EventBusFactory JSF1073

Question

I'm trying to implement logic in JSF that accepts parameters and then updates some output on the xhtml page. The following is all borrowed from the primefaces pushdata showcase

XHTML:

<f:view>
                <h:form id="form">
                    <f:metadata>
                        <f:viewParam name="data" value="#{viewParamPush.data}" />
                        <f:event type="preRenderView" listener="#{viewParamPush.prerender}" />
                    </f:metadata>

                    <h:outputText id="out" value="#{viewParamPush.data}" style="font-size:16px" />

                    <p:socket onMessage="handleMessage" channel="/QR" />

                    <script type="text/javascript">
                        function handleMessage(data) {
                            $('#out').text(data);
                        }
                    </script>
                </h:form>
            </f:view>

ViewParamPush:

    ManagedBean
    @RequestScoped
    public class ViewParamPush implements Serializable{

        private String data;

        public String getData() {
            return data;
        }

        public void setData(String data) {
            util.sysprint("setData " + data, true);
            this.data = data;
        }

        public void prerender() {
            util.sysprint("prerender", true);
            EventBus eventBus = EventBusFactory.getDefault().eventBus();
            util.sysprint("prerender2", true);
            even

tBus.publish("/QR", data);
        util.sysprint("prerender3", true);
    }
}

ViewParamResource:

@PushEndpoint("/QR")
public class ViewParamResource {

    @OnMessage(encoders = {JSONEncoder.class})
    public String onMessage(String data) {
         util.sysprint("ViewParamResource onMessage", true);
        return StringEscapeUtils.escapeHtml4(data);
    }
}

I get the following exception when eventBus.publish("/QR", data); is called. I understand what a null pointer is however I don't understand why publish("/QR", data); in this case is causing one. Is there something wrong with my syntax?

FATAL:   JSF1073: javax.el.ELException caught during processing of RENDER_RESPONSE 6 : UIComponent-ClientId=, Message=/QR.xhtml @21,95 listener="#{viewParamPush.prerender}": java.lang.NullPointerException
FATAL:   /QR.xhtml @21,95 listener="#{viewParamPush.prerender}": java.lang.NullPointerException
javax.el.ELException: /QR.xhtml @21,95 listener="#{viewParamPush.prerender}": java.lang.NullPointerException

I added *.xhtml to the url patterns in order to be able to call the script QR.xhtml?data=some data.. I assume that required in order to pass parameters to the script although I wonder if that affects the publish method

<servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>/faces/*</url-pattern>
        **<url-pattern>*.xhtml</url-pattern>**
    </servlet-mapping>

Dependencies:

 <dependencies>
        <dependency>
            <groupId>org.primefaces</groupId>
            <artifactId>primefaces</artifactId>
            <version>5.3</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.extras</groupId>
            <artifactId>appserv-rt</artifactId>
            <version>3.1.1</version>
        </dependency>
        <!-- http://mvnrepository.com/artifact/org.atmosphere/atmosphere-runtime -->
        <dependency>
            <groupId>org.atmosphere</groupId>
            <artifactId>atmosphere-runtime</artifactId>
            <version>2.4.4</version>
        </dependency>
        <dependency>
            <groupId>javax</groupId>
            <artifactId>javaee-web-api</artifactId>
            <version>7.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>com.marklogic</groupId>
            <artifactId>java-client-api</artifactId>
            <version>3.0.1</version>
        </dependency>
        <dependency>  
            <groupId>org.primefaces.themes</groupId>  
            <artifactId>cupertino</artifactId>  
            <version>1.0.10</version>  
        </dependency>
        <dependency>
            <groupId>org.primefaces.extensions</groupId>
            <artifactId>primefaces-extensions</artifactId>
            <version>4.0.0</version>
        </dependency>
        <dependency>
            <groupId>com.helger</groupId>
            <artifactId>ph-schematron</artifactId>
            <version>3.0.1</version>
        </dependency>
        <dependency>
            <groupId>com.lowagie</groupId>
            <artifactId>itext</artifactId>
            <version>2.1.7</version>
            <exclusions>
                <exclusion>
                    <groupId>bouncycastle</groupId>
                    <artifactId>bcprov-jdk14</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>bouncycastle</groupId>
                    <artifactId>bcmail-jdk14</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>org.bouncycastle</groupId>
                    <artifactId>bctsp-jdk14</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>3.9</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>3.9</version>
        </dependency>
        <dependency>
            <groupId>net.sf.barcode4j</groupId>
            <artifactId>barcode4j-light</artifactId>
            <version>2.1</version>
        </dependency>
        <dependency>
            <groupId>net.glxn</groupId>
            <artifactId>qrgen</artifactId>  <!-- QR code support -->
            <version>1.4</version>
        </dependency>
    </dependencies>

Possible duplicate of [What is a NullPointerException, and how do I fix it?](http://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it) — Kukeltje, Jun 01 '16 at 12:57
I understand what a null pointer is however I don't understand why publish("/QR", data); in this case is causing one. Is there something wrong with my syntax? — conteh, Jun 01 '16 at 13:43
There is an NPE in your code (`#{viewParamPush.prerender}`)... check that, debug, etc.... that is what the 'duplicate' is all about. Then maybe create a new question asking WHY something is null... — Kukeltje, Jun 01 '16 at 14:08
That much is very very clear. The NPE occurs when eventBus.publish("/QR", data) is called as I mentioned which is within the prerender method. As far as I know that is referring to the channel="/QR" in the p:socket. The problem is I don't understand why it's generating a NPE in this instance. — conteh, Jun 01 '16 at 16:04
That much is clear to you, at least you think it is... A stacktrace tells you **where** it happens. We are not clairvoyant. Sharing the stacktrace AND indicating which line in the bean a linenumber is, is of utmost importance. Add a try catch and find out. That is what the duplicat is about. This post/question is therefor still lacking info and therefor a duplicate..Good luck — Kukeltje, Jun 01 '16 at 18:01
If you'd actually investigated the npe, your question would have been identical to http://stackoverflow.com/questions/31985116/nullpointerexception-when-using-primepush. See the stacktrace there? And hence the better more explicit question. — Kukeltje, Jun 01 '16 at 18:07
That's a bit condescending to suggest that I didn't investigate. More accurate would be that I'm new to JSF and was searching with the wrong parameters. — conteh, Jun 01 '16 at 23:02

score 4 · Accepted Answer · answered Jun 01 '16 at 16:09

I've previously encountered this error. The reason for this failure is due to the Atmosphere version.

Then use it as below :

pom.xml

     <dependency>
        <groupId>org.atmosphere</groupId>
        <artifactId>atmosphere-runtime</artifactId>
        <version>2.4.3</version>
    </dependency>
    <dependency>
        <groupId>org.atmosphere</groupId>
        <artifactId>atmosphere-runtime-native</artifactId>
        <version>2.4.3</version>
    </dependency>

web.xml

<servlet>
    <servlet-name>Push Servlet</servlet-name>
    <servlet-class>org.primefaces.push.PushServlet</servlet-class>
    <init-param>
        <param-name>org.atmosphere.cpr.broadcasterCacheClass</param-name>
        <param-value>org.atmosphere.cache.UUIDBroadcasterCache</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
    <async-supported>true</async-supported>
</servlet>
<servlet-mapping> 
    <servlet-name>Push Servlet</servlet-name> 
    <url-pattern>/primepush/*</url-pattern> 
</servlet-mapping>

This way you can try. It works this for me.

So this question is actuallyba duplicate of http://stackoverflow.com/questions/31985116/nullpointerexception-when-using-primepush. Please next time mark it as such. It keeps stackoverflow clean. Tnx — Kukeltje, Jun 01 '16 at 18:09
While I see the similarity, that one did not fully answer my question. The configuration that Kurt put forward differs and solved my problem. I would disagree that having this question and solution causes any harm. it does certainly build upon that other question with a more up to date solution. Please though have someone else weigh in on it. Best Regards — conteh, Jun 01 '16 at 23:04

EventBusFactory JSF1073

XHTML:

ViewParamPush:

ViewParamResource:

Dependencies:

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