How to setup Intellij IDE war exploded artifact with multiple CDI dependent projects

I have a large Java project with many sub modules, and they have simple top down dependencies like this:

ProjectX
+-ModuleLibA
+-ModuleLibB
+-ModuleCdiLibC
+-ModuleCdiLibC2
+-ModuleLibD
+-ModuleCdiLibE
+-ModuleCdiLibE2
+-ModuleCdiLibE3
+-ModuleLibF
+-ModuleLibG
+-ModuleWebAppX

Each of these modules has their own third party dependency jars. When I say top down, it simply means Module from bottom have all the one above sub module and its third party dependencies as well. The project is large, and with many files, but the structure is straight forward. It does have large amount of third party jars though. At the end, the webapp would have over 100 jars packaged in WEB-INF/lib folder!

When you create this project structure in IntelliJ IDE (no I do not have the luxury of using Maven in this case), all the third party dependencies are nicely exported and managed from one Module to another as I create my Project with existing source and third parties jars. I do not need to re-define any redudant jars libraries definitions between Modules. When it come to define ModuleWebAppX at the end, all I have to do is to add ModuleLibG as a project dependency, and it brings all the other "transitives" dependent jars in! This is all done by IntelliJ IDE, which is very nice!

IntelliJ IDE also let you setup Artifacts from your project to prepare for package and deployment that can run inside your IDE servers. By default, any web application will have an option to create a war:exploded artifact definition, and the IDE will automatically copy and update your project build artifacts into this output folder, and it can be deploy/redeploy into any EE server as exploded mode nicely.

All these work really smoothly, until there is one problem that hit hard! The way IntelliJ IDE package default war:exploded artifact is that it will copy all the .class files generated from each Modules into a single "out/artifact/ProjectX_war_exploded" output folder. This works most of the time when our Java package and classes are unique, but not so with resource files that's not unique! My project uses several dependent CDI based modules. As you might know, each CDI module suppose to define their own, one and single location at META-INF/beans.xml to enable it and to customize CDI behavior. But becuase IntelliJ IDE flatten everything into a single output directory, I've lost the unique beans.xml file per each Module!

This problem is hard to troubleshoot since it doesn't produce any error at first, nor it stops the web app from running. It just not able to load certain CDI beans that you have customized in the beans.xml!!!

To resolve this, I have to make the IntelliJIDE artifact dependent modules to generate it's JAR instead of all copy into a single output. But we still want it to auto copy generated build files into the JAR archive automatically when we make a change. Lukcly IntelliJ has this feature. This is how I do it:

1. Open your project settings then select Artifacts on left.
2. Choose your war:exploded artifacts and look to your right.
3. Under OutputLayout tab, expand WEB-INF/lib, then right clik and "Create Archive" > Enter your moduleX name.jar.
4. Right click this newly created archive moduleX.jar name, then "Add Copy of" > "Module Output" and select one of your dependent module.
5. Repeat for each of the CDI based Modules!

I wish there is a easier way to do across all Modules for this, but at least this manual solution works!

How to package skinny war with plain maven-war-plugin

If you are not using maven EAR plugin, then you can also use plain maven-war-plugin to package a Skinny war package like this:
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>2.6</version>
                <configuration>
                    <!--
                    We want to package skinny war to avoid third party jars -->
                    <packagingExcludes>
                        WEB-INF/lib/*.jar
                    </packagingExcludes>
                    <archiveClasses>true</archiveClasses>
                </configuration>
            </plugin>

However, if you ran into the problem I described in last post, then you want a Skinny war, but still want to include the jar it produced from your own web project. In this case, you can try this:


            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>2.6</version>
                <configuration>
                    <!--
                    We want to package skinny war to avoid third party jars, but we do want the classes from
                    this project to be included -->
                    <packagingExcludes>
                        %regex[WEB-INF/lib/(?!my-project-artifact-name-.*\.jar).*\.jar]
                    </packagingExcludes>
                    <archiveClasses>true</archiveClasses>
                </configuration>
            </plugin>

The plugin would accept a REGEX expression for exclusion as well, but getting it to work might take you a few tries! If you need more than this, try this online Java REGEX testing tool: http://www.regexplanet.com/advanced/java/index.html

Getting version string from a Maven based web application

When you package a maven project, it will automatically generate a pom.properties file inside that will contains the version, artifactId and groupId information. These are handy to have and to display for your web application at runtime. One can use a method like following to retrive it.

public class Application {
     private String version;

     public String getVersion() {
        if (version == null) {
            String res = "META-INF/maven/myapp/pom.properties";
            URL url = Thread.currentThread().getContextClassLoader().getResource(res);
            if (url == null) {
                version = "SNAPSHOT." + Utils.timestamp();
            } else {
                Properties props = Utils.loadProperties(res);
                version = props.getProperty("version");
            }
        }
        return version;
    }
}

Sounds good? Not too fast! Turns out you have to do little more trick to have this working properly for deployment. By default the maven war plugin will package your classes files into the WEB-INF/classes, but the pom.properties are in META-INF at the same level, and not in WEB-INF/classes/META-INF! This resulted the above code not finding your resource pom.properties from classpath!

To fix this, you need to add the following to your pom.xml file:

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>2.6</version>
                <configuration>
                    <archiveClasses>true</archiveClasses>
                </configuration>
            </plugin>

This will tell maven to jar up your classes along with the pom.properties in a separate file, then place it in WEB-INF/lib folder instead of using the unpacked WEB-INF/classes version. This forces the pom.properties to be properly added and read by our getVersion() method.

NetBeans projects dependencies

With all the coolness of NetBeans, one of the feature I feel it's lacking is managing project denpendencies natively in IDE. Currently the only way to get this feature is if your Java projects are Maven based. If you have Ant based projects, then you would have to manually do this with hacks, and for each projects/sub-projects! Take a look at these two links:

http://stackoverflow.com/questions/13669237/netbeans-java-how-to-add-as-library-another-project-with-dependencies

https://netbeans.org/bugzilla/show_bug.cgi?id=47507

With today's EE projects, you likely going to have many sub projects, and manually handling their dependencies on each project within the IDE is not fun, and hard to maintain. Basically the time you used to setup third party libraries on a ProjectA is wasted and will not automatically exported to ProjectB if it depends on it within the IDE. NetBeans seems to only use project dependencies as way to link related projects together, and to export the main proejct jar/classes, not its third party libraries. A transitive dependencies management feature is needed. Some of user's responses on this topic seem to simply suggest one should go with Maven. Well, as much as I like to use Maven myself, I don't think it acceptable to tell users to convert their existing projects from Ant to Maven just to use an IDE. The IDE tool should be more transparent in this regard.

It's worth to note that both Eclipse and Intellij have this feature and it's productive. I wish NetBeans can improve on this and provide a solution in near future.

How to create multiple workspaces with NetBeans

Examples

• Windows:
  netbeans.exe --userdir C:\MyOtherUserdir --cachedir "%HOME%\Locale Settings\Application Data\NetBeans\7.1\cache"

• Unix:
  ./netbeans --userdir ~/my-other-userdir

• Mac OS:
  /Applications/NetBeans.app/Contents/MacOS/executable --userdir ~/my-other-userdir

Ref: http://wiki.netbeans.org/FaqAlternateUserdir

EE JSP: Generating Dynamic Content with JSTL Tag Libraries

Besides writing your own Custom Tags in JSP, you will find that Java EE actually provides a set of Java Standard Tag Library (JSTL) ready for you to use. These built-in tags include repeating (for-loop) tags, if condition tags, variable declaration and output tags etc. The Libraries also come with many utility functions and international message formatting tags. Here is an example how it looks like.

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="x" uri="http://java.sun.com/jsp/jstl/xml" %>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<%@ taglib prefix="sql" uri="http://java.sun.com/jsp/jstl/sql" %>
<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>
<!DOCTYPE html>
<html>
    <body>
        <h1>JSTL Examples</h1>
        <h2>List of Application Context: ${applicationScope}</h2>
        <table>
            <c:forEach var="entry" items="${applicationScope}">
            <tr>
                <td>${entry.key}</td>
                <td>
                    <c:out value="${entry.value}"/>
                </td>
            </tr>
            </c:forEach>
        </table>
       
        <h2>List of Session Context: ${sessionScope}</h2>
        <table>
            <c:forEach var="entry" items="${sessionScope}">
            <tr>
                <td>${entry.key}</td>
                <td>
                    <c:out value="${entry.value}"/>
                </td>
            </tr>
            </c:forEach>
        </table>
       
        <h2>List of Page Context: ${pageScope}</h2>
        <table>
            <c:forEach var="entry" items="${pageScope}">
            <tr>
                <td>${entry.key}</td>
                <td>
                    <c:out value="${entry.value}"/>
                </td>
            </tr>
            </c:forEach>
        </table>
       
        <h2>List of Request Context: ${requestSope}</h2>
        <table>
            <c:forEach var="entry" items="${requestSope}">
            <tr>
                <td>${entry.key}</td>
                <td>
                    <c:out value="${entry.value}"/>
                </td>
            </tr>
            </c:forEach>
        </table>
       
        <h2>List of Query Parameters: ${param}</h2>
        <table>
            <c:forEach var="entry" items="${param}">
            <tr>
                <td>${entry.key}</td>
                <td>
                    <c:out value="${entry.value}"/>
                </td>
            </tr>
            </c:forEach>
        </table>
       
        <h2>List of Header Parameters: ${header}</h2>
        <table>
            <c:forEach var="entry" items="${header}">
            <tr>
                <td>${entry.key}</td>
                <td>
                    <c:out value="${entry.value}"/>
                </td>
            </tr>
            </c:forEach>
        </table>       
       
        <h2>List of Cookies: ${cookie}</h2>
        <table>
            <c:forEach var="entry" items="${cookie}">
            <tr>
                <td>${entry.key}</td>
                <td>
                    <c:out value="${entry.value}"/>
                </td>
            </tr>
            </c:forEach>
        </table>
    </body>
</html>

I used the core tag here to display map entries of few implicit variables. You may explore more on those tags declarations I have define on top of the example page from the Spec. These code are from the jsp-example from GitHub.

GLASSFISH NOTE: When deploying above example in GlassFish 3/4, you will run into a NullPointerException and causing the page resulted in error. It turns out that GF server added a internal variable named com.sun.jsp.taglibraryCache  in ServletContext (Application Scope) that throws NPE when its toString() is called! To workaround this, I created jstl-example2.jsp that wraps the ${entry.value} into a custom JSTL function so that it guarantees to return an output without throwing exception. So the lesson learned is that you should always return a String and not throw Exception when overriding toString() of a Java class. It's just bad practice.

EE JSP: Generating Dynamic Content with Custom Tag Libraries

When developing View layer in a web application, you want to try not to duplicate content in JSP files as much as possible. The JSP spec API allows you to reduce this duplication by using tag libraries. A custom JSP tag is a user defined xml tag element that you can insert into JSP file to replace with some dynamic content.

Here is an simple jsp-example using a custom JSP tag that insert a server time stamp value:

<%@ taglib prefix="myapp" tagdir="/WEB-INF/myappTags" %>
<!DOCTYPE html>
<html>
    <body>
        <h1>Hello World!</h1>
        <p>Page served on <myapp:serverTime pattern="yyyy-MM-dd HH:mm:ss"/></p>
    </body>
</html>

JSP tags can also allow you to pass in parameters as attributes of the tag. In the example above <myapp:serverTime> tag uses a custom pattern attribute to control how the date string should be formatted.

JSP tags can also be nested with sub tags, or any HTML content elements. The nested JSP tags can provide a way for you to conditionally render the enclosed content. Using tag to render conditional content is more verbose due to XML structure, but it eliminates the use of direct Scriptlet code in JSP.

There are two ways you can create custom JSP tags. The first method is to implement the tag using pure Java code and then register it with a XML taglib definition file. I will skip this method for now and show you another easier way.

The second method uses "Tag Files" that are similar to JSP pages to construct a tag (remember that JSP tag is nothing more than just a placeholder for some content!). I am going to show you how the second method is done for above example. First create a serverTime.tag file under your src/main/webapp/WEB-INF/tags/myapp project folder.

<%@ attribute name="pattern" required="true" %>
<%@ tag import="java.util.Date, java.text.SimpleDateFormat" %>
<%= new SimpleDateFormat(pattern).format(new Date()) %>

The Tag File implementation depends on simple convention of file naming and location. Note that the src/main/webapp/WEB-INF/tags directory is a required path. Inside this folder,  you may create any sub folder you want to organize the tag files. In our case, it's the myapp directory. A Tag File can be just like any JSP file you would normally create, except the tag directives are little different. You can see the JSP spec for a complete list of them. Whatever you output from the Tag File, it will be inserted and replaced the caller of the tag. Notice how I use the pattern attribute parameter to allow user change the date pattern, and it's available in the Tag File inside the Scriptlet Java code as variable.

Since you can write Tag Files just as you would with JSP, I will again caution the excessive use of Java code Scriptlet even inside Tag Files. If you must call Java code, try to wrap the code and replace by single line call, or write the Tag implementation with pure Java code; especially if you have very complex business logic involve. This would bring debugging much easier on your code and to maintain.

JSP tags provide a powerful way to construct your View layer in the web application. It helps you reuse code or content, and generating a specific piece of response.