on the art of the software development

QMass M1

2012-01-10T13:22:00.000+02:00

It has been a while since I wrote anything on QMass. Here are the updates : Grid now tries to persists it's values, asynchronously, on given databases. Currently MongoDB is the default but this would be pluggable. I have tried various scripting languages for the console. I was not very happy with Groovy because it had too many dependencies and kind of a overkill for my needs. I replaced it with

Recognizing The Letters as Being Drawn With The Mouse

2011-11-28T13:43:00.001+02:00

While playing-out with a Kinect device, I think I will be writing more about this later, I had an idea. I could detect letters being drawn with the mouse and convert them to key presses enabling the user, use the mouse like a keyboard. It's basically same problem like they do with these pens. So while drawing the above with the mouse my app. prints "BABA" on where the cursor is. There are two

Hot R&D Topics At Itea 2011 co-summit

2011-10-31T14:42:00.000+02:00

Last week I attended the Itea2/Artemis co-summit. It's a showcase of Itea funded R&D projects. This year apparently most projects are focused on embeded software (Artemis), M2M Networks and Green Energy. There are several projects that focus on M2M architecture/applications, including ours A2Nets, which would allow M2M devices to connect and exchange information with each other. Notable

Creating a JSF2 Console Component

2011-09-23T14:32:00.001+03:00

Since most of the people coming to my site are still looking for JSF how-to's here is one more. This is an how-to on creating a console component, like the one here, with just the JSF2 api. A shell like console's basic requirements look like this ; Should prompt the user to enter a command. Evaluate the command and print the result. Should limit the text to be entered only on the prompt line

QMass, P2P Communication over TCP

2011-08-27T12:20:00.004+03:00

I have done significant refactoring and added new features to QMass :P2P, TCP communication, UDP for cluster discovery codeA new console app working online or at command shellSignificant performance improvementsYou may try out the console at http://qmass.cloudfoundry.com , which spans 8 instances.And here is my new logo :

QMass as an Data Grid

2011-06-07T12:03:00.013+03:00

Memcached defines it's self as in-memory object system. Hazelcast defines it's self as a distributed data grid. What they mean is there is cluster of instances that form a data grid, where a key value pair is hold on only one instance.I started developing QMass with cache data in mind. Particularly for use with Hibernate 2nd level cache where "a key value pair is hold on only one instance"

QMass for Sharing Sessions

2011-05-24T16:31:00.005+03:00

I have just committed code that adds session sharing support to QMass.By defining a filter QMass will share session attributes amongst cluster. It serializes/deserializes the values and does not work synchronously just yet. QMass project page, QMass wiki

Tip to Detect Connection Leaks

2011-05-17T09:41:00.002+03:00

To detect potential connections on a Weblogic backed connection pool set the "Inactive Connection Timeout" close to zero. Setting this feature will cause the application server to forcibly close the connections which have been left inactive for the timeout period. It will print out a stack trace which will guide you where the connection is acquired and not yet released so that you could

Paging with Hibernate

2011-05-14T14:24:00.007+03:00

Hibernate query api has setFirstResults and setMaxResults methods that restricts the result set for ceratain amaount. Typical usage inside a generic method would be like :public List find(String queryString, Object[] queryArgs, int first, int max) { Query q = getEntityManager().createQuery(queryString); if (queryArgs != null) { setParameters(q, queryArgs); } q.setFirstResult(first);

QMass, An API for Cluster Wide Operations

2011-04-19T16:35:00.007+03:00

I have started a new clustering api for Java. You can access the project page at http://code.google.com/p/qmass/. Very first version is ready to be downloaded.It's first application is an hibernate cache provider implementation. You can start using it by simply defining org.mca.qmass.cache.hibernate.provider.QMassHibernateCacheProvider as the hibernate cache provider. By default it will try to

New Languages on the JVM

2011-04-14T11:51:00.016+03:00

In case you didn't notice there is a trend for developing new languages that run on top of JVM. Jython, JRuby, Scala, Groovy, Clojure are examples. It seems latest addition will be the RedHat's Ceylon.I have tried some of these languages. I wrote my impressions on Groovy here. After 6 years of professional experience with Java, here is what I would do to fix it and what I wont touch.Don't touch

Comparing different cache products

2011-03-29T10:19:00.006+03:00

My app. relies heavily on cache to function. Although I use cache on the view, I use it mostly as Hibernate 2nd level cache. Here are some of the products I used and what I think about them.EhcacheI think this was used to be called Easy Hibernate Cache and Hibernate people promoted it's use. Now it's owned by Terracotta. I used this quite for a while, it's light, fast and mostly easy to use.

Hibernate Id Generation and Oracle Sequences

2010-12-29T14:08:00.012+02:00

I thought that @SequenceGenerator allocationSize attribute defined the number to increment the sequence. The API says that anyway... If you forget the fact that, you can't increment the Oracle Sequences more or less than the number you specified while you created them, you may find your self in a trap.By default you create your sequences with an increment of 1. This becomes a problem if your app.

Java Frameworks Presentation

2010-12-27T16:22:00.003+02:00

My little last minute in-house java frameworks presentation :Java frameworksView more presentations from Murat Can ALPAY.

About JSF

2010-11-26T15:51:00.006+02:00

I have been using JSF for at least 5 years I think. And here I am thinking how can I make my menu item, which is a JSF component, to open up its link on a new window. I know I should check the reference document and there is probably an attribute for it but that seems too much hassle. I could have set the target attribute on a standard html anchor. There is always an answer with JSF but it's not

JSF Page Fragment Caching

2010-10-25T11:17:00.005+03:00

Problem : Our menu took ages to render.Our application menu had links to various functions of the apps., 400+ nodes, which needed to be authorized based on EL. JSF has to execute certain EL for each node and decide if its to be rendered and than actually render the menu.Solution : Cache it.Simplest solution is to cache your menu. Our menu changes when the users roles changes which doesn't happen

Facelet tip

2010-05-27T17:05:00.002+03:00

A quick facelet tip. If you needed an extra attribute on a component you can add and access it easily with facelets. Here I needed to add an node attribute on boolean check box, which is part of rich faces tree.

Status

2010-05-19T11:01:00.006+03:00

I should have started using Maven earlier. If you want to manage an inhouse repository check out the Artifactory. Ill make better use of it on my next project.Hudson: More capable than CC, easily configurable UI, pluggable, integrates with svn, maven, ant... And don't forget to revert before update.HTML5 Canvas looks cool. 3D Games + Drawing tools + ?. If you haven't already check this out ;

Hibernate Usage Strategy

2010-03-24T10:14:00.007+02:00

Lately I got to refresh my hibernate knowledge. On previous posts I wrote about my experience with hibernate here and how things could get tangled up trying to load objects.When using hibernate most important decision you have to make is how you are going to manage sessions. Basically you have to choose from a method scoped (service) session or conversation scoped long running sessions. My choice

What I been up to last couple of weeks

2010-02-15T09:44:00.006+02:00

Day job kept quite busy last couple of weeks. Our new project is not managed in a agile way so after some months of preparing "big docs" we have finally hit the stage of coding. Just before starting to code, we have realised that we needed to change some of the architectural decisions we assumed and do some work on our code-base. We would have done that a lot earlier probably if we were on a

Multipart Requests and JSF

2010-01-11T12:01:00.002+02:00

Multipart requests are used when client needs to upload files to server. A multipart request has a different encoding and requires to be parsed.JSF2 doesn't come with any fileupload component nor it has any support with multipart requests. A multipart request to JSF (mojarra impl. 2.0.2) just executes the 'restore view' and 'render response' phases, simply because JSF can't extract the request

JSF PhaseListeners With Annotations

2009-12-21T16:30:00.007+02:00

Although JSF 2 moved most of it's configuration to annotations still some must be made on xml's, like the phase listeners.The most straight forward way to implement a mechanism that would enable defining them with annotations are treating phase listeners as singletons. Than we could simply annotate static methods with after phase, before phase annotations.A second and more elegant/useful way

Developing Custom Scopes/Contexts For Weld

2009-12-16T10:38:00.007+02:00

This one came up while developing an example JEE6 project, which I'll add it up here in the future. The case is I had a textbox bound to a request scoped bean. When user triggers the paint action the value in the textbox is to be added to the list below and the textbox should be empty. I thought marking the component request scoped should have been enough to empty its values but it

State of the 'Dependecy Injection'

2009-12-09T13:42:00.012+02:00

"Dependecy Injection" is one of the most popular design patterns on the Java platform. It was suggested by Martin Fowler, here, instead of the term "Inversion of control". Article was published on 2004. What it brings to a application is a way to create, compose, use and destroy any java object, which are called beans.The leading framework that first used this approach was the "the Spring

Sinek, spreadsheet component, for JSF 2

2009-11-19T10:14:00.005+02:00

Here are some notes on developing a spreadsheet component for JSF. Here is how it looks like :Cells contents are being updated with ajax, user is able to add rows/columns by clicking the buttons on the bottom-right corner. I am calling this component 'sinek'. Probably I will rename it later. To check the source code click here. Here are the parts that make up the component :org.mca.sinek.jsf This

JSF 2 Mind-Map

2009-11-12T16:29:00.006+02:00

JSF2 Notes

2009-11-10T12:04:00.010+02:00

These are the notes I derived from blogs on JSF 2 :From Ed Burns's blog, http://www.java.net/blogs/edburns/Composite ComponentsEd Burn's have a number of articles on developing 'composite components'. CC's are for creating true components that we can attach converters, listeners etc. Previously you could do the similar things with the help of the facelets, which was somewhat limited. Rick

ICEFaces

2009-10-27T11:22:00.002+02:00

Nice people at 'Packt Publishing' are sending me a copy of their new ICEfaces book, 'ICEfaces 1.8: Next Generation Enterprise Web Development', for me to review. You can check it out here.

Hibernate Journey

2009-10-21T11:50:00.013+03:00

NowSo we have started our new project and by default (not my decision, not saying its a bad decision either, just saying that there could be a better decision) we are going to be using Hibernate.For those who don't know Hibernate is 'the' ORM solution. ORM is for 'Object Relation Mapping' which is pretty much self explanatory. It maps your relational data model, such as a database schema, to the

Choosing an Expression Language

2009-09-23T10:19:00.006+03:00

On previous posts I talked about that I liked Jboss-EL. Here is an example of what you can do with jboss-el and not with the standard el:1: #{cityService.listCities(selectedCountry)}This EL is usefull on scenerios where the user selects a country from a combo (selectedCountry) which fires a ajax call and witch returns the cities of the country listing them in a sub combo.Since I relay wanted use

a ping-pong game (2)

2009-09-07T10:36:00.015+03:00

Continuing where we left from part 1. First we need a platform that the user control. Our platform will be a BarCallbacks with key handler. To control the movement of the objects we will introduce a new object 'World' which will handle the movement code. The world object is a timer object that will tick every few seconds and recalculate the coordinates of the registered vectors and redisplay the

What should new JEE developers learn

2009-09-01T10:30:00.014+03:00

We now started a new Enterprise project for Telecom and my first job is helping the new team get started. We are using, and seems will be using, the JSF, Spring and Hibernate technology stack. I am told that although some of them know some of the technologies we use, none know all.So what should they learn and where to start; JEEThe request & response lifecycle, State on AS. How does Session

a ping-pong game (1)

2009-08-31T13:47:00.012+03:00

One of the goals that I postponed long ago was learning OpenGL and creating games with it. I started learning OpenGL, and started building a toy project on the process. I decided to build a ping-pong game which will be simply a ball moving and hitting around. A simple 2D toy project.I chose to develop on my mac with XCode & Objective-C. XCode is a simple IDE that works fast and Objective-C is a

Summing up the photo gallery (part 6)

2009-07-29T11:17:00.010+03:00

I started building a photo gallery app., flickr in mind, as a means to learn the seam framework. To sum up here is my previous posts :1. "little restfull photo gallery example, with seam, which seams fine", here.2. "seamy photo gallery, securing it (part 2)", here.3. "seamy photo gallery, securing it (part 2)", here.4. "seamy photo gallery, resting easier (part 4)", here.5. "seamy photo gallery,

Groovy Impressions

2009-07-02T15:21:00.008+03:00

Groovy is a superset of the Java programming language with dynamic language constructs. Here are my notes on Groovy.1. Java is GroovyEvery Java sentence is a valid Groovy sentence but not the other way around. Which means you can use every Java library out there with Groovy classes. Infact Groovy classes in the end compile into Java code.2. Loose SyntaxNo need for a main method. No more a class

SCWCD

2009-06-19T11:05:00.004+03:00

I hate exams. Especially multi choice tests. Yet I have worked on the SCWCD exam fort the last weeks. I choose the "Head First Servlets and JSP" book to study for the exam mainly because it had more stars than this one. Besides "Head First ..." books are usually more brain friendly. Read the "Head First Design Patterns", a very good introduction to design patterns, so that you know what I mean by

seamy photo gallery, writing an authentication filter (part 5)

2009-05-28T10:02:00.009+03:00

On the 4th part I used an simple authentication filter, to secure my urls, that come out of the box. It only supported basic & digest authentication. With basic authentication what you get is a ugly browser dependent box which asks the credentials of the user. On IE its like:Instead of that I wanted the user to use the login page which I created. In order to do that I first removed basic

seamy photo gallery, resting easier (part 4)

2009-05-27T10:09:00.005+03:00

On my previous post I made a restful photo gallery that has a nice little feature where upon a restful request like 'http://.../mygallery/photo/photo/yoda' served the image named 'yoda' to the user. In order to achive that what I did was first I edited the pages.xml so that it could extract the name (id) part from the request url:

Moving the keyboard out of the way

2009-05-20T10:31:00.010+03:00

After happily doing a little work for iphone, being content for that I was finished with it, I made realize that the text boxes near the bottom of the screen disappeared when the keyboard appeared after saying "hmmmm...", I started searching for a solution. Apples iphone developer library suggest this solution and here I am going to write about how I used it in my project. Here is how the problem

seamy photo gallery, securing it (part 3)

2009-05-04T09:41:00.008+03:00

Previous part was about setting up security so that we have a admin user that could approve photos and an ordinary one. We have done basic authentication on this part we will look at handling authorization exceptions, securing our view and code based on authority.First thing I did was adding approve and disapprove (delete the photo) methods to my photoService and make them authorized :@Restrict("

seamy photo gallery, securing it (part 2)

2009-04-29T09:57:00.009+03:00

The new requirement that I wanted was "photos should be approved before being shown in the main page". For that I needed users with approving privledge or role, therefore it was time to dive in to the seam security part. I used simplest User and Role classes that I could think them and configured them :Seam requires

Bulldozer coding

2009-04-29T09:30:00.015+03:00

Jaroslav Tulach, designer of NetBeans API, defines the bulldozer coding as instead of designing elegant solutions to problems at hand, you choose to use heavy libraries which are good for manythings in "Practical API Design". Which kind of reminds me of the Developer Jar Ratio that I wrote here.Up side of the aproach is you are supposedly getting things done more quickly therefore increased

more notes on seam

2009-04-22T09:11:00.006+03:00

Here is more tips on seam;I found out that blog example I wrote about has a little bit of history behind it. Apparently it was developed in response to a blog of Simon Brown. He publishes a set of blogger application requirements to compare web frameworks. Although Gavin argues that a blogger application hardly JEE, he still developes the example. Read more on it here http://relation.to/Bloggers/

little restfull photo gallery example, with seam, which seams fine

2009-04-15T09:17:00.022+03:00

I have decided it was time to check out the seam framework since many of my friends gave it a thumbs up. Starting with the blog example that comes with the package I have built a little restfull image gallery. Which looked liked this;I started with a simple Photo domain object which has name as the id, and the data byte array as the photo file:@Entity@Name("newPhoto")@Scope(ScopeType.SESSION)

Developer JAR Ratio Hypothesis

2009-04-01T11:40:00.017+03:00

Ever felt like you are dealing with 3rd party jars and library's more than you have to ? They may make things easy but they come with a lot to know and nasty bugs that you have to track down. I believe making the decision of using a 3rd party jar, or building the solution yourself is not an easy one. On the one side of the problem is you don't want to reinvent the wheel and use the established

a Java developers Objective-C comments

2009-03-12T13:40:00.008+02:00

This my language flame post ;)So last month I have started developing for iPhone. In order to do so you have to use Objective-C because by default iPhone does not come with Java Virtual Machine. These are the things I most stumbled on Objective-C:1. Square brackets !When procedural language people see Lisp code first thing they say is : "What's with all that parentheses ?". Objective-C allthough

Use OGNL expressions to fill your SelectOneMenu

2009-03-11T11:32:00.003+02:00

JSF selectOneMenu component is loaded with "selectItems" tag. Like; With the help of some converter we are able to list cities in the combo with the expression "#{cityService.getCities}". But often what we realy

Smart JSF DataTable Columns

2009-03-11T10:57:00.005+02:00

One of the common and simple requirements of enterprise projects is that stylising your columns based on the data it contains like if the column is displaying a date it should be centered, if its a number it should be aligned right. The following will show you how you can make a smart enough datatable which knows what type needs what style.I did this on the richfaces datatable but same logic

Reorginized my blog

2009-03-11T10:53:00.003+02:00

My old blog is now at http://mcalalala.blogspot.com/. This one will be on software development while the other one will be on anything else...