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Showing posts with the label JSF

Creating a Chatbot with RiveScript in Java

Motivation"Artificial Intelligence (AI) is considered a major innovation that could disrupt many things. Some people even compare it to the Internet. A large investor firm predicted that some AI startups could become the next Apple, Google or Amazon within five years"
- Prof. John Vu, Carnegie Mellon University.

Using chatbots to support our daily tasks is super useful and interesting. In fact, "Jenkins CI, Jira Cloud, and Bitbucket" have been becoming must-have apps in Slack of my team these days.

There are some existing approaches for chatbots including pattern matching, algorithms, and neutral networks. RiveScript is a scripting language using "pattern matching" as a simple and powerful approach for building up a Chabot.
Architecture Actually, it was flexible to choose a programming language for the used Rivescript interpreter like Java, Go, Javascript, Python, and Perl. I went with Java.

Used Technologies and ToolsOracle JDK 1.8.0_151Apache Maven 3.5…

A Case Study of Custom JSF Converters - Automatically Converting Years With 2 Digits Into 4 Digits

You can find the demonstrated code of this post on my Github repo here.
The user story" As a banker, I want to enter a client's birthday like 01.01.80 or 01.01.1980,
So that the birthday can be displayed as 01.01.1980 "
Implementation Firstly, I thought about how to use a built-in converter likes the following.

<h:inputText id="birthdate" value="#{data.birthdate}" type="date" > <f:convertDateTime/> <f:ajax event="change" listener="#{data.onCalculate}" execute="@this" render="@this" /> </h:inputText>
However, without defining a pattern, JSF used its default one which was not my desire. It threw an exception when I tried to enter a date like "01.01.90".

> myform:birthdate: '01.01.90' could not be understood as a date. Example: Mar 4, 2018 

Actually, I even could not define either pattern "dd.MM.yyyy" or "dd.MM.yy" for "…

4 Remarkable Notes for JSF Apps Using HTML5

In the previous post, I've already shared with you how my team consults clients by using a HTML prototype. This post is about the used technologies for reusing the provided HTML template and communicating with backend.
What is the issue when using HTML elements with Primefaces components? Primefaces is a great extension for developing JSF web apps. However, it is really frustrating in case we have to make it work with an existing HTML template. Why?
- Primefaces has its own theme for styling.
- Primefaces changes the HTML structure.
Therefore, that would be a huge effort to use the Primefaces' components to replicate the elements of the HTML template; especially it is impossible for images drawing by "canvas" tag.

That requires us to find a better approach. Since Java EE 7 (introducing JSF 2.2 included), it supports to use HTML5 elements. The idea is that JSF components don't effect the style and HTML structure, so we can easily reuse the provided HTML template.…

JSF, Primefaces - Invoking Application Code Even When Validation Failed

A use case I have a form which has requirements as follow:
- There are some mandatory fields.
- Validation is triggered when changing value on each field.
- A button "Next" is enable only when all fields are entered. It turns to disabled if any field is empty.
My first approach I defined a variable "isDisableNext" at a backend bean "Controller" for dynamically disabling/enabling the "Next" button by performing event "onValueChange", but, it had a problem:
<h:form id="personForm"> <p:outputLabel value="First Name" for="firstName"/> <p:inputText id="firstName" value="#{person.firstName}" required="true"> <p:ajax event="change" listener="#{controller.onValueChange}" update="nextButton"/> </p:inputText> <p:outputLabel value="Last Name" for="lastName"/> <p:inputText …

Using Drools to Dynamically Manipulate Metadata of JSF Components

The post is just an approach to change metadata (e.g maxlength, required, etc) of JSF components (e.g. inputText, selectOneMenue, etc) by Drools.
Project structure Tools being usedJava version 1.8.0_131Apache Maven 3.5.0Apache Tomcat 8.0.16 Don't forget to configure your confidential information on  these following files: pom.xml, settings.xml (Maven) and tomcat-users.xml (Tomcat).
For example:
Source code

Building an App for Removing Multiple Slack's Files

You're a developer. What do you do in your spare time? One of my most excited task for sharpening my skills is starting build a pet project. MotivationSlack is cool! It's free. It supports for team collaboration very well.

However, my team only has storage limits due to a free account. We got a warning message as below:
Your file was uploaded — it’s safe and sound in Slack. Unfortunately your team doesn’t have any storage space left. To get more space, you can upgrade to a paid account or delete some of your older files. Since my team plan of upgrading to a paid account is still up in the air, I intended to go with "deleting some of our older files" first. (But we will, Slack. You are great!) Play Around I got started by googling keyword "remove slack files". Here it is:

Uh huh! But I only could delete one file at a time.
We're afraid it's not possible to bulk delete files. We kn…

Attribute 'for' of label component with id xxxx is not defined

I got the warning in the log file when I have used the tag <h:outputLabel> without attribute "for" in xhtml file. It was really polluting my server log files.

The logged information actually makes sense anyway! We could find an answer as the following:

"Having h:outputLabel without a "for" attribute is meaningless. If you are not attaching the label, you should be using h:outputText instead of h:outputLabel."

However, these solutions are not possible just for my situation. Instead of using h:outputText for only displaying text, my team has used h:outputLabel too many places. We were nearly in our release time (next day) so it is quite risky and takes much efforts if we try to correct it. Because the style (with CSS) is already done with h:ouputLabel. The alternative by adding attribute "for" the existing h:outputLabel is not reasonable either. I really need to find another solution.
Fortunately, I came across a way if I change to use p:out…

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="" 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 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…