it is downloaded, execute the below command
    java -jar
    I installed scala at this location
    Add the executable to the path.
    vim .profile
    # append or add to the PATH variable ~/scala/bin
    export PATH=$PATH:~/scala/bin
    (or to the bash profile i.e. vim .bash_profile)
    Open a terminal and type scala and you should see the below output
    Welcome to Scala version (Java HotSpot(TM) 64-Bit Server VM, Java 1.6.0_26).
    Type in expressions to have them evaluated.
    Type :help for more information.
    Try the below example:
    scala> val numbers = Map(1 -> "one", 2 -> "two")
    numbers: scala.collection.immutable.Map[Int,java.lang.String] = Map(1 -> one, 2 -> two)
    scala> numbers.get(2)
    res0: Option[java.lang.String] = Some(two)
    scala> numbers.get(3)
    res1: Option[java.lang.String] = None
    To quit the interpreter, just type quit.
    To begin -  here is the awesome link on Learning Scala for beginners.
    I also installed Scala Eclipse IDE - a plugin for Scala development on Eclipse.

    Until next time...

    September 25, 2011

    Packt - 6th Annual Open Source Awards - Finalists

    The final nomination list is out of the opensource software on the Packt website.

    Whats interesting is jQuery Mobile has gained lot of prominence in last few months. Its a strong contender on the Open Source Mobile Toolkits and Libraries.

    The other section which I always keep an watch is Most Promising Open Source Project. PHP rules the web - there are couple of php related frameworks. There one which I like most is the Impress Pages - its looks very promising and a very great content management software. Worth downloading and playing with it.

    Please visit the awards home page and vote your favorite one. I just finished voting.

    September 21, 2011

    Play Framework - Excel report example

    It's breeze to create excel reports using Play framework. Let me run thru an example.
    Let's create a sample project - excel-example.
    $ play new excel-example
    Then eclipsify and import into eclipse.
    $ play eclipsify excel-example
    Edit the dependencies.yml and include the excel module
    # Application dependencies
        - play 1.2.3
        - play -> excel 1.2.3
    Run the play dependencies command. Play connects to the web and downloads the excel-module into the modules directory
    $ play deps excel-example
    ~        _            _ 
    ~  _ __ | | __ _ _  _| |
    ~ | '_ \| |/ _' | || |_|
    ~ |  __/|_|\____|\__ (_)
    ~ |_|            |__/   
    ~ play! 1.2.3,
    ~ Resolving dependencies using /Users/play/excel-example/conf/dependencies.yml,
    ~  play->excel 1.2.3 (from playLocalModules)
    ~ Installing resolved dependencies,
    ~  modules/excel-1.2.3 -> /Users/play/frameworks/play-1.2.3/modules/excel-1.2.3
    ~ Done!
    Plays excel module uses jxls internally which uses Apache POI library - the one and only one library in Java world for excel manipulation. All the dependencies of jxls are bundled with excel-module and dependencies managed.
    However there is one additional library that would be required to ouptut xslx excel formats - which is the newer format depending on Office Open XML documents. This is because xslx is basically a zip format.
    Download the ooxml-schemas-1.1.jar from the maven repository and put it in the lib directory of the excel-example project.
    Then eclipsify again so that eclispe classpath reflects the new dependencies.
    $ play eclipsify excel-example
    Refresh the Project in eclipse.
    Start the play server.
    $ play run excel-example
    ~        _            _ 
    ~  _ __ | | __ _ _  _| |
    ~ | '_ \| |/ _' | || |_|
    ~ |  __/|_|\____|\__ (_)
    ~ |_|            |__/   
    ~ play! 1.2.3,
    ~ Ctrl+C to stop
    JPDA port 8000 is already used. Will try to use any free port for debugging
    Listening for transport dt_socket at address: 50675
    00:54:21,975 INFO  ~ Starting /Users/play/excel-example
    00:54:21,979 INFO  ~ Module excel is available (/Users/play/frameworks/play-1.2.3/modules/excel-1.2.3)
    00:54:22,603 WARN  ~ You're running Play! in DEV mode
    00:54:22,769 INFO  ~ Listening for HTTP on port 9000 (Waiting a first request to start) ...
    check at localhost:9000, you should see a welcome page (I'm just using command line to do a quick check).
    $ curl http://localhost:9000
    The next step is to Create Sample Excel template file
    I have created a simple xslx file which shows displays the list of customers and their phone numbers. You can get the file here. Below is an image for easy reference. Using jxls is a great advantage. Your excel template can contain all required formatting, formulas, macros etc which will be preserved intact. You need to use specific notation (common these days in groovy, ruby language) to indicate placement of data. Refer the below image.

    Save this file under under
    Lets edit the default index.html which is under excel-example/app/views/Application/
    The home page contains just one link to download the excel report as shown below
    #{extends 'main.html' /}
    #{set title:'Home' /}
    <a href="@{customerphonelist()}"/> Download Customer Phone Numbers Excel Report </a>

    Edit the controller and add a method - customerphonelist() which outputs the excel file as shown below:
    package controllers;
    import java.util.ArrayList;
    import java.util.Date;
    import java.util.List;
    import org.apache.commons.lang.RandomStringUtils;
    import models.Customer;
    import play.Logger;
    import play.modules.excel.RenderExcel;
    import play.mvc.Controller;
    import play.mvc.With;
    public class Application extends Controller {
        public static void index() {
        public static void customerphonelist(){"Generating Customer Phone List Excel report ");
         request.format = "xlsx";
            Date date = new Date();
            String user = "Bob";
            List customers = new ArrayList();
            for (int i = 0 ;i < 10; i++){
             customers.add(new Customer("Mr", RandomStringUtils.randomAlphabetic(15), RandomStringUtils.randomNumeric(10)));
         renderArgs.put("date", date);
         renderArgs.put("user", user);
         renderArgs.put("customers", customers);
         renderArgs.put(RenderExcel.RA_ASYNC, true);
         renderArgs.put(RenderExcel.RA_FILENAME, "customer_list_report.xlsx");
  "Completed Customer Phone List Excel report ");
    Above at line no 11 -
    annotation is used. ExcelControllerHelper class is part of play excel module. @With is an interceptor. This interceptor loads the excel template.
    Line No 22 to 25 creates a Customer model class and populates it with some random data.
    Line No 26 to 30 puts the objects in to the renderArgs map. These objects would be available as part of the actual excel file which can be used to render the dynamic content.
    Line No 29 is of special interest which sets the ASYNC to true. This is a very powerful feature of Play framework. This helps in transparent asynchronous rendering of the excel. You don't have to deal with Future, Promise, await, etc and you get the power for nearly free. The existing HTTP request is suspended and then when the excel report generation is done, this thread is resumed and the response sent back to the client. Think about the fact that a large Excel table rendering might take as long as 500ms and blocking request handling thread for half second is NOT acceptable in a high performance web server like play which use only limited thread (N+1) to handle web requests. Read more about this here.
    Last step :), Open
    and click on the Download Customer Phone Numbers Excel Report link. A excel report should be generated and should look some thing like below.

    That completes the example.

    September 19, 2011

    Let the Force be with you --Yoda :)

    Created a Salesforce developer account. Completed a simple cookbook example. No coding yet,  most of it from the developer portal, using mouse and clicking to create apps and entering label values.

    Everything is controlled on the platform - database tables (called as Custom Objects in Salesforce language),  form creation etc. Prima facie the tool looks like it targets Business users to create basic enterprise apps.
    All the development happens on the Web page (no IDE required). Also there is an Eclipse plugin available to do the development.

    The programming language is Apex (predominantly Java syntax) but the code gets compiled to a meta-data which gets interpreted by Apex runtime.

    Apps created on SalesForce are completely data-driven and tightly integrated with Data. You can create apps and share with others as well as use any of the available apps on the platform (provided you have rights).  Common enterprise services like user management, file upload, reports, search etc are available and usable without any customization.
    Its easy to get started and the developer account is free, register here.
    The example which I tried is Warehouse example.
    Some basics and fundamentals of the platform are here, which I have started going thru it.
    I have just spent 1 hr and it was fairly easy to try out hands on the Force platform. 
    I have barely scratched the surface ...will keep exploring it.

    Packt - 6th Annual Open Source Awards - Please vote your fav Open Source

    OpenSource has revolutionized the way - how the software is consumed and delivered these days. Opensource contributors, developers, professionals, users are truly passionate about their contribution and are thorough professionals.
    Packt is publishing its 6th Annual Open source awards.
    The Open Source Awards is a contest that aims to encourage, support, recognize and reward Open Source projects. There is reward for nominating your favorite OS in several categories :
    • Open Source CMS
    • Open Source Mobile Toolkits and Libraries
    • Most Promising Open Source project
    • Open Source Business Applications
    • Open Source JavaScript Libraries
    • Open Source Multimedia Software
    The details are here
    Last year my favourite jQuery made it to the top in JavaScript libraries category.
    Please nominate your favorites, vote and show your support for Open Source.

    September 15, 2011

    CoffeeScript - Nice session

    Bodil Stokke did a very good presentation at JavaZone on CoffeeScript with lots of code.
    She shows that code written in CoffeeScript is much, much lesser compared to sometimes 1/3 fewer lines. CS has lots of syntactic sugar borrowed heavily from Ruby, Python

    Check it out...

    September 14, 2011

    My Choice - Play Framework!

    At my work, there was a need to develop the same application for three different platforms - .NET, LAMP and for Java.  I was asked to pick a framework to develop this app in Java. It was easy for my other colleagues for .NET and LAMP as there was not much choice - ASP.NET was picked for .NET and Ruby on Rails for the LAMP stack.
    When it comes to Java, I need not say more, there are tons of choices. Burden of Choice. 
    The objectives were clear -
    • Rapid development (code - deploy - test cycle)
    • Deployable on popular Web/App servers (Apache Tomcat, JBoss, Oracle, Websphere etc)
    • Deployable on the cloud
    • Best engineering practices (unit testing, functional testing, clean code)
    My friend suggested that I don't have much choice - it has to be either Spring or Groovy on Grails. 

    Spring has kind of become the de-facto standard for enterprises, followed by JBoss SEAM.
    I have a good experience with Spring and have been an early adopter of this great framework. Spring became popular because of the pit-falls of EJB2 and heavyweight runtime.

    But over the past few releases, Spring has grown to be a huge framework. It takes a lifetime to be familiar with all the modules of the Spring and the features it supports.  Recent times - Spring is over-engineered, over-complicated and feature creep.
    With JBoss SEAM stack, you cannot avoid JSF. I never learnt JSF and would never learn it. There is already enough rants on the web about the design flaws of JSF.

    Spring Roo is another great tool to improve the developer productivity but again it's not straightforward. It involves GWT, Spring. Maven etc. Too much. All goes well for a trival hello-world or a simple CRUD app, the moment you try to do a little more complex web-app, things start falling apart.

    No doubt these are great frameworks, but I wanted to avoid maven and its pom file nightmares, classpath issues, layers and layers of abstraction, enforced rules,  high learning curve etc.

    Enter Play framework !

    I'm not advocating this is one of the best frameworks, but it truly matches the productivity of RoR, low learning curve, stateless architecture i.e. made for cloud, dramatically reduces the develop/test/deploy cycle, borrows the best things from RoR, DJango and still retaining the best things about Java (rock solid, enterprise strength scalability and security, great external libraries and developer community etc.).

    It has been already a month I'm using this great framework and I must say it has been a very memorable experience.
    In my next post, I would be giving some nifty features of this framework and more insights

    Until next time ..

    September 12, 2011

    Apache2 + Tomcat6 on Amazon Linux image

    From couple of days, I was having issues configuring Apache 2 to re-direct requests to Tomcat 6 on Ubuntu Linux image. Finally resolved the issue today.
    Amazon Linux image which I was configuring is linux-image-2.6.32-316-ec2
    Basic tutorial of Apache2 HTTPD is here.
    Below are the basic steps (assuming Tomcat 6 and Apache 2 are already installed and configured):
    apt-get install libapache2-mod-jk
    sudo vim /etc/apache2/
    # Define 1 real worker using ajp13
    # Set properties for worker1 (ajp13)
    sudo vim /etc/apache2/apache2.conf
    #Add the below content at the end of the file
    LoadModule    jk_module  /usr/lib/apache2/modules/
    JkWorkersFile /etc/apache2/
    JkShmFile     /var/log/apache2/mod_jk.shm
    JkLogFile     /var/log/apache2/mod_jk.log
    JkLogLevel    info
    JkLogStampFormat "[%a %b %d %H:%M:%S %Y] "
    sudo vim /etc/apache2/sites-enabled/000-default
    #Replace "DocumentRoot /var/www" 
    #with the below 
    JkMount / worker1
    JkMount /* worker1
    sudo /etc/init.d/apache2 restart
    Note: In my case Connector port="8009" was already enabled in /etc/tomcat6/server.xml.
    References : here