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Tuesday, August 19, 2014

JSF 2.1 Tip of the Day: Clearing the @ViewScope

Introduction

I was trying to solve an issue in our code where the @ViewScope beans were not being garbage collected. I spoke a number of times with Manfred Riem at Oracle about the weirdness of this issue. The issue simply put was that we were facing a memory leak where the instances of @ViewScope objects were not being removed from the view map. As a result, the pages were being kept in memory. The view map is limited to 32 views which helped to hide the issue. In most cases, it would not appear to normal users of our application. The issue was suddenly evident when the view contained tens of thousands of objects. 32 x 10k is REALLY BIG! It really never made it to 32, the system would stall and crash at about 6 instances.

The Culprit

We had implemented our own custom NavigationHandler. This was working quite well on JSF 2.0.x, but a couple of things happened. The JSF implementation was changed to handle another view scope issue, and our implementation of the NavigationHandler was changed from my original code. The new handler did not handle cleaning up the @ViewScope object view map which is stored in the session. Oh, yeah, the view map in the session was the change to the API too.

The Solution

The solution turned out to be something simple, re-implement the same mechanism in the default NavigationHandler to clear the @ViewScope objects from the view map in the session.

Interesting Observations

I was trying to come up with a mechanism to clear the view map data from the session, and came up with a SystemEventListener to test out some ideas. I thought I would share the code for people to see how the map is cleared. This is an approach to the issue, but as I noted, it was actually something missed in our NavigationHandler. I thought I should post the code for anyone who was looking for ideas on how to manipulate the map, or clear data in it. So without further hesitation. Here is the code.

ViewMapSystemEventListener.java


To implement the listener, you need to add an entry to the faces-config.xml file as shown below.

faces-config.xml


Saturday, July 26, 2014

JSF 1.2: Project Woodstock Application using JPA

Woodstock Dataprovider Entity Example
Here is another example of using Project Woodstock along with JPA in an Enterprise Application. The project requires the sample database included in NetBeans.

The project was updated using NetBeans 6.5.1.


The code for the project can be found on Bitbucket here: WoodstockJPAApplication

Friday, July 25, 2014

JSF 1.2: Project Woodstock Multiple Selection Table Example

Multiple Selection Table

This is another example of a Project Woodstock project that was converted from Project Rave and Sun Studio Creator 2. This example details a multiple selection table, and was originally created by Winston Prakash.

I have updated the project using NetBeans 6.5.1 and tested on GlassFish 2.1.1.

The updated project can be found on BitBucket here: MultipleSelectionTable

Thursday, July 24, 2014

JSF 1.2: Project Rave Single Selection Table

Single Selection Table
Here is another example Project Rave/Woodstock project originally written by Winston Prakash for Sun Studio Creator 2. It has been updated using NetBeans 6.5.1 and tested on Glassfish 2.1.1.

The project can be found on BitBucket here: SingleSelectionTable

JSF 1.2: Woodstock Collapsible Group Table Example

Collapsible Group Table Example
Here is another example of a Project Rave data table converted to Project Woodstock. Project Woodstock was a great idea and the implementation with Visual JSF was the right path to go with JSF development. It is a shame that the project was canceled by Sun. I met a lot of great people who worked on the projects, and are still friends today. The code for this project was originally developed by Winston Prakash at Sun.

The code was developed using NetBeans 6.5.1 and can be downloaded from BitBucket here: CollapsibleGroupTable


Monday, July 14, 2014

JSF 1.2: Project Woodstock Button Facet Table

I was going through some old code examples. I found one created with Sun Studio Creator. Yes, it was very old.

The original example was developed by Winston Prakash.

I did some updates to Project Woodstock from the original Project Rave, and came up with a pretty new example page.

The project can be downloaded here: ButtonHeaderTable

Note: You will need to use NetBeans 6.5.1, or 6.7.1 to run it.

Sunday, July 13, 2014

JSF 1.2: Visual Web Pack (Project Woodstock) Java Persistence API Example

Master-Detail Example
This is some example code that I have for a Visual Web Pack (VWP) project that demonstrates some complex data table examples.

I often fantasize about being able to get the band back together and make Woodstock 2.0. Here is an example of why. This was complex for JSF 1.2.

The code can be downloaded from: vwpjpaexamples

I would strongly recommend using NetBeans 6.5.1 to build and run the example project.

Thursday, July 10, 2014

A simple practical "pragmatic" Formatter for java.util.logging.Logger

I have quite a trove of code examples I have collected over the years. Here is another example of a Formatter used with the java.util.logging.Logger to generate a standard output.

PragmaticFormatter.java


The next question is how do you use it? Easy enough... here is an example for you. The code for the project is located here: pragmatic-logging-formatter

JSF 2.x Tip of the Day: Encoding Text for XML

I have a simple method to encode text to display inside an XML page, or to use inside other XML/JS for example SyntaxHighlighter.

XMLEncode


Creating a BLOB Image Table

I am going through some old code while I wait for my Windows VM to update. I came across some code to create an image BLOB table on MySQL. I thought I would publish it before deleting it from my system. It might be helpful to someone.

CreateImagesTable.java