Render parameter key or value must not be null or values be an empty array.

This error occurs when we store render parameters in Java Array. Generally, we store all the render parameters in separate Java String object which are working perfectly fine.

I tried this once with Java Array when I have more than 10 render parameters. I received the same error mentioned in subject line of post. The complete line of error is,

java.lang.IllegalArgumentException: Render parameter key or value must not be null or values be an empty array.

This issue occurred due to internal implementation of this method. It returns the value of a request parameter as a String, or null if the parameter does not exist.

If I try the line below for receiving render parameter, we will receive the same error.

String[] arrUserDetails1 = new String[2];
arrUserDetails[0] = request.getParameter("txtUserName");

If I try the line below for recieving render parameter, This will be working fine.

String[] arrUserDetails1 = new String[2];
String userName = request.getParameter("txtUserName");
arrUserDetails[0] = userName;

The conclusion is, render parameters can not store in to empty java array.

Portlet namespace

First, I would like to highlight some point for those who are new in portal and they are not aware of namespaces.

Basically 'namespace' term is used in portal terminology and this term comes from portal itself. Let me clear this point in easy way. Suppose, we have a large amount of data in database and we want to fetch a particular data from database. So what we will do? We would need a unique id for identifying the data which you want to fetch.

In a same way, portal manages all portlets with a unique id that called 'namespace'. I think, I am able to describe this think in simpler way.

Now the question is, if namespace is unique for each portlet so what happen if we use different instance of same portlet on a same page. The answer is, portal creates different namespaces for different instances.

Ok, this is with a single user. What happens if we use the same instances (2 instances on same page) with other user. This is a tricky question if you do not know. Here the answer is, namespaces are similar for other user.

Conclusion

In portal server, namespaces are managed according to portlet instances. Namespaces are changed according to instances of portlet, these are not changed with change user (i.e. other users).

Portlet request dispatcher inclusion error MXParserFactory not found

I would like to share one more experience which I have had with Web services API used with portal environment (using portlets). In this, I prepared a Java Client (Stub) using Axis2 1.5 tool which contains Java classes and XML files. While compiling this code, I faced some issues. At first, I found an error which is,



4/21/11 20:08:58:000 IST] 00000052 PortletReques E com.ibm.ws.portletcontainer.

core.impl.PortletRequestDispatcherImpl internal include EJPPC0172E: Error occurred during portlet request dispatcher inclusion
                                 java.lang.NoClassDefFoundError: javax.xml.stream.XMLStreamException
    at java.lang.J9VMInternals.verifyImpl(Native Method)
    at java.lang.J9VMInternals.verify(J9VMInternals.java:68)
    at java.lang.J9VMInternals.initialize(J9VMInternals.java:129)
    at com.yash.ews.connection.EWSBaseConnector.(EWSBaseConnector.java:113)

The resolution of the error is to set JSR173_API.jar in lib directory of your application. Your compile time issues will get resolved. Once you run this application, you will get another error which is,

[4/21/11 20:12:58:232 IST] 00000055 PortletReques E com.ibm.ws.portletcontainer.

core.impl.PortletRequestDispatcherImpl internal include EJPPC0172E: Error occurred during portlet request dispatcher inclusion
                                 javax.xml.stream.FactoryConfigurationError: Provider com.bea.xml.stream.MXParserFactory not found
    at javax.xml.stream.FactoryFinder.newInstance(FactoryFinder.java:72)
    at javax.xml.stream.FactoryFinder.find(FactoryFinder.java:176)
    at javax.xml.stream.FactoryFinder.find(FactoryFinder.java:92)
    at javax.xml.stream.XMLInputFactory.newInstance(XMLInputFactory.java:136)
    at org.apache.axiom.om.util.StAXUtils$7.run(StAXUtils.java:505)
    at java.security.AccessController.doPrivileged(AccessController.java:197)
    at org.apache.axiom.om.util.StAXUtils.newXMLInputFactory(StAXUtils.java:495)
    at org.apache.axiom.om.util.StAXUtils.getXMLInputFactory_perClassLoader(StAXUtils.java:566)
    at org.apache.axiom.om.util.StAXUtils.getXMLInputFactory(StAXUtils.java:172)
    at org.apache.axiom.om.util.StAXUtils.getXMLInputFactory(StAXUtils.java:137)
    at org.apache.axiom.om.util.StAXUtils.createXMLStreamReader(StAXUtils.java:224)
    at org.apache.axiom.om.util.StAXUtils.createXMLStreamReader(StAXUtils.java:218)
    at org.apache.axis2.util.XMLUtils.toOM(XMLUtils.java:596)
    at org.apache.axis2.util.XMLUtils.toOM(XMLUtils.java:581)

This error is related with XML parser. In java, we are aware of SAX parser however there is another parser StAX which is now used in latest programs and has the option of pausing and resuming the parsing process. Also works in similar streaming fashion. You can find this parser in sjsxp.jar which resolve this issue.

You can get more knowledge for the same in StAX.