SAP bug

[Former Member]

Hi,

I'm experiencing a Nullpointerexception when I click on a button in my Web Dynpro app.

For testing purposes I'm throwing a RuntimeException in the button action handler,

but that RuntimeException is never thrown, so the problem is happening before the action handler is called.

When inspecting the stacktrace I would say this is a SAP-side bug.

Can somebody confirm this?

Thanks,

Jeroen

Web Dynpro Runtime
Vendor: SAP, Build ID: 6.4015.00.0000.20060810110535.0000 (release=NW04_15_REL, buildtime=2006-08-10:09:21:36[UTC], changelist=20523, host=PWDFM087)
J2EE Engine	6.40 patchlevel 100627.313
Java VM	Classic VM, version:1.4.2, vendor: IBM Corporation

java.lang.NullPointerException
	at com.sap.tc.webdynpro.clientimpl.html.client.HtmlClient.handleUIElementEvent(HtmlClient.java(Compiled Code))
	at com.sap.tc.webdynpro.clientimpl.html.client.HtmlClient.updateEventQueue(HtmlClient.java(Compiled Code))
	at com.sap.tc.webdynpro.clientserver.cal.AbstractClient.initEvents(AbstractClient.java:131)
	at com.sap.tc.webdynpro.clientserver.cal.AbstractClient.prepareTasks(AbstractClient.java:99)
	at com.sap.tc.webdynpro.clientserver.cal.ClientManager.doProcessing(ClientManager.java:248)
	at com.sap.tc.webdynpro.serverimpl.defaultimpl.DispatcherServlet.doWebDynproProcessing(DispatcherServlet.java:154)
	at com.sap.tc.webdynpro.serverimpl.defaultimpl.DispatcherServlet.doContent(DispatcherServlet.java:116)
	at com.sap.tc.webdynpro.serverimpl.defaultimpl.DispatcherServlet.doPost(DispatcherServlet.java:55)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java(Compiled Code))
	at com.sap.engine.services.servlets_jsp.server.HttpHandlerImpl.runServlet(HttpHandlerImpl.java(Compiled Code))
	at com.sap.engine.services.servlets_jsp.server.HttpHandlerImpl.handleRequest(HttpHandlerImpl.java(Compiled Code))
	at com.sap.engine.services.httpserver.server.RequestAnalizer.startServlet(RequestAnalizer.java(Inlined Compiled Code))
	at com.sap.engine.services.httpserver.server.RequestAnalizer.startServlet(RequestAnalizer.java(Compiled Code))
	at com.sap.engine.services.httpserver.server.RequestAnalizer.invokeWebContainer(RequestAnalizer.java(Compiled Code))
	at com.sap.engine.services.httpserver.server.RequestAnalizer.handle(RequestAnalizer.java(Compiled Code))
	at com.sap.engine.services.httpserver.server.Client.handle(Client.java(Inlined Compiled Code))
	at com.sap.engine.services.httpserver.server.Processor.request(Processor.java(Compiled Code))
	at com.sap.engine.core.service630.context.cluster.session.ApplicationSessionMessageListener.process(ApplicationSessionMessageListener.java(Compiled Code))
	at com.sap.engine.core.cluster.impl6.session.MessageRunner.run(MessageRunner.java(Compiled Code))
	at com.sap.engine.core.thread.impl3.ActionObject.run(ActionObject.java(Compiled Code))
	at java.security.AccessController.doPrivileged1(Native Method)
	at java.security.AccessController.doPrivileged(AccessController.java(Compiled Code))
	at com.sap.engine.core.thread.impl3.SingleThread.execute(SingleThread.java(Compiled Code))
	at com.sap.engine.core.thread.impl3.SingleThread.run(SingleThread.java(Compiled Code))

[Former Member]

After decompiling the SAP binaries & some testing I found out that the problem was initially caused by:

someIWDButton.mappingOfOnAction().addParameter(name, value);

Apparently the <value> parameter (type String) may NOT contain '.'

Second condition to get the NPE is a call to

((IWDTransparentContainer)view.getRootElement()).destroyAllChildren()

This was hard to find out, I'm wondering why this is not mentioned in the API documentation (or am I looking over it?).

Jeroen

[Former Member]

Sounds strange.

I remember having seen this error if a UI element has a "." (dot) in the ID. This is not checked (in earlier version) if you create the UI element via API.

So please check the IDs of all programmatically created UI elements.

I don't think it has to do with a dot inside the value of an addParameter() statement.

And there also should never be a NPE in the statement ((IWDUIElementContainer)view.getRootElement()).destroyAllChildren(), because the root element is created automatically and cannot be removed afterwards.

Armin

[Former Member]

Hi,

Concerning the NPE: as you can see in the stacktrace it is not thrown when ((IWDUIElementContainer)view.getRootElement()).destroyAllChildren() is executed, but in HtmlClient.handleUIElementEvent (after clicking on a IWDButton).

What I found out is when the value of a mappingOfOnAction parameter contains a dot, only the part BEFORE the dot is passed to the action handler.

I rechecked my code and indeed, as you said, I'm also using the value of the mappingOfOnAction parameter as the ID of the corresponding button, so that probably caused the NPE

Jeroen

[Former Member]

Believe me, the dot in the UI element ID is the root of the evil, the rest are consequences.

Armin

[Former Member]

Open OSS message (BC-WD-CLT-HTML).

Armin