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Showing posts from May, 2016

Changing source code at run-time with Service Locator pattern

I have a service to get some data but the result can be different basing on where the implementation is. Technically, I have two or more concrete implementation of an interface and I am able to switch using these concrete classes at run-time. That means I have a place to configure it without re-deploying the application. In order to overcome this issue, I use Service Locator design pattern and here I only care about two advantages below:
Encapsulating the specific implementation, we just declare the name and don't care about the implementation of the service.Changing the implementation at run-time.


Client: an object that invokes the services via Service Locator Business services: services that is used by Client.

My impression of Google I/O 2016

I have not yet had a chance to attend this event but I just watched it on Youtube as usual. :)
Google Assistant You might be very familiar to Google Now if you're Android fan. I saw that Google Assistant is like an upgrade to Google Now. It looks smarter because we are able to make a conversation with Google rather than just saying "Ok Google" and getting the tasks done as Google Now. That means Google Assistant can understand our personal words in our contexts.

For example:
I: Who is Google CEO? Google: Sundar Pichai I: Show me his awards  => Here I don't need to say "Show me Sundar Pichai awards", because I don't know to pronounce his name correctly. :)
I am thinking about that we can compare Google Assistant to Siri of Apple. Google Home At Google I/O 2015 last year, Sundar mentioned about working on a exciting project with Internet of Things and I think Google Home is a result. Working with Google Assistant, Google home is a very smart and modern devi…

JSF 2 - Dynamically manipulating the component tree with system events

Let's suppose we want to modify the metadata (attributes)  of elements such as render, requried, maxlength but we do not define in JSF tags. The manipulating components can be conducted in Drools files, for example. How could we do? I think that is what we need to change something of component tree during JSF life-cycle.


JSF supports event handling throughout the JSF life-cycle. In this post, I use two events: postAddToView for scanning components tree and preRenderView for manipulating the meta of components before rendering to GUI.

I modified my own project from previous post for this example. This is my first further JSF trying out with the project as I said before. :)

We define the tags f:event below the form - a container component of the components which we want to work on. The valid values for the attribute type for f:event can be found from tag library document of JSF 2.

<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml" xmlns:f="http://java.…

The HelloWorld example of JSF 2.2 with Myfaces

I just did by myself create a very simple app "HelloWorld" of JSF 2.2 with a concrete implementation Myfaces that we can use it later on for our further JSF trying out. I attached the source code link at the end part. Just follow these steps below:

1. Create a Maven project in Eclipse (Kepler) with a simple Java web application archetype "maven-archetype-webapp". Maven should be the best choice for managing the dependencies, so far. JSF is a web framework that is the reason why I chose the mentioned archetype for my example.

2. Import dependencies for JSF implementation - Myfaces (v2.2.10) into file pom.xml. The following code that is easy to find from http://mvnrepository.com/ with key words "myfaces".

<dependency> <groupId>org.apache.myfaces.core</groupId> <artifactId>myfaces-api</artifactId> <version>2.2.10</version> </dependency> <dependency> <groupId>org.apache.myfaces.core</groupId&g…