NullPointer while trying to obtain headless client

Classic Servoy
1

We’re getting a NullPointerException when trying to get a handle on the headless client from a servlet deployed under Servoy’s Tomcat instance. Anyone have a suggestion?

java.lang.NullPointerException
at com.servoy.j2db.ClientState.aD(Unknown Source)
at com.servoy.j2db.server.headlessclient.a.(Unknown
Source)
at
com.servoy.j2db.server.headlessclient.HeadlessClientFactory.createSessionBean(Unknown Source)
at iwp.shc.four51.XmlPostHandler.doPost(XmlPostHandler.java:59)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:243)
at
org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:201)
at
org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at
org.apache.catalina.valves.CertificatesValve.invoke(CertificatesValve.java:246)
at
org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at
org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2344)
at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
at
org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at
org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170)
at
org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:170)
at
org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
at
org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:462)
at
org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:163)
at
org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at
org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor.java:1011)
at
org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.java:1106)
at java.lang.Thread.run(Thread.java:595)

The call is:

ISessionBean servoy_hc =
HeadlessClientFactory.createSessionBean(null, “”, “”,
“”, new Object{ “Headless” });

2

What joy it is to work with a closed and unsupported platform.

3

Hi notsew,

If you need immediate support you better mail directly to support@servoy.com with an example that shows the error.
The people of Servoy can’t track every message send on this forum.

As for your NullPointer error.

It’s a bit of a guess without seeing all the rest of the jsp code but let me take a shot at it.

ISessionBean servoy_hc =
HeadlessClientFactory.createSessionBean(null, “”, “”,
“”, new Object{ “Headless” });

When I look at my (working) jsp code it seems you miss a few steps:

	ISessionBean servoy_hc = (ISessionBean)application.getAttribute("servoy"); 
	if (servoy_hc == null) 
	{ 
		servoy_hc = HeadlessClientFactory.createSessionBean(request,"mySolutionName"); 
		application.setAttribute("servoy",servoy_hc); 
	}
	boolean ok = servoy_hc.setMainForm("mySolutionFormName");

So try this approach and see if that works for you.

4

Hi Robert,

Thanks for your response. Thing is, this call works from within a JSP, but not from a Servlet. Any thoughts on what the relevant difference might be? Could it matter that the latter is deployed in a .war archive while the former is sitting in the ROOT context?

Jason

5

Hi Jason,

I must admit my knowledge of servlets is very limited but let me try to work with you on this.
When I look at the headless-client API information I never see a null passed as a parameter of the HeadlessClientFactory.createSessionBean method. In fact it refers to ‘javax.servlet.ServletReques’ if that tells you something.
So there may lie your problem.

Hope this helps you further.

6

Robert –

There’s another thread in this forum (http://forum.servoy.com/viewtopic.php?t=6417) in which it was discussed that passing null for that request arg is ok.

Thanks,
Jason

7

Hi Jason,

Lets entertain the thought that it is required. Does it work then for you?

8

Na, that’s what we tried first, per the examples. We’ll take it up with support. Thanks for your help.